New life for old console amp.

Thatch_Ear

Addicted Member
RCA RS-193 SE 6BQ5 with small transformers a 5Y3GT rectifier, 6EU7 driver. I bought one of those wall mount plastic plates with RCA jacks on it at home depot, replaced the little lytic under the chassis and paralled a 150 ohm 2 watt and a 470 uF 50V lytic on each of the 6BQ5 cathodes and variaced it. You litterally have to solder the speaker wires on.

It actually sounds pretty good if the music isn't too demanding. The Bosa Nova tunes by Yo Yo sounded very nice over the EVs but the Steely Dan was a bit of a struggle. Without the tone controls and by lowering the volume to where it could handle it I would have not been able to enjoy it.

Not a lot of distortion but I wouldn't call it crisp and clean by any means. It cost me $10 plus parts and I had to pull a 6EU7 from something else to use it.

The 6BQ5s run a bit orange and if the PS is running like it should be the things are pushed right to spec with 250 on the plate and 240 on the grid.

Fun to mess with but no real potential. Bumping up the caps on the cathodes did boost the bass and except for the fact that I have bought nice Dyna ST-70s for less than $5 more than once I would call it a bargain for $10 and a few parts.
 
Yes, there's that certain point with the tone and volume controls that it turns to mush.
I just cranked the treble and ran the bass pot about midpoint depending on the music involved. It's a strange little amp/circuit.
I think the circuit inputs through the tone controls, then goes to the grids of 6EU7, then goes to the VC,(with a goofy RCA branded PEC) then to the balance pot and to the output tubes. Both sides of 6EU7 share the cathode resistor and cap. I dunno if the PEC in the VC is some sort of feedback compensation or what.....

Does it have a bit of line noise? The one's I had did.

I liked playing thrash music through them, they aren't that clean but they have kinda nice distortion. Worked kinda well with the right music....

I started tweaking one, and ended up with this in the end. I had some SE Ampex OPT's from a old tape recorder that measured better.
The only original RCA item left is the PS transformer.
The circuit in the pictured amp, needs some revision......It's been fun however....
I tried it with tone and VC controls, but they got ditched to get less noise.
 
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Thatch, here is the Console I called you about today. Snapped a couple pics while we were talking.

4 6v6, what looked like a 12ax7, and 2 5y3. Preamp /tuner section was on the other side of the cab.
 
Mike, yea the input gous through the 2 tone pots, then the triode. Normally you have some sort of low B+ come in to drive the plate of the triode (if that is how it works) and you have a low value cap and some resisters going to ground and then into the grid of the pentode. This thing has some kind of strange set up with caps and resisters that tie both channels together then there is a volume pot and then a balance pot, then it goes into the grid of the pentode. I figure there is all kinds of cross talk going on and it was on purpose. I remember the POS console I got this out of and it had 2 6X9 drivers and 2 tweeters. 6X9s distort things on there own, the cross talk on top of that and it created a virtual center bass speaker. My wild ass guess. Kinda interesting but not HiFi.
 
Russ,
There loks like a plug with black wires running up to the 12"ers next to what looks like an OPT. That would explain 2 of the 6V6s. Probably a pair of tiny SE OPTs under the chassis and that would explain 2 more 6V6s. Then you said there was a 5Y3, but from the looks of that imbulical with the octal plug running off I would bet that there is a second 5Y3 and the single PS tranformer is doing the job for the tuner/pre also.
 
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