Peavey Mace Vt Repair and Upgrade questions

[seekford148]

I hope this is not a site that bashes a new person, I am serious about this and have all intentions on doing this and I would like some help. This amp sounded really good even at pretty high levels then it started loosing power and breaking up to the point that it is now unplayable. I now it needed some new tubes and I would really like to replace the original fixed bias into a variable one. I have never done this and I would really like some help attaced are a few pics of what I believe needs replaced but I dont know exactly what to do.

Also I would like to simplify the amplifier by removing the reverb and phaser circuits and get rid of the automix feature and just get one good solid input. In theory it is possible but I am not sure.

Finally on the main board one of the resistors has a lot of corrosion on it and I would like to replace it and maybe others if you feel like it should be done. I guess I cant put in pictures with html so I guess its just links. Well I guess I cant do any pictures. If you can help me with any of this I will send schematics pictures anything I can to get this done. Thanks for your time

[Enzo]

CLick on "manage attachments" below the posting window. You should be able to attach photos directly unless they are huge files. Alternatively, sign up for one of the free photosharing web sites and post links to there. I occasionally use photobucket. We also have a sister web site here called AMpix, intended for posting photos. We also post schematics there. www.ampix.org

I am a professional amp repair tech, and I have one rule of thumb. When an amp comes in that doesn;t work right AND they want modifications done to it, MAKE THE AMP WORK FIRST, then do the mods.

Your problem might just be needing new tubes, and nothing more than that. Won't know until we try new tubes. Nothing wrong with a PV MAce the way it left the factory - mighty freaking loud.

If there is more wrong than simple tubes, then isolate the problem. PLug your guitar into the Power Amp In jack. Does that sound clear? Also, plug the guitar in out front, and with a spare cord connect the preamp out jack to the input of some other amplifier so we can listen to what is coming out of the preamp. Preamp problems and power amp problems are completely different things.

And for that matter, plug a cord from preamp out into power amp in and see if that helps.

Also, is there DC voltage on the tip in the preamp out jack? And verify the +15 and -15 volt supplies are both OK.

You could make the bias adjustable, but really, why? This amp is very loud and strong as it sits. The tone is largely made in the preamp. You won;t be getting power tube distortion until you have maxed out this 160 watt beast. If that appeals to you, you have better ear plugs than I do.

We'll have to wait for your pictures to address a corroded resistor. The factory schematic includes a parts layout, can you point out hte part identity number.

And I am not sure about "simplifying" the amp. You don;t want those features, then leave them turned off. I certainly wouldn;t try removing the circuits from the board. If you simply MUST disable them... PV uses a TL604 IC to switch features on and off. It is no longer available, and those chips are valuable. If we remove one, please wrap it in foil or park it in conductive foam, so someone else can use it to get their amp running. I highly recommend just leaving the amp alone.

If you ever want to sell it, potential buyers will NOT be happy if a bunch of stuff has been chopped out of this amp..

The reverb is U6 and U16. Removing one of them will disable the reverb.

The phasor is many chips, but pulling U13 should kill it.

But again, I don;t see how that simplifies the amp in any way.

This amp has two more or less identical amp channels - Normal and Effect. Difference is mainly the Effect channel has the phasor available to it. Reverb is there for either to use. Make sure their input jacks are clean and the nuts tight. The automix is simply another input jack the feeds both channels. Not much there to disable. If you don't want it, don't plug into it. Until you plug a footswitch into the amp, both channels are live anyway. Automix just lets you play through both channels at once so you can blend their sounds together with their post controls.

If you MUST remove it, then we would pull the wires off the Automix jack and ground them.

[seekford148]

Thanks for the input it helps to get some good info. I will get some new tubes and clean up as much as I can and see how she sounds, if it's just the tubes then I will leave it alone. If not then I will worry about that later, sometimes I over project something. Thanks again if I have any problems I will be sure to upload some pictures.

[iwantmypie]

i noticed my mace had a few corroded parts and the inside and i figured i would replace them while i had the amp open instead of not and then having something go wrong in the future. it takes a bit of work to get the main pcb out because all the pots are soldered directly to the board so you have to remove the knobs and remove the nuts which is a little time consuming but manageable.

oh yeah drain the filter caps before you do anything. i should have said that first but the mace already has bleed resistors on the filter caps so unplug the amp from the wall and switch the standby switch up and it'll drain them instantly, at least for me. i've been considering replacing those caps as well has most of the other electrolytic caps in the amp. i have the vt model too and they should be about 30 years old so new caps could be something to look into for a simple upgrade.

[baddog]

I have a Peavey Mace that sounds good the way it is. If you want to see what it sounds like wide open but dont want to kill your ear drums. Remove 2 of the 6L6 tubes. But make sure its one from each end of the 6 tubes and not 2 from one side. You will deffinetly get the a good Freebird sound from the amp. I wouldnt tare it apart. If you dont want to use the reverb of Phazer just turn them off. But thats just me. You have a good amp that welcomes pedal usage.

BD

[seekford148]

So I have been searching for the best tubes for my style and someone from a tube site told me that the Nos Sylvania 6l6 would be the best but they are 99 a pair. If I only use 4 I can afford it but am nervous of the results of two missing tubes. Any suggestions on tubes. I play harder rock, slight metal and tons of lead.

[baddog]

You could buy all 6 tube and try 4 of them and sell the other two if you like the results. I just bought Groove Tubes (cheeper ones)because they sold 6 mached tubes and they didnt sound bad . Groove Tubes has a rating chart that you could use if you buy tubes from them . Hte higher the number the later the breakup. good luck

BD

[seekford148]

I may be wrong but if I play heavier then I would like a low hte number right? I am not too sure about the breakup number. If I were playing a ton of clean jazz then a later breakup would be the right? Is this true

[baddog]

Yes you are wright but if you use pedals to get your distortion you may want a tube with later breakup( more clean headroom ). But if you are using the amps distortion you probibly want a lower number. Just a thought

BD

[Enzo]

Wow, I would not be thinking that the choice of power tubes was particularly important in a Mace. They don;t get driven to distortion much if ever. the whole idea behind PV power tube stages in these amps was looud and clean. You won;t be thinking in terms of breakup. Frankly I would consider something like a set of Ruby 6L6GCSTRM or whatever the alphabet soup on them is these days. Good sturdy tube, sounds good. The JJ is a fine tube here too. In fact, I can;t think of a tube that WOULDN'T work well in a MAce.

[baddog]

i have cranked mine with 4 tubes and love the tone and it doesnt kill your ears. All i now is the amp sounds kind if sterile if you dont overdrive it a little.

All the best
BD

[seekford148]

Finally got it done well about 6 months ago

I forgot about this site and appreciate everyones help. I replaced all the caps and resistors and most of the wiring, I cleaned and tightened every pin, replaced the old power cable with an enormous carol cable. Replaced the tubes and re-wired my cabinet and insulated it. This amp sounds awesome, super quiet, clean and really loud, I did remove the two tubes and it definitely helped. I cant wait to do it again on another amp.

[Gtr_tech]

Frankly I would consider something like a set of Ruby 6L6GCSTRM or whatever the alphabet soup on them is these days. Good sturdy tube, sounds good. The JJ is a fine tube here too. In fact, I can;t think of a tube that WOULDN'T work well in a MAce.

I like the Ruby STRs too. The JJ 6L is a staple around here. I also like the Sovtek 6L6WXT+ (also relabled as the EH 6L6), but they don't hang in screen tap designs.

Chinese/Russian skinny bottle "6L6s" and Chinese coke bottle varieties I wouldn't use for anything other than target practice. Maybe they'd be ok in a low plate supply cathode biased thing....never tried it.

[Enzo]

I always thought the Chinese coke bottles sounded OK.... at least for their 10 minute life-span.


OK, I think I had more in mind modern, good quality tubes when I said anything would work.

[christianbrady]

This is a little late in posting a reply to this - i have a peavey mace vt, that has never had any trouble until recently - it blew a fuse, i replaced the fuse, it worked fine for a week - went on tour, when i got back and plugged up to have practice, it sounded as if it had a permanent ring modulator effect happening.. when i play the note Bb the issue is not there, so constantly there is a Bb type frequency behind every note played, creating a wobbling.. weird.. ring mod type sound.

I plugged into the power amp, sound is clear. So no issue there.
Plugged a patch cable poweramp/preamp - no change.
I tried flipping the standby switch when it was off for drainage, no change.
Plugged into amp, ran a cable from preamp to another amp, same weird/ringmod tone came out of the other amp.
So it's the preamp - but whats the deal! help!

any advice, or information anyone can provide would be greatly appreciated.