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Plush 3000B...Need information!

Discussion in 'Amps and Cabs [BG]' started by RalphL, Mar 24, 2010.


  1. RalphL

    RalphL

    Nov 1, 2008
    I found an old Plush 3000B in storage. I got it 30 years ago after a friend handed it to me as he left town. I have looked all over the net and have found photos and some info (very little out there!) but this one is truly an oddity. In small ways, it looks older than what apparently became a standard look for these babys and also has the logo in a different spot. It has seven (7) 6L6 power tubes and 3 12AX7 preamp tubes. Though it will not work without all the tubes, the center power tube of the seven does not light up much nor get very hot. Both channels work as they should as far as I can tell.

    Can anyone give me some good information on this unit?

    Secondly, it has a slight hum that does not go up in volume when either volume is raised. What can that be??

    Finally, is this more valuable as it is or changing out obvious parts that wear such as the capacitors and pots? I already put in a matched set of winged SED 6L6s and Svetlana preamp tubes.

    I'll post photos in a day or two.

    Thanks in advance for any help!!
     
  2. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    I don't know any tech specs for that amp, but I can tell you for sure its value as a newly-fixed-up, recapped, properly grounded gigging machine would be far greater than its current value as an unmodified collectible.
     
  3. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    first of all, it doesn't have seven 6L6's. it supposed to have six of them. the center one may look like a 6L6 but its probably a 5U4GB (or possibly an OC3W) rectifier. IMO, they are very nice amps, mostly based on a Fender circuit.
     
    SherpaKahn and agedhorse like this.
  4. http://www.plush-amps.com/

    This site is alittle iffy some stuff loads some don't

    I also found this on GearSlutz http://www.gearslutz.com/board/inst...458118-plush-3000-guitar-amp.html#post5179344 note the comment about the schematics being "the same as 3000b minus reverb and tremalo"

    "Byoungman,

    I assume you have a Plush model 3000G sporting a white sparkle diamond tufted cabinet?

    These are rated at 160 watts RMS (A 6L6 has a max plate dissipation of 30 watts). The circuit varies from amp to amp...Plush was truly a fly-by-night operation during their brief 5 year existance. You never know what Power or Output trannies will be on board.

    Some have an OC3 screen voltage regulator tube...some don't.

    Regardless, most sound rather good. Don't expect anything other than clean and loud out of it though if you get it up and running. Even when dimed, it'll only break up slightly.

    The reverb will sound nice as will the tremolo assuming they are still functional.

    I have a schematic somewhere in my stash-o-stuff for the 3000B which is the same as the 3000G minus the reverb and tremelo. Of course, the odds of it being the same as what you've got is pretty slim though it'll be close enough.

    Some 3K series Plush amps are PC board while others are tag board Fender style construction. Some are hybrids mixing and matching PC boards with tag boards. I've even seen a few of them that are true "point-to-point" construction.

    Like I said, you never know what Plush did under the hood until you open the amp up.

    BTW, just about any competent tube amp repairman can fix the amp...they are very simple circuits. If the trannies are still good (probable) then it can be fixed."




    :bag:
     
  5. RalphL

    RalphL

    Nov 1, 2008
    Many thanks for the quick replys!
    Johnk_10, I had considered that but I am not much of a tube head; little experience in this corner. When given to me, they were all 6L6s. I'll find a 5U4GB and give it a shot, most certainly. But how can it work with the 6L6 in that position? Are they that similar?
    Bongomania, I'll pull the chassis and see what I am up against. I'm fairly good at wiring and soldering and understand how to read values, etc. But if this sucker is too complex, which I assume it is not if based on an early Fender design, I'll have a local pro go at it. Next is a road case.....
     
  6. RalphL

    RalphL

    Nov 1, 2008
    Check out this page:
    http://www.plush-amps.com/PhotoPage3.htm
    Mine is a combination of these two. The control plate is just like the brown one (3000B) but the case is like the black one (3000G). The rear of mine has 7 tubes like the black one (3000G) but connections like the brown one. My tube guard but has the blocks in place so I can rig one up. Also note on that page that the 3000B does not have preamp tubes (which mine has) and the 3000G does.
    My 3000B is like these 2 amps Frankensteined together!
     
  7. RalphL

    RalphL

    Nov 1, 2008
    Messed a sentence: My tube guard is gone (never was there) but the blocks are in place so I can rig one up.
     
  8. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    i don't know how it could work? my guess is that its not a 6L6 and its an OC3 or a 5U4GB in there. a 6L6 is a beam power tetrode, and an OC3 or a 5U4GB is a rectifier tube. you might try removing the center tube to see if if still works. if it does, then someone replaced the tube rectifier with diodes and the center tube socket isn't even in the circuit (also the reason it's not lit up). it won't hurt anything if you try it, as the amp won't power up if the rectifier isn't in the circuit.
     
  9. RalphL

    RalphL

    Nov 1, 2008
    Otis Thick, many thanks for the link!
     
  10. RalphL

    RalphL

    Nov 1, 2008
    Johnk_10, as I said, it has a 6L6 in that position and the amp works! As I said, it does not work without that tube in place. It does light a little and only gets warm. Is this a mystery or what??!! Yikes!
     
  11. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    crazy man, crazy.
     
  12. SherpaKahn

    SherpaKahn

    Dec 1, 2005
    Bronx, NYC
    ...necro-post: the 6l6GC (and other pentodes/tetrodes) can be employed as voltage regulators. So an amp could really require an odd-numbered complement of power valves.
     
    BassmanPaul likes this.
  13. Well I sure hope that he figured that out in the last 7 and a half years.
     
  14. RalphL

    RalphL

    Nov 1, 2008
    About a year after this post my loving wife died suddenly and so I decided to learn how to design and build amps as a form of therapy. And I am now proficient. However, I have not looked that that Plush since then ( my 2 rigs have much lighter amps, etc) and it is time. I'll recap it, change out funky resistors and other old parts and let you know how it goes. Thanks for the support!
     
  15. BassmanPaul

    BassmanPaul Inactive Suspended

    I seem to remember a few Plush schematics that used a 6L6GC as a regulator for the other output tubes screen grid supplies. Vey few other manufacturers did this. I think that Wards Airline did the same thing.
     
    SherpaKahn likes this.
  16. RalphL

    RalphL

    Nov 1, 2008
    It seems these amps routinely varied in numerous aspects; everything from case design, chassis and, I am sure, electronic choices. When I get around to re-capping it I'll draw it up and post.
     
  17. SherpaKahn

    SherpaKahn

    Dec 1, 2005
    Bronx, NYC

    ...hope this helps. I just picked up an old 3000B of Craigslist. I think it's an earlier model with type 0C3 regulator valve (7 octal sockets: 3x 6L6 then 0C3 in middle then 3 more 6L6). I haven't finished tracing out the wire runs & PCB, but it appears to match the 3000B sketched out in this other forum thread:

    http://el34world.com/Forum/index.php?topic=9366.0



    http://el34world.com/Forum/index.ph...be3&action=dlattach;topic=9366.0;attach=14336


    The schematic to a 3000B with 0C3 regulator and dual chokes seems to match mine, but I'll have to wait til I finish working through the innards.

    Mine is in dire need of a re-cap (one of the stacked 100uF/450V filter cans is visibly sprouting a fungal-looking crust from the top...All that matters is that the lovely lovely rusty trusty iron is intact and well. It's also lost a chunk of circuit board near an octal socket, and has been impressively repaired with jumpers across failed traces....Impressive or not, it was clearly a job with limited resources, and a filter cap for the bias supply had its casing leaning on a ground trace.....little hint: the metal casing of an electrolytic cap is often connected to the negative lead...so a filter cap for a negative [bias] supply leaves the casing floating at the negative bias supply voltage...short that to ground and no more bias. Anyway, this thing won't be powered on again until thoroughly re-capped, with film caps then tested for leakage. Maybe a PTP rebuild with turrets/terminal strips....and MOSFET source followers!
     
    Last edited: Jan 8, 2018
  18. SherpaKahn

    SherpaKahn

    Dec 1, 2005
    Bronx, NYC
    Uploaded to TB for archival purposes.
     

    Attached Files:

  19. RalphL

    RalphL

    Nov 1, 2008
    Good stuff! Check this out: O.T.B. Plush 3000B
    The schematic you posted was written in 2009. Likely the author had only one amp and that's what got sketched out. The history of these amps, layouts, changes....it's apparently pretty much across the board...all over the place. Mine looks a bit more primitive than some photos I have seen. And it could have been modded, etc. I really appreciate all the good info you've posted. I'll post again when I cut into this one within the next few months. Mosfet source followers? I like it!
     
  20. SherpaKahn

    SherpaKahn

    Dec 1, 2005
    Bronx, NYC
    Hopefully you've read the EL34world thread through to the invaluable comment by Paul Ruby about the "diabolical" power supply. The other schematic posted there is only of the PSU for a 3000B model with no regulator tube (similar to the blue one pictured in that thread). Note that it only has the single choke for the screen supply, and the empty hole where the VR tube's socket would, and a zillion other empty punched holes...

    ...the swiss-cheesed chassis possesses all the socket holes required for my model (which has a 2-3 extra empty holes, but nothing approaching that blue one!)...Notably, the preamp tubes on mine occupy those three holes in-line with the power tubes. This all leads me to think that the one pictured is a later model, and mine is moderately older.... They probably updated the design [ cut costs by eliminating a ~200mA rated choke, VR tube + socket, then replace PSU design with "diabolical" version], and just added more holes to existing prepunched chassis[plural mind!$#@].
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Nov 30, 2020

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