What do I have here?

Discussion in 'Shock Brother's DIY Amps' started by Ripdoozer, Dec 27, 2016.

  1. Ripdoozer

    Ripdoozer Tele-Meister

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    Hello all. My dad recently gave me my step-mom's old practice amp. Looks to be hand built. It works too. I assume intended to be a public address speaker. I am interested in knowing approximate wattage and impedance if possible.

    If I can swap the tubes, give it some new wired and a new speaker, might be a cool little amp.
    Thanks, in advance for any info you might have.

    1227161047a.jpg 1227161048a.jpg 1227161050.jpg 1227161050a.jpg 1227161051d.jpg
     
  2. jhundt

    jhundt Doctor of Teleocity

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    that is SO cool!
     
  3. old soul

    old soul Tele-Meister

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    Very cool. Good project
     
  4. Dan Miller

    Dan Miller Tele-Meister

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  5. dbl9

    dbl9 TDPRI Member

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    Very cool! I can't see the schematic in that link but, 5Y3 6V6 6SJ7, same tubes as a 5C1 Champ!
     
  6. D'tar

    D'tar Friend of Leo's

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    Schematic?
     

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  7. Ripdoozer

    Ripdoozer Tele-Meister

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    Ok, so I took my awesome new little amp the rehearsal tonight. It sounded completely amazing! For about 38 seconds, at which point I approached the microphone to sing. Once my lips touched the mic, I got a heck of a shock. Actually knocked my on my bottom. There's a serious ground problem with this thing. As a matter of fact, I we leery of when I saw what my music store friend called a "courtesy plug" on the side. You can see it on the right side of the amp in the 2nd picture. Basically looked like a $3.00 extension cord from a gas station (oh yeah....and also a very old cord.) I should have known better when I saw there was no ground plug. Apparently my step mom never sang into a microphone.
    I was on the fence about whether to rebuild this thing with better parts or leave it as original as possible for as long as possible. I think this incident decided for me. I think I'm gonna rebuild this thing, one part at a time.
     
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  8. CV Jee Beez

    CV Jee Beez Tele-Holic

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    It's probably 5-8 watts. 6V6 is the power tube, one rectifier, and one preamp tube. Do you want to use it as a PA or a guitar amp? It might be ready to roll as a guitar practice amp. Similar set up to my Supro 16T. You can replace the power cord with a 3 prong for ground. If it were me I'd try to keep it stock as much as possible.
     
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  9. Ripdoozer

    Ripdoozer Tele-Meister

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    Yeah. I can see that side of it too. It does sound great! I want to use it as a guitar amp. It sounds like one. My buddy that owns the local music store here was drooling over it. He plays through A LOT of amps....
     
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  10. Ripdoozer

    Ripdoozer Tele-Meister

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    Here's what the wiring looks like.....

    [​IMG]

    [​IMG]

    [​IMG]
     
  11. Wally

    Wally Telefied Ad Free Member

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    That amp is in need of tech work. I would suggest that you are a lucky person to be telling us the story of getting knock on your butt. It needs a good cleaning, a grounded AC power cord, fresh electrolytics, ....full and proper service.
    IF you want to play it, plug it in and turn it on. Listen. Then, flip the power cord in the outlet. Did the noise increase or decrease? IF the noise decreased, then this is the proper orientation for that two-prong power cord. IF the noise increased, foil it back the other way. I would still be hesitant to simply walk up to another piece of equipment....amp, mic, guitar that is plugged into another amp....without knowing how to check to see if that 'electrocution' was about to repeat.
    I would advise for the health of the amp NOT to plug it in again. IT is tech time.....

    The Rola speaker is dated to the 32nd week of 1953, if my eyes are seeing things correctly.....285332. Neat old amp.....it deserves proper service.
     
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  12. Doctorx33

    Doctorx33 Tele-Afflicted

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    What Wally said.... Amp needs a complete rebuild.

    You're lucky you aren't dead.

    Cool amp tho.
     
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  13. Ripdoozer

    Ripdoozer Tele-Meister

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    Simply installing a properly grounded, three prong cord would not be advisable? Needs more work than that huh? I want this thing to be in action for the long haul. I would love to use it weekly for rehearsal.

    Just not sure if I can find someone around here who can do the work. Any rough ideas on price is have to pay for the service that you describe?
     
  14. vid1900

    vid1900 Tele-Meister

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    It would not be an expensive job.

    New grounded cord, move fuse to Hot side of power, spray out vol control, replace electrolytic caps.

    That would keep her running for the next 15 years, or until you need tubes.
     
  15. Doctorx33

    Doctorx33 Tele-Afflicted

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    Seems to me the wiring should be replaced. It all looks like crap and some of that cloth insulation surely is brittle and cracked or even showing bare wire.

    Actually if it was me I would redo it with all new parts. It's a sure bet every resistor in that amp has drifted, and every cap is leaking dc.
     
    Last edited: Dec 29, 2016
  16. Wally

    Wally Telefied Ad Free Member

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    The grounded power cord might make it safer for you to use. However, regardless of how good you think this amp sounds, it is not doing what it should be doing. Those electrolytics are 63 years old. IF it has paper-in-oil coupling and tone caps, they are done for, ime. The resistors may have drifted and no longer are allowing the circuit to do what it needs to do. The amp needs service.
    Would you buy a 1953 Chevy pickup truck that had been sitting in a field, put some air in the tires--if they would hold air, some gas in the tank and...if it would start....drive it across country without replacing belts, hoses, doing a brake job, putting on fresh rubber, redoing the ignition system, setting the timing, changing the oil,etc???
    Just because it is making sounds doesn't mean it is making good sounds and that its transformers are safe from catastrophic failure of a cap.
    A good tech is going to spend some time just cleaning that amp up. IMe, you will not get a better amp for less money even if you spend $300....and it should not take that much.
     
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  17. Wally

    Wally Telefied Ad Free Member

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    There is too much dirt for me to see the need for wiring changes. I do see one burn spot that probably needs to be shrink wrapped. The first thing a good tech will do is to blow the dirt out of the chassis. I would do as little replacement of original wiring as possible.
     
  18. 24 track

    24 track Doctor of Teleocity Silver Supporter

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    would this be a widow maker? it does have a power transfoemer , it appears so.
     
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  19. Ripdoozer

    Ripdoozer Tele-Meister

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    Point taken Wally. Thank you.
     
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