Old Church Tube Amp

OK--this is the innards of the old church sound system amp we found. There are two inputs: "microphone" and "phono". The output seems to be an old obsolete four-pronged thingy. As you see--tubes. I want to make it a guit amp head. You amp/electronics people: What do I need to do to it to make it a guit amp head?
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  • Okay.  So, I called around, and I thought, heck, maybe my friend/regular guitar repair guy fixes amps too.  I called him.  He takes them and sends them to a guy.  I asked for the guy's contact info.  He said, "No, he doesn't like people."  So, the deal is you bring your amp to my repair guy/friend, he shows it to his amp guy, gets an estimate, and so on.  So, that's what I'll do. 

  • that looks like a pretty nice amp.  I wouldn't down rate it at all.  Shipping is trivial compared to the value of the amp.  I've been looking around a little to find an amp like that to use to build a guitar amp.  A buddy of mine has suddenly branched out into cigar box guitar playing.  I've known the guy since 1969, never showed any interest in music but suddenly busts out as a karaoke singer and now the whole cigar box guitar thing.  He's in his mid-70s, not afraid to try new stuff. My flabber was completely ghasted.

  • Thanks, Tom.  I just emailed Craig with pics of the amp and my story.  Being as I'm in Illinois, shipping there and back would be, I'm guessing, more than the darn thing is worth, or at least more than what Craig would charge.  Maybe I can find someone within driving distance who does that work.

    Your advice is well-taken.  I won't try to plug it in.

    Yea, vintageamps.com--not good.

    Thanks!

  • old paper caps are old original paper in oil capacitors.  after 50 years they are likely dried up. if you bring it up on 120 volts, the caps may as much as 450 volts.  have a fire extinguisher handy and wear safety glasses.  Don't ask how I know this. :)

    1 covered already

    2 yes

    3 There's a guy named Craig Ostby in Michigan who resurrects these thing for a living.  He's good and he's proven honest over many years.  he's at http://www.nosvalves.com/

    nos valves refers to New Old Stock tubes, which he has many of.  However, he is not good at updating his website.  ignore most of it and find his contact info.

    vintageamps.com is trying tell you something.  Listen carefully and think about where you want to spend your monmey

  • So, Tom, you're saying it wouldn't be a good idea just to plug it in and turn it on?  I confess I know very little about such things.  Permit me a few q's here:  1.) What are "old paper caps"? Does that mean the old tubes? 2.) So, if I use a Variac, that would allow me to ease the thing into the needed voltage slowly rather than all at once, which might be...dangerous? 3.) If I decide to say "to heck with it" and bring it somewhere to get worked on, where should I take it?  BTW, I posted these finds and a request for help on www.vintageamps.com/plexiboard, but they haven't seen fit to approve of the post yet.  Hmm.

  • that oddball plug is for power to a pre-amp.  be careful with it, it may have 400V in a couple of those pin holes.

    Looks like a really nice single channel amp.  feel free to post up any questions.

    Old paper caps sometimes object to fired up after sitting for years.  There's a thing called a Variac that allows adjustable voltage.  guys who work with these old amps use them religiously to bring up old tube amps.

  • Thanks Jerry.  What amp builder forums would you recommend?

  • What is the exact make n model? I would think that row of terminal would be the output.,with the unit turned off and unplugged you could probe the back with a multimeter looking for 8 ohm or 16 ohm secondary winding of the output transformer.,.,thats where the speakers go.,.,.,grab an electric guitar once a speaker is connected and try both inputs.,.,should nor need much to make a great guitar amp.,.,.,amp builder forums will tell you a lot about these conversions.,.,nice PA you have.,.,.

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