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Scary Homebrew Amp Build


thebes

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Bought this at a yard sale yesterday for $50.  Don't know why I bothered. It's a homebrew 5881 push pull monobloc. As you'll see in the underside pictures.  The power supply rectification was done by using  a string of diodes paralleled by resistors, and if you'll look at that big blob of solder at the top of the output stage there are about 20 wires from everywhere meeting there. I presume it's the builders version of star grounding but it sure looks scary in person. There's also a pot (hum?) in the middle just hanging loose with a couple of wires attached to it.

 

Some pretty good metal. The power transformer must weigh 25 lbs. , it's a "Crestran pf-7", the choke is a Rex 20henry/200ma, and the OPT is a Peerless s-526-S, which has16/8/4ohm taps at 6000ct. Can't find any online info or specs on the choke or the Crestfan.

homebrew1.jpg

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3 hours ago, Edgar said:

But it's "vintage" ... it has to be good.

 

You gonna build a second one, for a stereo pair? :wacko2:

Finding another  25 lb power transformer might be a challenge.  I could call it the Hernia-O-Nator".

 

Marvel, haven't tested the Peerless yet, but  I did note that the cover was loose. I was feeling bumptious when I bought it so not too worried about recouping my investment.

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I keep coming back to this thread and looking at those pictures and HONESTLY wondering if this is one of Marty's practical jokes and if the pictures are even real.

 

It looks like you got drunk and started soldering junk parts one on top of the other and posted this to try and fool us.  I swear it does not even look real to me the more I look at it.

 

Can anyone confirm this may have worked at one time...............or is this a joke?  :)

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If the Peerless output transformer checks out okay, it's worth more than 50 bucks I would guess.

The 5881s are worth a few bucks. You couldn't buy a PS transformer like that for 50 bucks in this day in age...

I think Rex was a predecessor of Tamura, I might be wrong. Rex made OPT's for Olson...or Olsen?

 

Good parts score.

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11 hours ago, Jeffrey D. Medwin said:

The problem with buying old "iron" is that the varnish they used, to cover the winding wires, will break down over time, UNLESS it was a certain type of varnish made by General Electric.

 

It is a safer and better bet to buy current production parts, from reliaqble people like Hammond, to avoid problems in the long term.

 

Jeff 

So I suppose that you are suggesting that no one should purchase vintage Scott, Fisher, or Mcintosh (etc) amplifiers because of the possibility that they didn't use the proper type of varnish (according to you)?  Do you happen to have the correct part numbers and specs for that varnish?

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5 minutes ago, jimjimbo said:

So I suppose that you are suggesting that no one should purchase vintage Scott, Fisher, or Mcintosh (etc) amplifiers because of the possibility that they didn't use the proper type of varnish (according to you)?  Do you happen to have the correct part numbers and specs for that varnish?

 

=== ‘Bo, stop fueling his fire. He has provided More than enough hot air on his own. And I see the KT88 amp build thread is closed for “review”. Stop with the review, just put the argumentative and tedious thread to bed - for good. 

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