Pentode/Triode Mod opinions?
giri iyengar
ability, but very few combos or heads do, unless they already have
a billion options.
Anyone out there run their amp in triode mode? What's the general
opinion of youse folks on the sound of triode operation vs. pentode
operation. (I'm thinking of EL84s here, in Class A)
Thankee..
.Giri
Dave Cigna
Hi Giri,
I've installed these switches on a variety of amps. I'd say that in
some cases the results are more satisfying than others. It will
reduce the power by 1/2 to 1/3, but as we've been reminded over and
over, this doesn't reduce the apparent loudness by that much. What I
notice most about triode mode is that the amp sounds looser with less
dynamics. This will warm up an amp that is a little hard and analytical
sounding.
I've tried the mod on 100 watt Marshalls and didn't like it at all
("just get a 50 watt", is what I say.) My opinion is that most black-
and silverfaced Fenders lose their spank in triode mode, but some
people like it for blues. I think that the later silver Fenders with
the ultralinear output transformers can benefit from this mod (O'Connor
seems to agree.) The most satisfying installation was in a 6 watt
Fender Champ. I can hear some of you laughing right now, but in triode
mode this amp was just right for the living room.
-- Dave Cigna
ANGELA BRUMLEY
the sound of the triode. BTW that amp is all tube 6l6 combo w/1 12" speaker.
Other opinions please!!
giri iyengar
>The most satisfying installation was in a 6 watt
>Fender Champ. I can hear some of you laughing right now, but in triode
>mode this amp was just right for the living room.
Thanks, Dave. I'm not laughing. That is *exactly* what I was thinking
of. A Champ and my Jet. I'd like both to start breaking up just a
little earlier.
Is this is a simple and non-screw-up-able mod that any tech could do?
(Maybe we should take this to e-mail?)
Thanks..
.Giri
JumpStrtKM
running 6V6's in triode mode into 2 10's (the top half of THD's "mickey
mouse" speakers), the other half is running EL-84's in pentode mode into a
12 (the lower half of the cab). In triode mode the 6V6's get a smoother
clean sound, not quite so "spanky" than when running in pentode mode. The
sound also seems a bit more balanced from bottom to top in triode mode,
with a more complex midrange.
-Ken
giri iyengar
>I run half of my Lennon stereo power amp in Triode mode. One channel is
>mouse" speakers,the other half is running EL-84's in pentode mode into a
>12 (the lower half of the cab). In triode mode the 6V6's get a smoother
>clean sound, not quite so "spanky" than when running in pentode mode.
>with a more complex midrange.
Drool, drool, DROOL!!!!
Oh man, DROOL!!!!! :-)
What preamp are you using for that setup. I thought long and hard about
the Lennon, but the price of the whole setup was prohibitive.
.Giri
Dave Cigna
Yeah. This is a very simple mod if the power tubes are chassis mounted
and are connected by wires. It gets more challenging if they're mounted
directly to a pc board and connect with traces. All that's required is
a large DPDT switch and a couple of resistors (100 - 1k ohm). We're
dealing with about 400 volts or so, and it's hard to find switches
rated for that voltage. What most people do is search for the largest
switch with the highest current rating we can find. I'm not entirely
convinced that you can trade current rating for voltage rating, but
it makes me feel better. (I buy 250 V, 6 amp switches and have never
had one fail in this application.) Any tech ought to be able to do
the mod.
-- Dave Cigna
JumpStrtKM
>>running 6V6's in triode mode into 2 10's, the top half of THD's "mickey
>>mouse" speakers,the other half is running EL-84's in pentode mode into a
>>12 (the lower half of the cab). In triode mode the 6V6's get a smoother
>>clean sound, not quite so "spanky" than when running in pentode mode.
>>sound also seems a bit more balanced from bottom to top in triode mode,
>>with a more complex midrange.
>What preamp are you using for that setup. I thought long and hard about
>the Lennon, but the price of the whole setup was prohibitive.
Thanks for compliment. The Lennon amp is absolutely the best thing I have
EVER done to improve my tone (and I've done a lot!)
Currently I'm using a Roland GP-100 preamp/effects into the amp. I know, I
know. It's digital. It has no tubes. It's a swiss-army-knife of effects.
But it's darn cool, and sounds great! I'm currently borrowing every amp I
can find, bringing it home, and totally grokking it's tone with the
GP-100. Just did a '65 Bassman and a '61 Princeton a while back... their
owners could not tell when I was switching amps.
-Ken