Home Made Pre amps...

It's pretty much identical as far as controls and labels, they did an awesome job copying the original.
The preamp was pretty much silent even without rebuilding it,(in phono as well) amazing for a 60+ year old piece of equipment.
 
The one I fired up yesterday is also quiet, no hum at all,,, just some noise from the dirty pots/switches... Do you remember how the original was grounded? these have the grounds soldered to the chassis, no star, or buss any where...
 
Yep,, these are too... RCA jacks are also soldered in place, the level pot grd lugs are just bent down and soldered also...Seems to be a pretty accurate clone... They are not exactly identically built, tho,,, seems the 12AU7 should be in between the 12AX7s, but only one is built that way, the level pots and some caps aren't exactly the same either,,, I'll see if it makes a difference when I get them both running... not going to make wholesale changes yet, tho...
Thanks for the pics...
 
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The Heathkit WA-P2 uses an almost exact same schematic. Your WA-P2 power supply may work well with these preamps.
 
Not quite the same... the WA-P2 has 6V filament supply,,, these have 36V series heaters and a separate winding for the pilot light... B+ may be close...
 
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Nothing to contribute besides nice find on the beautiful vintage preamps.I really like the industrial look, and the build quality looks very high.
 
Thanks,, first one is coming along slowly...got most of the pots quiet for input one... Bass and level pot are still a little scratchy,,, gave em another spray and exercise, just waiting for them to dry... May have to disassemble them to get them right, tho...

The metal work is very nice,,, he must have had access to a well stocked machine shop, as I don't think CNC machines were around then!! The components mounting and parts installation are not as neat, unfortunately... Too many connections without tags/lugs for me... On quick comparison, second preamp doesn't match component wise either,,, I think the builder made one for a mono system,, and then built another a bit later when stereo got popular... But the face plates and chassis match very well, so I may be wrong...

I'll sort out the first one as much as possible, then re-build the other one to match it... That's how I handled the WA-P2s and they came out pretty good...
 
Those are one of the cooler vintage finds I've seen here. Obvious question: I wonder what the amps were that went with them, 50A clones too? Regardless, a great save.

:thumbsup:
 
I'm not sure what amps he had... Pretty sure he used the separate PS, tho I only found one, and the umbilical that was with it only fits one amp, so there may have been another PS I didn't get...
I have one driving my 829B amp project,,, seem to work well together...

Working on a cap/resistor list now,,, seems the scratchy noise is mostly coming from the Bass section,,,
 
Exactly,,, he seemed to parallel caps quite a bit, and for pretty common sizes.... I think I'll replace them with proper values from the schematic... Going to rebuild the tone stacks 1st,,, pre amp is pretty quiet with them zeroed...

These things seem to have some promise, hope I can do em justice!!
 
very cool John! those chicken head knobs bug the hell out of me though. :D

They make me like it more.. makes them look like they're from the 40s. Same deal with those pilot lights, very rare to see hi-fi equipment built like a military radio.
 
Hey Paul,,,
I'm not a fan of them either!!!

Trying to get some time to spend with these, but the township took down a couple big Red Oaks, and I've been hauling, cutting, splitting and stacking wood!!! Really want to sort out the tone stack in the 1st one, just can't seem to get back to it!!!
I saw a couple threads about identifying the foil end of a film cap with a scope, but I couldn't get it to work,,, I'm sure its operator error!!! Need some quality time in the shop, and a little more reading, I guess...

Be safe up there, hope things are settling down, finally......
 
Hey Paul,,,
I'm not a fan of them either!!!

Trying to get some time to spend with these, but the township took down a couple big Red Oaks, and I've been hauling, cutting, splitting and stacking wood!!! Really want to sort out the tone stack in the 1st one, just can't seem to get back to it!!!
I saw a couple threads about identifying the foil end of a film cap with a scope, but I couldn't get it to work,,, I'm sure its operator error!!! Need some quality time in the shop, and a little more reading, I guess...

Be safe up there, hope things are settling down, finally......
Busy here too. fencing, new windows, ect. at leased the fires close to my other home are under control now. Have fun stacking that wood! :thumbsup:
 
That's good to hear!!! Hope the old place is out of harms way by now,,, HA,, yep that Oak's only fun when its in the stove in January!!!
 
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