How do I lower preamp gain on Studio .22? (Update)

[RR]

I like my Studio .22 for bedroom level or meddling in home recording.

But I don't need as much preamp tube distortion saturations. My lead channel preamp gain is like 1.5, I find anything after 4 un-useable, I don't need all that extra gain.

Do I change V1 tube to say 5751 or 12AT7 or do I change the V2 to one of these tubes?

 

[stokes]

Changing V1 and V2 to a 5751 will lower the gain on your lead and clean channel.V1 will lower the lead channel.

 

[RR]

Thanks stokes,

Currently it does have 5751 in the V1 position. I'm already consider going to a 12AT7, the gain is still too much.

I want to leave clean channel the same so I assume I don't touch V2.

 

[stokes]

The AT7 is pretty close to a 5751.AT7 has an amplification factor of 60,5751 is 70.I think the AT7 will not give a good tone,that is why you never see them in the V1pos.or tone shapping pos. in a pre-amp,just reverb or driver circuits.I would think you'd do better with a 12AY7 in that spot.It will lower your drive considerably but has a nicer tone than the AT7 which I have found is very flat and lifeless in the V1 position of any amp.Looking at the scem.,if you put a 5751 in V1 & V2 it will lower your lead channel some more because the lead channel uses both.It will lower the clean a little but you might like it.

 

[RR]

Actually I did experiment with an 12AT7 in the V1 position and I did not notice that much a gain drop difference compared tothe 5751.

But thanks for the input of not recommend the 12AT7, so I'll try a 12AY7.

I notice Vox has these tube preamp pedal stomp boxes and they're using (if I'm not mmistaken) a 12AU7 (19% to that of a 12AX7) ... Well, its like comparing apples and oranges comparing an amp's preamp to a tube pedal I supposed.

 

[stokes]

I feel the same about the AU7 in the pre-amp.If it used in front of the amp,like the peddle you mentioned you are adding a gain stage,so it doesnt affect the tone shaping as much as putting it in the pre-amp itself.With the pedal you are boosting the signal from the guitar going to the first stage of the amp itself.The AU7 I have found to be flat like the AT7.If you look at my last post I edited it but you replied before I did.I suggested that you try a 5751 in 1 & 2 pos.It will bring down the lead more because the lead uses both.It will reduce the gain in the clean but I dont think it will be that noticeable.I am a big fan of this tube and have them in all my amps.If you dont have a spare 5751 to try in both positions,I think you will get the best results with the AY7 in the V1.It has an amp factor of 40 as compared to 100 for an AX7.

 

[RR]

I kinda figured you meant both V1 and V2 having ea. a 5751 but weren't sure but glad you cleared it up.

Yeah, I think this would be my best bet with a better balance.

I'm not sure if I even have a 12AU7 tube in the first place (no pun intended) but seems like a good time to make a purchase order so I'll get another 5751. But isn't this tube has lower high frequency range? ( http://svvintageamps.com/tubes.php#question6 )
But then again, Studio .22's EL84s has upper harmonics in the first place.

 

[vcamargo99]

I agree with the previous posts. Even on my Fender amps the 12at7 or 12au7 sounds flat. The 12ay7 sound much better, while allowing the amp to stay cleaner longer on the dial. I was told years ago the the 12ay7 is closer to the 12ax7 (current draw, blah, blah, etc) than the au7 or at7.

 

[RR]

Thanks, so vcamargo99, are you suggesting a 12AY7 in the V1 position and leave V2 with 12AX7?

I'll experiement with that too. Thanks :wink:

 

[stokes]

Yeah,it takes the high "harshness" off.Really smooths out the response.I have'nt put one in an amp and not liked it.I even use them in the lead channel of my IIC+.

 

[vcamargo99]

Looking at the manual it does appear that V1 would be the best place to put it. But it even states that V2 and V3 can have an influence as well. I would stick to V1 and if it's still too powerful put that 5751 in V2!! :wink:

 

[RR]

Looking at the manual it does appear that V1 would be the best place to put it. But it even states that V2 and V3 can have an influence as well. I would stick to V1 and if it's still too powerful put that 5751 in V2!! :wink:

Yeah, I looked at my manual and notice that V2 has an effect on the lead channel too that's why my question I asked about both V1 and V2.

Yes, I notice when installing the 5751 (either V1 or V2 but not yet both), there was a subtle change in gain so I am going in the right direction.

So I'll try these two combination:

V1: 5751; V2 5751
V1: 12YA7; V2 12AX7

any other combination you guys recommend?
Thanks guys :wink:

 

[stokes]

V1 12AY7-V2 5751

 

[LHanson]

I have a .50 cal +, which has a similar (or identical, if your .22 is a +) preamp. I use a 12ay7 in V1, love it.

BTW, according to the schematic, V1 controls both the rythym and lead gain. Pulling the lead switch changes a number of things in the amp, one of which is that it adds the second half of V1 into the signal chain.

 

[stokes]

Look at the schem again,V1a &V1b are paralleled and dont operate independantly.When the tube is switched in both halves are switched in simultaneously.Neither half are in use except in the lead mode.LDR 1 connects your input to the grid of V1 and LDR 2 feeds the signal from the paralleled plates of V1 into the grid of V2a.

 

[pipedwho]

A 5751 or 12AY7 are your best bets.

The amount of gain in any single amplifier stage is a combination of both the tube's gain and its plate impedance. In a lot (most?) guitar amp preamp circuits a 12AT7 will end up being within a few percent gain-wise of a 12AX7, even though it is supposed to have a gain of 60 vs 100. This is because the plate impedance is much lower and isn't loaded as much by the rest of the circuit in its amp stage.

The 5751 and 12AY7 have a higher impedance that is much closer to the 12AX7, so you are likely to get better results there (ie. a more significant gain reduction).

In some circuits (eg. reverb tank drivers), a 12AT7 can actually have more gain than a 12AX7, as it won't have as much trouble driving the lower impedance load.

 

[RR]

I finally settle on:

V1 12AX7
V2: 12AY7

This really smoothen out the preamp drive. I did loose of the "gritty" and "shred" tone but that was my intention so I do not recommend this tube change for the shredders or metalist that has Studio .22.

When I say "smooth" overdrive think Jeff Healy, Santana Europa Era, and current Larry Calton's Dumble tone. It was sustain like mad but without the upper harshness. (But for metal you want that harshness).

But I don't know if this is attribute to changing the stock Black Shadow Eminence Vintage speaker (not a bad speaker by the way) to a ceramic Tubby Tone.

My intention was to get a small moderate gain amp and this does the job.