The Amp Garage

Note that 6BQ5 PP output stage needs 10 volts less of grid to grid drive signal then a 6V6 output stage does.

Please clarifie what your doing better. You can't be pumping in millamps ( MA ) of signal like you posted, millvolts yes. Interms of the MV level are you saying .037 volts or .137 volts, I use about .115 volts. (-10 DB ) which is about a single coil pick up output level, if your pumping in .137 then...

Of special interest to you if you want to print them off would be pages 31 thru 38.

Note that it only covers tubes that RCA made and there's quite a few that only GE made that will not be covered in detail if at all in the RC30 book.

That wattage rating of any tube is DC parameter, not AC voltage which is the audio output.

Go to the Tubes & more site a buy a copy of the RCA rc30 tube manual, it’s worth every penny as they say!

Here’s a example from the tube data section of the on line Duncan tube amp site.

With a -58 available I would also say that the amp was born with 6550s. With 34s in the amp you want to have the low end of the bias range go down to like-36. Start off with adding in series to the input side of the bias adjust pot a 10k to and then see what that gives you . Of course do this bias v...

If the level of Genius that Designer McIntosh had in him was happy to make a stereo tube amp with its major components laid out like this then suffice to say that you would be fine to do the same for your build.

Golden rule number 1. Whenever working on a amp and especially a customer amp where time is money, alway double check the for the needed resistor value with your ohm meter to confirm what you think your seeing with your eyes. Over the years I have had more then a few that had the wrong color bands i...

You have failing and or bad solder connections on the tube sockets, as such is common with this amp, and I would say at least one bad plate load resistor.

And yes, these amps are a flat out pain to work on!

No.
They likely have at least a 10% tolerance to them.
As long as they are rated for 50 volts more then the B+ they may be hit with your golden.

Yes I have a idea, post a schematic please!

If your thinking of feeding two different speakers a true 1/2 of a sine wave then I think you will end up with the worlds worst case of crossover distortion . Another concern is that for any amount of speakers I think you will end up with only 1/2 of the SPL that could have otherwise been had. Along...

I can't see why a 4 amp fuse is needed. Your speaker jack should be of a shorting type when there's nothing plugged in and having a 150 ohm 7 to 10 watt across it is a good & cheap no load save the OT way to go. Your output tube plate voltage will be on the low side especially once you factor in the...

What is up with that rectifier tube used in that schematic?

Just looked back thru my pictures and original Partridge transformers should have a yellow sticker on top the says Partridge.