Howdy Folks,
I did all this stuff years ago and was more interested in building the amps than knowing they might actually work... so it's the hands on stuff that appeals to me.
At the moment all my stuff's stashed away... badly, but I always pick up old radios and two lately have had loctal tubes from what I suppose is the late thirties early forties.
Anyways I've figured it might be a good starting venture to make a small champ style amp using the chassic I've got which has enough room for a rectifier tube, a coupla triodes and a pentode output tube.
The question I have revolves around the use of the triodes which feature a single triode and two little diodes on the cathode. The 7C6 is termed a duplex diode Hi Mu triode.
The triode with 250 and a 100k with 1.3mA shows a uFactor of 100 so that's pretty much 12AX7 territory isn't it?
Anyways what can we do, if anything, with the diode inputs? What might the output of a oscillator do to them? Or do we just tie them to the cathode and leave well enough alone?
Cheers New Buddies!
Loctal tubes to get back into it.
Moderators: pompeiisneaks, Colossal
Loctal tubes to get back into it.
I have no idea what I'm doing but it's fun.
Re: Loctal tubes to get back into it.
Greets!
The Ace Tone combo I just resurrected uses a 6av6 in the bias tremolo. It has one triode and two diodes. The diodes are just ignored. It's a cute little tube.
The Ace Tone combo I just resurrected uses a 6av6 in the bias tremolo. It has one triode and two diodes. The diodes are just ignored. It's a cute little tube.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Loctal tubes to get back into it.
Welcome, from way across the lake!
I'm very happy to have found that cute little 6AV6 as well. (And was happier to find out Telefunken made them too! I'm such a sucker for that brand..) I had to split a 12AX7 in half because two channels were sharing it, and cross-talk issues resulted.
I noticed no real sonic difference in the switch, which was thankfully way down the chain anyway. So if there was any, I wasn't able to detect it.
I've read the diodes can go to ground, or ignored. I also chose to ignore them, but would any characteristics change if they were to ground? I would guess not, but then again I'm not very good at that guessing stuff sometimes.
Never heard anything about tying it to the cathode though...
I'm very happy to have found that cute little 6AV6 as well. (And was happier to find out Telefunken made them too! I'm such a sucker for that brand..) I had to split a 12AX7 in half because two channels were sharing it, and cross-talk issues resulted.
I noticed no real sonic difference in the switch, which was thankfully way down the chain anyway. So if there was any, I wasn't able to detect it.
I've read the diodes can go to ground, or ignored. I also chose to ignore them, but would any characteristics change if they were to ground? I would guess not, but then again I'm not very good at that guessing stuff sometimes.
Never heard anything about tying it to the cathode though...
Re: Loctal tubes to get back into it.
I just ignored them in my loctal radio-to-guitar-amp conversion.
It's probably a directly heated common cathode, so there's limits to what you can use them for. You could asymmetrically clip the signal using one of the diodes. Add a resistor (and maybe a cap) between the signal & diode to tune the clipping. Might sound interesting, might be a hot mess.
If you have any remote cutoff tubes, they can be used as detectors for automatic volume control, which is probably the diodes' original purpose.
[edit - looked up the data sheet for 7C6, not directly heated, but it is common cathode, so I stick by my comments above]
It's probably a directly heated common cathode, so there's limits to what you can use them for. You could asymmetrically clip the signal using one of the diodes. Add a resistor (and maybe a cap) between the signal & diode to tune the clipping. Might sound interesting, might be a hot mess.
If you have any remote cutoff tubes, they can be used as detectors for automatic volume control, which is probably the diodes' original purpose.
[edit - looked up the data sheet for 7C6, not directly heated, but it is common cathode, so I stick by my comments above]