HOLY **** I SCORED I THINK?

That specific amp was designed for a phono only with that type of inverse cartridge. I don't care what the previous person said about it working normally, it will not work normally with other aux inputs. Listen to a stereo recording that you know in which certain instruments come from one channel only. Now play it through the Westinghouse. The stereo effect may be there but the balance will seem messed up but the amp does work fine, just not with any aux equipment until you get a matched pair of single ended output transformers.
 
If you didn't want to change out the output transformers, you could build an inverting audio stage, using a triode, after the plate circuit one of the input triodes ahead of the tone circuits. Probably use a 6C4, and the plate resistor and cathode resistor the same value, use the same value resistor 220K as that of the input triode's plate circuit. The 6C4 grid bias resistance should be like that of the load the tone circuits put on the input triode's plate, something like 470K?. . You want a gain of -1. AKA inversion. You could hide this tube below deck, looks like plenty of room there.
 
well guys I hooked it up and no capacitors exploded. this amp sounds..........Normal. No weird phase issues. it sounds almost perfectly fine. obviously it needs new caps ad resistors, and the left/right balance knob behaved in a funky way, but once you get it to work, it sounds almost fine.
 
Since this thread is about scoring a couple different amps and a bunch of tubes, if you want to discuss this particular amp (the Westinghouse) I'd suggest you post in the separate thread that you already started about this amp, instead of here.

https://www.audiokarma.org/forums/index.php?threads/westinghouse-conversion.875154/

Doing so will avoid confusion and, since the title of the other thread refers specifically to this amp, you'll likely get more useful responses.

Nobody suggested that it would not reproduce sound but, as has been pointed out in both threads, this is not a normal stereo design.

If you want something that works normally with normal modern sources you'll need to modify the amp.
 
No doubt that the amplifier will produce sound -- the question is whether when connected to good speakers the bass is full as it should be, or sucked out due to being out of phase, and whether it is producing proper stereo separation.

Dave
 
If it is out of phase instead of getting a new transformer couldn't he simple reverse the speaker wire on one channel?
 
Excellent question! Assuming that we're still talking about the Westinghouse amplifier, the answer is that doing so corrects one problem, but creates another. In this case, based on the circuit provided, using a conventional stereo source while reversing the phase of one speaker with this amplifier would correct the phase problem with any signals that are not common to both channels (call stereo information), but then cause any common mode (i.e. mono) signals to be out of phase between the two speaker systems. Also, the amplifier operates as a push-pull amplifier for common mode signals, precisely because the special phono pickup has it's two outputs wired out of phase with each other -- the pickup actually acting as the phase inverter stage in this case for those signals. If a conventional stereo signal is applied, then there is no push-pull action anymore, which destroys (by way of cancellation) much of the performance capability of the amplifier. So unfortunately, reversing the leads of one speaker with this amplifier is not an answer.

Dave
 
I wonder if anyone has been able to use those indicator tubes as bias meters (or bias balance meter) for fixed bias outputs....
 
nick parkin said:
I got TWO console amps. . . . One DuMont console amp. It has been recapped. A dumont tuner with a bunch of tubes on a PCB board so it’s good quality. Might convert to a preamp.
Click to expand...

Got a model number on the Dumont? What type tubes does it use?

The use of a PCB instead of point to point wiring doesn't say anything about quality. In fact, the PCB would make it very difficult, if not impossible, to convert it to a preamp if it's a tuner only in its present form.

However, based on the number of shafts sticking out the front, it looks like it's probably a combination pre / tuner. If so, you could certainly use the pre section. If it came from a console that had a turntable with a ceramic cartridge you could use those inputs. From the pic it also looks like it's powered by the PT on the amp chassis so you would have to build a separate PS if you wanted to use it with other amps.

The Dumont also looks like it's a SE amp. Depending on the tubes used, you might be able to use the OTs from the Dumont to replace the wacky, mismatched, OTs on the Westinghouse and turn it into a proper amp.
 
I suppose you could do that. The curve of volts vs shadow length isn't perfectly linear either. Its more linear closer to zero grid volts, which is full open on the eye. The more negative the grid goes, the more closed it gets.
 
You must log in or register to reply here.
Back
Top Bottom