Looking at this schematic, some resistor values are in "M" (which is not Megs) so, although some values are pretty obvious like the cathode or plate values etc, I have some doubts about other resistors, I know you can compare it to similar circuits to sort them out but, isn't it strange why they did this?
And this one as well:
An externally hosted image should be here but it was not working when we last tested it.
And this one as well:
An externally hosted image should be here but it was not working when we last tested it.
Bibliophile is right (as would be expected by his nickname choice )
"M" here means the Latin origin Mil, Mille (1000) found in Spanish, French, Portuguese and Italian ; k meaning kilo (1000) in Greek.
At least in the top schematic, most values make sense if old M is replaced by modern k , except the power tube cathode resistor which should be plain 200 ohms.
That said, that schematic looks like a modern redraw and the copyist might have miswritten.
Since all others carried one M or another, maybe he thought this one should also.
Of course, we know better.
The bottom schematic is almost illegible in my screen.
Why? (did they use such letters? )
Hey !!! we are talking 60 y.o. or more schematics, some even pre WW2 , go figure.
Some other old conventions, which might help you:
Mfd = uF = microfarad
mmfd = pF = picofarad
intermediate scales such as nano farad (nF) were "legal" way back then but not much used .
)"M" here means the Latin origin Mil, Mille (1000) found in Spanish, French, Portuguese and Italian ; k meaning kilo (1000) in Greek.
At least in the top schematic, most values make sense if old M is replaced by modern k , except the power tube cathode resistor which should be plain 200 ohms.
That said, that schematic looks like a modern redraw and the copyist might have miswritten.
Since all others carried one M or another, maybe he thought this one should also.
Of course, we know better.
The bottom schematic is almost illegible in my screen.
Why? (did they use such letters? )
Hey !!! we are talking 60 y.o. or more schematics, some even pre WW2 , go figure.
Some other old conventions, which might help you:
Mfd = uF = microfarad
mmfd = pF = picofarad
intermediate scales such as nano farad (nF) were "legal" way back then but not much used .
that's what I thought, hand written typos.
What about the "500M" resistor from B+ to the 100k plate load at the first triode, 500k sounds a little high to me, should this be something like 5k ? or may be 50k, it can't be higher than the plate which for sure it's 100k ohms.
Thanks JM.
mmmmmhhhh , 500k too high , 0.1uF filter cap too low.
Proper values would be 5 or 50k and at least 10uF .
Anyway these were very old very crude designs, there's a reason they did not survive the testb of time, in the 40's they were used just because there was nothing else.
Guitar amp design really took off with Fender, who started similar to this (remember those wooden case, wooden handle first amps) but soon upgraded.
Proper values would be 5 or 50k and at least 10uF .
Anyway these were very old very crude designs, there's a reason they did not survive the testb of time, in the 40's they were used just because there was nothing else.
Guitar amp design really took off with Fender, who started similar to this (remember those wooden case, wooden handle first amps) but soon upgraded.
An externally hosted image should be here but it was not working when we last tested it.
you are absolutely right, it just happens I have a stunning complement of nos 6sq7gt RCA and 6j5g by Mullard they look so cool really. May be, I'll try something different like sticking to a newer properly designed amp and use those tubes, or save the 6j5g for hifi or something else. Thanks.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.