The 6aq5 is more thought of as a mini 6v6. It handles a little less voltage and dissipation than the 6v6. The 6005 is the premium version and are cheap and easy to find NOS. They sound good if not slammed to the limits. The 6cm6 can also be used as a 6v6 replacement but is a 9pin base like an el84.
The 6AQ5 (EL90) is close to the EL84 in Pico 7 case.
https://btb-elektronik.de/suche/?searchterm=6005&searchform=Daten+absenden
https://btb-elektronik.de/suche/?searchterm=6005&searchform=Daten+absenden
6AQ5 is not near equivalent to EL84. It has essentially lower (some 4 mA/V) gm and thus lower gain.
Neither of these tubes is related to the 6BQ5 / EL84.
The 6CM6 is essentially a 6V6 stuffed into a 9 pin bottle. The plate size has been reduced to make it fit, so the dissipation should be kept below the spec. The octal 6V6GT can be reasonably abused in regard to dissipation and plate voltage without issue. I have not thoroughly explored the limits on the 6CM6 since I don't have many of them.
The 6AQ5 is similar to the 6V6GT with a reduction in plate and screen voltage specs. It has even smaller guts than the 6CM6. Experience has determined that only well constructed examples of the 6AQ5 can be operated at the 12 watt plate dissipation spec, and some will exhibit a red spot on the plate at 12 watts. The plate is very close to the glass, so there is a fine line between red spot and hole in the glass. I have made a few 6AQ5's suck air at 14 watts.
The 6005 is supposed to be high quality 6AQ5 for aircraft applications. The true GE 6005 does seem to hold up well. There are plenty of "things" called 6005 that are pure junk including two or three varieties of 6005's with a smaller set of guts than the 6AQ5. Beware of these tubes, some will melt at 10 watts.
The 6CM6 is essentially a 6V6 stuffed into a 9 pin bottle. The plate size has been reduced to make it fit, so the dissipation should be kept below the spec. The octal 6V6GT can be reasonably abused in regard to dissipation and plate voltage without issue. I have not thoroughly explored the limits on the 6CM6 since I don't have many of them.
The 6AQ5 is similar to the 6V6GT with a reduction in plate and screen voltage specs. It has even smaller guts than the 6CM6. Experience has determined that only well constructed examples of the 6AQ5 can be operated at the 12 watt plate dissipation spec, and some will exhibit a red spot on the plate at 12 watts. The plate is very close to the glass, so there is a fine line between red spot and hole in the glass. I have made a few 6AQ5's suck air at 14 watts.
The 6005 is supposed to be high quality 6AQ5 for aircraft applications. The true GE 6005 does seem to hold up well. There are plenty of "things" called 6005 that are pure junk including two or three varieties of 6005's with a smaller set of guts than the 6AQ5. Beware of these tubes, some will melt at 10 watts.
Just out of interest, I often read that a 6AQ5 is an analog of a 6V6, but I never see many amplifiers built with that tube. Is it just because the 7-pin variant is lower dissipation, or is it a poor performer across the board?
It was mainly used as single ended output in televisions...
I'm guessing that in the 1960's if you used TV tubes in an amplifier, nobody would buy it.
Except of course in the Soviet Union where 6P1P was the used in televisions but HI-FI as well.
I'm guessing that in the 1960's if you used TV tubes in an amplifier, nobody would buy it.
Except of course in the Soviet Union where 6P1P was the used in televisions but HI-FI as well.
The 6AQ5 found its way into several things for a relatively short time. It was used in TV's for both the audio output and vertical sweep (frame output). I remember seeing them in radios and some HiFi sets in SE and push pull applications. I once had an old Gibson guitar amp that ran a single 6AQ5. The 6BQ5 / EL84 came a few years later and stole the 6AQ5's thunder in many audio applications.
TV's, radios and HiFi sets all went on a diet over the years, getting smaller and smaller. The octal got replaced with the 9 pin miniature, which gave way to the 7 pin miniature, but the biggest size and weight reduction came when the power transformer was eliminated. That was when the 6 volt tubes morphed into series string equivalents. Tubes like the 6AQ5 with its 2.84 watt heater required several hundred volts to make a few watts of audio. To get the same power from 130 to 150 volts of B+ requires more current, which means a more emissive cathode, so an old octal that had a 7.5 watt heater spawned clones in several different heater voltages and envelope sizes.
The 6W6 became the 12W6, 12L6, 17L6, 25W6, 25L6, and 50L6. The 35L6 is different as it has a wimpy 5.25 watt heater, giving up output capability to make heater room for two more tubes in AM / FM radios. Of course, the size and weight reduction plan created 9 pin, the 6GC5 and 6DB5 and their associated series string equivalents, and the 7 pin 50B5, 50C5, 25C5, 17C5, 12C5 and 6CU5.
TV's, radios and HiFi sets all went on a diet over the years, getting smaller and smaller. The octal got replaced with the 9 pin miniature, which gave way to the 7 pin miniature, but the biggest size and weight reduction came when the power transformer was eliminated. That was when the 6 volt tubes morphed into series string equivalents. Tubes like the 6AQ5 with its 2.84 watt heater required several hundred volts to make a few watts of audio. To get the same power from 130 to 150 volts of B+ requires more current, which means a more emissive cathode, so an old octal that had a 7.5 watt heater spawned clones in several different heater voltages and envelope sizes.
The 6W6 became the 12W6, 12L6, 17L6, 25W6, 25L6, and 50L6. The 35L6 is different as it has a wimpy 5.25 watt heater, giving up output capability to make heater room for two more tubes in AM / FM radios. Of course, the size and weight reduction plan created 9 pin, the 6GC5 and 6DB5 and their associated series string equivalents, and the 7 pin 50B5, 50C5, 25C5, 17C5, 12C5 and 6CU5.
Another 9-pin equivalent to the 6V6 is the 6CZ5. RCA uprated this as the 6973, their attempt to compete with the 7189. The 6CZ5 can be subbed for 6973 in some cases - it won't take the high grid resistor values though. 6BW6 / 6061 is another, not common in the US.
12AB5 is equivalent to 12V6, was used in car radios (and a few Harman Kardon amps). 7061 is the industrial version.
12AB5 is equivalent to 12V6, was used in car radios (and a few Harman Kardon amps). 7061 is the industrial version.
