Peavey Mace Question ?

[skynyrd]

I have a vintage peavey mace vt series from the late 70`s, the amp that lynyrd skynyrd used and it is a hybrid with 6 6L6 power tubes and a SS pre amp. I would like to mod the pre amp so it packs a little more distortion, would love to have a cross between skynyrds sound and blackfoots sound. Naturally I play southern rock so hence the 2 sounds. I am going to get a shematic on the amp from peavey and would GREATLY appreciate any and all help that you can offer. I know throwing in a pedal is the easiest option but I would really like to stay on a straight plug and play basis if possible.

[EddieTavares]

Hi, I'm brasiliam forgive my poor english

I bought years ago a cousin of your amp, a PV Classic VT that its circuit is almost the same of mace/deuce. My amp has just one tonestack and just 2 6l6 in the power section.

When I bougth the amp I tested it in the shop, the amp shows a lot of punch and bass frequences but not nuck mids and treebles enough and the tonestack seems didn't work at all... but it was

too cheap!!! Aproximately U$ 200.

I bought!

So I replaced all electrolitic caps, the smaller values I decided to use a bipolar electrolitic. This changes was not enough to becomes the amp brighter to my taste but becomes perfect to play jazz.

Some months reading manuals and schematics of Classic and deuce/mace in addiction other amps that have two tubes in the power section like bassmann and Hiwatt and schematics of solid states preamps, Too many hours trying different values of resisistors in different places... But just few and not complex mods made all difference, follow:

- I Added a presence control in phase splitter/power section. I made this With a 2x2 circuit board, 1 resistor, 1 trimpot and one cap, follow:


         22K    680N
   |---\/\/\/\/\--||--|
   | |   /\               |
   | |____|             |
   |                       |
   |     5k1             |
   |--/\/\/\/\/------|
   |                      |
   |                      |
  ---             fd back
   -

  This circuit must replace the IR24 (1k).

- I replaced the IR14 (1k) with 5k1 resistor.

- In the preamp section I replace R42 (33k) to 47k and R51 (33k) to 22k, this change makes the tonestack more effective.

All this changes make the amp more louder with mids and highs, Increased the distortion of power section, tonestack more effective ... perfect to rock'n'roll!!!

[EddieTavares]

Sorry, the schematics:

http://music-electronics-forum.com/attachments/7192d1260305788-pv_classic_vt.pdf
http://music-electronics-forum.com/attachments/6852-pv-mace-series.pdf

[J M Fahey]

Hi skynyrd (I loved them too).
Really the best and shortest path to what you need *is* adding a clean boost ahead of the amp.
If you have the soldering iron itch, on which I agree, build it yourself.
On the Peavey, modding it has more possibilities to mess the fine sound it has now, than to improve it.
Oi Tavares, todo bem amigo? Bem-vindo no Fórum.

[EddieTavares]

Thank you J M Fahey, tudo na paz!


So if you use a cleam bosst it will increase the preamp distortion... remember it's a ss preamp... It'll distort in the second stage opamp (u5a), maybe some diodes in paralel to r42 will give you something like tubescreamer...

Something that I think now is increase the r100, it will increse the amount o signal to power amp!



Sorry one more time... this is the correct version of peavey mace:

http://www.abeltronics.co.uk/download.php?manu=peavey&file=peavey-mace-deuce-vt.pdf

[skynyrd]

Thanks for the replies, I have talked with a couple of techs ;ocally and none of them really seem to know much about the electronics of the hybrid which I found hard to believe with them being techs. Now the resistors you mentioned to change Eddie?  Have you had any problems out of the amp since you changed them? I do fine with simple cap and diode and resistor changes but building circuit boards I have zero luck with and as much as I would like to build the presence control I best leave that alone,,lol.

[EddieTavares]

skynyrd

         I bought this amp in 2006, in the beginning I intended to replace the old ss preamp to all tube, but the solid state phase splitter make the amp much more louder tham a tube long tail pair specialy with that mods becouse became brighter. I compared with a Jcm800 side by side and my amp seems to be louder with more top-end and less mids.

        No problems with eletronics, heating, the power supply is ok, I ask a friend to mesure the bias and its all ok.

[Enzo]

I guess a good question is what do you want the techs to know.  The fact it is hybrid doesn;t really matter.  The amp is a solid state amp with a very basic tube power amp on the back.  That same preamp could just as easily have fed a solid state powr amp, and in fact PV made a few that way.  SO your techs should know how a PV SS preamp works, because it works like any other PV SS preamp.  HAving specific part number knowledge would be ther only if they had occasion to study the particular amp circuit.

I am not sure about that R100 reference,  in the VT version R100 is the feed resistor to the reverb drive.

The diode trick would be simple to try, and easy to remove if not pleased.  R42 is in the Normal channel.  The same position resistor in the effects channel is R11.

[skynyrd]

Thanks for the replies, Enzo I didn`t mean to sound like I was putting down the local guys. I had talked with them about Eddies mods he listed and they were very apprehensive in even talking about it, all they would say is they know nothing about the hybrid amps ? I pretty much took it they weren`t into doing mods to adds and left the subject alone out of respect for their feelings. I will give Eddies mods a try, I found a duece vt that has the same board as the mace vt and may be able to get it ultra cheap and use it for a tester. I appreciate the help and the info.

[skynyrd]

- I replaced the IR14 (1k) with 5k1 resistor.

- In the preamp section I replace R42 (33k) to 47k and R51 (33k) to 22k, this change makes the tonestack more effective.

All this changes make the amp more louder with mids and highs, Increased the distortion of power section, tonestack more effective ... perfect to rock'n'roll!!!
[/quote]

There must be some difference between the 2 amps, I checked over the schematic I have and found that R42 is a 22k and R51 is a 4.7k ?  not sure if I need to find the resistors in that area that match your numbers or what?

[skynyrd]

To do the 2 diode clipper trick I would basically lift 1 end of R42 and R11, put 2 diodes side by side and solder the resistor leg to the 2 legs of 1 end of the diode and run the other 2 legs to the hole where the end of the resistor came out? Assuming the cathode end of the diodes would go to the board connection and not the resistor?

[skynyrd]

Well done some homework, it looks like I remove the resistor and put the 2 diodes in its place. Going to pick up some 1n4007`s and give it a shot on 1 channel to see how it sounds.

[Jack1962]

you can try the diode clipping circuit , the peavey Triumph used it , I removed it from mine , but you may like it. I personnally like my overdrive to realy be overdrive not clipping from diodes lol lol lol

[Enzo]

The Triumph is all tube, the Mace is solid state but for the power tubes.

The diodes in the Triumph are not clipping diodes, they are noise reduction diodes. They never did any clipping.  Totally different function from those in the Mace.

[skynyrd]

One of these days when I learn much much more about amp electronics I want to set this amp up like its first version where I can run both channels in series rather than paralell.  I wish Hartley hadn`t of changed that aspect of the origonal Mace, maybe I will get lucky and find an old 320T Mace that isn`t completely trashed and set it up as a spare head to have both.