Preamp or power tubes will affect tone more?

[football13]

In general, changing which out will result in more tonal difference? I have an Invader with el84s... been messing with the preamps, but haven't touched the power tubes yet which are JJs.

[Exothermia]

If your amp has a master volume / preamp gain control, most likely the preamp. If your amp is a simple crank-it-the-F-up type amp the power tubes will have more effect on the amp (provided you actually crank it)

[rockon1]

The most? While they all affect tone I'd have to say the pre amp tubes. The V1 a bit more than the rest. Aside from having tonal differences pre amp tubes also "break up"(distort) differently. Some distort earlier giving more distortion and also slighly different sounding.This becomes more of a factor in the later gain stages-usually the V2 on most amps. Bob

[Swarty]

I'd say V1 has way more influence on the overall sound than the other preamp tubes. The differences between output tubes is not going to be real apparent until you get the amp cranked up.

[John Phillips]

I think the tone effect of the power tubes is very noticeable at any volume, even with amps which get all of their distortion from the preamp. I would say that the power tubes have more effect than any of the preamp tubes individually, if perhaps not as much as all of them together - because the power tubes (even if there are several of them) are just one stage of gain in parallel, whereas the preamp has several stages in series, so the effect of the individual tubes is multiplied.

Of the preamp tubes, usually V1 makes the most difference, but the phase inverter (which might strictly be considered part of the power amp anyway) can make at least as much often. Other positions may have more effect than V1 depending on the preamp architecture - an amp which for example uses only one half of V1 for the dirty channel, but both halves of V2, will be more dependent on V2 for the dirty tone. They all have an effect though - IMO it's not so much that individual tubes 'add' tone, but that they subtract (filter) it... so IMO it doesn't work well to use one really good tube in V1, and less good ones in the others - better to use fairly decent ones in all the positions.

But the power tubes are the final filter before the OT and the speakers, and affect everything that happens before that point. I've certainly noticed this with my amps - mostly channel-switchers, and which I rarely crank right up.

[rockon1]

I think the tone effect of the power tubes is very noticeable at any volume, even with amps which get all of their distortion from the preamp. I would say that the power tubes have more effect than any of the preamp tubes individually, if perhaps not as much as all of them together - because the power tubes (even if there are several of them) are just one stage of gain in parallel, whereas the preamp has several stages in series, so the effect of the individual tubes is multiplied.

Of the preamp tubes, usually V1 makes the most difference, but the phase inverter (which might strictly be considered part of the power amp anyway) can make at least as much often. Other positions may have more effect than V1 depending on the preamp architecture - an amp which for example uses only one half of V1 for the dirty channel, but both halves of V2, will be more dependent on V2 for the dirty tone. They all have an effect though - IMO it's not so much that individual tubes 'add' tone, but that they subtract (filter) it... so IMO it doesn't work well to use one really good tube in V1, and less good ones in the others - better to use fairly decent ones in all the positions.

But the power tubes are the final filter before the OT and the speakers, and affect everything that happens before that point. I've certainly noticed this with my amps - mostly channel-switchers, and which I rarely crank right up.

As I respect your opinion Ive got to go and do some power tube swapping again! It makes sense but Ive never really heard that much difference. Ive got a good test in mind too. Swap out my GE6L6gc's for Sovtek 5881's. Bob

[Buffaloamps]

I suggest reading this link...http://www.thegearpage.net/board/showthread.php?t=202244

[football13]

Thank you all- very interesting info. After swapping the JJ 12AX7s to a variety of older tubes, it will be hard to ever use current production tubes because of the harshness (haven't tried 'em all but..). Now I just have to wait for the older power tubes to arrive, but I can't imagine that the amp could sound even better than it does now :)