Tube bloat in an RCA? - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Other Radios (Non-Philco) (https://philcoradio.com/phorum/forumdisplay.php?fid=12)
+--- Thread: Tube bloat in an RCA? (/showthread.php?tid=6803)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Other Radios (Non-Philco) (https://philcoradio.com/phorum/forumdisplay.php?fid=12)
+--- Thread: Tube bloat in an RCA? (/showthread.php?tid=6803)
Pages:
1
2
Tube bloat in an RCA? - Jayce - 06-05-2013
I was taking pity on an RCA radio yesterday that really needs to find a better home and I noticed something odd that I never expected in an RCA. This was a model K130 I was looking at and I noticed it uses four 6F6 tubes! Are those all outputs and if so, why? It also uses a rather hefty looking power chassis with two 5U4 rectifier tubes. I would almost accuse them of tube bloat with this model, but that seems rather heavy and the wattage draw is rated at 200 watts on the tag. So... is this just a radio with tube bloat or is it actually a performer?
RE: Tube bloat in an RCA? - Marsupial - 06-05-2013
might be wrong, but doesn't that radio outputs 20W? maybe its a 2-stage amp, push-pull (2x 6F6) plus some preamp (2x 6F6)? Or maybe some hefty bass control?
RE: Tube bloat in an RCA? - TA Forbes - 06-05-2013
Looks like it's parallel push pull 6F6s.
Set has dual 5U4G rectifiers, 6SF5 driver and inverter tubes, and has an unusually high 365V on the 6F6 plates. 20W undistorted/ 22W max.
Interesting set.
RE: Tube bloat in an RCA? - Jayce - 06-05-2013
Hmm, makes me more interested in trying to get that one off the guy I know. He wants to sell off some radios and the finish on this set is being ruined because of storage. Of course price might be an issue...
RE: Tube bloat in an RCA? - TA Forbes - 06-05-2013
Good luck. It is a neat radio!
RE: Tube bloat in an RCA? - Jayce - 06-06-2013
I just got off work and called the guy. Negotiations might begin tomorrow!
RE: Tube bloat in an RCA? - TA Forbes - 06-07-2013
RE: Tube bloat in an RCA? - codefox1 - 06-07-2013
Great space heater for apartment with no electric utility charge.
RE: Tube bloat in an RCA? - Jayce - 06-07-2013
Well, the guy still has the radio. He wants to do more research on it first, but it's not looking any better sitting in that damp back room.
RE: Tube bloat in an RCA? - y2kbruce - 06-07-2013
My RCA D-22 has 22 tubes. It uses 4-2A3 outputs and 2-5Z3's.
It adds an expander system to a C-15 and a few more goodies.
Output would be similar to a Scott AW23 but with better timbre sound IMO.
RE: Tube bloat in an RCA? - SteveJB - 06-08-2013
I restored a K130 last year. I liked how well it sounded and it looks pretty good also. It plays loud and has a lot of bass. The RCA jacks make it easy to add a matching transformer and iPod.
I gave it to my brother in law for his birthday and he uses it often as he likes the sound as well. I would recommend it to anyone wanting a decent performing radio.
Be careful removing the chassis. The tone switch isn't on the chassis like most radios. The tone switch is mounted to the cabinet and you will pull it apart if you remove the chassis without loosening the nut that holds it in the cabinet first. I had to replace mine for that reason.
I am looking at an 813k tomorrow. Hopefully it is as good a player as the k130 was.
Steve
RE: Tube bloat in an RCA? - Doug Houston - 06-09-2013
In general, RCA didn't bloat tube counts. Indeed, the D22-1 used all tubes properly. When you wanted superb audio, you used 2A3's for power amplifiers. The D22 was RCA's finest offering in that year, and that was the reason for the Push-Pull Parallel 2A3 power amplifier.
RCA went on in the next year to use volume expander, as on the D22 for phono, and a "High Fidelity Electrola" R99. Vary few of those are known, but I'm lucky to have one. there were other Hi-Fi RCA model phonographs, that used 2A3 power amps. While RCA loved to us 6F6's, they used 2A3's when they got serious about high audio quality.
If you want to see the best example of tube bloat, have a look at the schematic for the Crosley 37 tube set. It's just plain disgusting.
RE: Tube bloat in an RCA? - BrendaAnnD - 06-09-2013
The only Crosley 37 I can find is a 1942 model AA6 with an extra 12SK7. Hardly bloat. Maybe I'm looking at the wrong one?
RE: Tube bloat in an RCA? - TA Forbes - 06-09-2013
Steve, the 813K is an excellent set!!!!
I would like to get my hands on an 816K. BUT for now I have my hands full with the Stromberg 180L, Philco 15, and Zenith 12S471 cabinets. Also have a Philco 91LZX that is next.
RE: Tube bloat in an RCA? - Doug Houston - 06-10-2013
You miht need to go o a Crosley service book, or to the Rider manual that covers around 1936-37. I think tha mmonstrosity's model is something like 1637, but I'm not sure.
As for the nRCA 816K, there is usually one popping up on eBat for sale. There aren't many around, but they're not extinct, either. I can vouch for the 861K's audio. It can probably loosen plaster in the house.