Converting Peavy Deuce amp

[beasleybodyshop]

Here are some photos of my "barn find" Peavy. It's obvious this thing has been played to the ends of East Texas and back (That's where i'm from ) When I got it, it had at least 3 pounds of rat poop inside of it, but the chassis looks pretty clean. I did have to clear out a big female black widow too. PCB looks like its in good shape as well, think Its worth robbing anything off this for my JMP? and yeah there was a big dried up spider on the chassis, i decided to leave him there haha.

[cbass]

Old peavey's had good iron.ALmost all thrier old 6l6gc desogns ran around 500VDC on the plates and a few less on the screens.

[beasleybodyshop]

So how would I go about converting my OT/PT for plexi use?

[beasleybodyshop]

Update: I have stripped everything out of the chassis, everything looks pretty clean. I have also started making a new plexiglass control plate. Ive got to see if the peavy's OT/PT will be ok for the JMP circuit. Ive dug through several of the threads here at TAG - All lots of amazing information! Ive been learning my leaps and bounds in the last few days. I'm already thinking about my next build (all the Dumble info looks super tempting ) but I must focus.

[cbass]

They will work your b+ maybe kinda high I'm not sure about this particular amp but a lot of peaveys from that era used FWB rectifiers On the HT and bias taps.
I measued a 100 watt PV OT once if I remember it was around 2.3k primary

[martin manning]

Someone was going to measure some transformers a short while ago: https://tubeamparchive.com/viewtopic.ph ... 933#257933 Follow those instructions, but your lead colors are different:

On the PT, brown and orange are filament, Red and red/yellow are the high voltage, and yellow is grounded so it's likely the high voltage center tap. Purple is probably the bias tap. I'd measure red and red/yellow to yellow, looking for 300-350 volts on each side, purple to yellow maybe 60 volts, and orange to brown 6.5-7 volts. All of these are AC, and be careful!

Looks like your OT primary wires are standard red, blue, brown; can't tell which secondary tap is which... maybe you made a note?

[cbass]

Martin I'm not sure if you are aware but I belive this amp uses a full wave bridge Rectifier.So no ground on the HT.
The yellow wire going to ground I think is for the bias tap.(Purple wire)

[martin manning]

Martin I'm not sure if you are aware but I belive this amp uses a full wave bridge Rectifier.So no ground on the HT.
The yellow wire going to ground I think is for the bias tap.(Purple wire)

You may very well be right CB, thanks. If so, purple to yellow will still be around 60V, and red to red/yellow will be 300-350 volts.

[beasleybodyshop]

Martin and Cbass, thanks for the info! Being that the PT might be a little hot for what the JMP needs, does that mean i need to hook up some resistors to the HV tap to bring it down to what the JMP calls for?

[M Fowler]

So you want to build a JMP 50w 1987?

Here is a layout and schematic.

[martin manning]

Martin and Cbass, thanks for the info! Being that the PT might be a little hot for what the JMP needs, does that mean i need to hook up some resistors to the HV tap to bring it down to what the JMP calls for?

I suggest you measure it and see what you have for the unloaded AC voltage on the secondary, then decide how to proceed.

[Leo_Gnardo]

Being that the PT might be a little hot for what the JMP needs, does that mean i need to hook up some resistors to the HV tap to bring it down to what the JMP calls for?

With the present PT, you'll wind up with an extra powerful "50W" JMP. Many late 60's - early 70's Marshall 50 watters actually measure more like 30W at clip, with a B+ around 410V at idle and 380V at clip.

A customer took it upon himself to replace the PT in a JMP 50W I had repaired some years earlier. Then he couldn't understand why the output tubes red plated & fuses blew. He selected a "more powerfuller" PT and B+ was in the 500V region, also very stiff, not much sag in the voltage as full power was delivered. A pair of non roasted output tubes and a bias reset, and he was on his way with a 60-65W JMP, more powerfuller indeed!

If having some extra power appeals to you (also saving money & hassle) your present PT I'm sure will be fine. If you want to dial down the power then a replacement PT is one solution, or you can follow the recommendations of some of the other knowledgable TAG circuit meisters.

If you do stick with the present PT, you might want to consider KT88 for your output tubes. In my experience they deliver an ear-friendly tone with a pleasing low-mid resonance. They're also good about handling higher voltages.

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A top rated FOH mixer I worked with had also worked with 38 Special when they were at the top of their touring career. He said Peavey gave them tons of gear. One thing you might have noticed if you looked carefully at 38's backline, after a short while the dashboards of their combo amps turned to gold. They swapped Marshalls into them preferring their tone and reliability. I thought that was hilarious also thought provoking...

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Peavey on vacation? Consider Meridian Mississippi is @ 105F with 105% humidity this time of year it's a wonder they don't take the whole summer off.

[martin manning]

Here are a couple of 4x 6L6 Deuce schematics:

http://blueguitar.org/new/schem/peavey/ ... series.pdf
http://blueguitar.org/new/schem/peavey/pv_deuce-b.pdf

Same PT lead colors as the one here... 500V B+ is way too much for a JMP, and if the OT primary is ~2k (for a quad of 6L6), that will be way too low for a pair of EL34's, and still too low for a quad running at that plate voltage.

[beasleybodyshop]

Interesting. I think the stock Iron is going to be more than I want. I really want to get as close as I can to a stock 1987 lead. I can use the xformers on another project, or if anyone wants them they can have em. Thanks for all the help folks. I'm going to place some orders on valvestorm and update when I start bolting things together.

[Leo_Gnardo]

Now that you've set a course, a question about something completely different. beasleybodyshop do you by chance know the Gillette brothers? Guy & Pipp Gillette. They had a heck of a good band in these parts (Hudson Valley NY) in the mid 70s-early 80's then moved to East Texas (their roots territory) to take up cattle ranching. Heard they're still playing some music too. They had a great N'Olins style groove but wouldn't admit it. "Naaah, we're East Texas." I know E. Texas is a lot of territory but thought I'd ask. Nothing ventured nothing gained.