The 'magic' of the V1 pre amp tube

[Demanic]

I agree. I experimented with using the 5751 30 years ago in my blackface Fender Pro Reverb. Left it in for a day or two. Yes it lowers the gain and has a certain tone that's kind of useful for some things. But generally, to my ears, it made the amp sound bland and unexciting.

Which is why it's perfect for a tube amp that you are planning on hitting the front end with an obscene amount of gain.
Ask me how I know.

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[Lewguitar]

there is not infinite info on this..but through trial & error I found a lower gain in the pre amp limits what you can do...even playing clean sounds. a bit of gain..a bit of break up adds character. With a 5751 you wont get this until the gain is fully cranked .ie too loud !

I agree. I experimented with using the 5751 30 years ago in my blackface Fender Pro Reverb. Left it in for a day or two. Yes it lowers the gain and has a certain tone that's kind of useful for some things. But generally, to my ears, it made the amp sound bland and unexciting.

[Gold star]

Re: The 'magic' of the V1 pre amp tube

It's funny and somehow comforting that (in the age of infinite information), there are still bizarre myths being perpetuated.

My favorites from back in the day involved pickups, in that you couldn't mix active and passive, or Strat and Tele pickups.

there is not infinite info on this..but through trial & error I found a lower gain in the pre amp limits what you can do...even playing clean sounds. a bit of gain..a bit of break up adds character. With a 5751 you wont get this until the gain is fully cranked .ie too loud !

[Gold star]

Re: The 'magic' of the V1 pre amp tube



Your correct, what you read is incorrect. It won't harm anything. It may affect the sound or it may not depending on the amp and how it is being used. The 5751 just has lower gain compared to the common 12AX7. In a high gain amp that gets its distortion mostly in the preamp it could reduce the buzzy sound to the distortion that can often be a problem in a high gain amp.

The amps SRV mostly used depended on power amp distortion to get that sound. And he played very very loud, which is how you get power amp distortion going.

The exceptions would be his Soldano SLO100 that he began using shortly before his tragic passing, and/or his Dumble amps. In these such amps the use of lower gain tube in V1 or in V2 will have a profound effect on the gain structure of the amp. It could have been used to help that amp get a bluesier tone and to help tame the high gain nature of that amp, assuming they were speaking about a high gain amp.

Nevertheless, speaking in just general terms, the tube used in V1 of just about any amp is of vital importance, because it sets the tone at the beginning that will be amplified through out the rest the amp. Rolling in and trying different tubes, usually all 12AX7s, there as a trial and error processes, is a way of fine tuning the tone of an amp.

Since my original post about this, I put the ECC83 back in. The 5751 does not come as standard in most amps I know of and the thing with these is if you then apply a treble boost or overdrive..distortion pedal it will not work ..or not work as well. some songs require clean & overdriven sounds but if you have a single channel amp (like mine) then you need the ECC83/ 12AX7 in the pre amp, you need a certain amount of distortion to begin with and the lower gain tube wont allow this. In general..stick to what is supplied. The only plus side is that the amp electrics as a whole, may run cooler..but not much.

[Jacew]

Re: The 'magic' of the V1 pre amp tube

It's not just about V1 tube, but big thing is how all the gain stages work in conjunction.

Personally I did a bit of tube swapping last year: First switched all to JJ ECC83's, which made the amp tighter and added a bit of clarity. Stock Sovteks had as much low end, but much looser and smoother.

Itried also to switch Sovtek in to V2 and JJ to V1 and vice versa. Sovtek in front of JJ actually sounded pretty good overall. Added more vintagey smoothness and bloom to the tone. Other way around it sounded turd.

I opted for keeping all JJ's.

I tried JJ 5751 in front end as well, which was huge improvement for clean tones. They were not bad to begin with, but 5751 added really nice clarity and spark to it. However, it also made the drive shrill and lose lot of the best mid-range growl, which was dealbreaker there.

I tried Tung-Sol too with JJ's in both positions. Was hot and gritty, but lacked body, and generally just didn't had the same growl I like with JJ's. Might say that Tung-Sol had distortion "tuned in" at bit higher register tonewise, which I didn't like at all.

[Gold star]

Re: The 'magic' of the V1 pre amp tube

I started this thread and just recently , tried a JJ 5751 in the 1st position. on my single channel amp. As the gain is turned up further than before with less distortion the sound seemed thicker single notes 'bloom' as some say, the voicing/tone doesn't change much or sound better-not really. My hearing is good and overall, it was NOT worth doing. I put the old ECC83 tube back in. With simple gain and master volume, it's a case of balancing the two so that at any level I can get clean sounds. You cant tell until you try...

[misterwhizzy]

Re: The 'magic' of the V1 pre amp tube

OK. Electronics is complex so you read things that are not always correct. One post I read, (not here) suggested a lower gain tube in the first position can harm other parts of the circuit and make the power section work harder as it was not designed for something like a 5751 . I doubt it if people have tried it. In my case the amp is a single channel with single volume & gain knob . ECC83 / EL84 tubes. It's actually a Vox AC10 re issue. Is the 5751 tube of higher resistance?

By that logic, turning down your guitar's volume knob would have the same effect.

[LLL]

Re: The 'magic' of the V1 pre amp tube

This is all good (lower gain 12AX/ECC in V1), but IMO, the "magic" (mystical magical killer tube amp tone) happens when the PI tube is begging for mercy.

Which means ya gotta crank it.

[Demanic]

Re: The 'magic' of the V1 pre amp tube

It's funny and somehow comforting that (in the age of infinite information), there are still bizarre myths being perpetuated.

My favorites from back in the day involved pickups, in that you couldn't mix active and passive, or Strat and Tele pickups.

You can certainly mix active and passive. It's just a pita to do it properly.

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[JB_From_Hell]

Re: The 'magic' of the V1 pre amp tube

It's funny and somehow comforting that (in the age of infinite information), there are still bizarre myths being perpetuated.

My favorites from back in the day involved pickups, in that you couldn't mix active and passive, or Strat and Tele pickups.

[Gold star]

Re: The 'magic' of the V1 pre amp tube

OK thanks; so it should not have a negative impact on the amp as some suggest. It could be that being able to open up the pre amp more with less distortion could improve tone slightly..I'm guessing !

[beaubrummels]

The 'magic' of the V1 pre amp tube

The only thing I would add to that is how it (5751)distorts less in the first place ? externally it looks the same as an ECC83. I wonder if it has more resistance to the voltage applied. Maybe that's why some suggest it may have an adverse effect on other components..but again, people have tried it and not reported damage to their amps

Tubes don’t have resistance. They operate on transconductance. The flow is regulated by a negative voltage on the grid.

The 12AX7 has a transconductance of 1600mhos, with a power factor of 100. The 5751 has a transconductance of 1200mhos with a power factor of 70. That’s why the 5751 provides less gain.

[Gold star]

Re: The 'magic' of the V1 pre amp tube

The only thing I would add to that is how it (5751)distorts less in the first place ? externally it looks the same as an ECC83. I wonder if it has more resistance to the voltage applied. Maybe that's why some suggest it may have an adverse effect on other components..but again, people have tried it and not reported damage to their amps

[beaubrummels]

Re: The 'magic' of the V1 pre amp tube

OK. Electronics is complex so you read things that are not always correct. One post I read, (not here) suggested a lower gain tube in the first position can harm other parts of the circuit and make the power section work harder as it was not designed for something like a 5751 . I doubt it if people have tried it. In my case the amp is a single channel with single volume & gain knob . ECC83 / EL84 tubes. It's actually a Vox AC10 re issue. Is the 5751 tube of higher resistance?

If what you were saying were true, no amp would have a gain knob at the input, or running it on 1 or 2 would blow it up. IME, it works just the opposite.

[Gold star]

Re: The 'magic' of the V1 pre amp tube

OK thanks..