Ideas for using the extra triode?

[mountainhick]

I'll be building a wreck with three dual triodes (6N2P-EV) and push pull 6P6S for a friend soon.

What kind of variations have y'all done using the extra triode? I found one reference for @gingertube 's junkbox trainwreck, but thinking maybe making a primary triode stock 100K/1.5L 22uf, and a second configured differently to be switched in parallel.

Anyone done something like this, or other ideas?

[xtian]

I also dislike an unused triode. But the Express and Liverpool have so much gain on tap, we end up dumping it to ground between stages. So I got rid of one preamp tube, and used an LND150 MOSFET to replace the first gain stage. The result is excellent, and can be found here: https://ampgarage.com/forum/viewtopic.php?f=6&t=38641

[stephen_w_keller]

Run them in parallel like a Matchless Chieftan. It won't boost the gain (assuming you adjust the loads accordingly) but you might get better noise performance out of the circuit. A lot depend on where the extra triode sits in the circuit.

[mountainhick]

Run them in parallel like a Matchless Chieftan. It won't boost the gain (assuming you adjust the loads accordingly) but you might get better noise performance out of the circuit. A lot depend on where the extra triode sits in the circuit.

Thinking as input stage, not later, and more along the lines of two individually configured discrete triodes with separate plate resistors and cathodes rather than a pair sharing those components. Hopefully would provide a little different harmonic content. Agree, it is not needed for gain.

I guess I can just try it, and even with a switch added for solo vs the pair, can just cover the hole with a face plate if it isn't worth it.

Other option for no triode to go unused would be a 6AV6 first stage. I have some.

[Roe]

alternatively, you can add a cathode follower (like the k50). Unfortunately, the cathode follower dues not sound too good with 10k cold biased stage. The k50 used 3k3, which increases gain greatly.

[mountainhick]

alternatively, you can add a cathode follower (like the k50). Unfortunately, the cathode follower dues not sound too good with 10k cold biased stage. The k50 used 3k3, which increases gain greatly.

Cathode follower to what end?

I am familiar as a low impedance driver, say for effects loop, and to drive a tone stack, but I don't want to veer that far away from Trainwreck configuration?

I am not familiar with K50, search found Dean Markley and Kustom, but they are both solid state.

[Roe]

alternatively, you can add a cathode follower (like the k50). Unfortunately, the cathode follower dues not sound too good with 10k cold biased stage. The k50 used 3k3, which increases gain greatly.

Cathode follower to what end?

I am familiar as a low impedance driver, say for effects loop, and to drive a tone stack, but I don't want to veer that far away from Trainwreck configuration?

I am not familiar with K50, search found Dean Markley and Kustom, but they are both solid state.

the komet k50 used the cathode follower on v2, replacing the 10k cold clipper with a 3k3 and adding a cathode follower that feeds the phase inverter

[RockinRocket]

Run them in parallel like a Matchless Chieftan. It won't boost the gain (assuming you adjust the loads accordingly) but you might get better noise performance out of the circuit. A lot depend on where the extra triode sits in the circuit.

But there was a tradeoff. Noise for touch dynamics I think it was (read merrlins book) and you defiantly don't want that in a Wreck.

Really no reason to use it as its not needed

[mountainhick]

Just tried paralleling two triodes on my Thrifty Wreck, the second with a 220K plate and 3K/1uf cathode, each triode with its' own .022 coupling cap, into a pair of 470K mixing resistors. Volume is tamed significantly with the added voltage divider. Doesn't seem like anything's better about it. Might try decreasing or removing the mix resistors...

[Mark]

Have you thought of having the first stage in parallel, halving the resistor values?

The Ampeg option might be worth a try, have a cathode follower after the first stage to reduce losses from the tone controls?

This is just me thinking out loud.

[Colossal]

The Ampeg option might be worth a try, have a cathode follower after the first stage to reduce losses from the tone controls?

On a Blonde Bassman, the Bass channel has this arrangement and it is significantly louder than the Normal channel.

[mountainhick]

Thanks,

In theory, interesting propositions. I've built a 6G6B bass channel into an amp before, different beast than the wreck for sure. Begs the question though what about cascading the extra triode as first input stage into the Wreck's three. Four triodes, high gain, would need to attenuate along the way. No longer a wreck.

I will ponder this idea. On first think, seems this amp is not laid out to accommodate the extra triode later in the circuit, but perhaps could do it before the rest. I don't want to lose the stock Wreck circuit in the process, but maybe clever switching could do it.

In the meantime, I reconfigured again, removed the mixing resistors, and wired with two jacks so #1 is just the usual input triode and jack #2 is the two in parallel. Each triode still has independent plates/cathodes and coupling caps. The result is pretty good with single coil pickups, but too much with humbuckers. I will try tweaking this further.

[johnnyreece]

No longer a wreck.

This is why I just let the extra triode not worry me on my little Express variant. That's one circuit that I tried to leave mostly as intended. I was just playing mine again the other day, and it really does cut through like my other amps don't.

[mountainhick]

No longer a wreck.

This is why I just let the extra triode not worry me on my little Express variant. That's one circuit that I tried to leave mostly as intended. I was just playing mine again the other day, and it really does cut through like my other amps don't.

Glad you enjoy it. I like mine in stock configuration as well, but I am not one to leave well enough alone!

It is not a worry, it is experimentation.

[johnnyreece]

To each his own! There was a point where I had thought about switching what side gets used. That way, if you get a 12AX7 with one side dead, you could still use the other side.