What do preamp tubes in a Traynor YCV40 do?

[GuitarStv]

I've been thinking about playing around with the preamp tubes in my amp, and was just wondering if anyone can tell me what the likely effect is going to be. The Traynor I've got has two 5881s in the output section (Cathode biased), and three 12ax7s in the preamp. It's a two channel amp with reverb. Are there any hard and fast rules for this? Specifically,

1. Which tube has the greatest effect on the amount of distortion on the gain channel?

2. Which tube would have greatest effect on overall volume of the amp?

[CTN]

Re: What do preamp tubes in a Traynor YCV40 do?

1) probably V2. Not sure if your reverb unit is tube driven or not, but if not, then V1 = clean channel/first amplification stage, V2 = overdrive/2nd stage, and V3 = phase inverter. if it is tube driven, then V1 is probably clean and OD, V2 would likely be the reverb driver, and V3, the phase inverter.

2) Depends. if you put in lower output tubes in any of the slots, your volume will drop a bit. by lower output i mean 5751s, 12au7s, 12ay7s, 12at7s.

edit:

ok ya, the reverb isn't tube driven. so V2 = overdrive, V3 = phase inverter.

[GuitarStv]

Re: What do preamp tubes in a Traynor YCV40 do?

Cool, that's pretty helpful! What effect does changing the phase inverter have on an amp?

[CTN]

Re: What do preamp tubes in a Traynor YCV40 do?

lol that's a can of worms.

The gain factor of a preamp tube doesn't really matter in the phase inverter slot. What matters there is the current that the tube pushes. for example:

• 12AX7
o Has a published spec gain of 100
o Has a publishes spec current output of 1.2 milliamps

• 12AT7
o Has a published spec gain of 60-70
o Has a published spec current output of 10.0 milliamps (ten times that of the 12AX7 as a side note)

so a 12at7 in the PI slot will push your power amp section harder than a 12ax7 would, even though the 12ax7 will yield more gain in any other preamp tube slot.

have a read through here for some more info on this topic:

http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CFYQFjAD&url=http%3A%2F%2Fwww.guitaramplifierblueprinting.com%2Ffiles%2FPhaseinverter.pdf&ei=x_tRUOffD8ju0gHD04CgBA&usg=AFQjCNFncInw60hv99_j4xMS3uRTP5RwnQ&cad=rja

[GuitarStv]

Re: What do preamp tubes in a Traynor YCV40 do?

Hmmm . . . so,

- V1 tube changes would effect the clean and dirty channels gain level
- V2 changes would effect the dirty channel only
- PI changes effect how much gain is sent out to each output tube, so changes are probably most noticible at high volume?

The gain factor of a preamp tube doesn't really matter in the phase inverter slot. What matters there is the current that the tube pushes. for example:

• 12AX7
o Has a published spec gain of 100
o Has a publishes spec current output of 1.2 milliamps

• 12AT7
o Has a published spec gain of 60-70
o Has a published spec current output of 10.0 milliamps (ten times that of the 12AX7 as a side note)

So a 12at7 in the PI slot will push your power amp section harder than a 12ax7 would, even though the 12ax7 will yield more gain in any other preamp tube slot.

Would it even be safe to use in your amp if it's so far off spec current-wise?

[jeremy]

Re: What do preamp tubes in a Traynor YCV40 do?

just cause the tube is capable of pushing that much doesnt mean it will the way its configured in an amp. its a fine thing to try and shouldnt hurt anything

[CTN]

Re: What do preamp tubes in a Traynor YCV40 do?

Hmmm . . . so,

- V1 tube changes would effect the clean and dirty channels gain level
- V2 changes would effect the dirty channel only
- PI changes effect how much gain is sent out to each output tube, so changes are probably most noticible at high volume?

yesh, although with the PI, changes should be noticeable at almost any volume, except the softest.

Would it even be safe to use in your amp if it's so far off spec current-wise?

yeah, it should be fine. the whole family of guitar preamp tubes are all basically interchangeable:
12ax7, 12at7, 12ay7, 12au7, 12dw7, 5751