Adding Master Volume

[skynyrd]

I have a old Peavey Mace and a Peavey Heritage both do not have a master volume and I would like to add one so I can crank the main volume up and level out the sound with a master, that way the amp can function normally through their proper chain and I can get the cranked sound at low volume. I got one of those pre amp out power amp in boxes and not really enthused about it. My thought is to tie in a 50k audio taper at the speaker output stage so that the power chain is not altered and just the true output is all thats controlled. My first thought is what ohm pot to use so I don`t alter the operating impedance of the system??? IS 50K to much or not enough? Both amps have separate ohm outputs a 4 ohm and a 8 ohm, if anyone has any experince with these amps and could suggest the best place to patch in the master volume put it would be greatly appreciated and save alot of trial and error searching. Thanks for any input offered.

[Gtr_tech]

Just get a Hotplate or similar pwr attenuator. Thats the "safest" way to go about it, but you still risk damage to the output section. If it were me I'd not go that route....I'd get a pedal or preamp that I liked the sound of and run that in front of it. That way you're not beating the output section to death and replacing output tubes every 3 months. Those hybrid PVs are not known for good sounding front ends.....

[skynyrd]

The more I look into it am thinking getting a good tube driver pedal to boost whats already there may very well be the best way to go. I had thought about the seymour duncan 25 db boost pedal but not sure if it would drive the SS pre amp more or not, I know it would a tube pre amp.

[Gtr_tech]

A clean boost only works well with tube preamps. The SS pre you have prob'ly won't get along with a clean boost. You need a pedal/preamp with an overdrive sound you like. Then run that into the amp using the clean channel.

If you end up with a rack style pre with a *line* level output, you can bypass teh front end altogether and run the pre into the "pwr/main amp in" or FX return" jack. That way you control *everything* with the outboard preamp.

[shredhead]

Any true tube amp sounds meaner when you push the front end a bit. A good boost like a rat or a metal muff will do. Then again, the only real way is to crank it past 11. Full out or fu*k all!

[shredhead]

IMHO I would buy earplugs before an attenuator... A lot cheaper, and better sounding.

[skynyrd]

I picked up 1 of Lee Jacksons amp mod books and he has a schematic for a master volume that is attached between the speaker outputs with a 250K pot? I thought that would burn up the power section before long doing it that way?

[jetcode]

Do NOT put a pot in the power chain!!!! You will smoke that pot instantly. Pots typically handle 1-2 watts and often much less. Where you want to add the volume control is in the signal chain before the phase splitter!

My recommendation is to pay an amp guru to make the mod! The chance of getting shocked is high in amplifiers.

I have a old Peavey Mace and a Peavey Heritage both do not have a master volume and I would like to add one so I can crank the main volume up and level out the sound with a master, that way the amp can function normally through their proper chain and I can get the cranked sound at low volume. I got one of those pre amp out power amp in boxes and not really enthused about it. My thought is to tie in a 50k audio taper at the speaker output stage so that the power chain is not altered and just the true output is all thats controlled. My first thought is what ohm pot to use so I don`t alter the operating impedance of the system??? IS 50K to much or not enough? Both amps have separate ohm outputs a 4 ohm and a 8 ohm, if anyone has any experince with these amps and could suggest the best place to patch in the master volume put it would be greatly appreciated and save alot of trial and error searching. Thanks for any input offered.

[skynyrd]

I am going to have this guy here in Indy that works on alot of the big names equipment look into that, he gave me a mod for it that really opened it up tonally and the mud is gone and have full control over the eq section now.

[jetcode]

I am going to have this guy here in Indy that works on alot of the big names equipment look into that, he gave me a mod for it that really opened it up tonally and the mud is gone and have full control over the eq section now.

Hope it works out for you. Should be a great mod. For me (circuit debug) if I can't drool on it and survive I give the job to someone with a better medical plan !

[EFK]

Best master I have ever used - with a Marshall - is the PPIMV "Lar/Mar" off the Metroamp board, basically a refined and safer version of one the older Fischer type 2. However, for it to work well, what is really necessary is the addition of a NFB pot so you can adjust the nfb to compensate for the loss when you dial back the master and retain usefulness of your presence pot. 2 knobs, works wonderfully - can easily retain the amp tone.