NAD: $60 Peavey Studio Pro 40 (plus lots of noise and hum for free)

Discussion in 'Amp Central Station' started by ukepicker, Feb 4, 2019.

  1. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    I've been jonesing for a Bandit 65 since the walmart blooze daddy thread. Even bought one from a GC in OKC but it showed up in very poor condition and I didn't keep it.

    Then a Studio Pro 40 showed up on the local CL and I snagged it for $60.

    Inspection tells me that ALL the pots are in terrible condition. Very noisy. Hopefully they are salvageable. Also, the reverb is unusably noisy. I'm hoping that it's just dirty RCA contacts.

    The only real downer was the plug - someone had ripped the 3rd ground prong off of it. I'll just wire up a replacement plug, unless one of you experienced guys makes a good case for a full lead replacement.

    It's plenty loud for my tastes. Solid as a tank and has great bones. It doesn't look like it's ever been monkeyed with. Powerful EQ sections (at least from what I could tell with the bad pots). Two inputs (one at -6db). Line out. Effects loop. I even liked the sound of the tiny reverb tank (at least what I could hear of it through all the noise).

    If I can get it back to 100%, I think I'll like it more than my old blues jr!
    JustABluesGuy and bftfender like this.
  2. bftfender

    bftfender Friend of Leo's

    Dec 21, 2017
    York PA
    i already like it more than the blues jr
    ukepicker likes this.
  3. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

    Mar 17, 2003
    Fort Collins, CO
    I have a Backstage Plus that I use all the time. I bought it as a living room practice amp, but it sounds so good and is so easy to carry that it goes out to the gigs the other amps used to go on.

    Put a little love into that Pro-40 and it will serve you well.
  4. JustABluesGuy

    JustABluesGuy Friend of Leo's

    Sep 2, 2016
    Houston, TX
    Congratulations! I just recently found a good deal on an old Bandit after looking for a couple of years. I’m also keeping an eye out for a cheap Envoy for when I don’t need that much power!

    I picked mine up for use as a “throw down” amp that I won’t have to worry about, but it sounds better than I expected, tube snob that I am. :rolleyes: In my brief tests with it so far even the dirt channel isn’t as awful (to me) as I was lead to believe (when used sparingly). I also want to try using the preamps of my lower powered tube amps with it and see what sonic mayhem is possible there! :lol:

    It proably won’t become my #1, but when I really need “loud” it’s definitely my go to. It’s definitely one of the better sounding analog SS amps I’ve ever played, especially for the price!
    Paul in Colorado and ukepicker like this.
  5. Ringo

    Ringo Poster Extraordinaire

    Mar 16, 2003
    Memphis TN
    Pull the chassis clean it real good, try some good contact cleaner lube in the pots, clean the input and output jacks, reverb connections, and you should be good to go.

    My buddy has a Backstage 50 that he got new in the mid 80s , it's been a great practice / small gig amp for him, just now starting to have some issues, he probably needs to do what I just advised you with his amp.
    JayFreddy and ukepicker like this.
  6. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    I got a little more time with it today on my lunch break. Man, there's some serious potential here. When the pots aren't making everything crack and sputter, it sounds great! I've always kinda liked the quick thwack of a solid state amp.

    The interaction of the pre- and post- gain knobs yield a bunch of subtle colors. And I think the EQ is gonna be very powerful. I don't have much use for the saturation circuit. If I can figure out where it is, I might try some different diodes.
    I'm also more impressed with the speaker today - lots and lots and crystal clarity in the upper frequencies. Probably enough low end for now. Overall, I don't find it overly inspiring, but it is more than adequate for my little space.

    I'm anxious to pull the chassis and see what I'm dealing with. I'm half expecting bad filter caps (to go along with the scratchy pots). Maybe I'll get the chance tonight!
  7. Ed Storer

    Ed Storer Tele-Holic Silver Supporter

    May 27, 2010
    Seattle WA
    Dr. Z's video on amp maintenance is definitely worth watching, .

    You need to clean your pots, but also make sure the pots are making good ground.
    ukepicker and JayFreddy like this.
  8. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    Well, last night, I followed Dr. Z's advice. I pulled the chassis, loosened all the pots and other connections, sprayed in cleaner and re-tightened. Cleaned all the pots twice and turned them until my hands cramped. I also cleaned the whole thing, top-to-bottom, inside-and-out. I don't think it had ever been opened before - I was her first :)

    I didn't have time to go get the new plug last night. But I'll try to make it happen tonight. I'm anxious to try it out!

    I'll see if I can post some "before pics" for posterity.
    JustABluesGuy likes this.
  9. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    Nevermind about the pictures.
    Can't do it from the app anymore. Creating a TDPRI album is an extra step, and I tried - but it won't take my pics because they are too large.

    You know what? No thanks. I'll take an extra step, but not 15 extra steps.

    I guess you guys will just have to take my word for it.

    I was excited to post a pic of how clean and healthy the caps look! My hopes are getting high that this is gonna be a "very good++" keeper, just needed a little cleaning.
    ce24 likes this.
  10. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    Well, I got all the pots back up to 95% function and fixed the plug. Sounds great, everything works great....mostly.

    The reverb has a 60-cycle-ish thing that gets louder with the reverb dial, but doesn't increase with the volume of the amp. I guess it's just the nature of the unshielded wires to the pan and back? It's not a reverb sound that I will turn up very much anyway, and the hum is hardly noticeable at lower reverb levels where I'll probably keep it.

    But every once in a while, the amp will loose about 90% of it's volume. It happens suddenly, and usually when I'm moving something (today it was pulling out the knob for the bright circuit). It behaves a little like a short, but won't respond to further knob tweaking or the ol' Fonzie whack. Then it'll suddenly come back on and stay normal and sound great. (Well, actually, today when it came back on, it crackled and popped a little like an old tube amp warming up.) I'm not an amp guru, but my spidey-sense is telling me it's either a short somewhere in the circuit or the filter caps are intermittently not charging up the way they should. But it seems weird that they should work most of the time - I'd think a failing cap might be a little more consistent in its behavior.

    So there's a little more work to do, but man I like this thing a lot. Totally worth the effort.
  11. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    A quick browse of the interwebs tells me that my volume drop problem may be the very common "effects loop" problem that Peaveys (and others) have. A short in the jacks. Easy fix is to run a patch cable from the preamp out to the power amp in.

    I just cleaned and checked those jacks, but I'll try jumpering them if the volume drops out again.
  12. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    The jumpering of the effects loop worked. And made the whole thing quiet as a church mouse. Even the reverb is quiet now. All back to 100% - What a deal!

    So, now that everything is working, I can really tell what the amp is doing. And it's ice picky to my ears. Sadly. ODs and fuzzes are almost painful. If I knock the highs down, I lose the open sound and it turns "boxy" quickly.

    So I'm thinking a new speaker. Leaning towards a C-Rex first. But I've always wanted to try a Swamp Thang, too. I think the amp could use a little help adding more character and CRex will surely add some of that. Anyone ever try both in an 80s Peavey solid state?

    For now, I'm having great success putting my klone in the effects loop. Turn the amp way up, get the dynamics really singing, then put it through the klone, dial out a little treble, get that great round klon bass and turn the volume to where I like it in the room. And it has a little more character. Inspired me to play for hours yesterday, and I hadn't done that since Christmas.
    Last edited: Feb 11, 2019
    Nickadermis and JustABluesGuy like this.
  13. goyo4400

    goyo4400 TDPRI Member

    Jul 16, 2004
    Fort Valley, GA
    Bought my studio pro 40 new in the mid 80's later replaced stock speaker with swamp thang. Huge improvement. More bass tones. More overall volume
    ukepicker likes this.
  14. ukepicker

    ukepicker Tele-Afflicted

    Oct 15, 2013
    East Texas
    Thanks for the reply! I'm looking hard at the swamp thang.

    Did it smooth out the ice pick highs at all? Does it fit pretty well in the cab?
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