Hot Rod 093TI

[NewZenith]

Ever since my fascination with dome speakers began about two years ago I have had a love-hate relationship with the JBL 093Ti. I was always curious what would happen if you replaced or modified the rather anemic looking magnet structure. Having a pair of 112A baskets lying around with no cones in sight I thought it acceptable to cannibalize their magnet structures and combine them with the 093Ti diaphragm to see what might happen.

Has anyone else tried this or similar modifications to other speakers?
It essentially grants the voice coil endless reserves and a much denser magnetic field.
The voice coil also becomes under-hung.
Efficiency and usable range increased dramatically, I would guess on the efficiency range + 3 decibels and at least 500 Hz of increased bandwidth capacity.

I do not currently own an RTA. I've been told that you got to spend five grand to get a good one? I am very curious what the theoretical disadvantages might be considering the design of the 093Ti diaphragm.
I would also like to share my observations if there is interest.
Sincerely NZ.

[NewZenith]

Isn't Your reply a little off-topic?
Speaker humanitarianism or speaker ethics is not my primary objective, nor do I care to discuss it in this thread!
Have a nice day:)
PS, did I mention that I have an early D4400.
I was thinking of gutting out the inside and installing some Bose speakers.
That ought to help the resale.

[NewZenith]

Too bad I can't share a hobby interest here on LH without being ridiculed. I sent you a private message because I felt it was too strong for the public forum. It was however truthful, it was the first thing that came to my mind.
So you lob it up anyway, as far as I'm concerned you look like a big jerk!

[Guido]

I made an adult decision to take my things and modify them

Then don't ask and leave us alone.

Damned, I hate to read such s#?t at morning.

[NewZenith]

[quote=Guido;146062]Then don't ask and leave us alone.

When you refer to us? You mean there's more than one of you?

Anyhow this thread is dead, thanks Dave.
I don't care about politics here on Lansing heritage, there is no justice in human politics.
I was not out of line, asking a question or defending myself or my beliefs.
If Dave wanted to discuss his feelings about appropriate speaker use he could have simply started a thread titled, the way I think speakers should be used.
Perhaps I was out of line coming on so strong, keep in mind that more than 50% of my experiences posting here on LH have been exceptionally negative! I was extremely reluctant to post, and when I did the shit started.
Tell me how many things of value have any of you restored or saved from the junk heap?

At what point may I decide that it's OK to modify something that is potentially rare?
Perhaps I'm taking this too seriously, I mean the question is rather absurd in the first place.

[Ian Mackenzie]

Hi NZ,

I enjoyed your initial post and I can see where you are coming from.

Some of the best diy drivers (tweeters) I have heard use big JBL magnets!!:applaud: .

Have you thought about acquaplasing the dome? I would.

This is a diy thread and anything goes. Perhaps if you are able to send the driver to perhaps Robert H our XP diy King or Lord Zilch von Cablemaker they could evaluate its performance under the zee microscope.

To the rest of you if I felt I would get stoned every time I did something outside the square of your seriously tiny little universe I would have left eons ago.

That's how you learn how things work.



Ian

[Guido]

Calm down Zenith.

You can burn your speakers if you want. But don't expect applause when you announce it here.

I think you once pointed me to a pair of those rare drivers located in taiwan. Wasn't it you?
I am so happy to have found one of the latest pairs on earth. Many of us are still searching and then it just hurts if someone risk to trash them.

It's all about different opinions.

You shouldn't mess with them.

[NewZenith]

First off I want to state that I was incredibly reluctant to modify anything, however my curiosity got the best of me and I'm glad it did!
To answer your first question I do intend on using antivibe on the domes. But I must acquire some first.
It's nice that there will be no negative efficiency loss due to antivibe coating because of the sensitivity gained, these drivers are now the hottest out of the bunch, beating out the 112a's by a few decibels, of course the 093's are 4 ohm.
My main concern with my modification is how flat the driver remains with the greater dampening, this I do not completely understand nor can I test for it yet.
The tuning behind the dome is completely left to chance, the driver now resembles a compression driver missing its phase plug due to the vent hole through the magnet.
I added lightly packed fiberglass and capped the back.
I also made a open cell foam damper with light compression against the inside.
I was able to avoid serious modifications to the 112A magnets, only having to put a small chamfer on the top plate to accommodate the new driver.
If there is continued interest I can show photos.
It is worth noting, and I will go as far as saying that the difference this magnet structure made was astonishing! Although it's too soon to tell exactly everything that has changed.
I was able to spread my crossover points apart almost a whole octave, now I'm crossing at 1100 hertz and somewhere above 5K to the tweeder.

I have a couple of pairs of TI domes left for comparison should I decide to do so again.
Although I think this mod is a keeper.
Most enthusiastically
NEW FART.

[NewZenith]

Calm down Zenith.

You can burn your speakers if you want. But don't expect applause when you announce it here.

I think you once pointed me to a pair of those rare drivers located in taiwan. Wasn't it you?
I am so happy to have found one of the latest pairs on earth. Many of us are still searching and then it just hurts if someone risk to trash them.

It's all about different opinions.

You shouldn't mess with them.

I'm just trying to take them on one at a time, I don't burn speakers! I think there's something larger at work here. Maybe I'm wrong but there's a certain style about many exchanges here that is familiar to me.
Let's get real, people modify things all the time and as a matter of fact it's actually encouraged.
No one has yet come up with a legitimate criticism, to say you shouldn't do it just because it's ridiculous, how about something like this instead.
Newzenith, I would not have recommended that modification without first considering XYZ because I think you will not be happy with the results and therefore wasted valuable things.
I know people here are sentimental, but that does not change the fact that I did something and I can think of no better place to talk about it.
Besides there are probably other nutty people, like myself that might find this sort of thing intriguing.
How about we engage in some technical discussion, as technical as I can be anyhow. I know I'm a shoemaker, but I'm a clever shoemaker.
I'm learning, two years ago I didn't know crap! Now I just smell like crap. and someday I may be King crap.
NF.

[Guido]

How did you manage to get the 093 VC horizontally centered to the 112 pole plate? Or is the 112 pole plate similar to the 093ti pole plate by coincidence?

[macaroonie]

If you havn't tried it how do you know you dont like it ? Lets have a look please.

[Ian Mackenzie]

I'm just trying to take them on one at a time, I don't burn speakers! I think there's something larger at work here. Maybe I'm wrong but there's a certain style about many exchanges here that is familiar to me.
Let's get real, people modify things all the time and as a matter of fact it's actually encouraged.
No one has yet come up with a legitimate criticism, to say you shouldn't do it just because it's ridiculous, how about something like this instead.
Newzenith, I would not have recommended that modification without first considering XYZ because I think you will not be happy with the results and therefore wasted valuable things.
I know people here are sentimental, but that does not change the fact that I did something and I can think of no better place to talk about it.
Besides there are probably other nutty people, like myself that might find this sort of thing intriguing.
How about we engage in some technical discussion, as technical as I can be anyhow. I know I'm a shoemaker, but I'm a clever shoemaker.
I'm learning, two years ago I didn't know crap! Now I just smell like crap. and someday I may be King crap.
NF.

Quite a few hi end loudspeaker outfits modify drivers to their own specific needs..Wilson for one, and locally VAF.
Whats new.

NZ,

This is a big like Bruce Edgar using a 2105 as a compression driver, wrong appliciation but it works.

The only thing about going lower is the excursion Xmax and the compliance of the surround.

I would not rule out a wave guide if you want to reduce distortion in the low end and control those early reflections. Sometime ago I was considering this driver as the change out for the 2307 flog horn. Among other things its limited bandwidth and efficiency for non negotiable.

These particular species are apparently as rare as Hen's teeth and are craved by XP clone propeller heads.

Gordon W is about the only member I know of who has amended JBL drivers. Earl might also chime in on this one.

[Robh3606]

I have had a love-hate relationship with the JBL 093Ti. I was always curious what would happen if you replaced or modified the rather anemic looking magnet structure.

No that's a first as far as I know. Do you know what the flux density is in the 093 gap??


It essentially grants the voice coil endless reserves and a much denser magnetic field.

Well you don't really know that. Larger pot doesn't always mean higher flux density by itself. An example would be the LE-15 and k-145. Largest pots JBL made howerer lower flux density than say a K 130


Efficiency and usable range increased dramatically, I would guess on the efficiency range + 3 decibels and at least 500 Hz of increased bandwidth capacity.


How do you know whats really happening??? You have any measurement capability??


That diaphram has limited excursion capability. I was designed to be used with a tuned and sealed pot structure. There are None avaliable from JBL. If you overdrive it and that fractures the surround your out of luck.


I do not currently own an RTA. I've been told that you got to spend five grand to get a good one?

You can do a lot more with a lot less money.

Guido already covered the rest.

Rob:blink:

[kingjames]

AS you are all aware I am a very (NON) technical kind of person and I joined this forum because I know most of you to be experts when dealing with JBL and the tips and bits that you offer are indespensible.

This site is about information and what a great site it is for that. I would never come here and brag about BOSE speakers because they suck and more than that you think they suck too.It is good to come here and learn and though I don't have the knowledge to build something I still read the threads. Hell, you can stay here and read for hours and, I must say that I learn something new everyday.

I realize that tearing something up(JBL) in your opinion is taboo and insensitive and maybe rightfully so but, who is the judge of that?

This is a good site that has good idea's that has good people,that have different opinions and thank God for the different opinions because without that this site would be meaningless.

Idea's should never be discouraged here and if something is about to be torn up and destroyed in your opinion then there are ways to confront this. Explain what you might think might go wrong,explain that you have a rare driver that someone might need because maybe just maybe this guy doesn't think the way you do and that's not bad at all.

When you jump all over a post because of your opinion you make it harder for other people to post. Who wants to post something here if your going to be slammed for it.The DIY area experiments all the time,is this such a bad thing?

After all this site isin't just for the experts but for everyone who believe's in the genius of JBL.

And to think I was going to ask opinions about removing the driver's from my 250TI'S and replacing them with BOSE drivers. (JUST KIDDING):applaud:

If sometime down the road I ask a stupid question in your opinion then all I ask is that you explain why it's stupid in a civil manner.

Remember the ole sayin" there is no such thing as a stupid question"? That should also apply here as well and when you start calling people on what you think is a stupid question then you will do this site a disservice.

Idea's should never be discouraged nor condemned because this site wouldn't be much without them.

ya, I know, I have no life and this is why I stated my liberal views here.:bouncy:

[NewZenith]

How did you manage to get the 093 VC horizontally centered to the 112 pole plate? Or is the 112 pole plate similar to the 093ti pole plate by coincidence?

I did not achieve perfect VC alignment. However the voice coil is still between the top plate, I'm not exactly sure if centering it perfectly would have any beneficial effects. If I want to I can make a shim or gasket to move it up about .030 inches, should do the trick.

[NewZenith]

[quote=Robh3606;146084]No that's a first as far as I know. Do you know what the flux density is in the 093 gap??

I have no idea, my guess would be very poor.
NZ.

"Well you don't really know that. Larger pot doesn't always mean higher flux density by itself. An example would be the LE-15 and k-145. Largest pots JBL made howerer lower flux density than say a K 130"

I realize that many things affect the flux density in the magnetic gap, i.e. top plate thickness, voice coil gap, voice coil diameter, magnet size, magnet material, the design of the pot and its efficiency. I realize 112A magnet pots may not have the same level of flux density as your typical compression driver, however I believe it is a safe guess that it is much stronger than the stock 093Ti. I do not believe that simply making the voice coil underhung was responsible for the sizable efficiency gain. If there is someone who can measure the flux density of a stock 093 magnet pot, I would gladly mail it to them with no need for it to be returned.
I imagine that some members here might even know what that particular specification is.
NZ.


"How do you know whats really happening??? You have any measurement capability??"

Well, it's not something I care to brag about. The only acoustical measurement capability I have is a RadioShack analog sound level meter, I use it for crude comparison on pink noise.

"That diaphram has limited excursion capability. I was designed to be used with a tuned and sealed pot structure. There are None avaliable from JBL. If you overdrive it and that fractures the surround your out of luck."

More limited than say a compression driver?
Anyhow I have six more diaphragms if somehow I need them.
If it's traveling beyond its design parameters I imagine it's going to be making higher sound pressure levels somewhere in its audio spectrum. I am not crossing this driver outside its designed range, I am also using 24 dB per octave slopes. If it is resonating so intensely that it is over excursioning then I believe it would sound appalling.
I am well aware that the pot structure is integral part of the driver design, however without proper testing I cannot know what is happening exactly in the resonance department. What I can say is that this driver seems to be behaving extremely well. Regardless I do want to be more scientific in my approach to this hobby. In any case there was no way for me, RTA or not, to know in advance what would happen by using the 112A magnet structure on the 093Ti diaphragm assembly.
NZ.

"You can do a lot more with a lot less money."

Then I will try.
NZ.

[NewZenith]

If you havn't tried it how do you know you dont like it ? Lets have a look please.

I'm going to clean up the cosmetics a little, for example I want to get the proper mounting screws installed and the 093Ti screens rather than the T030 jobs on there now.
Then I will post some pics.
NZ.

[NewZenith]

Here are some photos taken tonight. Hope to have impedance plots tomorrow; I will take a stock 093Ti and run it alongside the modified unit. Hopefully it will do well; I may have to remove the damper will see.

[Robh3606]

Hello New Zenith

Is that the final configuration??? You really need to do something to protect the insulation on the VC wires where it passes through the surrounds. If it chaffs through it will short to the diaphram. Can you get a piece of sleeving down the wire and into the pinholes to keep the wire isolated or pot it. You can't run the wire like the original 093???

Rob:)

[NewZenith]

Hello New Zenith

Is that the final configuration??? You really need to do something to protect the insulation on the VC wires where it passes through the surrounds. If it chaffs through it will short to the diaphram. Can you get a piece of sleeving down the wire and into the pinholes to keep the wire isolated or pot it. You can't run the wire like the original 093???

Rob:)

Rob, thanks for the input. I will seal the wires where they go through the diaphram in the near future.
It is not possible for me to route the wires on the underside of the diaphram assembly due to the excess size of a magnet, it would also necessitate irreversible negative modifications to the magnet structures which I am unwilling to sacrifice permanently, I like 112A’s too much to do that. Should cones turn up I will probably try and find some other magnets to use on the converted 093 diaphragms.
With a bit of luck this evening I will be running impedance plots on the composite driver and also on a stock 093Ti/112A /044Ti. I will experiment with the turning of the cavity behind the diaphragm and the homemade damper, which I did not put a photo of because of the five photo limit. I would be extremely interested in what you have to say in regard to the impedance curves and what that might mean in terms of driver performance and health.
Hopefully I can put the results up tonight.
Until then, thank you.
NZ.

[NewZenith]

Ok, well things not turn out as good as I'd hoped, but not as bad as they could have been.
I'm not an expert at interpreting the numbers but I would say it makes sense to me. The first plot is the 093Ti composite. and the second plot is the 093Ti stock with tuning can. Because I did not have enough time I was not able to attempt to tune the composite driver but I'm going to make a rudimentary impedance tester with a resistor volt meter and signal generator.
If I can tune out the resonance bump as did JBL I may consider this project a success.
Note the low resistance increase as the composite 093Ti extends into the higher frequencies, this may be because of the underhung voice coil but I am not sure. I will also test efficiency in the near future.
If anyone has suggestions on how to better tune this driver or how to better evaluate its performance I am all ears.
NZ:) PS, also note the phase scale for the composite driver is 0 to 50 degrees; it is 0 to 100 for the 093Ti in stock form.

[Robh3606]

What is that a WT2?? How many points on the impedance runs?? Did you do an X Q, FS run or an arbitrary sweep?? You may want to do more points to get a little better resolution. That resonance could be where the added response is coming from. Do you have the dampening ring installed under the diamond surround?? You obviously have a much smaller volume behind the diaphragm. What happens if you unstuff the pole piece vent??

[NewZenith]

What is that a WT2?? How many points on the impeadence runs?? You may want to do more to get a little better resolution. That resoance could be where the added response is coming from.

Yes, it is a WT2, is that bad? As far as the added response you could be right, but it's too soon to tell, I want to get the driver's response to flatten out before I make any more claims or judgments. As far as points on the impedance run is concerned, it is not my program so I have no idea how to use it. I want to get my own equipment so I can play and take as much time as I need to figure things out.
Yes I did do a X Q, FS run, I have those except I did not want to waste space or clutter things up, if it's helpful I will post them as well.
NZ.

[NewZenith]

Do you have the dampening ring installed under the diamond surround?? You obviously have a much smaller volume behind the diaphragm. What happens if you unstuff the pole piece vent??[/quote]

Well it's obvious you really know your $hitt,
first off you know I do not have a dampening ring installed around the diamond surround because these are old diaphragms and the dampening ring was liquefied beyond reuse.
I thought about making a new one but have not gotten that far yet. If you unstuff the pole piece vent the resonance peaks below 1000K go real ugly, with two distinct peaks, however if I recall correctly phase and output above 1000K look good. I have five plots with different configurations. I also tried adding extra dampening material to the dome but all that did was push up the Fs and put the ugly resonance closer to where I cross. What I want to do is basically what JBL did, put a chamber at the end of the vent, experiment with valium and dampening until it hopefully flattens out. If that works I will do extensive listing test, maybe I can even rent a good RTA until I can decide on one for myself.
By the way this driver measured best with the fiberglass packing in the vent hole, it had to be fairly dense to work. My next concern is want effect does the air valuem trapped between the diamond surround have on things, some energy must be lost as air rushes around the coil into the large magnet pot?
NZ.

[NewZenith]

Stock 093Ti

Q test completed: Wed Jan 31 20:12:15 2007
Q drive current 2389.34 uA
Shunts: No Shunts Used
;------------------------------------------------------------------
Revc 3.997 ohms
Fms 15.503 KHz
Zmax 8.062 ohms
Ro 5.383 ohms
F0 6.085 KHz
F1 16.278 KHz
Fmin 16.131 KHz
Qms 2.160E+00
Qes 2.124E+00
Qts 1.071E+00
Le 75.472 uH @1k
XLe 4.677 ohms @1k
PLe 5.819 Degrees @1kHz
;------------------------------------------------;
; Approximate Impedance Fitting Constants ;
; (Improved with Completion of Vas Test) ;
;------------------------------------------------;
Krm 0.000E+00 ohms Freq dependent resistance
Erm 0.000E+00 Rem=Krm*(2*pi*f)^Erm
Kxm 15.034E-06 Henries Freq dependent reactance
Exm 1.129E+00 Xem=Kxm*(2*pi*f)^Exm, Lem=Kxm*(2*pi*f)^(Exm-1)

[Robh3606]

Hello New Zenith

These are 2 runs I ran with an 093ti today. The first is the driver as is. The second is without the can with the back of the driver open. You can clearly see the resonance peaks without the can in place. It does not look anything like the measurements you did on your hybrid. There is obviously more going on than just loosing the back can dampening on the resonance peaks. I didn't know if the pad was there or not. In the driver I tested it's still there and if I remember right it's got a sticky back so it's glued in place to the frame. It's a white foam and was still quite flexible. No real signs of deterioration.

Rob:)

[NewZenith]

I tried the stock 093Ti with the can removed as well, but my foam pad was not glued in place.
Without the pad the driver behaved very closely to the composite. My guess is that this type of driver must stay acoustically loaded through its resonance, somehow the foam pad directly behind the magnet pot has a lot to with it.
I'm going to be making some measurements to find out exactly how I have affected the air volume behind the diaphragm; as you had gassed Rob the volume behind the composite 093's is less than with a stock 093. In one regard because I have not kept spacing from the magnet exactly the same, this I can correct with a gasket of the appropriate thickness.
Here is the impedance plot taken with a stock 093 diaphragm with its tuning can and padding removed, it looks nearly identical to the composite drivers behavior.

[WTPRO]

A hint on using the WT2 if you want to measure the TS of mids and tweets.

- Without Rem/Xem measurement and modeling, phase will never cross zero. (Got version 2.0 sw?)

- It looks like you are using the supplied test leads. Inductance will change quite a lot at this scale. You may want to make a set of test leads using ZIP cord to keep the wire spacing constant.

- The 1 pt Rem/Xem method should work well here

- If Rem/Xem is found properly, the sweep starting from the bottom will look for the first zero phase crossing (after subtracting Rem/Xem effects). If SweepLo is set too low, this could happen sooner than expected. Raise SweepLo.

- The double hump could also cause some fits, but from the plots I see it looks like the algorithm should find the first hump.

- The sweep step rate can leave a few of those jaggies. You can add more 'points of interest' using the left and right mouse button to set the test frequency and then add the data point. This does not affect the test results. It is just to beutify the plot.

Hope this helps,
WTPro

[NewZenith]

Thank you kindly for the input WTPRO.
NZ:)

[bldozier]

is your driver dead.