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Zenith Allegro 3000 Speakers - Surprising!

Ds2000 said:
Are these the smaller 70’s model with the fixed split grille, or the 80’s version with the removable grille?
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Removable grill. Look like these -

xzu1dqhrv4m11.jpg
 
onwardjames said:
Hello, and welcome to AK !!

Did you happen to recap??? It makes a staggering difference, as well as removing the knob (simply take it out of the loop).

Glad to have you here.
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I didn't recap them or remove the L-pad from the equation. I cleaned them with up with Deoxit though and they were pretty smooth afterwards.
 
4mer.JTF2 said:
I didn't recap them or remove the L-pad from the equation. I cleaned them with up with Deoxit though and they were pretty smooth afterwards.
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If you are running the l-pad wide open, go ahead and delete it. It's a limitation. If you like that ability to roll off highs, they by all means keep it.

But, please, consider recapping. Those caps are tired, and likely far out of spec.

The difference upon changing my friend's pair with poly's, even the humble Dayton poly, was immense.
 
kirk57 said:
In the project queue for me are those drivers in a new enclosure with a DIY aperiodic vent, based upon the TS parameters (I tested them). Should be fun.
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Okay, me and Vegaman9 are about to do some work on these little dandies. I see some nice crossovers offered from Dayton, see below -

https://www.parts-express.com/Dayton-Audio-XO2W-2.5K-2-Way-Crossover-2-500-Hz-260-142?quantity=1

I am making the assumption that Zenith allowed the woofer to roll off, and the cheap stock crossover is just a high pass. Not sure if the above crossover would help or not.

Kirk, if you could, could you provide some ballpark idea of cabinet dimensions with the aperiodic design??

Me and Vegaman are gonna tear off that shitty vinyl wrap, picked out some fine veneer, and want to see just how far these can be taken. I'm planning adding mass, sandbags, dynamat on the woofer basket, the whole enchilada. Why?? Because we're bored, and it pleases us, lol.
 
Hi James-

Speaker projects are a warm weather thing for me (no garage) so I have made no progress here.

If I were to take it up I’d either learn how to use one of the on-line box like WinISD and model it as a leaky box, or just post the TS parameter over at the PartsExpress speaker design forums and see if anybody will help. I think once you understand the software it’s pretty easy to model, and the people on that forum seem to understand the software.

Kirk
 
kirk57 said:
Hi James-

Speaker projects are a warm weather thing for me (no garage) so I have made no progress here.

If I were to take it up I’d either learn how to use one of the on-line box like WinISD and model it as a leaky box, or just post the TS parameter over at the PartsExpress speaker design forums and see if anybody will help. I think once you understand the software it’s pretty easy to model, and the people on that forum seem to understand the software.

Kirk
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Thanks for the tips, Kirk! Appreciate the good info, will head over to PartsExpress, see what shakes out.
 
I have a pair of 10" woofers from some old Allegro speakers. They are nicely made but the treated accordion surrounds are quite stiff. I managed to soften one up a bit by scrubbing with acetone using a toothbrush and paper towels. I have done this to some Realistic speakers with good results afterward resealing with the famous AR sealer from @RoyC. I was able to get the old surrounds cleaned to bare cloth and then resealed. Fs went from somewhere around 100Hz (quite high for a 10" woofer) and after cleaning and sealing had Fs in the high 30's. I think the Zenith woofers might need the same treatment if yours are like mine.
Have fun,
John
 
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Looking forward to this project. I have the parts from 2 pairs of the 3000’s and would like to do something with them.
 
@nerdorama I will be sure to do the acetone trick and follow up with the resealer. If the Fs was that off, it sounds prudent and necessary.

Been wondering if putting window caulk on the back of that tweeter horn might help tame resonance?? I know some do that with other horn tweeters.
 
@nerdorama I'm having a helluva time finding that resealer stuff.

Being ported, and not sealed like the AR3, would this be a huge deal to not do?

I have a spare pair of woofers, never treated them, but they're the accordion style, and I'd like to do Vegaman's set correctly.
 
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Do you have a way to measure woofer parameters? I use Arta software with an external usb soundcard, an amp and an interface box which I built from a design in one of the Arta manuals. It's a little bit of work to get all the stuff but once you have it, measuring a woofer takes about a minute to get all of the parameters. As I work through cleaning the surround on an old woofer I make a measurement every couple of cleanings to see how it is progressing and to know where it started.

I imagine that the accordion surrounds could be removed and replaced with foam roll surrounds too.
 
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kirk57 said:
Here ya go, John:

* This data was exported from DATS the Dayton Audio Test System
*
* Manufacturer: Rola
* Model: 40671
* f(s)= 37.68 Hz
* R(e)= 6.942 Ohms
* Z(max)= 161.5 Ohms
* Q(ms)= 9.743
* Q(es)= 0.4376
* Q(ts)= 0.4188
* K(r)= 0.02283
* X(r)= 0.6643
* K(i)= 0.03007
* X(i)= 0.6785
*
*
View attachment 660818
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nerdorama said:
Do you have a way to measure woofer parameters? I use Arta software with an external usb soundcard, an amp and an interface box which I built from a design in one of the Arta manuals. It's a little bit of work to get all the stuff but once you have it, measuring a woofer takes about a minute to get all of the parameters. As I work through cleaning the surround on an old woofer I make a measurement every couple of cleanings to see how it is progressing and to know where it started.
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Expand the first quote. I think that's what you're wanting.
 
I wasn't really asking for the data. Just wondering if you had a way to check the status of your woofers and to know if they need to be loosened with the acetone stripping a way to monitor the progress of it. My pair of woofers are Rola eia code and it is easy to tell by feel that they are very stiff. I have one of them about halfway loosened after several rounds with the acetone.
 
Simply using the speaker will loosen up the surround. This can be verified by checking TS parameters before and after use (Fs will go down)
Personally, I'd avoid the acetone.
 
With an initial Fs of over 100Hz I doubt a woofer would loosen enough to work properly. I've tried it. Just doesn't do enough to restore an old woofer IMO. User choice of course. You have to be careful to not use the solvent on the glue at the frame and cone edges. I paint it onto the moving part of the surround with an acid brush, work it in with a soft toothbrush and wipe with an acetone dampened paper towel. Wear gloves that are resistant.
John
 
kirk57 said:
Simply using the speaker will loosen up the surround. This can be verified by checking TS parameters before and after use (Fs will go down)
Personally, I'd avoid the acetone.
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nerdorama said:
With an initial Fs of over 100Hz I doubt a woofer would loosen enough to work properly. I've tried it. Just doesn't do enough to restore an old woofer IMO. User choice of course. You have to be careful to not use the solvent on the glue at the frame and cone edges. I paint it onto the moving part of the surround with an acid brush, work it in with a soft toothbrush and wipe with an acetone dampened paper towel. Wear gloves that are resistant.
John
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It's a bit of a gamble, but I'm going to avoid the acetone. The woofers, which I heard just yesterday, move very freely, and produce solid, quality bass. When pushed, they have about as much resistance as you would expect, neither too hard, or too soft.

I think I might like to put a small coat of this on the surround, just to shore it up, but again, I defer to those more knowledgeable than myself.

https://www.simplyspeakers.com/speaker-repair-cone-edge-sealer-mi-1291fg.html
 
You are likely fine. I wouldn't do it unless the woofers were stiffened the way mine are. I don't think yours are the same woofer as mine. I have stripped one of the pair and I made some comparative measurements this morning. I will post the data later.
John
 
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