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Couple of questions about Peavey Deuce.


 
7/9/1999 8:59 PM
T.B.
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Couple of questions about Peavey Deuce.
I've got this Peavey Deuce amp that I purchased new in about 1978. I recently replaced the power supply caps and one bad screen resistor. I haven't played it in years until recently. It had sounded like hell recently until I replaced those items. I was used to playing a 72 twin reverb amp until I got the Deuce. I retubed the Deuce with a quad of Svetlana 6L6GC's, had those Sylvania STR387's originally.  
 
 
 
Questions are as follows.  
 
1)Has anyone gotten into the preamp and tried to brighten this amp up? It sounds a little heavy on the bass and midrange. Also, the treble and upper mids seem a little harsh. What's your opinion of Deuce's? Tone and such?  
 
 
 
2) When changing caps in the tone section, should I be using low voltage caps or is it ok to use the 600 volt caps I use on tube preamps? Is there any time thing to consider or any other detrimental thing I should be aware of? I had read once that it's not a good idea to use a cap with a voltage way higher than what's needed because of the time factor and phase shift.  
 
 
 
3)From input jack to the first IC stage, there is a 100pf  
 
cap going to ground. Obviously this is bleeding highs off. Between the 1st stage and the 2nd stage is the pregain pot and a few components, no big deal, from the 2nd stage going down to the tone stack there is a .1uf cap going to ground. Doesn't this suck a lot of life out of the tone? Or are IC's such animals that they generate so much highs that this is necessary. (Boy! I sure like tubes better) The tone stack is fairly similar to a Fender type. From the tone stack it goes to two more IC stages. After this second IC stage there is another 100pf cap to ground, and the coupling cap going to the post gain pot is a .22uf.  
 
 
 
4)The amp was just way too stong on the bass and lower midrange. I changed the slope resistor at the tone stack from a 47k to a 100k, made a huge difference. Also I changed that one coupling cap from a .22uf down to a .022uf, that also made a difference. What about that .1uf cap to ground before the tone stack? Any reason why I can't remove it and add a resistor in series going to the tone stack if there's too much gain.  
 
 
 
5) I need to study up on the topology of IC circuitry as related to guitar amps, but it's taken me a good while to feel comfortable messing with tubes. If all solid state amps share a similar design (like learn one then you can handle the rest) then that would be a piece of cake. However, I'm afraid that's not the case. That's why I was hoping that someone has had the opportunity to understand what makes the Deuce click. Why the differences in design from IC's and transistors to tubes? Does Peavey just throw in some excess baggage that could be weeded out or is it necessary for the amp to work or are they just trying to strive for a particular tone.  
 
 
 
6) The amp does not sound as warm as a tube amp. The tube power amp doesn't sound bad though when I patch in a Cream machine or even the POD into the Line in. There are some good features in this Deuce, channel switching and the ability to combine channels, line in and out, phasor and reverb. I just would like to mess with the tone to suit my tastes but felt I should at least ask a couple of questions so as not to do something stupid and mess up what is a working amp.  
 
 
 
Well, didn't mean for this to get so long. This is the last question. What's the general opinion of the Black Widow speakers that came with this amp?  
 
 
 
Any feed back would be greatly appreciated. Thanks, T.B.  
 
 
7/9/1999 9:41 PM
Don Symes
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2) When changing caps in the tone section, should I be using low voltage caps or is it ok to use the 600 volt caps I use on tube preamps? Is there any time thing to consider or any other detrimental thing I should be aware of? I had read once that it's not a good idea to use a cap with a voltage way higher than what's needed because of the time factor and phase shift.  
 
 
 
I don't know who told you this, but I want some of whatever they were smoking!  
 
 
 
The voltage rating on a cap is a do-not-exceed number ONLY.  
 
 
 
The real factor is the dielectric material, and there are some strongly held opinions around here. Do a search on this page, and RG's SteveAhola, and GFR's pages for details.  
 
 
 
5) ... ... Why the differences in design from IC's and transistors to tubes? Does Peavey just throw in some excess baggage that could be weeded out or is it necessary for the amp to work or are they just trying to strive for a particular tone.  
 
 
 
Tubes are extremely high impedance devices at input and output. IC's are high input impedance and very low output impedance and have very different clipping and overdrive characteristics than tubes. It's tough to get an op-amp stage to sound anything like a tube.  
 
 
 
6) The amp does not sound as warm as a tube amp. The tube power amp doesn't sound bad though when I patch in a Cream machine or even the POD into the Line in. There are some good features in this Deuce, channel switching and the ability to combine channels, line in and out, phasor and reverb. I just would like to mess with the tone to suit my tastes but felt I should at least ask a couple of questions so as not to do something stupid and mess up what is a working amp.  
 
 
 
Check out the LXH (LHX?) website. They claim a solid-state marshall stack emulator. Maybe some of their ideas apply.
 
7/14/1999 5:00 AM
Jon Blackstone
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>The real factor is the dielectric material, and there are some strongly held opinions around here. Do a search on this page, and RG's SteveAhola, and GFR's pages for details.  
 
 
 
 
 
 
 
Also, Steve Bench has a technical article on The Sound Of Capacitors at http://members.aol.com/sbench102/caps.html  
 
 
 
Jon B.
 
7/14/1999 1:48 PM
ken g Cap article link WAS Couple of questions about Peavey Deuce.
Steve Bench's pages are good reading, as always. There's also the seminal work by Marsh and Jung found here:  
 
http://www.capacitors.com/pickcap/pickcap.htm  
 
which was one of the first things I ever downloaded from the internet.  
 
 
 
~KG~
 
7/14/1999 11:51 PM
T.B.
email

Thanks gentlemen for all your information. I will check into everything as time permits. Usually that's two or three times a week. I do enjoy reading up on various aspects of tube amps (mostly guitar amps) and have soooo much more to learn. T.B.  
 
 
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