Is it possible to wire Conrad Johnson amps in Triode mode? ....

joeinid

joeinid

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I seem to remember some amps were available wired for Triode operation. Does anyone know if it's still possible? I sent a note to CJ and I'm still waiting for their response.
 
Two questions here:
1) is it possible to wire CJ amps in triode? The answer is yes.
2) Will CJ perform this for you? The answer is I have no idea.
 
Thanks Mark. I am waiting for an official answer but may have to call next week.


mep said:
Two questions here:
1) is it possible to wire CJ amps in triode? The answer is yes.
2) Will CJ perform this for you? The answer is I have no idea.
Click to expand...
 
If you were handy with a soldering iron, you could do it yourself. You basically are just electrically connecting the grid to the plate so they are at the same electrical potential which turns a pentode into a triode (pin 4 to pin 3). There is usually a 100 ohm resistor that goes from the grid to ground as well.
 
Sorry mep, not quite right. It is pins 3 and 4, but it is called the screen grid. Just "grid" usually means control grid which is the tubes input (pin 5). I mention this, because incorrect wiring will result in fireworks.
The 100 ohm resistor you mention goes between the plate and screen, not to ground. It's there to limit current to the screen which is far more delicate than the plate.
Pin numbers are for kt88, el34 etc.
 
I've yet to hear a pentode based amplifier sound better run in triode. Last cj amplifier I remember that was convertible was the Prem. 8. Think that says a lot. If it was better, cj would offer it. :) You just sacrifice way too running in triode.
 
blackdog said:
Sorry mep, not quite right. It is pins 3 and 4, but it is called the screen grid. Just "grid" usually means control grid which is the tubes input (pin 5). I mention this, because incorrect wiring will result in fireworks.
The 100 ohm resistor you mention goes between the plate and screen, not to ground. It's there to limit current to the screen which is far more delicate than the plate.
Pin numbers are for kt88, el34 etc.
Click to expand...

Yes, it's called the screen grid which is pin 4 as I said. If you tied the control grid (pin 5) that would be a problem. As for the 100 ohm resistor, I just remember that it's usually necessary and I may have been mistaken for where it's tied to. It's been a long time since that was on my tube radar.
 
Myles B. Astor said:
I've yet to hear a pentode based amplifier sound better run in triode. Last cj amplifier I remember that was convertible was the Prem. 8. Think that says a lot. If it was better, cj would offer it. :) You just sacrifice way too running in triode.
Click to expand...

You give up power and some control/punch in the bass typically. You normally lose about 1/2 of your pentode output power. Some people love the sweetness of the triode sound and are willing to sacrifice the bass punch and extra power to gain that sweetness. Not so good for rock, but some jazz people and chamber music people think it's the bomb. Some amps give you a switch so you can listen in either mode vice having it hardwired in.
 
mep said:
You give up power and some control/punch in the bass typically. You normally lose about 1/2 of your pentode output power. Some people love the sweetness of the triode sound and are willing to sacrifice the bass punch and extra power to gain that sweetness. Not so good for rock, but some jazz people and chamber music people think it's the bomb. Some amps give you a switch so you can listen in either mode vice having it hardwired in.
Click to expand...

Agreed but it's sweet because the upper octaves are rolled off. Plus it's kinda boring. Now not saying triode amps are bad but there's something about 6550s run in triode. You want a triode? Give me a 211 based amplifier. :)
 
Myles B. Astor said:
Agreed but it's sweet because the upper octaves are rolled off. Plus it's kinda boring. Now not saying triode amps are bad but there's something about 6550s run in triode. You want a triode? Give me a 211 based amplifier. :)
Click to expand...

I'm not a big fan of 6550s in the first place and that goes for the vaunted Tung-Sol 6550 as well. Don't get me wrong, I would take Tung-Sol 6550s over GE 6550s all day long.
 
I appreciate everyone's thoughts. I would not do it on my ART monos but would consider ordering an amp wired that way if CJ gives the thumbs up or says they like what they hear. I do agree Myles, that the fact it's not offered currently kind of says something.
 
Myles B. Astor said:
Agreed but it's sweet because the upper octaves are rolled off. Plus it's kinda boring. Now not saying triode amps are bad but there's something about 6550s run in triode. You want a triode? Give me a 211 based amplifier. :)
Click to expand...

Hi Myles

Any recommendations for a 211 amp? Thanks.
 
Haven't listened to any lately seriously since they all tend to be lower powered. (Isn't the Cary Mike was talking about recently 211 based?). Two that I would check out are the Tube Guru and Tron. I think AirTight did at one time make a 211 based amp too.

Best I ever heard was a 100 watt 211 based amp from Sonic Frontiers. You've never heard things sound more real or images feel more palpable.
 
Isn't the Cary Mike was talking about recently 211 based?)
Click to expand...
Cary makes one that you can switch between 211 and 845 tubes. The CAD805SE.
You could also try the Coincident 211 Dragon. Two 211's in push pull.
 
Myles B. Astor said:
I've yet to hear a pentode based amplifier sound better run in triode. Last cj amplifier I remember that was convertible was the Prem. 8. Think that says a lot. If it was better, cj would offer it. :) You just sacrifice way too running in triode.
Click to expand...

I agree with Myles, no pentode amp I've heard sounds better in triode mode.
 
Update:

Conrad Johnson will wire an ARTsa in triode mode and substitute the KT120 for Mullard EL34's.

That could be fun!
 
Same could be said of both of my Bob Latino amps. Easily switchable to triode mode with toggles on the top deck. I could experiment endlessly. Eventually just left them in ultralinear. Far more lively with more the "bite" of the real thing. If I did such a mod, I would certainly make it switchable.
 
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