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Figge
07-23-2004, 06:20 AM
hi! im having some problems tuning the l-pads so the speakers sound goon on most records. is there any tips or tricks i dont know about? when playing a cd for exaple, i fiddle with them till it sounds perfect, then thow in another cd it sometimes sounds like crap! and im there fiddling again! cd:s from early 90:s seem to have exessive treble...maybe to compensate all the crappy speakers sold that decade? :)

however: when playing vinyl this problem doesnt occur! well atleast not so much that it bothers me!


any suggestions on a "neutral" record i can tune after?

4313B
07-23-2004, 06:44 AM
Ah! The perils of owning JBL Studio Monitors! You need to get a different brand loudspeaker, something like an Audiophile loudspeaker that masks everything to the extent that all recordings sound listenable. :D

Robh3606
07-23-2004, 07:26 AM
First off get yourself some kind of measurement capability. Only because you cannot reliably use any kind of source material to set your driver balance. Sure you can listen to your set-up disks and use those but it helps to know how they are set and you can go through the range and see what they really do. As for me once they are set they stay that way. Same for EQ ect. I gave up chassing my tail over poorly balanced recordings years ago. If they are awful well then so be it.

Rob:)

boputnam
07-23-2004, 07:54 AM
Originally posted by Robh3606
...once they are set they stay that way. Same for EQ ect. Hey, Figge...

Rob's got my take on this. :yes: Are you using EQ? If not, think about it to better tune the system to the room acoustic response. Set the EQ and L-pads for best result on some proper source material, and then tweak to personal taste.

Then, take CD's that don't sound right and put them into a pile that doesn't get played much, or leave them in the car where it is less noticable... :D

4313B
07-23-2004, 09:18 AM
:bs: Don't believe them! Lies! ALL LIES! :die:

The only records that need to sound good are "Dark Side of the Moon", "Aja", and "Crime of the Century". If you dial those three in your golden. :rotfl:

Mr. Widget
07-23-2004, 10:50 AM
Originally posted by Giskard

The only records that need to sound good are "Dark Side of the Moon", "Aja", and "Crime of the Century". If you dial those three in your golden. :rotfl:

...but, I don't like Aja. Now what will I do?:banghead:


Widget

Figge
07-23-2004, 11:19 AM
Originally posted by Giskard
:bs: Don't believe them! Lies! ALL LIES! :die:

The only records that need to sound good are "Dark Side of the Moon", "Aja", and "Crime of the Century". If you dial those three in your golden. :rotfl:


Dark Side of the Moon are one of my favorite albums ever! and it sounds good too! on vinyl that is! CD:s just dont compare!

well supertramp works too...

Rob; what kind of meashuringdevice? i need some help on this one. if i just knew the speakers were "right" on the pads then i wouldnt care. but u never know do ya? unless u meashure the system.

Bo: no i´m not using Eq. i have an old one somewhere...but i dont know if it´s quality meets with the JBL:s

boputnam
07-23-2004, 11:20 AM
Originally posted by Giskard
:bs: Don't believe them! Lies! ALL LIES! :die:
Giskard!! :scold:

Figge
07-23-2004, 11:24 AM
Originally posted by Giskard
You need to get a different brand loudspeaker, something like an Audiophile loudspeaker that masks everything to the extent that all recordings sound listenable. :D



Bose? missions? any suggestions?
maybe even a pair of infinity? :)


just foolin´around i never will let these go! best damn speakers i ever heard! even on crappy records!.....

with the "right" records they can easyli recreate a band as if they were playin´in my living room. i didnt know a pair of speakers could do that. but i guess u guys allready knew that?

boputnam
07-23-2004, 11:26 AM
Originally posted by Figge
Bo: no i´m not using Eq. i have an old one somewhere...but i dont know if it´s quality meets with the JBL:s Hell, I know some luminaries here are using Rane's, knowing full-well there are other brands - but they enjoy them none-the-less. You might drag it out, and give it a try. It could be that a global taming some of the acoustics of that room might be a more satifsying solution...

Figge
07-23-2004, 11:32 AM
Originally posted by boputnam
You might drag it out, and give it a try.


well i aint seen it for a while...but thanx for finding it for me!

ps: how the heck did it get up there? beats me:confused:

DavidF
07-23-2004, 12:26 PM
hi! im having some problems tuning the l-pads so the speakers sound goon on most records. is there any tips or tricks i dont know about? when playing a cd for exaple, i fiddle with them till it sounds perfect, then thow in another cd it sometimes sounds like crap! and im there fiddling again! cd:s from early 90:s seem to have exessive treble...maybe to compensate all the crappy speakers sold that decade? :)

however: when playing vinyl this problem doesnt occur! well atleast not so much that it bothers me![B]

_________________________________________________

CDs (not all of course) have been accused of being recorded on the bright side to begin with. Vinyl records (or the way the sound was changed by the time it hit the lathe) have a tendency to roll off the highs which can also vary from track to track as you move toward the center of the disk. You may be finding you have some acuity to the difference in highs for this reason.

As for tuning the Lpads, I can suggest two cheap ways using mostly your ears. The basic method is to turn down all controls to the minimum, then start from the bottom-up to level the sound. Start with the mid control to bring the level up compared to the woofer just to where it sounds balanced to your ears, that is no one speaker is dominating the output. Then repeat the process with the high range to balance that driver with the other two.

Second is use the same approach above but using recorded white noise available on test CDs. This may be easier to tell when one speaker is louder over the other.

4313B
07-23-2004, 02:29 PM
Originally posted by Mr. Widget
...but, I don't like Aja. Now what will I do?:banghead:


Widget Completely irrelevant! It only needs to sound good :D

jandregg
07-23-2004, 02:50 PM
Dump your current speakers and fill up on L100s. Remove the grills and put them in the 4 corners of the room. Take your clothes off and sit crosslegged in the middle of the room. Turn the volume all the way up and play all those cds that don't sound good now. Take another slug of red anytime that sensation returns.

Zilch
07-23-2004, 03:12 PM
"OHMMMMMMMmmmmm" between tracks. Harmonic convergence matters.

It's a technical thing....

R=E/I

Figge
07-24-2004, 01:42 AM
Originally posted by DavidF
Second is use the same approach above but using recorded white noise available on test CDs. This may be easier to tell when one speaker is louder over the other.


only one problem: the 2 pads mid/high is for the same driver.
and where can i get the noise? can i download it somwhere and burn it onto a cd?

Figge
07-24-2004, 01:56 AM
i found the eq! it´s a jvc sea80 with rackhandles! heavy hu?
well it shure has some features: 2*10 band, spectrum analyser and so on.

but check this out! it has PINK NOISE generator for L&R channel and a mic input that u can hookup a mic and run the noise and it shows a graph right in the display! u simply fiddle with the bars til the graph is flat....cool! but probably not very reliable?

im shure gonna give it a try though!

Robh3606
07-24-2004, 05:44 AM
You can use a PC as your entire measuring set-up. You can get a noise source on CD to. Almost any test CD has Pink Noise bands so you can see what the room response is on an RTA. You can get True RTA for free. Then you need a measurement microphone. I use the Behringer it's inexpensive. You should be able to use it with your EQ but if you go with the Behringer you will need a phantom power source. There are several of those around I got a Crown PH-1A for $24 delivered off E-Bay. I have an old ADC Sound Shaper RTA that had a small battery powered microphone sound like yours is a similar set-up. If it working you should be able to get what you need done. I used the 10 band Sound Shaper for years and it correlated very well to the Behringer. If I remember right white noise is broad band and a constant amplitude with frequency. Pink noise is rolled off to compensate for the increased frequency range each octave covers. If you look at pink noise in say Cool Edit it rolls off. On an RTA which looks for power/level distribution octave to octave its flat.

Rob:)

Mr. Widget
07-24-2004, 02:37 PM
Simply put, white noise has the same power at all frequencies and pink noise has the same power for each octave. As a result white noise sounds brighter. We use pink noise to balance a sound system to generate a "flat" response.

Flat response is a bit of a fantasy though as rooms affect the sound and even air has an effect. High frequencies roll off with distance from the source due to air loss (friction) so a speaker that is ruler flat at 3 feet will not be ruler flat at 30 feet.

Widget

Ian Mackenzie
07-24-2004, 05:39 PM
Figg,

If you download the 4430 data it will help you understand what the contols do.

The contols effect the 2 Khertz zone and the 16Kherts extension.
The ffect is enhancment of midrange imaging and HF spatial ambiance.

This monitor is very smooth and should need little Eq unless you have significant room relections etc

I am surprised to have this problem with the 4430's. The problem could be the CD player?? Also are you Bi amping.

When I heard John Nebel's 4435's it was with NO Eq and they were silky smooth and sweet no matter what we played

How are they set up? For home use you may find placing them equidistant from the side/rear walls and towed in a bit, but not too much.

Try a different CD player, I doubt if the RTA EQ is the solution. Also check the conditon of the compression driver.

Ian:cool:

Figge
07-25-2004, 06:13 AM
Originally posted by Ian Mackenzie
This monitor is very smooth and should need little Eq unless you have significant room relections etc........How are they set up? For home use you may find placing them equidistant from the side/rear walls and towed in a bit, but not too much.



i can imagine this being the two major problems to work with. maybe i need to get em out of the livingroom and in to a separate "hifi-only" room.

its not a very high "WAF" on working with room reflections in the livingroom!

if the drivers were damaged in some way it should be heard very clearly? or maybe i should pull the horns and see just in case?

Ian Mackenzie
07-25-2004, 07:03 AM
I am not familiar with your 4430 acquisition.

Were they tested when purchased?

You could refer to one of the members who has experience with driver diaphragm fatigue/ damage.

If they are old or damaged it would certainly effect the HF performance.

Try another room and see how it goes but don't get your balls ripped off trying. Use the enclosure as a base for a nice Vase.

Ian

Figge
07-25-2004, 08:27 AM
Originally posted by Ian Mackenzie
You could refer to one of the members who has experience with driver diaphragm fatigue/ damage.


ok! how do i see if its damaged. wouldnt it be a distorted sound in whole range of the driver?

guy i bought em from claims they are 1989:s and my guess is its the original diaphragms in there.

so it could in fact be as simple as to change diaphragms?

i´ll pull the horns and see how it looks in there...seems like a good start, then move on from there....probably end up throwing the cd:s and player up on ebay:)

Figge
07-26-2004, 03:18 AM
ok! pulled!

it appears as they are not as claimed 89:s must be earlier? 2421A

Figge
07-26-2004, 03:19 AM
back of the diapragm! looks allright to me!

Figge
07-26-2004, 03:20 AM
and pulled diaphragm!

i really dont know how to se if its fatigue...

this is original...i can tell. all screws holding the horn were untouched!

Ian Mackenzie
07-26-2004, 03:41 AM
Hey,

They look nice, Can I swap you for my 2425 diaphragms? (joke)

I am not able to comment if good or not.

Ask the Widget he may know.

Ian

Figge
07-26-2004, 04:01 AM
and the other one!

this speaker has been screwed with!

Figge
07-26-2004, 04:01 AM
back of it!

these are 210 dollars each here in sweden! so they better not be damaged or tierd!:)

does the black marking at one of the screws indicate + or minus?
i found that they were wired diffrently inside the drivers!!
this must be corrected!

Figge
07-26-2004, 04:10 AM
this howerer i find strange!

the other driverback is totally flat look at the other pic:
this one is not flat.
is this normal?

Ian Mackenzie
07-26-2004, 05:57 AM
Better check they are genuine JBL parts also.

They are not cheap are they. I remember when I bought my 2425's the kits they were $200 each.

While you have them open I would verify everthing is working in A1 condition. I assume you bought them from a trader so a check up is a good idea particularly given the age of the system, even the Pads. That's the down side of dabbling with all these older monitors and probably why some are less than satisfied about about the sound of their 70's vintage systems.

Its like buying a T model Ford with the original tyres, if its mechanical it can and will wear out eventually. Get it reconditoned and it will run as good as new.

Regards the polarity, I would think black is electrical negative by convention. Assuming identical pairs inside and out symmetry of wiring in each driver should be maintained.

I would not worry too much about the back covers, that may just be a different manufacturing batch.

Figge, for more specific information on this monitor you need to get expert advise on the drivers and someone with hands on experience with the 4430, I am sure plenty of 4430 owners with the 2421 drivers on the Forums have been here and seen this before.

You could Pm John Nebel our site sponsor. John's got most the better JBL monitors including the 4430, 4435. I was very impressed with the way John's JBL 4435's performed when I heard them so I am sure he will put you on the right track.


Ian

Figge
07-26-2004, 06:11 AM
genuine jbl: i took the pic:s so the little numbers and letters on the coils are shown. thinking some of our experts here can tell a little what they are.

as for the price: i can buy used 2425:s or 26:s for less money than the new diaphragms. crazy price!

phase: well if its infact wrongly wired this most sertainly would affect the sound making exessive treble right?
i assume both driver diaphragms should be wired the same way. but must know for shure what the black mark is for.

authorized JBL: well i called them and asked about new diaphragms he said these "old" 2421 has a diaphragm that dont fit into the 2425, and the other way around. and he didnt seem to have heard about aluminium and titanium eather.

now giskard posted somewhere that the diaphragms are changeble between the 2421,2425 and 2426 cores. i do ceartainly trust giskard on this one. so i dunno how good/reliable answers i can get from them!

really need some serious help on this!

John Nebel
07-26-2004, 07:20 AM
The 2421's should probably be remagnetized if you are replacing the diaphrams.

Why not test it again, making sure that the wires with the black trace are on the black speaker terminals? Check the 2235s too.

I've been using 2426s and bought those new. They sound fine.

John

Figge
07-26-2004, 07:23 AM
well the wires from the crossover to the drivers were right!
but inside the 2421 it was diffrent between the two spakers.


so 2421 = alnico and 2425/26 = ferrite?

John Nebel
07-26-2004, 08:06 AM
Originally posted by Figge

so 2421 = alnico and 2425/26 = ferrite?

Yes, the older is alnico and newer ferrite. If replacement is cheaper, why not do that? It would eliminate guessing.

The JBL specs and Giskard both say the crossovers were unchanged through the driver changes.

You might check the power handling specs on the older vs newer drivers if you want to play the systems loudly - the capacity was increased.

John

PS one might suspect that the drivers were f**ked with because one was blown. That could indicate that both the diaphrams and magnets were affected.

Figge
07-26-2004, 08:13 AM
Originally posted by John Nebel
If replacement is cheaper, why not do that? It would eliminate guessing.




im thinking about it! and then sell my 2421:s maybe ít evens up so i didnt spend a dime?

BUT! the black mark on the diaphragm (the right screw in the pic below)
wich cable goes there red or black?

one of the drivers had black wire on the marking and the other one had red wire there!. shouldnt they be wired the same way?

this seem strange to me! someone obviosly has been fiddling around in there!

4313B
07-26-2004, 08:17 AM
"so 2421 = alnico and 2425/26 = ferrite?"

The alnico 2421A core running the aluminum D8R2421 diaphragm was the original driver for the 4430/4435. JBL switched to the ferrite 2425H core running the titanium D8R2425 diaphragm in subsequent runs. Final versions used the ferrite 2426H core running the titanium D8R2425 diaphragm.

The alnico 2421B core running the aluminum D16R2421 diaphragm was the original driver for the 4345. JBL switched to the ferrite 2425J core running the titanium D16R2425 diaphragm in subsequent runs.

The diaphragms/cores are interchangeble. The difference between the alnico LE85/2420 core and the alnico 2421 core is supposed to be that the LE85/2420 core runs the aluminum DxR2420 diaphragm without the diamond pattern surround. The actual cores are supposed to be the same, only the foilcals and diaphragms are different between the LE85, 2420, and 2421.

*****

"BUT! the black mark on the diaphragm (the right screw in the pic below) wich cable goes there red or black?

one of the drivers had black wire on the marking and the other one had red wire there!. shouldnt they be wired the same way?"

Hook the wires up so the diaphragm moves out towards you (away from the phasing plug) when you apply a 1.5V battery to the terminals. + terminal on battery to red post on core. If you have a hard time seeing the movement put something across the diaphragm mount to better see the change in distance.

Since you have two different back covers check their volumes to see if they are the same.

Figge
07-26-2004, 09:56 AM
ok! finished with the battery!

it appears in this case the black marking was + (red wire).
now when i put positive signal on it it pops up(away from the 2344).

gonna listen to it later on...neighbors are home :(

and the two diffrent backcovers seem to have the same volume.

im gonna check into changing them for 2425:s or 26:s. but they must be "H" right? J is 16ohm?

oh! and thanx all!

Mr. Widget
07-26-2004, 10:04 AM
Here's my 2 cents worth on this.

My guess is that these diaphragms are indeed fatigued. The likelihood of them needing to be remaged is not high but if convenient it wouldn't be a bad idea.

Replacing the drivers with newer used titanium ones would be the least expensive option especially if you sold your alnico 2421As. I imagine a pair of 2426s would give you slightly more top end than perfect 2421As.

It seems that either one of your drivers was replaced or these 4430s were not siblings. What are the serial numbers of the 4430s? If they match then someone replaced a driver.

Personally, if they were mine, I would get the new JBL 2421A diaphragms and stay with the original aluminum diaphragms. While the aluminum does wear out faster than titanium, it is smoother sounding when good and will certainly last longer than you keep these speakers in a home environment. (Sure you will listen to these until you die they are that good... we have all said that before... realistically in a home environment the fatigue issue is almost nonexistent as long as you aren't blasting your neighbors on a daily basis.) These original drivers were not replaced because the newer drivers were better... the 2425 and subsequent 2426 were significantly less expensive for JBL to make!

Ok, maybe that was 4 cents worth.

Widget

Figge
07-26-2004, 10:14 AM
Originally posted by Mr. Widget
What are the serial numbers of the 4430s?

255273 and 255530. any ideas what year that is?

Mr. Widget
07-26-2004, 10:31 AM
Nope, but that seems far enough apart that they are probably outfitted with their original components.

Based on the 2421As they must be from the first year or two of production. Giskard has posted a matrix of the different monitors and the years they were in production. Doing a quick search I couldn't find it though.

Widget

Figge
07-26-2004, 10:41 AM
this one?

4313B
07-26-2004, 11:16 AM
"These original drivers were not replaced because the newer drivers were better... the 2425 and subsequent 2426 were significantly less expensive for JBL to make!"

Depends on your point of view. From a manufacturing perspective the titanium diaphragms offered substantially improved reliability. They also offered slightly increased high frequency response. In Pro applications the titanium diaphragms were unquestionably superior. The old aluminum diaphragms would shatter against the phasing plug. For home use, for which these systems were never intended, the increased damping of the aluminum diaphragms is generally preferred.

"and the two diffrent backcovers seem to have the same volume"

I figured as much but it's nice to be certain.

"ok! finished with the battery!"

You checked both drivers?

Mr. Widget
07-26-2004, 11:22 AM
Originally posted by Giskard
"These original drivers were not replaced because the newer drivers were better... the 2425 and subsequent 2426 were significantly less expensive for JBL to make!"

Depends on your point of view. From a manufacturing perspective the titanium diaphragms offered substantially improved reliability. They also offered slightly increased high frequency response. In Pro applications the titanium diaphragms were unquestionably superior. The old aluminum diaphragms would shatter against the phasing plug.



Hey, I'm not dumping on JBL, but for critical listening in a studio or home environment it is my opinion and that shared by many others that aluminum diaphragms sound better as well as measure better in the area of distortion. I agree that the titanium diaphragms do have a bit more top end and to some that might be the tipping point.

Ultimately it's all personal preference... I am on a Beryllium kick these days myself. :D

Widget

4313B
07-26-2004, 12:05 PM
I didn't think we were debating the fact that aluminum sounded better. I was trying to get across why JBL went with titanium. There is a very specific reason that has nothing to do with personal preference.

Don McRitchie
07-26-2004, 12:13 PM
Here's some background on JBL compression driver and diaphragm evolution. There is more detail here:

http://www.audioheritage.org/html/projectmay/technology/435be.htm

From the very first JBL compression driver of 1948 (the D175), until 1980, there was no change in the basic engineering of JBL's small format compression drivers. They all used an Alnico motor with an aluminum diaphragm and tangential surround. 1980 saw the first major change with the development of the diamond surround. While still constructing the diaphragm out of aluminum, the surround was pressed into a series of diamond shaped polygons. The reason for this was to increase the HF extension by taking advantage of a phenomenon known as parasitic resonance. The smaller diamond polygons increase the second resonance to the point that it reinforces HF response in the highest audible octave. This was primarily intended for the large format 375/2440, which otherwise was restricted in response to 10khz. Using parasitic resonance, extension could be pushed to 18khz and eliminate the need for three-way systems in most pro applications. While the small format compression drivers were in less need of this HF boost, they were found to benefit as well and they were converted to diamond surrounds at the same time.

However, there was a penalty to be paid for this change that did not become fully apparent until a high profile incident in 1982. The problem was that the diamond peaks concentrated stresses to a much greater degree than the previous tangential geometry. The stress concentration led to premature failures of the diaphragms. The incident in question was the premier of the brand new JBL installation at the Academy of Motion Picture Arts and Sciences theatre. It was considered quite a coup for JBL to replace the old Altec sound system with their then state-of-the-art cinema system (for which JBL would later win an Academy Technical Award). However, during the premiere, the diaphragms on nearly all of the 2441’s failed. As a result, an edict was issued from on high at JBL to immediately fix this issue. Six months later, the result was the titanium diaphragm.

Titanium is an order of magnitude more resistant to fatigue failure. The diamond surrounds, with their increased HF response, could still be employed, but power handling was increased by 30% with greatly increased longevity. Nonetheless, there were tradeoffs involved. As Giskard stated, titanium has poorer internal damping than aluminum. Further, titanium has reduced stiffness meaning that it is driven to breakup at a lower frequency than aluminum. The net result is increased distortion. This increase is relatively miniscule, but many listeners find it audible in critical applications like monitoring or home hi-fi.

For this reason, JBL has reverted to aluminum and introduced beryllium diaphragms on their latest compression drivers. The use of a composite mylar surround has solved the fatigue problem. The use of beryllium has solved the diaphragm breakup issue so that these drivers have the lowest levels of distortion of any compression driver yet built by JBL. The smaller diaphrams (3" vs 4") of these newer drivers furhter pushes the frequency of breakup modes and increases overall HF response. Finally, applying EQ allowed these drivers to have the same UHF extension without the need for parasitic resonance and its attendent distortion.

John Nebel
07-26-2004, 12:20 PM
As for the remagnetization - JBL service has always recommended such to me when an older driver is sent in for repair and I've followed their advice.

Maybe I'm too conservative, but so much of my life is dealing with electrical and electronic failures as to make me a strong Murphy adherent.

http://www.murphys-laws.com/murphy/murphy-true.html

John

4313B
07-26-2004, 12:41 PM
Fantastic information as usual Don. :)

*****

"This increase is relatively miniscule, but many listeners find it audible in critical applications like monitoring or home hi-fi."

Back when I bought my personal pair of 4430's it was suggested by JBL that I buy the 2421A instead of the 2425H for Home use (even though "JBL Professional Products are not intended for Home use" and JBL has little sympathy for individuals who insist on running Pro gear at home). For several days I A/B'd the "2421A" 4430's against the "2425H" 4430's and could not discern the sonic superiority of the aluminums. I chose the 2425H's. At the time, all I had was Crown gear (considered only slightly better than a direct AC outlet dump at the time, perfectly adequate for Pro use but utterly pathetic for Home use). It wasn't until I got a Citation XX hooked up to the 4430's that I was able to appreciate the difference aluminum could make. Today I run the aluminum diaphragms in the 2425H cores. Ultimately though, do I really care? No. I could pop the titaniums back in and live a happy life.

Figge
07-26-2004, 12:59 PM
to Giskard: yes i tested both. and one was wrong!

i found two 2425:s with "new" as in (not used since he bought them) alu diaphragms still in theyr boxes! on an add i maild up the guy and he wants 234 bucks. should i jump at them? seem like a killer price!

4313B
07-26-2004, 01:03 PM
Originally posted by John Nebel
As for the remagnetization - JBL service has always recommended such to me when an older driver is sent in for repair and I've followed their advice.Yeah, I just do the remag and worry about other stuff instead. Mr. Widget is probably right but why refuse a remag if it's offered as a service.
Originally posted by Figge
to Giskard: yes i tested both. and one was wrong!

i found two 2425:s with "new" as in (not used since he bought them) alu diaphragms still in theyr boxes! on an add i maild up the guy and he wants 234 bucks. should i jump at them? seem like a killer price! Good. So what wiring scheme did you end up with? The terminal with the dot going to which spring loaded post?

The 2425 doesn't come stock with the aluminum diaphragm.

Figge
07-26-2004, 01:25 PM
Originally posted by Giskard
Good. So what wiring scheme did you end up with? The terminal with the dot going to which spring loaded post?

red wire on the "dot"! is this "normal"?



The 2425 doesn't come stock with the aluminum diaphragm

i know. he had bought the drivers onceupon a time with crappy diaphragms in them. and had two new in box alu lying around so he threw em in! tested and decieded to go with 2" instead for som big Fostexhorn he had!

i guess there are no sonical diffrent between the 2421 and 2425 cores?

Zilch
07-26-2004, 02:08 PM
Originally posted by Figge
to Giskard: yes i tested both. and one was wrong!


It sounds like you've found and fixed the problem, a phase reversal. Hook 'em back up and enjoy!

[Unless you just HAVE to experiment some more, of course.... :D ]

Figge
07-26-2004, 03:25 PM
i love experimenting.....well aslong as it gives results anyway :)

boputnam
07-26-2004, 05:01 PM
Originally posted by Figge
one of the drivers had black wire on the marking and the other one had red wire there!. shouldnt they be wired the same way?
I can not believe it! A polarity quiz and I slept through it... :(

Giskard got it right, and for all, the black mark on JBL diaphrams, from my testing, should be wired Red. That is somehow JBL's logic to denote both the "negative" side of the diaphragm and the position of the Red lead.

Dang it, missed the whole thing. Dang it... :banghead:

Figge
07-27-2004, 01:52 AM
hi bo!

no worries!

strange tough this is the second pair of jbl:s ive had with wrong wierin´! my 4311:s had swaped cables on one woofer! and now this....

well listned to them to day and yea! sound good, but not so big diffrens i would have thought! (might have been that the cables were switched on that driver to compensate the wrong inside it) cant remember how that horn was wired. i didnt look just unhooked it, since it was the second speaker i worked on.

and now its obvious: the 2344 is doing something funny to the room, sertain frequences in the mids becomes boosted(not much) .this is where i work with speaker placements and roomreflections?. problem is the speakers cant be moved they gotta stand where they are.

as for room reflections: i just wouldnt be a popular guy here if started with damping the livingroom.

is this where the eq comes in?

as u can see the placing is not very good!...the room aint very good eather!

Windows! not good!

Figge
07-27-2004, 01:54 AM
uh oh!! doorway!

grilles are off couse our damn cat is walking by here in the doorway thinking its claws are not as sharp as they should be, so he looks at the grilles and start out sharpening em! now he does it on the sofa....who cares? :)

Figge
07-27-2004, 01:55 AM
listening position! not very high waf as it is:) personaly i dont care how it looks. i´ll leave that up to the gal...

Ian Mackenzie
07-27-2004, 03:38 AM
I would buy one of those audio check out CD's with phase tests L + R check OR with the rear terminal polarity reversed red and black. This assumes you are convinced horns are now in identical phase and also in absolute phase with the woofers.

If the image is centre b/n the speakers and not pressured in both ears at least they are setup okay.

Your room has plenty of reflective surfaces and with the 100 x 100 dispersion of the horns there will be some odd response characteristics.

"IF " you can put a throw rug (a nice expensive persian rug) immediately in front of the speakers it will damp some of the early reflections. Furniture in ther vacinity of the listening position will also improve the subjective evaluation. I doubt if an equaliser will help much.

Ian

Chas
07-27-2004, 06:21 AM
Hey Figge, when I first got my 4430's, I positioned them in front of my large 43XX's that were already about 5-6' from the rear wall. I had wierd stuff happening too.

Once I moved the "big guys" out and replaced them with the 4430's in the same location, things improved considerably. They definitely liked to have some space around them, I was surprised that they were sensitive to objects behind them. May have been a consequence of the room, furniture placement, etc.

You might try an experiment by moving them forward, away from the back wall, into the room and see how they perform.

BTW; I have yet to open and examine the drivers and wiring inside my 4430's, they are put away for a while until I am finished dabbling with the 43XX's. I'll let you know if see anything odd with mine.

I think mine will need diaphragms too, as the midrange resolution and definition does not come close to a 2441/2311/2308 based system. Also there is a noticable lack of HF apparent.

Figge
07-28-2004, 03:57 AM
hi chas! as u say they like some workingspace!

i moved them about a meter out in the room and i put some BIG pillows in front of them...and wow! i could play much higher without the horns hurting my ears! a more detailed sound over all! but the bass punch did become nonexisting! however the deepest bass improved!


i then placed them back as before and pushed them in flat agaist the wall! this was allso better than before. i think that doorway is not helping me here!

gotta talk the gouvernment into replacing the furnituring in the whole room. so i get the speakers onto the opposite wall! there it dont matter if the speakers stands in the middle of the floor.
however i dont think this will take only one "romantic" dinner out!!

plan B: is to move down in the basement! there is a room about the same size not used down there...its concrete ofcourse but with wood ribs allover and small windows up near the cealing.... down there i can do whatever i want!

Ian Mackenzie
07-28-2004, 05:15 AM
Yes,

Time to see the Boss..

Enjoy, they are a fine loudspeaker.

Ian

Figge
07-28-2004, 10:23 AM
just wondering: how were/is these beuties installed in the real studio? in corners, flat against wall? on wall? i´ve seen one setup even was installed in the wall!.

johnaec
07-28-2004, 10:50 AM
I've seen pictures of the 4430 with the horn mounted sideways - was this a standard user "option"? I'm sure this was for horizontal mounting.

John

Figge
07-28-2004, 11:07 AM
Originally posted by Zilch
R=E/I


oh! missed this one!

shouldnt it be R=U/I?

Zilch
07-28-2004, 11:47 AM
:rockon1: :bouncy:

Alex Lancaster
07-28-2004, 02:02 PM
Actually V=RI, or R=V/I, whatever.

Figge
07-29-2004, 09:42 AM
i tried moving em out about 2m in the room. and shit! what an improvement! suddenly there´s new instruments playning! never heard before....cool! bass is crystalclear. the problem i had when starting this thread is gone shure some crappy recording still sounds like crap...but good crap, no brainfrying treble anymore!


however theres something funny going on around 1khz. i belive this would be the crossover? bi-amping maybe will solve this?

johnaec
07-29-2004, 09:51 AM
Originally posted by Figge
however theres something funny going on around 1khz. i belive this would be the crossover? bi-amping maybe will solve this? What's it doing? If the HF phase is backwards, (easy to do with JBL's confusing standards), it will definitely cause anomolies at crossover. Maybe you could switch the HF polarity as a check...

John

Figge
07-29-2004, 10:22 AM
Originally posted by johnaec
What's it doing?


first: everything is in phase...now...doubblechecked!


well for ex. was playing van the man "streets only knew your name" room was rockin´and i was happy! then the girls in the quire came in and started off! i believe it is somewhere around 1khz maybe just under....dunno! anyway it sounded like "dunno the word" (if ur on stage and take the mic ur singing in and put it infront of the speakers u get a horrible hurtin´ thing going!) thats the word im seeking here... something like that happend to the girls! and some other records too...just that frequency!

everything else is just fabolouse!

oh! and i aint been smokin´! :no:

Zilch
07-29-2004, 10:25 AM
Originally posted by johnaec
Maybe you could switch the HF polarity as a check...

LOL!!

[Alas, poor Figge is doomed...]

It's the DOOR, I tell ya!

Damping with naked pulchritude is the only appropriate solution.

Trust me, here....


[Or, maybe, Widget will suggest something....]

Mr. Widget
07-29-2004, 10:27 AM
Hey Figge,

Are you saying that you are getting a 1KHz sound out of the speakers kind of like feedback?

If so, are you sure the compression driver's diaphragms are properly centered? Could it be a rubbing coil from one of the woofers? Is this sound the same in both speakers?

Widget

Figge
07-29-2004, 10:33 AM
well not exactly...but the freq around there is how should i put it very.....intense would be a better word! even at pretty low volumes...almost as if there was a phase problem between the woofs and horns?? my first guess was someting like the crossovers but...those horns shure loads up the room...could be some reflections also.

otherwise theyre now very smooth...compared to when placed in the corners.

Figge
07-29-2004, 10:40 AM
Originally posted by Zilch
Alas, poor Figge is doomed



beggining to believe that myself!:p

was alot easier owning the damn L-100:s never any problems! everything i did with em sounded the same :)

Figge
07-29-2004, 11:02 AM
im 200% shure the drivers are correct wired. i will check once again! i have hooked the cable with black stripe onto the black terminal on all 4 drivers. the woofs are supposed to pop in when given positive signal on the red terminal....right? i have tested this on the compressiondrivers and they did what they should!
and so does da woofys!

boputnam
07-29-2004, 11:20 AM
Originally posted by Figge
was alot easier owning the damn L-100:s never any problems! everything i did with em sounded the same :) Don't get me started... :no:

OK, Figge, I give - send me your 4430's and I'll let loose of a pair of splendiferous L100's. Deal??

Figge
07-29-2004, 11:23 AM
i just knew u were gonna wake up on that one! :)

well when i said:
everything i did with em sounded the same

i didnt mean good!:)

Chas
07-29-2004, 11:25 AM
then the girls in the quire came in and started off!

Geez, that never happens when I play my JBL's - you're a lucky guy.....hmm....must be Swedish girls too....:banana:

But seriously, does it happen with vinyl AND CD? If it's vinyl only, then it could be acoustic feedback through your turntable.

Figge
07-29-2004, 11:29 AM
lo chas!


well in this case and all others so far is on cd...the vinyl simply rock´n roll!

soon u can see both my cd-player and cd:s on ebay! :)


that never happens when I play my JBL's - you're a lucky guy

well u gotta check the phase on the drivers and then move em around a day or two...then it just happens! :)

it did infact show up a swedish girl too! asking questions about my fine placement of the speakers!
this was not on CD it turned out she was the girlfriend!

Mr. Widget
07-29-2004, 11:54 AM
Originally posted by Figge
well not exactly...but the freq around there is how should i put it very.....intense would be a better word! even at pretty low volumes...almost as if there was a phase problem between the woofs and horns?? my first guess was someting like the crossovers but...those horns shure loads up the room...could be some reflections also.

otherwise theyre now very smooth...compared to when placed in the corners.

Something seems very wrong here. Switching polarity of the drivers will yield a fairly subtle change. You are not going to get a huge 1KHz peak by switching the driver polarity. A small 1KHz bump will give the speakers a honky horn like quality. If your issue is very pronounced as you have said I would assume you have a significant problem. You need to go about this methodically changing one thing at a time. Have you listened to both speakers independently? Have you tried switching left and right speakers? Have you tried changing your electronics. Could you have a defective amp or preamp?

Widget

Figge
07-29-2004, 12:42 PM
ok listned to them separately. slight honking in one ch (i cant mono) but girls sounded very fine :)

electronics: well ive changed da amp from a quad 405 to a 405mk2:) the first was a little brighter!

preamp i dont have at the moment. doing some business with HP to get his sony TAE86B. shure it will be fine. right now i use a thing i built in school:) its a box with a pot in so i can adjust volume between cd and amp. well well.

cd is a denon dual dj cd....wich is a suspect in this case!

Ian Mackenzie
07-29-2004, 01:37 PM
i tried moving em out about 2m in the room. and shit! what an improvement! suddenly there´s new instruments playning! never heard before....cool! bass is crystal clear. the problem i had when starting this thread is gone shure some crappy recording still sounds like crap...but good crap, no brainfrying treble anymore!

however theres something funny going on around 1khz. i belive this would be the crossover? bi-amping maybe will solve this?

Figge,

I tend to agree with The Widget.

Suggest you play a well known classical recording with good production values, even the Chesky audiophile demonstration disk. You will find it hard to assess subjectively whats going on otherwise.

Moving the enclosures back and forth from the rear wall will alter the sound significantly but you may be trading one problem for another.

The 1 khertz anomally could be a reflection from the near field object in your room causing a peak The 4430 should well clear of any objects in the room at least a metre due to the wide off axis reverberant response (power response).

Do you have a PC with a Sound Card? If you have buy your self a Beringer microphone and starting doing some measurements by down loading RTA analyser which will allow you to measure the response at the listening position.

Do a search on on the forums for Spectra Plus. Bo has played around with this thing a fair bit.

Ian

Paul D
07-29-2004, 03:00 PM
Are you sure that the crossovers are the correct one's!
They have built in EQ for the 2344 horn. Without this EQ, the horn tends to have a peak between 1 & 2 KHZ. I had a pair of these horns with 2426's and the peak definitely bothered my ears!! I bought a JBL 5234A electronic crossover and the correct cards for the 4430 and noticed a huge difference.

I still have the crossover and cards if you are interested.

Figge
07-29-2004, 04:20 PM
Originally posted by Ian Mackenzie
The 1 khertz anomally could be a reflection from the near field object in your room causing a peak The 4430 should well clear of any objects in the room at least a metre due to the wide off axis reverberant response (power response).

Do you have a PC with a Sound Card? If you have buy your self a Beringer microphone and starting doing some measurements by down loading RTA analyser which will allow you to measure the response at the listening position.

Do a search on on the forums for Spectra Plus. Bo has played around with this thing a fair bit.

Ian



1. probably is some funny reflection making the bump!
paul: i believe its the right xovers. but what do i know?
my first thought was that it was some funny in the xoverfrequency and bi-amping would solve it...i dunno. do u have he 4430/35 cards in it?


2. yes i have a laptop located on the livingroomtable...how practical!


3. allready d/l:ed the spectra plus


just the mic is missing! i guess borrowing a "allround" mic from my buddies studio is out of the question?

Figge
07-30-2004, 02:30 AM
when bi amping these speakers: is the eq in the crossover still available? or is it bypassed?

oh! i swaped places on the speakers so that the horns are "out" then the honking went down pretty much...still a little left sometimes. but since the room aint a studio i guess i have come up to pretty good results.

also gonna try another cd player.

Ian Mackenzie
07-30-2004, 04:00 AM
The horn Eq is intregral, the active crossover feeds the woofers directly as I recall and the horn via a 20 uf capacitor which forms parts of the crossover function.

Giskard is the Guru on that one, he has owned th 4430.

Ian

Chas
07-30-2004, 05:38 AM
Hey Figge, if you have had the HF diaphragms removed from their drivers, this might be causing your troubles. When re-installing the diaphragms, it is necessary to sweep a range of frequencies at a specific voltage level per JBL specifications.

This is done to insure the voice coil is properly aligned and true in the gap. Otherwise a resonance is possible at various frequncies due to intereference with the motor assembly. Did you remove the diaphragms? I seem to recall that you posted some photos of them.

Figge
07-30-2004, 05:50 AM
yepp i removed em..

i had something like this in mind when puting them back...
but there where 2 pins to "steer" it right when i put them back.
once on the pins it was "almost" solid, couldnt movit! sideways that is. well ok! very very very little....

very nice precision!, compared to when i was changing the tweeters on my infinity sm-120:s u had to center the coil by feeling that it didnt rub! crap!

Ian Mackenzie
07-30-2004, 06:09 AM
Figge,

Does your CD player have digital out?

If so consider the Apogee Mini DAC, Apogee is the world leader in D/A converters.

http://www.apogeedigital.com/products/minidac.php

I will be considering this unit for my own use at some stage.

Ian

Paul D
07-30-2004, 07:16 AM
[QUOTE]Originally posted by Figge
[B]1. probably is some funny reflection making the bump!
paul: i believe its the right xovers. but what do i know?
my first thought was that it was some funny in the xoverfrequency and bi-amping would solve it...i dunno. do u have he 4430/35 cards in it?


Yes, the cards are for the 4430/35. The only problem I had with the 5234A is that it was set up for hard wiring. I put some female RCA terminals on it but still had a grounding problem. As suggested by a JBL Tech, I ran a ground wire connecting all my components together and the noise went away.

You can have the crossover & Cards for $50 + shipping if you want it. But it sounds like this will not solve your problem.

Chas
07-30-2004, 07:47 AM
Hi again Figge,

It seems like this could be the problem. Despite the fact that the locating pins create a tight, snug fit, there is still alignment required as the screws are tightened down. You need an AF oscillator (signal generator) connected to a power amp and the driver.

Perhaps someone here (Giskard, maybe) could tell us what the sweep frquency range and voltage level is that needs to be applied to the driver terminals.
:help:

Figge
07-30-2004, 11:48 AM
ok now i have cleared out the bedroom for damping material and have been doin´a little testing. heres an example that improved very much...and theres pillows and clothes just about everywhere in the vicinity of me and the speakers. now it´s litteraly rockin´in here! and the little quad is doin´ a fabolouse work!
it is still some problems from the cealing and backwall...but nothing that bothers!

amongst many records played i threw on AC/DC "The Jack" havnt listned to that one since i had my (dead dog) infinity Q jr...no im holding the ace!....ehm i mean the Jack...

well well its just too damn fun experimenting with this...soon i gotta put all stuff back into the bedroom...and move back the speakers:(

have any one heard these speakers in a real damped out studio?

can imagine them beeing very hard to beat when in there right inviroment!

Figge
07-31-2004, 04:01 AM
Originally posted by Ian Mackenzie
Does your CD player have digital out?



i checked and it dont.

that little thing looks pretty damn nice! whats the prize on it? i didnt see any pricetag

Ian Mackenzie
07-31-2004, 05:23 AM
Figge,

Without digital out of the CD your a no show, unless of course the Laptop plays CD roms.

Its whats called a Trans-Mogg-Rification according to "The Who.".(the 70s Expression of the Internet).

Ian

Zilch
07-31-2004, 11:24 AM
guessin' a random stack of CD jewel boxes sittin' on top of a 4430 are gonna resonate at:

Oh, I dunno, maybe 1000 Hz? :p

I'm sayin' it for the last time, now: A lineup of babes in the doorway is the ONLY workable damping scheme here.

[Arrange pillows accordingly...]

Ian Mackenzie
07-31-2004, 12:26 PM
Figge,

As an idea, search for another forum members in your location and arrange a second opinion on your speaker / location.

You may even be able to compare alternate JBL models (ones with more tightly controlled dispersion)

Ian

Figge
07-31-2004, 06:35 PM
no no...no 4343:s here! these just gotta be "tamed" then its all good!

btw 434x is just far from easy to get hold of!

OH! and daddys L-300:s IMO dont compare!

Ian Mackenzie
07-31-2004, 06:41 PM
OH! and daddys L-300:s IMO dont compare!

That may not be politically correct.

Ian

Figge
07-31-2004, 06:59 PM
were not talkin` politics!:)

well his 300:s sounds damn fine...infact theyr really reelin´& rockin`


both he and i agree the 4430:s sounds very much less like loudspeakers.

Ian Mackenzie
07-31-2004, 07:07 PM
Yeah,

A bum cheek upgrade might be required, just tell that to all the 4333 owners.



Ian

4313B
08-02-2004, 05:26 AM
Originally posted by Figge
OH! and daddys L-300:s IMO dont compare! While I am certainly an advocate of the 4430, I have to say in defense of the L300/4333 that updating the older networks to at least "4430 standards" is worthwhile.

Figge
08-02-2004, 06:14 AM
Originally posted by Giskard
I have to say in defense of the L300/4333 that updating the older networks to at least "4430 standards" is worthwhile.


i can imagine...and it would be rather intressting to do just that!

btw is there a thread somewhere around here on that?.


an idéa could be to add a DIY/modification forum-section.

Figge
08-02-2004, 12:16 PM
ok since other people use these speakers in a non-studio enviroment and get good results: its simply my room that sucks...cant be no other explenation. tested em today in the other end of the room and the 1khz thing dissapeared but now theres something going on higher up in voices...i get tinitus with a few watts... with l-pads down on -3. thats a little extreme.

when i come to think of it: the 4311 was screchy in here too

Mr. Widget
08-02-2004, 01:09 PM
I bet you are right about the room. It does seem to be a bit lacking in sound deadening, carpets, drapes, or over stuffed furniture. For my HT I lined all of the walls with curtains. It really helped, and when I am not using it for audio they compress into the corners.

I would also bet some of the harshness and screechiness would be improved with new 2421 diaphragms. When Bo replaced his on his 4345s he was blown away by the improvement.

Widget

Figge
08-02-2004, 02:25 PM
i gues i understand a little how these speakers work now..so i have some experiments lined up that im gonna start with.

about the diaphragm: is it age or use that weakens them...

reason i ask is there was a guy who had "new in box" diaphragms for sale nearby. dunno how old they are...he said they were a couple of years but who knows?

boputnam
08-02-2004, 03:16 PM
Originally posted by Figge
about the diaphragm: is it age or use that weakens them... Use. It is expected for metal to fatigue with use. Some have posited that diaphragms could brittle with age, but I cannot comment on that.

Figge
08-04-2004, 09:04 AM
3 questions:

1 if bi amping these speakers must one have the JBL 5234 with 4430 cards or do a whatever brand crossover at 1Khz work as well?

2 i have two quad 405:s could i use these (no level controls on them) or must i have amps with levels?

3 what is radian diaphragms for JBL and altec?

speakerdave
08-04-2004, 09:08 AM
1 The 4430 cards would be much better. I wouldn't biamp these speakers.

2 The crossover will have level controls.

3 They are aftermarket/third party replacements.

David

John Nebel
08-04-2004, 10:14 AM
There is also Ian's crossover project on another thread or $$$ http://www.passlabs.com/prodlit/xvr1lit.htm

John

Figge
08-06-2004, 09:34 AM
Originally posted by speakerdave
1 The 4430 cards would be much better. I wouldn't biamp these speakers.


ok i can understand the 4430 cards are better to use than some other...but why not bi-amp them?

Ian Mackenzie
08-06-2004, 11:38 AM
Its depends on ''how good the xover is and how good your amp is.

I tell you what...I'll make you a couple of xover project boards for you.

Ian

Figge
08-06-2004, 12:00 PM
hi ian!

im a total noob to this bi-amping thing...

i have the 2 quads and thought: what the heck!..why not?

i did imagine that the amps will be less strained when they dont have to take care of the fullrange...am i correct?




I'll make you a couple of xover project boards for you

thats great of you! how does those work?

Ian Mackenzie
08-06-2004, 04:02 PM
See the crossover project thread for details.

Actually for the best sound, if you are smart enough you can form a passive 6/octave HP filter on the input of your amp and use a buffered active filter for the LP filter.

Ian

Figge
08-06-2004, 05:34 PM
ok...im smart :)

sounds good would this work with my 4430:s




you can form a passive 6/octave HP filter on the input of your amp and use a buffered active filter for the LP filter.


i have no clue how to do that...:)

tell me how to do...and i´ll try.

speakerdave
08-06-2004, 07:26 PM
Originally posted by Figge
...but why not bi-amp them?

I have no experience with this speaker, so those who do should be listened to harder. But to me it would be a question of return for time and money. Truthfully, part of my input is this: until recently the crossover assembly for that speaker was available in the miscellaneous parts list--for $565. That suggests to me a good bit of effort and resources went into matching that driver/horn combo with that woofer. Then I would ask myself how much engineering expertise and hardware resources am I going to be able to bring to bear on the problem. That's what I mean, really, when I say I wouldn't biamp those speakers. Do you own a SACD player? If not, the return of sonic improvement for money would be greater there, I think.

But it's up to you.

David

Edit: So, I mean to say, I would consider the above, but I would also look in the box at the crossover, and see if the quality of the parts and the complexity of it impressed me. The schematic looks not too simple, not too complicated, but it does net tell the exact nature of the components that were used. If I had a JBL crossover and the 4430 card or could make one, and had an extra amp sitting around, I would try it. But I don't think I would invest a lot of resources on speculation that the difference between biamping and passive crossover would in this case knock me over.

If you are hearing upper register edginess, I think you have done a good job of tracking down room problems, but you should also consider that this is a speaker that might be telling you things about your electronics and your program source material, as happened to me when I got my LSR32's.

Enjoy the hunt!

David

Ian Mackenzie
08-06-2004, 08:05 PM
I agree that perception is 9/10 of reality, particularly with audio.

However, JBL has included bi amping for a reason. Bi amping can bring improvements in certain situations like bass damping at Fb, and improved dynamics and reduction in harmonic distortion.

Of course it wan't overcome room treatment problems or location of the boxes which should be addressed first.

Obviously the source should be the best you can afford.

And without sounding harsh, the much loved Quad 405's are a bit anal and lack the sound stage these monitors deserve.

Another reason to bi amp with a better amp on the highs.

Ian

edit

Good post Speakerdave.

Perhaps a new Cd player is first and foremost!

speakerdave
08-06-2004, 08:13 PM
Hi, Ian.

Figge
08-07-2004, 04:41 AM
hi dave!

thats some very intressting pionts u made there! worth thinking about!

well if i get hold of a crossover i´ll try bi-amping.

the quads are vintage gear and it´s basicly a good amp...it makes a nice sound, however it renders voices pretty poor(like they are behind a blanket)...

seen some modifications on www i´ll try them on one amp and if no good they both goes for sale...

the room reflections: i think i have a clue now whats going on in the room...ive put in a big rug/carpet. and if i pull the curtains over the windows it makes pretty good in there!

also noticed that moving the speakers change the reflective sound very much, even if moved very little!.

im beggining to find the "right" spot for them.


but one thing that have bothered me since i bought these speakers is: one L-pad seems to be fiddled with! the knobs are not centred and sitts about 2mm in behind the foilcal. very irritating due to: its impossible to set it like the other one. say if i want to set mid to -1db i do it on the untouched L-pad first and then i have to simply look at the angle on the nob and set the other the same angle. since the db scale dont match. heres some pic:s

any idea what to do. is it easy to fix? i took a look at it when i pulled the horns. but i didnt wanna make it worse so i let it be.


btw: this is the same speaker that was wireswapped on the diaphragm. hmm...

Figge
08-07-2004, 04:43 AM
the pics dont really show how much wrong they are

speakerdave
08-07-2004, 08:16 AM
Other 4430 owners may be able to tell you whether that misalignment of the controls with the foilcal cover is common. If it were me, having found the wiring error, if that is in fact what it was, and the crossover were accessible, I would give it a complete inspection and look for signs of "fiddlling."

However, the difference in the scales is obviously original. Why do you want the knobs to be at the same angle? Or at the same "dB"? I would think you would set these based on your preference for what it sounds like in your room, beginning with the mid level.

David

Figge
08-07-2004, 08:21 AM
Originally posted by speakerdave
Why do you want the knobs to be at the same angle? Or at the same "dB"?


just thought that it would be good to have the levels set the same on both speakers with some kind of accuracy.

speakerdave
08-07-2004, 08:41 AM
Oh, I see. You mean the same from speaker to speaker. Yes, I think ordinarily you would. Can't you do it?

Figge
08-08-2004, 08:00 AM
not by the db scale i cant...since it dont match the knob...on one speaker that is...the other is just perfect!

speakerdave
08-08-2004, 10:15 AM
I think I understand. A photo showing the difference would help. You may be stuck with trusting your ears, not a bad thing. Perhaps you can balance them be centering pink noise on mono. If you don't have a test CD with pink noise, try interstation hiss from the FM tuner. Switch the tuner or preamp to mono, put yourself in the prime listening position and see if the sound is centered between the speakers. Be aware other factors may influence this, such as asymetrical speaker placement. If you can get a test CD with tones in the relevant frequency bands that would be more accurate. Be careful not to play test tones too loud.

Another thing you might do is try a sweep tone (again, on a test CD). If it seems to move as you sweep through the low mid and high frequency bands, then there is an imbalance. Sometimes you can discern the same thing with passages of music that go up or down the scale, but with a speaker whose first crossover is at 1000 cycles, that may not be true.

David

Figge
08-08-2004, 10:24 AM
well look at them pic:s i posted...the knobs are supposed to stick out of the holes a little... on the pic u see the knobs on that speaker is behind the foilcal and not centered in the hole wich makes inaccurate readings towards the scale.

i really dont understand how they have become this was...or how to correct them....

i cant imagine jbl letting them out of the factory this way...so someone must have been there screwing around behind the foilcal..

Mr. Widget
08-08-2004, 10:53 AM
Originally posted by Figge


i cant imagine jbl letting them out of the factory this way...so someone must have been there screwing around behind the foilcal..


I am sorry to say that even our beloved JBL let's things out of the factory they shouldn't when Jim Lansing's ghost is taking a break and not keeping an eye on quality.:)

Seriously, you can't fully rely on the screen printed graphics. Those numbers are indications and are not laboratory calibrated. If you want to set them up so that the response is reasonably accurate and the same left to right, you need a test signal source. It could be an audio generator or test CD and you need at least an SPL meter and preferably an SPL meter and a RTA of some type.

With these simple goodies you can rough in a balance in a few minutes and after extended listening, if something bugs you, you can tweak by ear.

Widget

BTW Get some curtains or Sonex panels or other room treatment. It will make more of an improvement than changing any cable in your system. Even between Radio Shack to $1000 a meter interconnects.

Figge
08-13-2004, 12:38 PM
ok now i´v got HP:s sony TA-E86B preamp and i "borrowed" a son of ampzilla from.. ole daddy and this shure made a big diffrence from the quad driven by my home made volume-pot! infact it like day and night...not that the quads are bad amps....just that they are pretty hard to drive with other pre-amps the quads own! i used my homebuilt pot for a luxman M120A once and it was Sweet!

herki the cat
03-02-2010, 01:34 AM
Here's some background on JBL compression driver and diaphragm evolution. There is more detail here:

http://www.audioheritage.org/html/projectmay/technology/435be.htm

From the very first JBL compression driver of 1948 (the D175), until 1980, there was no change in the basic engineering of JBL's small format compression drivers. They all used an Alnico motor with an aluminum diaphragm and tangential surround. 1980 saw the first major change with the development of the diamond surround. While still constructing the diaphragm out of aluminum, the surround was pressed into a series of diamond shaped polygons. The reason for this was to increase the HF extension by taking advantage of a phenomenon known as parasitic resonance. The smaller diamond polygons increase the second resonance to the point that it reinforces HF response in the highest audible octave. This was primarily intended for the large format 375/2440, which otherwise was restricted in response to 10khz. Using parasitic resonance, extension could be pushed to 18khz and eliminate the need for three-way systems in most pro applications. While the small format compression drivers were in less need of this HF boost, they were found to benefit as well and they were converted to diamond surrounds at the same time.

However, there was a penalty to be paid for this change that did not become fully apparent until a high profile incident in 1982. The problem was that the diamond peaks concentrated stresses to a much greater degree than the previous tangential geometry. The stress concentration led to premature failures of the diaphragms. The incident in question was the premier of the brand new JBL installation at the Academy of Motion Picture Arts and Sciences theatre. It was considered quite a coup for JBL to replace the old Altec sound system with their then state-of-the-art cinema system (for which JBL would later win an Academy Technical Award). However, during the premiere, the diaphragms on nearly all of the 2441’s failed. As a result, an edict was issued from on high at JBL to immediately fix this issue. Six months later, the result was the titanium diaphragm.

Titanium is an order of magnitude more resistant to fatigue failure. The diamond surrounds, with their increased HF response, could still be employed, but power handling was increased by 30% with greatly increased longevity. Nonetheless, there were tradeoffs involved. As Giskard stated, titanium has poorer internal damping than aluminum. Further, titanium has reduced stiffness meaning that it is driven to breakup at a lower frequency than aluminum. The net result is increased distortion. This increase is relatively miniscule, but many listeners find it audible in critical applications like monitoring or home hi-fi.

For this reason, JBL has reverted to aluminum and introduced beryllium diaphragms on their latest compression drivers. The use of a composite mylar surround has solved the fatigue problem. The use of beryllium has solved the diaphragm breakup issue so that these drivers have the lowest levels of distortion of any compression driver yet built by JBL. The smaller diaphrams (3" vs 4") of these newer drivers furhter pushes the frequency of breakup modes and increases overall HF response. Finally, applying EQ allowed these drivers to have the same UHF extension without the need for parasitic resonance and its attendent distortion.

cheers, herki