What characteristics do you get from parallel tridoes?

[CitizenCain]

What are the typical attributes that paralleling triodes in a tube give you? Is it quieter, more powerful, ???

Just trying to increase the wrinkles in the gray matter

[Paul P]

I asked this question two days ago and received the following from kg :

well the theory behind it is that paralleled sections give you twice the gm, half the rp, and the same mu.

that is good from a noise standpoint, both "internal" to the tube, and external/induced due to the lower plate node impedance.

however if the lowest input stage noise were really your goal you wouldn't be using a 12ax7.

Paul P

[CitizenCain]

So the main benefit is noise reduction? Maybe a lower output impedance...for driving a tone stack, too? Forthat you'd probably be better off with a single gain stage and a cathode follower though I bet.

[mooreamps]

So the main benefit is noise reduction? Maybe a lower output impedance...for driving a tone stack, too? Forthat you'd probably be better off with a single gain stage and a cathode follower though I bet.

I would agree, a better solution to drive a tone stack would be a single gain stage boot-strapped to a cathode follower. I believe the main benefit of running parallel triodes is to fatten up the tone. I did this on my first 5 watt prototype amp. However, on my next 18 watt prototype, I'll run a triode in parallel with a pentode front-end. Maybe I'm giving away too much on how I am intending how to bring back the pentode front-end on a guitar amp.

-g

[CitizenCain]

I Maybe I'm giving away too much on how I am intending how to bring back the pentode front-end on a guitar amp.

-g

Trade secrets revealed!

[tubeswell]

Yeap I thought parallel triodes fattened up the tone too. In fact I heard this for myself for the first time the year before last when I observed a local musician plug a short lead from the lo gain input of one channel to the hi gain input of the other channel of his 5E3 - which is one of the things that inspired me to build a 5G9. I can't wait to finish it and take it for a test drive. :-)

[CitizenCain]

Hmmm, a fatter tone is something that sounds interesting to me.

[Paul P]

Hmmm, a fatter tone is something that sounds interesting to me.

Being the tone grasshopper around here, could someone explain to me what is
meant by "fatter tone". It sounds appealing. More <width, depth, crunch,?>
Actually, crunch could use a definition as well.

Technically, does it mean that a sine wave would be squared up a little bit,
like in fattening up the sine wave ? Seeing as this is only one stage, does
this fattening apply only to half of the wave ?

Paul P

[hasserl]

I would agree, a better solution to drive a tone stack would be a single gain stage boot-strapped to a cathode follower. I believe the main benefit of running parallel triodes is to fatten up the tone. I did this on my first 5 watt prototype amp. However, on my next 18 watt prototype, I'll run a triode in parallel with a pentode front-end. Maybe I'm giving away too much on how I am intending how to bring back the pentode front-end on a guitar amp.

-g

You're late, some of us are already building pentode preamps.

[mooreamps]

You're late, some of us are already building pentode preamps.

I've disected a couple of old burned out pre-amp pentode tubes, put them under a microscope, and I believe I have determined the failure mechanism. I'll find out later on if my fix abates this problem.

-g

[tubeswell]

Being the tone grasshopper around here, could someone explain to me what is
meant by "fatter tone". It sounds appealing. More <width, depth, crunch,?>

Paul P

'Thicker' and fuller with more stuffing, I would say

[CitizenCain]

So, to actually wire up parallel triodes, is it simply jumpering 1-6, 2-7, and 3-8? Do you treat is as one triode when figuring the plate and cathode resistors? I suppose it doesn't make any difference which pin of each pair you use to make connetions to?

[cminor9]

Being the tone grasshopper around here, could someone explain to me what is
meant by "fatter tone". It sounds appealing. More <width, depth, crunch,?>
Actually, crunch could use a definition as well.

Paul P

I'd define it as more lower midrange. A scooped tone isn't fat. A tweedy tone (defined as sounding like a Tweed Fender) is fat. Lots of that nice lower midrange. But that's just me.

[Paul P]

I'd define it as more lower midrange. A scooped tone isn't fat. A tweedy tone (defined as sounding like a Tweed Fender) is fat. Lots of that nice lower midrange. But that's just me.

Thanks. This makes sense, and something I can sort of imagine. I searched
for a tone glossary on the net but found nothing, surprisingly. There are a
lot of terms floating around like grind, grit, punch, crunch, squish, sponge,
dynamic, dirt, bees in a can, icepick in the head, etc, etc...

A glossary with sound clips would be really nice.

Paul P

[mooreamps]

So, to actually wire up parallel triodes, is it simply jumpering 1-6, 2-7, and 3-8? Do you treat is as one triode when figuring the plate and cathode resistors? I suppose it doesn't make any difference which pin of each pair you use to make connetions to?

That would be one way to do it. My circuits are little more complex.

-g