I have a pair of Ampex 6973 mono amplifiers, can I sub the 6CM6 for the 6973. I have noticed adapters on eBay for such a sub.
6CM6 is rated 315V, 6973 440V. While these are different systems, the 6973 is clearly intended for more voltage.
6973 is available:
Vacuum Tube - 6973, Electro-Harmonix | Antique Electronic Supply
These are all "6V6 types". Depending on space, you could ream out for octal sockets and stuff 6V6 in. While 6V6 is another "315V" tube, all you buy today will live at 400+V because Fender abused them that way. EDIT- ah, I see the 6973 are already cheek-by-jowl, 6V6 won't fit with a hammer.
6973 is available:
Vacuum Tube - 6973, Electro-Harmonix | Antique Electronic Supply
These are all "6V6 types". Depending on space, you could ream out for octal sockets and stuff 6V6 in. While 6V6 is another "315V" tube, all you buy today will live at 400+V because Fender abused them that way. EDIT- ah, I see the 6973 are already cheek-by-jowl, 6V6 won't fit with a hammer.
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6em5 may work with rewiring, my first pp amp was made from this tube borrowed from our 21 inch admiral tv...
6gm5 is a sure bet....https://frank.pocnet.net/sheets/084/6/6GM5.pdf
6gm5 is a sure bet....https://frank.pocnet.net/sheets/084/6/6GM5.pdf
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> 6gm5 is a sure bet
Much higher heater current. The Ampex chassis is tight and the PT surely carefully engineered. If you have to ask... it may not be a happy result.
Much higher heater current. The Ampex chassis is tight and the PT surely carefully engineered. If you have to ask... it may not be a happy result.
6GM5 is electrically equivalent to the 7591 and 7868.
The key difference among members of the 6V6 "clan" is g2 toughness or lack thereof.
I'd like to see Ampex's schematic. However, inserting safety/stopper resistors in the lines that energize the O/P tube screen grids may be all that's needed for 6CM6 substitution. Within reason, mere volts rarely cause trouble. Excessive power dissipation and the associated heat is the destroyer of tubes and many other parts.
The key difference among members of the 6V6 "clan" is g2 toughness or lack thereof.
I'd like to see Ampex's schematic. However, inserting safety/stopper resistors in the lines that energize the O/P tube screen grids may be all that's needed for 6CM6 substitution. Within reason, mere volts rarely cause trouble. Excessive power dissipation and the associated heat is the destroyer of tubes and many other parts.
yes, higher current indeed, but as long as the ac heater voltage at the heater pins do not go way below 5.9 volts, i think you can get away with it...
Norman Crowhurst once wrote, "a filament winding rated for 3 amps usually can supply an additional 1 amp more without problems...."
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6CZ5 is electrically equivalent to 6973 - same heater too
Just beware the 6973 pinout differs in ONE IMPORTANT WAY from that of the 6CZ5.
6973 - pins 1 and 8 go to g2 (screen).
6CZ5 - pin 1 goes to g2 (screen) while pin 8 is designated IC (Internal Connection).
6CZ5s FAIL when plugged straight into the socket of a 6973 amp in which pin 8 is intended to do screen duty.
This has been blamed on the 6CZ5 so that they now have an unwarranted reputation as a dud valve. This is not helped by the data sheets - the 6CZ5 sheets usually cite design centre values that are lower than the design maximum values cited for the 6973. At first glance, the 6CZ5 looks to have lower ratings than the 6973.
Rather, it's worth considering the circuit into which the 6CZ5 will be plugged. In which case, the 6973's sole advantage seems to boil down to having an extra screen connection which would permit better heat management of the screen which might help when running it close to its maxima, as in Supro guitar amps.
On which, I know of a Supro clone built with 6CZ5s that works very well with no better or worse reliability than with 6973s.
Just beware the 6973 pinout differs in ONE IMPORTANT WAY from that of the 6CZ5.
6973 - pins 1 and 8 go to g2 (screen).
6CZ5 - pin 1 goes to g2 (screen) while pin 8 is designated IC (Internal Connection).
6CZ5s FAIL when plugged straight into the socket of a 6973 amp in which pin 8 is intended to do screen duty.
This has been blamed on the 6CZ5 so that they now have an unwarranted reputation as a dud valve. This is not helped by the data sheets - the 6CZ5 sheets usually cite design centre values that are lower than the design maximum values cited for the 6973. At first glance, the 6CZ5 looks to have lower ratings than the 6973.
Rather, it's worth considering the circuit into which the 6CZ5 will be plugged. In which case, the 6973's sole advantage seems to boil down to having an extra screen connection which would permit better heat management of the screen which might help when running it close to its maxima, as in Supro guitar amps.
On which, I know of a Supro clone built with 6CZ5s that works very well with no better or worse reliability than with 6973s.