Converting Peavy Deuce amp

[Cygnus X1]

Adding the preamp tubes to the mix will help bring the B+ down a little.

[DonMoose]

The one that connected to the power cord/fuse/switch would be the PT, the other connects to the power tube PCB and speaker jacks - assuming it was still assembled when you got it.

A lot of companies shut down for Xmas-NewYears' week, and a good percentage of those also break for 4July week. Not much good for customer support, but at least mgmt knows when folks'll be gone.

[beasleybodyshop]

Leo, I can't say that the names ring a bell. I am from Greenville ( about an hour and 20 minutes east of Dallas) Lots of guys out here have been playing Texas country in the last ten or so years (thanks to Pat Green lol)

coincidentally,this amp originally belonged to a old fiddle player friend of mine. He bought it new and hooked it up to his fiddle through an old barcus berry pickup system.

As for Mississippi, I know the feeling. hundred degree days are already here in Texas, iv'e already swapped in my window units in lol

Update: I have placed orders at valvestorm and classictone. Ordered new iron (their "vintage" spec stuff) and mostly mechanical things from the other place (sockets, hardware, bridge recto, etc) hope to get rolling on this puppy when all the goodies come in. Im hoping the big square cutout is going to be the right size for my xformer, but i will cross that bridge when I get there!

[Leo_Gnardo]

Leo, I can't say that the names ring a bell.

oh well had to try.

Im hoping the big square cutout is going to be the right size for my xformer, but i will cross that bridge when I get there!

whaaat? I saw "bodyshop" and figured this guy's got the metalwork tools & talent. Of course it's very handy when the transformer sets just right in the hole and no more cutting need be done. I hope that happens for you.

Also trying to figure out where your signoff line came from.

[beasleybodyshop]

Yeah my family owns a body shop, I worked there since I was ten up through grad school - Your right, the cutout isnt a big deal i was overthinking it, I could take a die grinder to it if for some reason its too small, but its a rather large square so i think im good.

As for my sig, its a line from the Big Lebowski. Im a big fan of Coen Brother movies!

[beasleybodyshop]

I have another thought: The Peavy originally had a reverb tank and RCA connectors on the chassis for a reverb circuit. How difficult would it be to make a reverb circuit for this build? Any info I could look at?

[Leo_Gnardo]

I have another thought: The Peavy originally had a reverb tank and RCA connectors on the chassis for a reverb circuit. How difficult would it be to make a reverb circuit for this build? Any info I could look at?

You've got plenty of chassis space, preamp tube sockets etc. No reason you couldn't add a reverb. One way is have a look at Fender's method for their classic black- and silver-face amps. HOWEVER there's of course a tradeoff and that's the dry/reverb mix junction and makeup stage. When you change somethin' you change somethin' and the sound will be different.* Can still be very acceptable. I like all those Fenders and so do millions of others. I s'pose you could design in a toggle or relay switched bypass that skips the mixer/makeup stage and takes you back to stock JMP 50.

*Customers of mine who have owned both the reverb and non reverb BF Deluxe pointed this out to me a long time ago. There's a little more clarity in the non reverb version. Shows us once again, simple circuits yield clarity.

[beasleybodyshop]

Yeah I had read that it could alter the overall tone. Hmm. Well I could always gut a good sounding reverb pedal and wire it after the preamp? reroute the knobs to the chassis and mount a toggle....Or am I getting too redneck in my approach?

[Leo_Gnardo]

Yeah I had read that it could alter the overall tone. Hmm. Well I could always gut a good sounding reverb pedal and wire it after the preamp? reroute the knobs to the chassis and mount a toggle....Or am I getting too redneck in my approach?

FX loop, you could do that too and insert a really good reverb + any other time delay FX on sidechain so as to minimally disturb the original signal path but that STILL requires a mix stage so . . . pick your poison. If you allow for a bypass switch that restores the minimum signal path (without reverb) then you have it when you want it.

[beasleybodyshop]

Yeah, Effects loop it is! I like the flexibility. The loop is going to need a 12AX7 as well right?

[Leo_Gnardo]

Yeah, Effects loop it is! I like the flexibility. The loop is going to need a 12AX7 as well right?

Good to have a bypassable gain stage on the return for sure, if you want the flexibility of using all sorts of delay FX. Pedals and "semi pro" FX designed for -10 dB levels may need a little help, that's why it's good to have that gain on the return. Pro gear designed for +4 levels will proabably allow you to bypass that gain stage and skip whatever noise it would add.

[beasleybodyshop]

Yeah, Effects loop it is! I like the flexibility. The loop is going to need a 12AX7 as well right?

Good to have a bypassable gain stage on the return for sure, if you want the flexibility of using all sorts of delay FX. Pedals and "semi pro" FX designed for -10 dB levels may need a little help, that's why it's good to have that gain on the return. Pro gear designed for +4 levels will proabably allow you to bypass that gain stage and skip whatever noise it would add.

When you say pro gear vs pedals, what do you mean?

[Leo_Gnardo]

When you say pro gear vs pedals, what do you mean?

Pedals generally expect to run off a 9V battery for power, and expect to have a guitar plugged into them, also one could expect a guitar size signal to come out. Guitars, unless you're bashing very hard with a very sensitive pickup, turn out a signal of say 100 to 200 millivolts AKA a tenth of a volt or two. And that 9V battery or wall wart limits the absolute maximum signal to about 3 or 4 volts AC (that's signal AC not power). So you can see you'd better scale your sends/returns to these low values if any of the general run of guitar pedals are to be used in the FX loop. Semi pro equipment handling -10 dB signals, similar. Pro equipment, rated at nominally +4 dB levels what you find in studio racks, is generally run from +15 and -15V power rails and sometimes larger, so you can see they can handle much larger signals. Pro delays, reverbs, graphic EQ's, limiter/compressors, and multi effects and others. Larger signal, hopefully better signal to noise ratio. If you run a small signal into these +4 devices, they'll pass the signal all right but you will find sssssshshhhh much more audible too. Many have a good bit of gain, but if you use it, noise comes up too. There are a couple "good old" rack devices that have a button in back to adapt them for use in low or hi signal setups, Roland's 1980's DDL's and digital reverbs come to mind. Most of the studio +4 devices can turn out a signal well in excess of a couple of volts, figure 10 to 15 VAC at peaks. You can see why some amps FX loops don't get along well with pedals, if they're sending out large signals and expecting the same to come back in.

In conclusion it's good to have a variable send level, so you can dial it down for pedals and up for studio gear. A preamp stage on the return side allows for the use of pedals & can bump the signal level up so that it's not lost in the sauce. Bypass that pre stage if you have a big signal returning from a studio +4 level gadget - it turns out enough signal to be heard without another pre stage. Some amps have a return volume control, no bypass, and a preamp stage that's always in circuit. Every sort of variation has been made by now I'm sure. If you know what you're definitely going to use, you can design for that. Otherwise plan your FX loop for versatility.

[beasleybodyshop]

When you say pro gear vs pedals, what do you mean?

Pedals generally expect to run off a 9V battery for power, and expect to have a guitar plugged into them, also one could expect a guitar size signal to come out. Guitars, unless you're bashing very hard with a very sensitive pickup, turn out a signal of say 100 to 200 millivolts AKA a tenth of a volt or two. And that 9V battery or wall wart limits the absolute maximum signal to about 3 or 4 volts AC (that's signal AC not power). So you can see you'd better scale your sends/returns to these low values if any of the general run of guitar pedals are to be used in the FX loop. Semi pro equipment handling -10 dB signals, similar. Pro equipment, rated at nominally +4 dB levels what you find in studio racks, is generally run from +15 and -15V power rails and sometimes larger, so you can see they can handle much larger signals. Pro delays, reverbs, graphic EQ's, limiter/compressors, and multi effects and others. Larger signal, hopefully better signal to noise ratio. If you run a small signal into these +4 devices, they'll pass the signal all right but you will find sssssshshhhh much more audible too. Many have a good bit of gain, but if you use it, noise comes up too. There are a couple "good old" rack devices that have a button in back to adapt them for use in low or hi signal setups, Roland's 1980's DDL's and digital reverbs come to mind. Most of the studio +4 devices can turn out a signal well in excess of a couple of volts, figure 10 to 15 VAC at peaks. You can see why some amps FX loops don't get along well with pedals, if they're sending out large signals and expecting the same to come back in.

In conclusion it's good to have a variable send level, so you can dial it down for pedals and up for studio gear. A preamp stage on the return side allows for the use of pedals & can bump the signal level up so that it's not lost in the sauce. Bypass that pre stage if you have a big signal returning from a studio +4 level gadget - it turns out enough signal to be heard without another pre stage. Some amps have a return volume control, no bypass, and a preamp stage that's always in circuit. Every sort of variation has been made by now I'm sure. If you know what you're definitely going to use, you can design for that. Otherwise plan your FX loop for versatility.

I had no idea! I always assumed that rackmount units were just pedals in another form. Hmm. So a tube powered effects loop is definitely something I want to have. Is this something I build on a separate board and insert before the preamp stage?

[Leo_Gnardo]

had no idea! I always assumed that rackmount units were just pedals in another form. Hmm. So a tube powered effects loop is definitely something I want to have. Is this something I build on a separate board and insert before the preamp stage?

Good thing you found out then innit? And you can sling pedals into a rack shelf or drawer. Doesn't give 'em any more headroom. I've dealt with "Bradshaw" rack switching systems for le beeg beeg rock stah, and every kind of FX can be accommodated, even using entire AMPS as preamp stages, Marshalls, Boogies, etc.

Traditionally FX loops are located after the pre and before the power amp in guitar amps.

To keep things simple for folks who don't have big buck budgets I recommend that guitar pedals are used as intended, with guitar levels going in, and outputs going to the amp's input. Big-signal studio gear is happier in the FX loop. That way you can pretty well skip a gain stage on the FX return side. If you design the FX return to appear before the master volume in the amp's functional chain I reckon you're better off and can control overall volume while keeping noise to a minimum. Then you can play the Blue Hair Ladies' Garden Club luncheon gig at noon, and dial it up for the Grunge Klub midnight show.