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Peavey Mace Question ?

Started by skynyrd, March 17, 2010, 06:25:51 PM

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Jack1962

I call it a clipping circuit because it actually does clip , peavey calls it a noise reduction circuit, and it does reduce noise , I suppose it really depends on who your talking to and in what context what this circuit would be called. however if you call Peavey or a authorized service center and ask about this circuit , they refer to it as a noise reduction circuit. To make a long story short , I have bridged this circuit many times for customers as well as on my own Triumph the amp in my opinion sounds better without it.


                                                     Rock On

skynyrd

Well here is is after the mods I did, I like the sound alot better, am going to do the bias mod as well shortly. My bridge tone pot is going bad and need to get a CTS for it.
http://www.youtube.com/watch?v=rOieBJplBIE

Jack1962

Sounds good  :tu:

                                 Rock On

skynyrd

Thanks Jack, I got the tone pot replaced and that lends much more to the variety of tones possible. I have been comparing several different amp schematics with my mace schematic and found a few things that I thought may lend to the elder Peavey mud tone. There is a resistor in the mace that is a 10K it goes between the bass pot and the treble pot, I noticed on a few marshall models they have 100K resistors. Makes me wonder if switching the 10K to maybe a 50K  would also help with the mud tone and give the bass and treble more independant tonal characters.

phatt

Hi Skynyrd,
               Re the tone tweaking;
Think long and hard before changing much in the circuit because by the time you find the magic R and C for that tone circuit the tracks will have been destroyed from so much reheating.
No matter how you tweak it that tone circuit is rather mundane no matter how much you wish to change the surrounding values.

What is often missed in the pursuit of greater tone is that the only part that *Cannot be replaced* is the PCB itself.
(parts are easy to find,,Boards are NOT) :'(

You would be far better served by using an outboard circuit for tone.
Tweak a new circuit on a bread board until you are happy, That way no harm comes to the Amp.
A quick simulation tells me what I already knew, that being about 10~14 Db of difference at any freq of interest. (i.e. from 100hZ to 4kHz,,, guitar response worth boosting or cutting)

Read my post for a simple off board tone control that can deliver a 35Db cut at 400hZ.
You will be pleasantly supprised.
http://www.ssguitar.com/index.php?topic=1136.0

I've added my findings of your circuit at full boost and full cut.
My *PhAbbTone* (at full boost) is added for ref.

Mace Trace1 B=0, M=10, T=0  (Green)
Mace trace2 B=10, M=0, T=10  (Yellow)
PhAbbTone   B=10, M=0, T=10  (violet)

Note,
       Passive Tone circuits like these can only actually cut
(no real boosting)
So the only way to make them effective is create the biggest possible cut/difference, especially in the mid bands.

Big shallow dips tend to pull too much out and hence you are always fighting against something,,Tone/verses Signal loss.

You will find that pulling a deep notch in the mid band delivers the best possible result.
Delivers a more defined tone alteration with minumal signal loss. 

Having played with gear for many years it eventually dawns on you that you are far better to work *outside of amps,, not in them*.

Unless there is something major wrong it's easier to work with external circuits.
you can still use the onboard Tone to do some extra tweaking. :tu:
Have fun,,, Phil.







Jack1962

I have do disagree with Phatt , the tone tank in this amp as with most peavey's is just a variation of the FMV tone tank the most common tone tank in the indusrty, with may variations to give each amp a different flavor , I would advise you to go to http://www.schematicheaven and check out the different tone tanks and there configurations, you can greatly alter your tone thru the tone tank.

                                                  Rock On

skynyrd


phatt

If you are happy then it matters little but I heard a lot of blocking type distortion happening in your clip.
Of course it's hard to tell with clips.

Having also peeked at the schematic then I doubt if the tone controls are doing much.
For me personally I would be wanting more clarity from my chords but again some folks may want all the muddyness.
All just my observations.
Cheers Phil.


skynyrd

I found out that my volume pot has issues, and the noise was getting worse and the distortion started sounding like it was compressed badly, changed out the volume pot to a new CTS and it cleared it up alot, plus I found that the 1/4 jack plug on the cable going from the amp to the cab was crackling when I wiggled it, replaced it with a new heavy duty audio cable ( the old 1 was a elcheapo) and she is much much better. I wouldn`t have thought the cable would make the difference it did but that brought the biggest change in the sound, it doesn`t sound like the amp is forcing the sound through the cab anymore.

Steve Dalllman

I recently obtained a Peavey Bravo 112. I put a switch across the diodes and listened to it carefully for a while. (BTW, I am an amp tech, authorized by many companies like Line 6, Fender, etc.)

The diodes only work when the gain boost is on, and they do work well. I can hear no discernable difference with the diodes working or shorted in the guitar tone, but the noise is unbearable with the diodes shorted. The decay is as smooth with or without the diodes. I hear no gating action.

I'm quite happy with this simple circuit.

Jack1962

Steve a lot of people like these amps just like they are
(BTW I am a Authorized tech also by Fender, Peavey, Mesa , Korg(that's Marshall and Vox) and a few others  )