High end RCA console stereo

[Phototone]

I acquired this relatively high-end (for RCA) console stereo. I felt it was tube, and taking off the back, I found out that not only was it tube, but it has a push-pull 6BQ5 stereo power amp separate from the tuner, which is all tube. This leads me to believe this was probably the top RCA console stereo for the model year. Can anyone tell me the model year and anything else about it? It hums, will need to be recapped, which I will get to shortly.

 

[Dswankey]

The amp is a RS-177, here's a pic on mine after it was redone. There's some good threads here if you search RS-177.

As for the model year it's gotta be early 60's. Here's a thread, while not helpful in your case you might find it interesting.

http://www.audiokarma.org/forums/index.php?threads/rca-console-catalog-reference-tool.691693/

 

[Dswankey]

Some more info

http://www.radiomuseum.org/r/rca_4vf4804_vf_48_ch_rc_1211a.html

http://vintagehifi.net/index.php/board,28.0.html?PHPSESSID=9urgd628im4ubk0thb84lg14t5

 

[orthophonic]

That is a 1964 model, one step below their top of the line model.

 

[macyjrm]

That RS-177 makes a sweet stand alone power amp.

 

[Kingfisher]

You have a couple of choices with that console. Leave it stock and just recap it or make the amp a stand-alone. If you choose the second option you're going to have to change the circuit to allow 12AX7's to be used in place of the 6FQ7's. I made mine into an "umbilical stand-alone" so I could use the same tubes. I actually like the sound of the 6CG7/6FQ7's, but tube rolling options are more limited. IIRC, that amp is a 177J which has a bunch of PEC's in it. It was the last of the 177 series before everything went to SS.

Oh, one other thing...the console uses non-standard connections. It's an RCA console without RCA connectors. (Ironic or what?)

 

[Dswankey]

make the amp a stand-alone. If you choose the second option you're going to have to change the circuit to allow 12AX7's to be used in place of the 6FQ7's. I made mine into an "umbilical stand-alone" so I could use the same tubes. I actually like the sound of the 6CG7/6FQ7's, but tube rolling options are more limited.

Hi Kingfisher,

I'm curious, do you know of anyone who has done this? I still have the 6FQ7's and my tech went ahead and added some 12AV6's. I think he wanted to keep it he liked it so much.

I dig the amp and compared to my standalone Maggie 9302 I prefer this one.

 

[Phototone]

Well, due to the fact that it is so near the top of the line for RCA in 1964, I'm not going to gut it. The cabinet is in very very good shape, no top scuffs. One tiny gouge in grill cloth, I'm going to recap it, and see what I've got.

 

[Kingfisher]

Hi Kingfisher,

I'm curious, do you know of anyone who has done this? I still have the 6FQ7's and my tech went ahead and added some 12AV6's. I think he wanted to keep it he liked it so much.

I dig the amp and compared to my standalone Maggie 9302 I prefer this one.

Dswankey, I got the idea for replacing the 6FQ7 here at AK. I haven't actually tried it myself. Because the RS-177 series amps have low gain, either changing the 6FQ7 to accept a different tube is necessary or add another gain stage in front of it like that found in the tuner-preamp. Yours has obviously been modded to accept another gain stage. Based on threads I've read here at AK, the 6FQ7/6CG7 tube is somewhat similar to a 6SN7 in a smaller package.

Phototone....Good luck...it should sound great when you are finished.

 

[gadget73]

I'd go for the gain stage. I kind of suspect that just changing the tube to one with higher gain within the feedback loop won't really change things a terrible amount. The feedback would increase as the gain increases, and at the end of the day the input sensitivity would be largely unchanged. You'd also need to consult the schematic to see if the last stage in the preamp is part of the feedback circuit. No clue if RCA did it, but I know other folks have had console amps that operated that way. The clue would be that a connection between the speaker terminals and that umbilical cord into the preamp exists. Checking the preamp schematic would confirm though.

Other option is to run it with a preamp that has a really hot output. Better signal to noise ratio doing it that way, which is probably what RCA was going for. If you make your power amp relatively insensitive and feed it a high level of signal it won't be so inclined to amplify every bit of stray noise going on inside the cabinet.

 

[Phototone]

Please note: I'm not modifying anything, just refurbishing.

 

[gadget73]

That was more intended for general commentary for anyone planning to run one of these stand-alone. When run as the complete, original type unit none of that sort of thing would be needed.