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norealtalent
08-04-2005, 04:39 PM
Finally got my little grubbies on a REAL 435BEhttp://audioheritage.org/vbulletin/images/smilies/applaud.gif . Heres my observations between the two;
BOTH have ferro fluid.http://audioheritage.org/vbulletin/images/smilies/blink.gif
Both appear as identical drivers in EVERY way.
Diaphragms do interchange and appear identical in every regard excepting that: the 435BE has a black coating on the front of the diaphragm and is bare on the back:
the 2435HPL is a bare diaphragm on both sides.
http://audioheritage.org/vbulletin/images/smilies/bouncy.gif http://audioheritage.org/vbulletin/images/smilies/bouncy.gif http://audioheritage.org/vbulletin/images/smilies/bouncy.gif

speakerdave
08-04-2005, 05:06 PM
A dusting of aquaplas I 'spects. Don said in one of his posts that they had considered this but indicated they had abandoned it, as I recall.

David

Zilch
08-04-2005, 05:22 PM
:hmm: I recall the 435Be I examined did not have ferrofluid.

However, in frequency response tests at least, any performance differences were indiscernable:

http://audioheritage.org/vbulletin/showthread.php?t=6050&page=5&p=63329

stevem
08-04-2005, 05:53 PM
I'm really glad to hear all this 'cause I'm expecting my 2435H drivers tomorrow!:)

Guido
08-05-2005, 03:27 AM
However, in frequency response tests at least, any performance differences were indiscernable:

I think the aquaplas coating is highly audible and should result in a smoother sound.
Anyway I do only guess here as I don't have 2435 and 435 drivers. :o:

Zilch
08-05-2005, 10:11 AM
Keep to the path, Guido:

2431H has better extension.... :p

Mr. Widget
08-05-2005, 10:27 AM
I think the aquaplas coating is highly audible and should result in a smoother sound.
Anyway I do only guess here as I don't have 2435 and 435 drivers. :o:

I would tend to agree with you. While we had examples of both drivers here and their measured frequency response plots were very similar, that doesn't mean that while listening to music they would sound exactly the same. I really don't think JBL is spraying the aquaplas for their ego's. The same goes for the larger back cap. While our measurements didn't show a significant difference at lower frequencies, that doesn't mean that they will subjectively perform the same way when used down to 800Hz. Again, I think the back cap is there for a reason. The heat sink ribs are there for a reason too... to look cool and sell more speakers.:D

Mr. Talent,

As for both drivers using ferofluids? I was under the impression that the 435Be is not supposed to have ferrofluids in the gap. I assume you bought the 435Bes on the used market? Perhaps the fluid was added?

Have you done any listening comparisons? What horns are you/will you be using with them?

Widget

Zilch
08-05-2005, 11:34 AM
If the 435Be does not have ferrofluid, the larger back cap with fins would make sense for heat dissipation.

In the same vein, 2435 (and the rest of them 243x) has Silpad on the face for thermal conductivity to metal horns. Where plastic horns are used, JBL places a heat sink plate between the driver and the horn in some products.

435Be would have the same issues on the S9800 polymer horn. That's not an aluminum block it bolts to on that, is it? No fins there, in any case....

Mr. Widget
08-05-2005, 11:41 AM
If the 435Be does not have ferrofluid, the larger back cap with fins would make sense for heat dissipation.

Let's see... with a basic sensitivity of 108dB/watt and a typical loud domestic listening level of 98dB ... that would require 100 milliwatts... how much heat?;)


Widget

Zilch
08-05-2005, 12:05 PM
... that would require 100 milliwatts... how much heat?;)


WidgetThat depends on the total thermal resistance. Heat sinks don't make much sense for home use, I agree. JBL does it, though, maybe to minimize power compression in high end stuff....

[Don't MAKE me find where I saw that now.... ;) ]

edgewound
08-05-2005, 12:07 PM
Let's not forget that when a compression driver is crossed-over lower, say 800hz, there will be some sacrifice to the high end. That diaphragm can only do so much till it says "no more". The aquaplas coating does a fine job of smoothing out the distortion of the titanium....some would argue that it doesn't "cut through" as well with the damping....when what's really going on is the distortion that's "cutting through" is cut down, and your ear's are thankful for that. Ferrofluid has some of the same effect at dampening the moving mass, albeit at the slight expense of sensitivity...but can help power compression too. What can raise some eyebrows though, is why is there a need to dampen a beryllium diaphragm? The JBL casting technique must not quite reach the results of the TAD vapor deposition process of manufacture. The first resonance of the TAD is 25KHZ!

Zilch
08-05-2005, 12:23 PM
The aquaplas coating does a fine job of smoothing out the distortion of the titanium....some would argue that it doesn't "cut through" as well with the damping....when what's really going on is the distortion that's "cutting through" is cut down, and your ear's are thankful for that.I've had that concern when boosting HF. I can't actually hear that stuff approaching 20 kHz, though I see it on the RTA, and wonder if all I'm doing is boosting the distortion up there. I've come to desiring to see some roll-off starting at the UHF.

It's pretty easy to make a 2425/6/7 titanium sound nasty, for sure.... :p

norealtalent
08-05-2005, 08:02 PM
http://audioheritage.org/vbulletin/images/smilies/biggrin.gif

Mr. Talent,

As for both drivers using ferofluids? I was under the impression that the 435Be is not supposed to have ferrofluids in the gap. I assume you bought the 435Bes on the used market? Perhaps the fluid was added?

Have you done any listening comparisons? What horns are you/will you be using with them?

Widget
Thank you Mr. Widget,
Yes, it came used from a man with 4 K2's. Apparently JBL gave him a new driver under warranty and this one was supposed to be DOA. When I got it, there was no output. I pulled it apart to check for the obvious and found none. (It definitely has ferro fluid and I have every reason to believe it was factory. Maybe JBL tried both? I've heard they no longer coat the diaphragms either. I take everything with a lick of salt.) I expected a burt or open coil. I put it back together and put a signal to it and it appears to play perfectly. I suspect one of the contact pins to diaphragm was not located properly on original installation.
I only have the one with a coated diaphragm but have several 2435's I've been playing with for close to a year now. I have been using them on one of my Smith horn pairs on top of my 4343's. I pulled the 2420 out, made a plate to block off the 2307 and ran the wires out the back to the 2435's. I love them. I know the crossover was not designed for these but the 2420/2307 in them sucks. I've had 7 pairs of 4343's and every pair acted the same way, HARSH. This last pair is the first I have biamped and its better but the factory horns just don't cut it. The 2307 is too short and the L91's are not near as smooth as L94's. The Smoth Horns are awesome.
Now I am test driving a 2 way 4648(I think thats the #) cabs loaded with dual 2220's powered by 300 wpc Perreaux SS bottom. I 've got 2360a's on top and 2435's with the 435be back caps powered by 30 wpc Cary EL34 tube amp. Crossover point is 800hz via Urei 525. I'm playing with preamps. I like the Goldentube Audio SEP1 SE best. The SEP3 is too top heavy. My SS perreaux is very nice but the SEP1 takes the cake.
I tried a pair of completely factory 2420's on the 2360's. They were nicer at 500 hz than 800 hz but the 2345's at 800 hz are nirvana for a 2-way. Soon I will run a pair of those ragged cats eyes off a tube amp for some boost in the ultra highs. The 2435's are there but not like a UHF. I am spoiled by the big 4-ways and know that I am sacrificing some things for others in the 2 way but I've had the most joy of listening in the last 2 weeks than I've had all year! Those 2360A's are AWESOME!!!
Someday I'll A/B 2435's w/ factory back caps and 2435's with 435 backcaps on Smith Horns. More on that later...http://audioheritage.org/vbulletin/images/smilies/biggrin.gif Dave

Lancer
08-06-2005, 03:04 AM
Soon I will run a pair of those ragged cats eyes off a tube amp for some boost in the ultra highs.While the ring radiators are indeed pretty ragged, there are a couple things you can do to improve their overall performance (their ragged response is responsible for their poor decay characteristics). They respond much better connected directly to their own small amp, no passive components between them and the amp whatsoever. The latest word on the old ring radiators is "if you power them directly off a small amplifier (like the small chip amps you can get now) they can sound quite amazing".

Guido
05-24-2006, 06:55 AM
I want to re-fresh this thread as I own two 2435 Drivers now and think about aquaplasing or non-aquaplasing the diaphragms.

This I found at the JBL website
K2-Series:
The result is the 435Be, a 3-inch (76mm) compression driver of pure cast-beryllium, capable of unequalled high-frequency response.
• The 3-inch (76mm), Aquaplas-coated diaphragm – the first of this size for JBL – has pistonic motion beyond 15kHz.
• To reduce weight, the aluminum ribbon wire of the voice coil is attached to a one-piece, molded-edge coil support. Together, the voice coil and diaphragm comprise a moving mass of just 0.044 oz (1.25g).

The question is now
2435 = pure Be dia plus Ferrofluid
435Be = aquaplased coated Be dia w/o Ferrofluid

So the 2435 with Ferrofluid plus added aquaplas might be a bit to much damped.

What do you guys think?

Zilch
05-24-2006, 11:41 AM
In my experience 2435HPL does not "push" gracefully, perhaps because of the inherent stiffness of Be. The literature suggests it operates pistonic up to 17 kHz, anyway, plenty high enough. Aquaplas would add significant mass to that diaphragm, which I wouldn't consider advantageous.

I'm now just letting them roll off above there on 2352 horns, and it's the best sounding two-way combination running here....

norealtalent
05-24-2006, 12:58 PM
[quote=Guido]I want to re-fresh this thread as I own two 2435 Drivers now and think about aquaplasing or non-aquaplasing the diaphragms.

The question is now
2435 = pure Be dia plus Ferrofluid
435Be = aquaplased coated Be dia w/o Ferrofluid

[quote]

The stock 435's that I have seen have ferrofluid from the factory. I have pairs of both and personally compared 2435's to 435be's side by each on Smith horns. The 2435 is wonderful but has what I call a hot spot for frequencies around 10k. They're not harsh, just louder. I imagine it could be eq'ed to satisfaction. The 435be has tamed that hot spot but lost a little of the sizzle on the top end, perfect for a 3 or 4 way. Some day I'll RTA them but just haven't taken the time. There's a whole lot more to consider than these simple words, ie: what's the equipment driving them (tube or ss), what's the crossover system (2, 3 or 4 way) being used, what's the desired spl requirements. Ultimately you need to try it for yourself. At the price of used 2435's on ebay, I'd buy a pair and have them coated just for the fun of it. They are the way of the future...:thmbsup:

4313B
05-24-2006, 01:54 PM
Aquaplas would add significant mass to that diaphragm, which I wouldn't consider advantageous.Wrong! You aren't supposed to dump a gallon of the stuff on diaphragms. The Be diaphragms also benefit from a coat of aquaplas.

Zilch
05-24-2006, 02:03 PM
Wrong! You aren't supposed to dump a gallon of the stuff on diaphragms. The Be diaphragms also benefit from a coat of aquaplas.Fortunately, I don't have any Aquaplas to mess with.... :p

Going to Mylar, are we? ;)

[30 kHz....]

moldyoldy
05-24-2006, 02:44 PM
I'm still curious at what point a UHF (audio terminology) xdcr could also be considered a VLF (radio terminology) directional antenna? I know what the books say, just wonder if anyone has considered the practical implications, or have just chosen to 'wait and see' instead? Audio program material contains both FM and AM components, even though usually brief in duration, and the FCC regulates even fractional-wattage xmtrs.......

Mr. Widget
05-24-2006, 03:18 PM
I'm still curious at what point a UHF (audio terminology) xdcr could also be considered a VLF (radio terminology) directional antenna? I know what the books say, just wonder if anyone has considered the practical implications, or have just chosen to 'wait and see' instead? Audio program material contains both FM and AM components, even though usually brief in duration, and the FCC regulates even fractional-wattage xmtrs.......Here is a chart from NASA. Of course soundwaves are not part of the electromagnetic spectrum... but I think you were joking about the FCC and all that...


Widget

norealtalent
05-24-2006, 03:19 PM
No.

BTW - I had to edit my post so you guys will have to follow suit.


Most people can't afford JBL's latest and greatest because they do not offer it or at least for a reasonable price that most people can afford. The 2435 is OUTSTANDING and can be had for an affordable price on ebay.
435 IS the 375 of the future, WATCH...

Mr. Widget
05-24-2006, 03:21 PM
435 IS the 375 of the future, WATCH...Nice try.... but no, you are wrong... the future hasn't happened yet... the 435 has.:D


Widget

moldyoldy
05-24-2006, 03:42 PM
Here is a chart from NASA. Of course soundwaves are not part of the electromagnetic spectrum...Widget

Then how come there's a band labeled "audio" on the NASA "electromagnetic spectrum"?:dont-know

Yeah, I was joking about the FCC....sort of.

4313B
05-24-2006, 03:45 PM
Going to Mylar, are we? ;)No.

BTW - I had to edit my post so you guys will have to follow suit.

norealtalent
05-25-2006, 07:42 AM
Nice try.... but no, you are wrong... the future hasn't happened yet... the 435 has.:D


Widget

You are so right Widget. Please excuse me, I had a momentary lapse and almost took my own experience seriously. I'll go read the 4345 club thread for a dose of reality and do 10 hail mary's before posting anymore illegitimate thoughts based on actual experience. . . :rotfl: :yes: :rotfl:

Mr. Widget
05-25-2006, 09:09 AM
You are so right Widget. Please excuse me, I had a momentary lapse and almost took my own experience seriously. I'll go read the 4345 club thread for a dose of reality and do 10 hail mary's before posting anymore illegitimate thoughts based on actual experience. . . :rotfl: :yes: :rotfl:You sarcastic so and so... my point is that who knows what the future may bring.... we may see a resurgence in ion tweeters or something...

I know you are in love with the 435Be, and it is indeed a fine piece, but I expect it will be superseded.
The plain and simple reason for the existence of the 045Be and 045Ti is that the 435Be and 435Al (2430 and 2435 are similar) have a substantial response problem around 10 kHz...
So unless you have a crystal ball and aren't telling us something... I wouldn't speculate what the future will be.:D


Widget

norealtalent
05-25-2006, 10:18 AM
You sarcastic so and so... I know you are in love with the 435Be, and it is indeed a fine piece, but I expect it will be superseded.
..:D


Widget

As I said, you are so right... the 375/2440 HAS been superceded and IS still the benchmark JBL driver by which ALL others are compared...

Sarcasm? :dont-know Not from me...;)

Zilch
05-25-2006, 10:21 AM
http://audioheritage.org/vbulletin/showthread.php?p=54744#post54744

It's for sure I could do with a little tweak in that area:

LE15-Thumper
06-02-2006, 07:22 PM
Ok guys, time for a Chill-Pill.

pos
09-15-2007, 07:44 AM
Sorry to refresh this old thread.

I just received two 2435HPL from an ebay auction, and I decieded to open them to check if they diphragms were correct.

As I understood it, if I simply open them but do not remove the diaphragm then I should be safe: no need to clean the gap or refill ferrofluid.

So I just removed the 4 bolts and gently pull the backcap.
I was surpised to see that the diaphragm is fixed to the backcap. I though it would be like the old 1" drivers. What I had was two independant parts.
So I don't understand the second photo in the first post of this thread, because it seems to show a diaphragm fixed to the front of the driver, the backcap being removed?
Have I done something wrong?
I also don't really understand were the ferrofluid is supposed to lay.

Could somebody explain this?

EDIT: and yes, the diaphragms were beryllium :)

Robh3606
09-15-2007, 08:02 AM
That's how those drivers come apart. The screws hold down both the diaphram ring and the cover. There is a pair of spring clips that make the electrical contact between the diaphram contacts and the outside terminals. The tension of the clips is on the high side so when you open the driver it lifts the diaphram out of the gap.

Rob:)

pos
09-15-2007, 08:41 AM
Ok I understand
So I would have to remove the 5th bolt to actually separate the diaphragm from the backcap.

So I guess I have opened it the wrong way, And now I should clean the gap (I haven't seen any ferrofluid by the way) ?
Also, am I supposed to play some tones while tightening the bolts, to make sure the coil is not rubbing in the gap now?

Robh3606
09-15-2007, 10:00 AM
There is no 5th bolt.

You can easilly pry out the diaphram from the back cap.

Don't do a thing if it's operating OK. I would run a sweep to make sure the diaphrams back in place.

You won't see the Ferro Fluid. It's viscous and stays mostly in the gap when the diaphram is removed. The charge is only 100ul so it's not alot by any means. You may see a dark brown line at the bottom edge of the coil. That's the fluid base of the ferro.

This is what you get when you open one up. The diaphram in the cover. You can use the allen wrench to gently pry it out of the cover. When it all goes back together you use the key notch to line up the spring clips so you have the correct orientation with the slots in the gap so the voice coil doesn't bind in the gap. You can see the Ferro Fluid on the bottom of the coil.

Rob:)

Zilch
09-15-2007, 10:33 AM
I posit that the purpose of the ferrofluid (high viscosity, small charge) is to create a seal between the front and rear of the diaphragm, i.e., to perfect the compression chamber between the diaphragm and phase plug.

I've never studied the construction in detail. Does that make sense?

Robh3606
09-15-2007, 11:02 AM
I've never studied the construction in detail. Does that make sense?

Hello Zilch

Yes, but I think it's both for a 2435. Figure heat is a killer and anything to get rid of it is good. That Ferro is high viscosity at room temperature might change when it's hot. Here are some phase plug shots.

Rob:)

Mr. Widget
09-15-2007, 11:47 AM
Hi Rob,

Thanks for that thorough exploration/explanation... I'll add that even though the 435Be back cap is much larger it clamps onto the diaphragm in the same manner.

I have never seen one of these phase plugs sans their protective wire mesh. Is that a damaged phase plug or are the chips along the razor thin edges "normal"?


Widget

Earl K
09-15-2007, 12:12 PM
Zilch,


I posit that the purpose of the ferrofluid (high viscosity, small charge) is to create a seal between the front and rear of the diaphragm, i.e., to perfect the compression chamber between the diaphragm and phase plug.

- You're describing a partially vented voice-coil gap ( exiting into the phase plug ) which has been patented by JBL .

- I thought only JBLs' most recent, 4" diaphragmed drivers used this newer phase plug topology ( just an assumption ) .
- Can you see light in the gap when it's shone into the phase plug on these 3" dia. drivers / or / can you poke a thin wire all the way through ?


http://www.google.com/patents?id=_igkAAAAEBAJ&pg=PP3&img=1&zoom=4&hl=en&q=inassignee:JBL&sig=kOKWClE7JS8Hn47h-uXnr1uJcIY

:)

JBL Patent, as a pdf (http://www.google.com/patents/pdf/Phasing_plug_for_compression_driver.pdf?id=_igkAAA AEBAJ&ie=ISO-8859-1&output=pdf&sig=CKrSkd10XjPyQdbk85mwuZFDCk0)

PATENT # 5117462 at Google (http://www.google.com/patents?zoom=4&num=20&ie=ISO-8859-1&output=html&as_drrb_ap=q&as_minm_ap=1&as_miny_ap=2007&as_maxm_ap=1&as_maxy_ap=2007&as_drrb_is=b&as_minm_is=1&as_miny_is=1990&as_maxm_is=1&as_maxy_is=2007&id=_igkAAAAEBAJ&dq=inassignee%3AJBL&jtp=1)

4313B
09-15-2007, 12:26 PM
Doug mentioned that he used the ferrofluid to get rid of a response anomally. Both he and Greg have said to either use the correct 100 ul or none at all. Some of these 2435's I've been going through were way overloaded with the stuff. Some had the double stick tape creep, perhaps due to heat, which forced me to carefully remove any that was directly touching the diaphragm.

They really are pretty decent little units.

They look absolutely rediculous bolted onto the H4338 or H9800 horns. :p Something like a 2441 might look alot better.

They sound really good though so whatever...

pos
09-15-2007, 01:33 PM
They look absolutely rediculous bolted onto the H4338 or H9800 horns. :p Something like a 2441 might look alot better.
Do you think this is the reason the larger back cap of the 435? :D

Widget, Zilch, have you carried on new tests regarding distortion of the 2435 ?

In your last published tests the 2435 showed very high third harmonic distortion compared to the 435be, and also greater than the 2431 :
http://audioheritage.org/vbulletin/showthread.php?t=6050&page=2#28 (http://audioheritage.csdco.com/vbulletin/showthread.php?t=6050&page=2#28)

Robh3606
09-15-2007, 02:03 PM
Hello Widget

I would have to say they normally would not be chipped. That driver had the screen all disturbed. Here is what I got my 2435's distortion wise. The red is 2nd and the green is 3rd. The last 2 are composites from the pairs Giskard had to Aquaplas. First is 2nd and last is 3rd. I can wait to get them back to see what happens to the distortion levels after the coating.

Rob:)

Robh3606
09-15-2007, 02:18 PM
Hello Earl

From the cross section it's clear that the 2435 voice coil is not vented into phase plug.

Rob:)

pos
09-16-2007, 01:52 AM
Rob, your mesurements are similars to Widget's ones (distortion raised 30db, blue second, green third)

2435 :
http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=8488&stc=1&d=1118990608

435Be :
http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=8487&stc=1&d=1118990460

Widget and Zilch didn't knwo at that time if the difference was due to a bad driver, but your results seems to confirm that it was normal.

So the three last factors that could explain the superiority of the 435Be are :

absence of ferrofluid
aquaplas
large back capI can't wait to see your mesurements when you get back your aquaplased 2435 !

4313B
09-16-2007, 04:04 AM
Do you think this is the reason the larger back cap of the 435? :DWell it was definitely meant to look like a finished Consumer product. That was a design goal. Same for the 045Be.


So the three last factors that could explain the superiority of the 435Be are :

absence of ferrofluid
aquaplas
large back capThe 435Be also uses ferrofluid. The aquaplas reduces spurious resonances of the diaphragm material. I've not directly measured the volume of either back cap so I honestly don't know if one is larger than the other. Early comments from JBL suggested that it was larger to allow a lower crossover point, later comments from JBL were that it wasn't.

I think I have seven more 2435's left to do; Maybe if I have time I will post some graphs. I had planned to early on but frankly, the 2435's I had for the "before" snapshot were sufficiently jacked up to negate any meaningful measurements. These 2435's have also varied wildly with the amount of ferrofluid they've containted.

I think both subwoof and RobH were going to provide various information with respect to distortion analysis. It's good to get data from multiple sources.

Earl K
09-19-2007, 07:44 AM
Hi


They (2435H ) really are pretty decent little units.

I agree, JBL ( Pro ) really hit a home run when they designed up this series of 3 inchers for their Vertec line .


Doug mentioned that he used the ferrofluid to get rid of a response anomally. Both he and Greg have said to either use the correct 100 ul or none at all. Some of these 2435's I've been going through were way overloaded with the stuff. Some had the double stick tape creep, perhaps due to heat, which forced me to carefully remove any that was directly touching the diaphragm.

Thanks for mentioning the "tape creep" ( it's new information for most of us here ).

- A year ago I bought 8 used 2431H drivers ( now used in SR work ). Most measured noticeably different from each other . They all seemed to have "cooked ferrofluid" splattered about, under the dome.
- I cleaned them up and currently I'm running a few with dry gaps.
- The cleaning, restored 6 maybe 7 back to respectable response curves.
- Perhaps the other(s) have this tape creep that you mention. If not, new diaphragms will be in order / they're inexpensive enough .

So again , thankyou for bringing this information forward .

:)

4313B
09-19-2007, 09:11 AM
So the three last factors that could explain the superiority of the 435Be are :

absence of ferrofluid
aquaplas
large back capI can't wait to see your mesurements when you get back your aquaplased 2435 !I would say it is all in the aquaplas. Rob sent me his data files and I will normalize them. I'm also evidently going to have to go through a 2435 and ensure it is "good" along with new ferrofluid, measure it, aquaplas it, and measure it again. I'll also compare it against a stock 435Be. I guess I'll use an H9800 or H4338 for the measurements. I really wish I had more time for this kind of stuff..........

pos
09-19-2007, 03:39 PM
That will be a great resource!:applaud:

4313B
09-19-2007, 04:35 PM
Rob sent me his data files and I will normalize them.I did that and here are the graphs. We will have to redistribute the ferrofluid and possibly add a bit more to flatten out the curves in the 1.8 kHz region. It could be as simple as spinning the diaphragms around in the gap a turn or two. Rob measured these on one of those 1010 thingies. PWT would be ideal for this kind of stuff but we are fresh out of them.

None of these curves have smoothing applied.

pos
09-20-2007, 01:14 AM
The blue curve is with too much ferrofluid, or no ferrofluid at all? The response above 10khz seems flatter with the blue curve, so maybe a good option for two ways?

Do you have harmonic distortion curves?

4313B
09-20-2007, 05:17 AM
The blue curve is before anything at all was done to each driver. The red curve is after the removal of all the original ferrofluid, application of 100 ul of new ferrofluid and the coat of aquaplas.

Rob added an additional 100 ul of ferrofluid to each driver last night and re-measured them. Doing so flattened out the bottom end but it also reduced the very top end further.

4313B
09-20-2007, 06:16 AM
a good option for two ways?There are a couple options:

2435HPL at $1,399 each
2452H-SL at $1,315 each

Robh3606
09-20-2007, 07:22 AM
I will put up some distortion plots later today. OK looks like a wash to me. The only place you can see a reduction is above 5khz. The blue is after the green before. The light blue and purple go with the blue plot. The lower plots are 2nd and 3rd harmonic distortion with the 3rd the lower of the two.

Rob:)

edgewound
09-20-2007, 04:27 PM
By the looks of the graphs with the raw response curves...it would look to indicate that aquaplas isn't of much benefit to the Be diaphragms.

Actually, it looks to hinder more than than help...by adding excess mass.

4313B
09-20-2007, 04:35 PM
By the looks of the graphs with the raw response curves...it would look to indicate that aquaplas isn't of much benefit to the Be diaphragms.

Actually, it looks to hinder more than than help...by adding excess mass.Yeah, JBL probably just put it on so they could say they did, you know, for the product literature. Kind of like they added that 045Be to the E2.

At least we got to the bottom of it.

I'm sure not doing any more of them. :no:

edgewound
09-20-2007, 04:49 PM
Yeah, JBL probably just put it on so they could say they did, you know, for the product literature. Kind of like they added that 045Be to the E2.

At least we got to the bottom of it.

I'm sure not doing any more of them. :no:

Well...at least it does do wonders for the Ti diaphragms. For less than a third the cost of the Be units (diaphragms, that is).

Robh3606
09-20-2007, 08:18 PM
Well the most important thing hasn't been done yet. That's simply having a listen. I know from measuring for differences with the Titaniums to expect some HF roll-off and a drop in level.

What is surprising to me is the 1K wide shelf in some on the drivers at the top end and the 2k rise. My original drivers had god knows how much ferro in them but they did have a smooth roll-off. Looks like we sacrificed a bit of high end response and that smoothness for some extra dampening.

Time will tell if it was worth it but after the first song we should know for sure. Based on what it does for Titanium I not sure what to expect with these. I will let you know once I power them up.

Rob:)

4313B
09-21-2007, 12:00 AM
Well the most important thing hasn't been done yet. That's simply having a listen.I suppose. These guys evidently did just that.
Later that day, we were invited to Greg Timbers's home for a listening session of his custom built stereo and home theatre. This system is described in detail here (http://audioheritage.org/vbulletin/showthread.php?t=9951). Suffice it to say that this ranks as the finest system I have heard in a home environment. For this visit, we were joined by Paul Bente, president of JBL. He is pictured at the back left in the fourth photo.I've posted before how to use these aquaplased drivers and I think it's best if I just leave it at that. Some people will prefer the 2435 and some people will prefer the 435Be and that about sums it up. :) At this point I don't think too many people care since they will use the cheaper 2452H-SL.

Chas
09-22-2007, 05:38 AM
I suppose. These guys evidently did just that.I've posted before how to use these aquaplased drivers and I think it's best if I just leave it at that. Some people will prefer the 2435 and some people will prefer the 435Be and that about sums it up. :) At this point I don't think too many people care since they will use the cheaper 2452H-SL.


I have really enjoyed the info posted here, thanks guys. However I am still a little confused regarding the 2452H and 2452H-SL differences. Am I correct in assuming the only difference is that Aquaplas is added to the SL version? Both are Ti, right?

Ian Mackenzie
09-22-2007, 06:04 AM
I suppose. These guys evidently did just that.I've posted before how to use these aquaplased drivers and I think it's best if I just leave it at that. Some people will prefer the 2435 and some people will prefer the 435Be and that about sums it up. :) At this point I don't think too many people care since they will use the cheaper 2452H-SL.

I agree. This is why its important to consider what is meant by voicing and make your own observations. Not just someone else's impressions.

When I was at Rob's we played a familiar tune on using a titanium equiped JBL driver and the JBL Be equiped driver.

Despite the two systems used in the camparison having different horns there was no denying the brillance of the titanium compared to the relatively damped and somewhat dry sound of the Be.

I was so used to hearing this tune on the titanium equiped 2344 horns I did not know what to think at first. Depending on how fussy you are there is also the not all be drivers are the same issue. I would speculate the tad Be drivers are different beast to the Be JBL's based on what I have heard to date. You owe it to hear the tad stuff to appreciate this even if the are unobtanium at this stage.

No doubt depending on how a whole system is finally adjusted and setup you could be quite happy with either but the Be definately has more resolving power. I am not sure Be in the UHF area would be everyones cup of tea particularly on DVD's.

I guess Greg runs his system without the 045 for a reason!

Just food for thought.

Ian

Zilch
09-22-2007, 12:26 PM
I have really enjoyed the info posted here, thanks guys. However I am still a little confused regarding the 2452H and 2452H-SL difference. Am I correct in assuming the only difference is that Aquaplas added tothe SL version? Both are Ti, right?http://audioheritage.org/vbulletin/showthread.php?p=185313#post185313

They are both titanium, but not the same diaphragm.

Perhaps Techbot can post the EDSs for these for us, now that they've moved up to "Honorable Mention" here.... :yes:

4313B
09-22-2007, 12:41 PM
now that they've moved up to "Honorable Mention" here.... :yes:Good grief...

Thom
09-22-2007, 12:42 PM
Is anyone sure that differences men in there 40's and 50's hear has any thing to do with response around 18k. I'm not trying to say I know more but I'm doubtful if response up there has anything to do with anything but bragging rights or perhaps marriage depending on the age and interest of your wife. I can remember televisions that emitted noises that really bothered women and men didn't hear them and I think that was around 15K. Again, I'm just asking.

speakerdave
09-22-2007, 01:28 PM
[URL] . . . . now that they've moved up to "Honorable Mention" here . . . .

Not sure who's opinion you are referring to here. I've been listening to the 2450 with powdered diaphragm (on the round exponential with diffuser) for many months. I have yet to compare it to the new Al 2421 diaphragms, but it is well above honorable mention, in my opinion, though not a contender for Grand Prix, and I think the 2452SL on the right horn could only be better.

As I recall reading, the titanium starts rattling at about 3-3.5 kHz, so I should think the dusted titanium diaphragms would be a desireable upgrade for any kind of SR work, cheap and merciful to ticket buyers, who, if they are like me, are merely tolerating the sound system most of the time. Downside is that it may call out for a tweeter added to two-ways.

David

Robh3606
09-23-2007, 05:53 PM
Here's some food for thought. Take a look at how smooth the decay is after the Aquaplas. They sound really nice as well. The second plot is coated.

Rob:)

grumpy
09-23-2007, 06:01 PM
Nice work Rob :applaud:

Mr. Widget
09-23-2007, 10:58 PM
Take a look at how smooth the decay is after the Aquaplas. They sound really nice as well.Thanks Rob... I agree with your earlier comment about the proof being in the listening, but these plots do seem to be a nice visual to back it up.


Widget

Guido
09-24-2007, 02:29 AM
Yeah!

That's what is audible.

SMOOOOTH

timc
09-24-2007, 03:02 AM
Only goes to show that response curve ain't everything. Very good job!

-Tim

Earl K
09-24-2007, 08:17 AM
Here's some food for thought. Take a look at how smooth the decay is after the Aquaplas. They sound really nice as well. The second plot is coated.

Real Nice Work Rob ! :)

As a side note ,,,

(i) Are you able to colorize CLIOs' CSD "waterfall plots" , similar to what's seen in the following 2 pics ?
- Due to the use of colors, I find it easier to follow ARTAs' plots ( these are borrowed pics ) when needing to establish a comparitive reference, say "halfway down a waterfall" .

(ii) Also, will CLIO display CSD plots which are measured in "Periods" , and are triggered from a gated Tone Burst ( as displayed in the last pic ) ?

??? -This second CSD seems to better highlight ( than the first CSD ) some unusual time domain behaviors ( within this particular transducers' decay signature ). This visualization ( info/behavior ) appears to be lost due ( in the first CSD ), most likely to the algorithm used to patch together the sinusoidal sweep ( or so I've read ) .

:)

Robh3606
09-24-2007, 10:17 AM
Thanks Guys

Earl I don't think you can. I will give it a look when I get home but I don't remember color as an option. It's a nice one and it does make it much easier to read them.

The time slices are equal divisions of the sample time. You can select how many slices you want and it just divides them up. You can then go in and look at the levels of each slice anywhere along the frequency axis. Geez I hope I am explaining this right:blink:

I have to get back to you on the rest

Rob:)

Earl K
09-24-2007, 10:33 AM
I have to get back to you on the rest

Okay, Thanks <> :)

Zilch
09-24-2007, 01:09 PM
Only goes to show that response curve ain't everything.Well, I'll stand up for FR here; we'd kinda like not to trash that in the process, I would presume.

Let's see 435Be for comparison. :yes:

And 275nd, which, contrary to assumption, is not the same diaphragm as 2425, I don't believe....

Zilch
09-24-2007, 01:36 PM
It has been asserted numerous times here that there was no impact upon FR, rather merely a 1 dB drop in sensitivity. I believe that's possible, if the diaphragm is operating pistonically out to 18 kHz and not relying upon "spurious" resonances for enhanced HF response. Verification with 435Be would clairify the issue.

I bring up 275nd because that was the first application of the Aquaplas damping technique to these diaphragms, to my knowledge, and my own evaluation of it revealed a smoother sound, but significant response changes requiring rework of passive filters in existing designs.

Ian Mackenzie
09-24-2007, 02:01 PM
Hi Zilch,

if you have a look at the 4344mk11 schematic you can see some impediance compensation on the HF filter right behind the driver.

Ian

Will edit and delete later.

Guido
09-24-2007, 02:26 PM
deleted

Earl K
09-24-2007, 03:06 PM
- This thread used to be about 3" Be domed drivers, but now it's veering OT, oh well ;
http://www.lansingheritage.org/images/jbl/specs/home-speakers/1993-k2-s5500/page09.jpg

The above S5500 cut sheet suggests the following to me;

- In a two or three-way, where one wants a 1.75" Ti domed aquaplased driver to cover upper mid as well as HF, one should order the D8R275nd diaphragm ( since it starts life 25% thinner & lighter / before being aquaplased ) . This ought to offer the most HF extension with a reasonable amount of modal damping ( dampening ??? ) .

- In a 4-way using a 1" exit driver , aquaplasing a stock 2425 or 26 is a better option, IMO .

:)

Robh3606
09-24-2007, 04:42 PM
Well here's what we have on the site for 435Be measurements. Two are Widgets. The next 2 are my 4 drivers for comparison. The last is JBL's measurements for the 435 in Project May. Take a look see what you think

Rob:)

Thom
09-24-2007, 08:49 PM
Is the magnet structure on the 275nd a different design (I realise it's a different size) than the 2435? The article talks about self shielding. Sounds like JBL's alnico designs. The 2435's I have will pull a tweaker screwdriver out of your pocket at about a yard (think meter). Obviously I'm exaggerating but they aren't even close to being shielded. I wondered when I got them why they weren't. I thought it would be like alnico only much smaller.
When they say dusted is that a figure of speech or a dry process?
When they differentiate a four way where are they figuring on the 275nd being used?

Thom
09-25-2007, 07:09 AM
Must be fairly massive for being neodymium. Maybe thats from building it with a throat. Perhaps there isn't room to build it with an iron pot throat less. Interesting how they call, what I would think of as the back cover, the front cover.

Robh3606
09-25-2007, 07:30 AM
Well, I'll stand up for FR here; we'd kinda like not to trash that in the process, I would presume.

Let's see 435Be for comparison. :yes:

Hello Zilch

I posted the 435Be measurements we had on the site. All of the drivers have a drop at 10k followed by a notch at or around 15K or so then some recovery. The depth of the notch and the recovery are driver dependent from what we have.

When I remeasured the drivers I was surprised to see what the changes were. The problem with this is we changed 2 variables at once. The Ferro Fluid and the added mass of the Aquaplas. I don't know how much Ferro was in them but it certainly is more than I have now.

After added another 100ul and moving it around in the gap it helped reduce the peak. If you look at the curves the were changes in FR but all in the same directions and at the same frequencies.

You are correct about the implications and effects on a passive crossover. There were both impedence and FR changes that required the passive networks I had in the can to be reworked. That said I was able to get good curves but I had to change where the notch filters were and the Q and depth of them as well.

In my active set-up I was able to easilly integrate the drivers with an existing crossover by using a change in EQ in one band and increasing the driver level about 2 db to get within a db of the original curve on the RTA.

The changes above 10K were more than I expected. The original curves on the 2435's were smooth without the notches you see know. Fortunately they don't seem to be as audible as you would think once you get them compensated and running in a system.

Rob:)

4313B
09-25-2007, 08:00 AM
Well, I'll stand up for FR here; we'd kinda like not to trash that in the process, I would presume.Zilch, you don't want me to publicly post G.T.'s answer to that statement. :rotfl:

In any case, nice work Rob but honesty, I'm not sure why you are bothering. Here's the scoop. The aquapas and the cc networks are options that some people can implement at their discretion. Not implementing them isn't a "bad" thing. All this stuff still works just fine without these mods. The point is, a whole bunch of people have been sending emails and PM's to various people and it has to stop. These two topics should never have been brought up on this website in public. They absolutely should have stayed in the private forums.

Rob, start over again and suck all the ferrofluid back out. You should not need more than 100 ul at all. Of course, you can do as you wish since they are yours but the point is, that 100 ul all the way around both sides of the coil should do the trick and additional ferrofluid is detrimental. I pulled almost 400 ul from one of the 2435's.

Robh3606
09-25-2007, 08:22 AM
Rob, start over again and suck all the ferrofluid back out. You should not need more than 100 ul at all.

I was thinking about that.

Rob:)

4313B
09-25-2007, 08:31 AM
It has been asserted numerous times here that there was no impact upon FR, rather merely a 1 dB drop in sensitivity.Asserted with respect to the Ti and Al diaphragms used in the old large format 43xx series studio monitors. "The L-pads can be used to adjust for any potential changes".
Verification with 435Be would clairify the issue.I'll get to that when I have time although G.T. has already done it. My results will remain in the private forum where they belong. None of these discussions about aquaplas and charge coupled networks should ever have left the private forums. Why? Because they have generated a ton of emails and PM's that simply have to stop. This stuff doesn't belong out on the Internet where anyone and everyone can get involved. I expressed my concern when those Google bots started scrapping the site and we really should have taken steps to block off alot of the forum at that time.
I bring up 275nd because that was the first application of the Aquaplas damping technique to these diaphragms, to my knowledge, and my own evaluation of it revealed a smoother sound, but significant response changes requiring rework of passive filters in existing designs.I understand your concerns Zilch but you are basically going up against G.T. here and he really isn't the arguing type. His statement with respect to the aquaplas and the 1 dB change at the top end was directed at the Ti and Al diaphragms based on his work in the lab at JBL. If anyone out here isn't getting similar results then they can probably assume that they aren't G.T., they don't have 35 years of experience doing this audio thing alongside all the other brilliant people who've also worked at JBL over the years and that they don't have quite enough funds tied up in their equipment as Harman does.

Going forward it is probably best to post what you discover and let everyone know something to the effect "here's what I measured, what did you get." and definitely don't publicly post any kinds of recommendations based on what you discover. Suggestions yes, recommendations probably not. I hate to post this publicly but just because people are polite in person doesn't mean they give the same glowing remarks in private. That is a problem with this "Internet thing" and having people one doesn't necessarily know show up at one's house to hear what one is doing. They're just going to run back to others and say how they really feel. I refuse to get involved in any of it anymore.

4313B
09-25-2007, 08:32 AM
I was thinking about that.

Rob:)It was recommended. ;)

When they say dusted is that a figure of speech or a dry process?Manufacturing hits the diaphragm with a spray coating carefully measured and no one here is going to duplicate that. G.T. paints on two thin coats with a paintbrush after watering down the aquaplas so it is more easily manipulated.
When they differentiate a four way where are they figuring on the 275nd being used?For all intent and purpose the 275Nd is gone as are the diaphragms. It's too bad because it was a nice looking driver.

4313B
09-25-2007, 08:53 AM
I posted the 435Be measurements we had on the site. All of the drivers have a drop at 10k followed by a notch at or around 15K or so then some recovery. The depth of the notch and the recovery are driver dependent from what we have.No public comment available at this time.
I don't know how much Ferro was in them but it certainly is more than I have now.The amounts varied dramatically. My quess is some of the diaphragms were replaced, some several times, and they just kept dumping more ferrofluid into the drivers? I know JBL doesn't just dump arbitrary amounts in. :rotfl:
After added another 100ul and moving it around in the gap it helped reduce the peak. If you look at the curves the were changes in FR but all in the same directions and at the same frequencies.And rather than using more ferrofluid we have looked at a filter or two and saw that the notch filters were applied there instead. I have to think that the electrical solution is the better one.
You are correct about the implications and effects on a passive crossover. There were both impedence and FR changes that required the passive networks I had in the can to be reworked. That said I was able to get good curves but I had to change where the notch filters were and the Q and depth of them as well.Yes, it seems this kind of activity really isn't suited for the "It's a Bolt-in!" crowd.
The changes above 10K were more than I expected.Yes, especially after discussions with G.T. and D.S. with respect to the Ti and Al diaphragms. But, we (JBL included) are also dealing with a different mechanical structure here and that has evidently changed things. Also note that there is only a certain level of interest available. These are now no longer cutting edge and the few of us who use them "just do it" and don't keep hashing it all over fretting about how it measures or whether or not "it's the right thing to do". They work great, they sound great and that's about it. BTW - You've been able to match pairs reasonably well right?
The original curves on the 2435's were smooth without the notches you see know.And for the sake of argument, or lack thereof, it is probably best for most people to stick with the stock 2435's. :)
Fortunately they don't seem to be as audible as you would think once you get them compensated and running in a system.Indeed. I think you are doing a really nice job fleshing all this out.



I have to stress one more time though that this is a hobby with respect to this website and it should be taken that way. "Full disclosure" on a public Internet forum is out of scope. No one has to run aquaplased anything or charge coupled networks either. These are things some of us do, G.T. included, and these things have found their way into Production JBL loudspeaker systems where they are correctly implemented. Some people have made the decision to apply these techniques to legacy product. Some people will like the results and some won't. Some people will absolutely prefer stock to mod and in that respect no argument is probably valid. People are naturally free to post negative comments or negative results along with pictures and graphs but that really won't have much of an effect on RL. As for the private emails and PM's asking whether or not "is it really worth it?" - I don't think anyone else can tell you that. There appears to be little substitute for personal experience. Have fun. :)

timc
09-25-2007, 10:36 AM
Very good Giskard! :applaud:

edgewound
09-25-2007, 11:22 AM
The 2435's I have will pull a tweaker screwdriver out of your pocket at about a yard (think meter). Obviously I'm exaggerating but they aren't even close to being shielded. I wondered when I got them why they weren't. I thought it would be like alnico only much smaller.


The 2435HPL was designed specifically for the Vertec Line Array. How do I know this? I was at AES in Los Angeles several years ago when they announced the development of some new transducers for pro sound reinforcement...namely the Vertec Line Array. Shielding isn't an issue when the system is flown several meters from the floor away from CRT's and computers. Carry your pocket protector screw driver at your own risk;):p...preferably away from women and children....and Mackie users.

The 2435HPL is being used in HiFi systems now as a matter of discovering an alternate use for a cool driver. It's also originally utilized in groups of three at a time bolted to a purpose built wave guide.

Ian Mackenzie
09-25-2007, 02:20 PM
Rob,

Nice post and coverage of what you are doing with your drivers.

I know Rob fairly well and he is a perfectionist.

I think the latter discussion over acqualpas which is becoming a tired topic is not what this thread is or was meant to be about.

Fortunately or otherwise it (aquaplas coating) is what many and even the majority will end up doing if at all. I say that because in IMHO with the older vintage drivers you can come a long way with that treatment and to do seriously better would mean an equally serious amount of money on new soa drivers and then you have to make it work.

On that score I talked with Rob about his various systems when I visited NY and when it comes to incorporating new drivers Rob is very thorough. We even pulled a 2435 apart. Its very different mechanically from the older drivers.

Given the previous outlay on test and measurement equipment I think it is normal more anyone who has the skills to explore and understand what is going on this with stuff for themselves and to post the results which probably took quite a while to organise. But they pertain to their own test setup and their particular project.

Most drivers are like animals, they all have their own quirks and personalities. Unless you understand what they are your not going to get the best out of your individualised project. Similarly no two baffles or driver layouts are identical for personalised projects and its going to take some work to set it up . The first place to start is the drivers.

I have heard some Hi end diy loudspeaker projects that sounded wanting namely because the guy had his head stuck up his arse over a bunch of assumptions. The system was unfinished because it had not been optimised. Without , Clio, LEAP or SoundEasy that will take a very long time and is nearly improssible.

But I think what appear to be the concerns here over the post(s) around the mere generic modifications are a dramatisation of the reality. Its the major in the minor to take too much notice of one post that speculates the effects. If someone says they got oddball results who cares. I have personally met more people face to face on the forums then anyone I am aware of and they are all happy campers with CC and aquaplas treatment.

Some of the the modifications are going to have generic effects but you still need to understand what is going on as you wont always see the measured impact.

4313B
09-25-2007, 05:45 PM
I have personally met more people face to face on the forums then anyone I am aware of and they are all happy campers with CC and aquaplas treatment.Yep, there are definitely those who try things that are suggested and end up happy. They use the information as intended and don't get wrapped up in the daily discourse. They might have a question or two about this or that and once answered they can go on with their lives. :) Others make it a lifestyle. Those people actually end up creating a whole bunch of unneccessary work for others.

Ian Mackenzie
09-25-2007, 09:38 PM
Well I stopped concerning myself about such matters when I realised 50% of what I hear is my room...but that is another topic.

Lets hope the thread can stay on topic from here on.

Rob,

Have you attempted to model the driver or was it an impediance run with Clio on your drivers?

If it could be modelled it would help explain certain things.


Ian

pos
09-26-2007, 01:26 AM
Giskard, the main subject in this thread was the difference between the stock 2435 and the stock 435Be, the first being the pro version of the second.
I think that now, thanks to yours and Rob mesurements we can conclude that a -properly- aquaplased 2435 will be sonically identical to a 435Be (or am I all wrong?).
I think that is the point, and an interesting one for all of us. I don't think it has to be kept secret: JBL has always have pro and consumers drivers that where identical but of different prices. And by aquaplasing a 2435 you are not making a franken-driver: you are turning a stock driver (2435) into another stock driver clone (435be). So the results are predictable, and people can just listen to a S9800 to decide if this modification is worth it.


Yep, there are definitely those who try things that are suggested and end up happy. They use the information as intended and don't get wrapped up in the daily discourse. They might have a question or two about this or that and once answered they can go on with their lives. :) Others make it a lifestyle. Those people actually end up creating a whole bunch of unneccessary work for others.

I really appreciate your reference work on the forum.
I did buy a pair of 2123 a while back, and recently 2435 (cheap from ebay) because of what I read on this forum. I am also thinking about buying 2 pairs of LE14H-3 when the finances are back.
I don't think you are talking about me here, but I feel the urge to justify my approach on this subject: I am really sorry if I create a lot of unnecessary work for others. I did open some threads about the choice of a bass driver, and send a few PMs to Zilch regarding the 2435. I got helpful responses and I hope I didn't bother anyone too much in the process. I want to try and experience these things by myself, but for now I have to wait before buying or building anything more. For now I have a pair of 2123 and 2435 waiting on the shelf, and it makes me happy because I know I will be able to build a killer speaker with them one day :D

Mr. Widget
09-26-2007, 07:42 AM
... And by aquaplasing a 2435 you are not making a franken-driver: you are turning a stock driver (2435) into another stock driver clone (435be). So the results are predictable, and people can just listen to a S9800 to decide if this modification is worth it.I think the point that Giskard was making is that an over simplified approach that we at home must take while designing these systems and possibly modifying these drivers should not be confused with the work that JBL does. For example if you or I take a 2435 disassemble it, coat the diaphragm with aquaplas, and put the unit back together we actually can't be certain that we will have a 435Be... the variables of alignment, the correct amount of ferrofluid, and the correct amount and application of aquaplas are beyond the DIY set.

Now, that is not to say that you, or I or Zilch can't have fun with these things, but we simply shouldn't confuse our "clones" with the real deal. The level of precision and QC that is possible at the factory is beyond what we can do... with tools like CLIO and others we can get a better handle on what we are doing, but even the most experienced among us do not have JBL's test facilities and I don't think any of us have the human resources of JBL. At the end of the day we will have a system that is successful or not based on our best efforts and careful listening, but it is still a DIY speaker.

The work done by Rick Reissen and a few others where they take properly rebuilt drivers and painstakingly recreate a JBL by carefully copying it is a different story... those truly are clones... and then there are those projects where we take a little of this and a little of that and come up with our own stew... those systems are flavored to our personal taste (whether the FR curve says it is flat or not) and should be considered in a very different light than the clones.

Ultimately this thread while veering off and on topic over all of these posts does ultimately fully explore the comparison that Norealtalent original posted.


Widget

4313B
09-26-2007, 08:20 AM
Giskard, the main subject in this thread was the difference between the stock 2435 and the stock 435Be, the first being the pro version of the second.
I think that now, thanks to yours and Rob mesurements we can conclude that a -properly- aquaplased 2435 will be sonically identical to a 435Be (or am I all wrong?).The 435Be is the Consumer version of the Pro 2435. It has a "pretty" finish as all TOTL Consumer products have traditionally had. Additionally, the diaphragm has a light coating of aquaplas to dampen spurious response. This coating yields a level of detail not found nor required in the Pro 2435. The S/N level in a typical home environment allows for much finer detail to be appreciated.
I think that is the point, and an interesting one for all of us. I don't think it has to be kept secret:One of my points was that these two topics have generated a large amount of private discussion and as more and more people become involved it becomes unmanageable. Five people sending email asking questions is one thing, one hundred people is another. This is a public Internet forum and therefore generates more discourse than one might think.
I really appreciate your reference work on the forum.I've pretty much stopped that for the most part for several reasons, one of which is the fact that I really need to narrow my scope and concentrate on tasks currently at hand.
I did buy a pair of 2123 a while back, and recently 2435 (cheap from ebay) because of what I read on this forum.This is dangerous because a whole lot of people buy a whole lot of stuff because of what they read here and although most are happy all it takes in one who isn't to ruin the whole process. One thing is absolutely true "One person's junk is another person's treasure." and I guess I'd rather not be involve in any of that.
I am really sorry if I create a lot of unnecessary work for others.Nope, I was specifically thinking about the group that showed up in the summer of '04. It's now generally regarded as having been a particularly bad summer. :rotfl: But, it takes all kinds to fill the freeways and some of us, like me, just have to accept that fact.
I did open some threads about the choice of a bass driver, and send a few PMs to Zilch regarding the 2435. I got helpful responses and I hope I didn't bother anyone too much in the process.Yeah, whatever, I really don't care what he or anyone else has to say at this point just so long as A.) It isn't misinformation and B.) It has zero effect on current Production Models. Legacy product is fair game although it is in the best interest of everyone to try and keep misinformation at a minimum. You guys can make this forum whatever you want. You can make it something to be real proud of with great information or you can turn it into just another gabfest on the net.
I want to try and experience these things by myself, but for now I have to wait before buying or building anything more. For now I have a pair of 2123 and 2435 waiting on the shelf, and it makes me happy because I know I will be able to build a killer speaker with them one day :DCool! :) I think we are all very interested in projects and the more posted the better. :yes:

4313B
09-26-2007, 09:11 AM
I think the point that Giskard was making is...Thanks Mr. Widget.

I really envy Don for his ability to carefully craft his posts so as to cover as much as practical with as little ambiguity as possible.

timc
09-26-2007, 09:31 AM
My 2435's arrived yesterday. I disasembled them to check them out. They look good. Not too much fluid.

Im waiting for JohnW to ship me a pair of 2332 horns. Cant wait to get them going :)

Small question: Will a 6db/okt highpass filter at 1khz be good enough, or do i have to go with 12db/okt?

-Tim

Earl K
09-26-2007, 11:17 AM
My 2435's arrived yesterday,,, snip,,,,,,,They look good. Not too much fluid.

- How can you properly conclude by a simple visual inspection, what is "too much" or "not enough" ferrofluid ?
- You have no benchmark to make a statement such as you've made .



Im waiting for JohnW to ship me a pair of 2332 horns. Cant wait to get them going

- 2332 are SR horn/waveguides that are very challenged in regards to LF loading.
- Respectfully, I'd say forget the 2332s / and instead pay John to make you some decent sounding wood horns ( this, will no doubt cost much, much more than a pair of metal SR wavequides ) .
ie; get something like either a pair of his H9800-type wannabes or maybe some Lathe-Turned 350 hz Tractrix "Salad-Bowls".



Small question: Will a 6db/okt highpass filter at 1khz be good enough, or do i have to go with 12db/okt?

- No, 6 db is too shallow a slope for these newer SR waveguides .

- Respectfully ( again ), I'll suggest that you are a "victim of fashion" when it comes to discussing & choosing crossover slopes .
- Luckily ( for JBLs' DD66000, E2 Project ) Greg Timbers, ( JBLs', if not the worlds' top system designer ) is not handicapped by such "stylishly/blinkered" thinking .
- ie; Why do you feel the need to embrace 6 db slopes ?

- Anyways, if you must have a 6 db HP filter in your system make sure your chosen mid-horn is able to "fully-load" the lower frequencies, to a bare minimum of 1 octave below your preferred crossover point ( 1.5 octaves of loading safety, would be better ) .
- ie; you should at least be looking at using 500 hz horns, if this ( single pole HP ) is the path you must pursue .

<> :)

pos
09-26-2007, 11:21 AM
Not too much fluid.
Where did you check this?
Despite all the descriptions, I still don't really understand where this fluid is supposed to be (and why it doesn't run out of the gap whern the driver is on its side). Language barrier I guess.


Small question: Will a 6db/okt highpass filter at 1khz be good enough, or do i have to go with 12db/okt?
check this:
http://www.audioheritage.org/vbulletin/showthread.php?t=17513

timc
09-26-2007, 12:00 PM
- How can you properly conclude by a simple visual inspection, what is "too much" or "not enough" ferrofluid ?
- You have no benchmark to make a statement such as you've made.

The fluid just touches the voice coil. This is the way it is meant to be. (stated in another thread. Is it wrong?)






- 2332 are SR horn/waveguides that are very challenged in regards to LF loading.
- Respectfully, I'd say forget the 2332s / and instead pay John to make you some decent sounding wood horns ( this, will no doubt cost much, much more than a pair of metal SR wavequides ) .
ie; get something like either a pair of his H9800-type wannabes or maybe some Lathe-Turned 350 hz Tractrix "Salad-Bowls".



Im fully aware of that. I'm going to have H9800 horns made later. Money is the "holding back" factor. The 2332 was so cheap it.s mostly just for fun.





- No, 6 db is too shallow a slope for these newer SR waveguides .

- Respectfully ( again ), I'll suggest that you are a "victim of fashion" when it comes to discussing & choosing crossover slopes .
- Luckily ( for JBLs' DD66000, E2 Project ) Greg Timbers, ( JBLs', if not the worlds' top system designer ) is not handicapped by such "stylishly/blinkered" thinking .
- ie; Why do you feel the need to embrace 6 db slopes ?



I'm not at all "bound" to 6db slopes. It was just a question. How steep slope would you suggest for a 1khz crossoverpoint?

-Tim


Edit: An when it comes to beeing fashion victim. That is one thing I'm NOT :) I'm just new at speaker diy, so bear with me.

Earl K
09-26-2007, 12:26 PM
How steep slope would you suggest for a 1khz crossoverpoint?

- At least 12 db .

- Buy some RTA software such as TrueRTA so that you can discover for yourself the deficiencies in your new purchases. You'll need this info to be able to design custom filters to rectify your particular drivers' response anamolies.

- You do realize that just about all these eBay "backdoor" specials ( 2435h ) are either customer returns or "factory seconds" that don't measure up to JBLs' spec. . As a result, be prepared to learn lots about filter design so that you can design yourself a set of custom filters that fix your particular drivers' shortcomings.

:)

timc
09-26-2007, 12:42 PM
Thanks for the tip about TrueRTA? Wich lvl would you recomend to get, and do you have any suggestion on wich microphone ?

My 2435HPL have been used for PA and have been refurbished by JBL. Dunno exactly what that means but we'll see. Im taking it all as a "learing project" If the result is good that is just a big bonus :applaud:

-Tim

Earl K
09-26-2007, 02:27 PM
Thanks for the tip about TrueRTA?

You're welcome !

W(h)ich level would you recom(m)end to get, and do you have any suggestion(s) on w(h)ich microphone ?

- Level 3 or 4 ( 1/6 octave is adequate for newbies ) / though the extra $30.00 for level 4 is really peanuts / so just buy it .
- The "Quick Sweep" FR trace ends up giving a fairly decent facsimile of the sinusoidal MLS look ( CLIO ) .

- The Behringer ECM8000 test mic (http://www.behringer.com/ECM8000/index.cfm?lang=eng) is just fine for this level of measurement .

- You may need to upgrade your soundcard / so pay attention to True Audios' recommendations for "supported cards" . Don't hesitate to send them an email asking about the compatibilty of your existing card .

:)

4313B
09-26-2007, 09:02 PM
Despite all the descriptions, I still don't really understand where this fluid is supposed to be (and why it doesn't run out of the gap whern the driver is on its side).The fluid is magnetic and remains in the gap. It has to be drawn out with absorbent paper. Technically it should equalize itself all the way around the gap but in reality one has to "help it" by rotating the diaphragm 90 degrees each way once it is inserted into the gap.

pos
09-27-2007, 01:41 AM
Ok, I understand. Thank you Giskard.

timc
09-27-2007, 01:54 AM
Earl: I tried to send you a PM to keep this from going way OT but i wasn't able. Would you mind adding me to your buddylist?

-Tim

4313B
09-27-2007, 08:04 AM
to keep this from going way OTThat is the only way it can go at this point. The original scope has been beaten to death.

Robh3606
09-27-2007, 09:43 AM
The original scope has been beaten to death.

Hello Giskard

I am going to drive the stake into it's heart and just finish off with how the driver changes effected the measure FR with the networks in the mix.


Have you attempted to model the driver or was it an impediance run with Clio on your drivers?

If it could be modelled it would help explain certain things.

Hello Ian

I am thinking this is what you meant. I will post the impedence plots before and after later. The first plots are a "canned" crossover with 2 of the 2435's before the ferro and aquaplas. The next is with the new measured response and impedence plots. The last is the "corrected" networks. I am doing this to show what impact the changes had and what you might expect to see. In the end it was some additional work but the results met my expectations.

Rob:)

Mr. Widget
09-27-2007, 09:49 AM
That is the only way it can go at this point. The original scope has been beaten to death.I'd suggest that through yours and Rob's posts the topic has been thoroughly covered.
:D


Widget

pos
10-30-2007, 08:56 AM
My 2435's arrived yesterday. I disasembled them to check them out. They look good. Not too much fluid.

Im waiting for JohnW to ship me a pair of 2332 horns. Cant wait to get them going :)

Small question: Will a 6db/okt highpass filter at 1khz be good enough, or do i have to go with 12db/okt?

-Tim

Hi Tim,

So did you had a chance to listen to this 2435/2332 combo?
How does it sound?

timc
10-31-2007, 12:19 AM
Hi.

Yes i have. BUT i havent built a new crossover for the woofer i tested with so some phase problems at the crossover point occured (as expected)

The 2332 didn't sound very good (FR wise), however it was easy to hear that the sound was VERY detailed. From about 11k and upwards there is nearly zero dispersion so not suitable for 2 way systems. I knew this already and the 2332 horn was bought just to play around with the drivers untill i can afford H9800 clones.

-Tim

pos
10-31-2007, 02:00 AM
thank you

Damn! This seems to be the weakest point of the DMS-1 then. How could they do so bad after the almighty 2344 ?

Zilch
10-31-2007, 02:38 AM
http://audioheritage.org/vbulletin/showthread.php?p=64513#post64513

http://audioheritage.org/vbulletin/showthread.php?p=65902#post65902