Mojokane
478 posts
Dec 05, 2011
2:43 PM
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I have a question for anyone who may be able to tellme the best way to go. I am changing out the old Sprague tone caps. What would be the best caps to replace with?
And any other suggestions would be appreciated...
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Why is it that we all just can't get along?<
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HawkeyeKane
517 posts
Dec 05, 2011
2:47 PM
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You might as well just email Greg. I don't think anyone's worked on as many 'Zoos as he has.
Just out of curiosity, is this just a restoration job, or a customization job, or what?
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Hawkeye Kane
Last Edited by on Dec 05, 2011 2:57 PM
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Mojokane
480 posts
Dec 05, 2011
3:27 PM
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Yeah, thanks, I first considered a direct email to Greg.
My friend here is basically a guitar amp builder.
I am trying to get him to hear things through a harp players ears.
Terms like; compression, spongy, etc have different meanings. A learning process for me, too.
The Zoo is a good start.
We're noticing, the Sanoette is riddled with "pancakes".
And this would make sense, as the tone is really too crisp and "harsh". Almost like a SS amp.
The pix in my previous post, of the Sanoette, mentioned how close they were in design to the Zoo. But I have not seen any pancakes in the Zoo..
The Zoo has the tone harp players are after. Especially with 12" speakers. Any relation to the harshness, to the "pancakes"??
The python 12X10 Sanoette, made me think also, that the 10 was ribbed and may have been (in part) the problem. I'm going to change out the ribbed 10", and replace it with an affordable smooth rola 10" alnico.
ANYWAAAAY, I was looking at the best way to go, with Dijons, oil n foil, or what?
I was hoping to ejamacate him a little.
He's very good at what he does, and could potentially benefit from the many harp players I know here, and around Honolulu. And if nothing else happens, I have an "in" on a good amp builder over here, who can rebuild, repair, re-design, and build amps completely from the ground up. I just don't want to spend any more than I have to to find out which is the best way to go...maybe a website?
Leaving the Zoo alone, as it was originally intended, is fine, too. I have one stock already.
MP has it now. He loves it.
Rightly so, it sounds awesome.
Thanks!
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Why is it that we all just can't get along?<
Last Edited by on Dec 05, 2011 3:30 PM
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MJ
332 posts
Dec 05, 2011
4:17 PM
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Some or actually a lot of the Kalamazoos tone has to do I believe with the OT.
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HawkeyeKane
519 posts
Dec 05, 2011
5:07 PM
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There's a good field guide out there on all Kalamazoo amps. There's a link to it on the Zoo section of Greg's site. It's helped me out immensely on the research I've done on Zoo amps.
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Hawkeye Kane
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Mojokane
482 posts
Dec 05, 2011
6:11 PM
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thankyou! Hawkeykane..
I don't see others eager to share...thanks. The gear part of "harp playerdome", is optional. Just learning to play the harp is plenty for most. For me, the many models and inner workings of amplifiers which are suitable for harp, have always fascinated me. There are countless opportunities to acquire at relatively low cost. Though, after adding up all the pros and cons, sometimes the simplest way is to buy one. Rather than make one....
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Why is it that we all just can't get along?<
Last Edited by on Dec 05, 2011 6:13 PM
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Ray
362 posts
Dec 05, 2011
6:16 PM
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Hers a good Kalamazoo site.
http://www.rru.com/~meo/Guitar/Amps/Kalamazoo/
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HawkeyeKane
520 posts
Dec 05, 2011
7:38 PM
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That'd be the one I meant Ray. I'm on my phone here so I couldn't post a link. Thank you for doing so.
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Hawkeye Kane
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Tuckster
903 posts
Dec 06, 2011
11:02 AM
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I was waiting for either Greg or 5F6H to chime in on this,but they must be busy. I'd think a polystyrene cap would be good in the tone stack.Unless you really know about this stuff,I wouldn't change the values. Very generally,in a harp amp,they increase the values on the coupling and bypass caps for better bass response.
Mojokane: I don't understand what you mean when you say "pancake"
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MJ
334 posts
Dec 06, 2011
11:28 AM
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Greg normally suggests leaving the values of the Kalamazoo as they are.
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HawkeyeKane
524 posts
Dec 06, 2011
11:34 AM
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"Greg normally suggests leaving the values of the Kalamazoo as they are."
Very true. As does Sonny Jr. himself.
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Hawkeye Kane
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Greg Heumann
1368 posts
Dec 06, 2011
4:10 PM
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If you're talking about the power filter caps, DO use the same value and DON'T spend on exotic caps, not necessary. If you mean the smaller caps that DO affect tone - like coupling caps - why replace them at all? I've never had a Zoo with a bad one and that's over 200 amps now. The originals make it sound, well.... like a Kalamazoo. IF you want to CHANGE the sound, then experiement away.
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/Greg
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MP
1903 posts
Dec 06, 2011
4:36 PM
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WOW, GREGG!! over 200 Zoos!? i just love those little beasts.
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MP
doctor of semiotics and reed replacement.
"making the world a better place, one harmonica at a time"
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HawkeyeKane
529 posts
Dec 07, 2011
6:56 AM
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You know Greg, you oughta consider putting a little metal tag on the inside of the cabinets. "This Kalamazoo amplifier was Heumannized on ??/??/???? at BlowsMeAway Productions - Geyserville, CA". Could add to their value down the road. :-)
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Hawkeye Kane
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chromaticblues
1437 posts
Aug 14, 2013
9:50 AM
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I have owned my third zoo for about a year and a half and have done many mods. Then undoing them just to make comparisons for myself. After many different versions of this amp there are a few things that dramatically make this a better amp for playing harp IMHO.
The first is a design flaw with the power supply. The first resister was 1K on the first version of this amp and quickly changed to 3.3k for the remainder of the run. Well making voltage measurements at the plate and grid I found the grid was higher than the plate. Electrically that's just wrong! I changed the value to 4.7k and the voltage difference was one volt higher at the plate.
As soon as you start playing there is going to be a voltage drop at the plate much greater than at the grid because the plate draws more current. So while playing the grid voltage would probably be higher I thought.
Anyway I tested the amp with the 4.7k resister and I couldn't really hear any difference from the 3.3k.
I then tried a 10k in place of the 3.3k and hello! Now were talking! what a figin' difference!
Next the kalamazoo is the most conservitive preamp design I have ever seen. 4.7k cathode resisters?
I have never seen another schematic of an amp with values this high! 2.7k is usually a high value. So I stated there. I'm not sure if it made enough of a difference in the sound or if I wanted to hear something great. So I tried 2.2k. Now that is better without a doubt. I settled on 1.5k.
Making circuit changes will make it sound like a different amp. To me these changes make it sound better. Now not everyone is going to agree and I know that. I'm just sharing my experiences here.
Now that I think about it I did the preamp change first before the power supply.
I also changed the speaker, center tapped the heater circuit and installed a bigger 10 watt 8 ohm output tranformer.
I also changed the preamp tube and don't know what the number of the tube is, but I do know it's basically a 12au7 for the first triode and a 12ax7 for the second half. It just gives me more use of the volume knob. I could even go to a 12au7, but I don't have one and this works fine (I'm not having feedback isues at all)
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blueswannabe
257 posts
Aug 14, 2013
6:52 PM
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Here's a youtbe of my zoo. Only mods were grounded power supply and filter cap removed with 3 individual caps replaced of equal value. One cap was 22uf 500v instead of 20uf 450 v., very marginal difference with no effect. I would agree with Greg keep original values. It sounds great as is.
Last Edited by blueswannabe on Aug 14, 2013 6:59 PM
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Mojokane
714 posts
Aug 15, 2013
2:28 AM
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I ended up doing the same set up...above. Thanks!
Thanks every one. I am now over my Kalamazoo Fever.
It comes and goes.
I am happiest with the ole 72 Princeton(thankyou MP). Lightweight and easy to dial in. Great through the PA.
I get to take out the 59Bassman(early 90's)this weekend.
It's been almost too long since I played it. Goota do it, MAN!
The Bassman is good outdoors.
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Why is it that we all just can't get along?<
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chromaticblues
1438 posts
Aug 15, 2013
5:02 AM
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@ Mojo Man
I stumbled across this thread looking for your kalamazoo with the extension speaker box. I thought it was two 10's not two 12's. I'm in the process of building extension cabinet with two 10's. So I thought I would read some of your threads about it before completed it. I want to build it so it will be capable of running as a one 10" setup or a three 10" setup with the amp on top of the extension cabinet.
The amp has a 8 ohm output and an 8 ohm 10" speaker in it. I have two 4 ohm 10" speakers to put in the cabinet. So I'm going to have the two in there wired in series so the cabinet will be 8 ohms and run that in parallel with the speaker in the amp. So the total load will be 4 ohms, but through 3 10" speakers.
I think it will work?
Ofcourse mine isn't going to look as cool as yours. Kevin your amp is very nice!
My main attention was inside the amp (and I couldn't build an amp to look that nice if I tried). I wanted to undo all the short cuts and make it a good sounding loud amp and try to incorporate all the noise reduction tricks I've read about in various books.
These were made as cheaply as possible to be sold as student amps. I'm not trying to bash on all the Kalamazoo lovers, but Fender champs and all the single ended amps of that period were engineered cheaply. They cut corners to make a cheap amp that beginners could afford.
But on the flip side these make GREAT amps to modify/reenginneer!
Last Edited by chromaticblues on Aug 15, 2013 5:29 AM
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