Prosonic owners...good choice for preamp tubes?

StompBoxBlues

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20,573
Any Fender Prosonic owners have some recommendations for preamp tubes (especially V1 I am guessing) to get a little less brittleness out of the amp?

I run mine currently (have tried other settings too) in "class A" mode, with 2 x 12" 8 ohm out.

The OD goes from brittle (but it is ALMOST where I want it to be...just can't get that last 15%) to muffled no matter how carefully or how many permutations I do with EQ and gain 1 and gain 2.

It's frustrating, I keep feeling like "there....wait, not quite" and am thinking maybe a change of preamp tubes could get me in a better place.

Mine is the head version, no reverb.

Thanks for any tips!
 

StompBoxBlues

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20,573
For new production tubes, the Tung Sol Reissue 12AX7s win hands down.

You mean specifically for Prosonic, or just in general? The reason I ask, I think the prosonic is quite different than many other amps in its voicing, and easily gets brittle...am even thinking of changing maybe to 12AT7's or something lower...the gain is off the charts, but not in a good way at the moment.
 

Blue Strat

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30,696
You mean specifically for Prosonic, or just in general? The reason I ask, I think the prosonic is quite different than many other amps in its voicing, and easily gets brittle...am even thinking of changing maybe to 12AT7's or something lower...the gain is off the charts, but not in a good way at the moment.

In general but my response was based on your "brittle" description.

12AT7s are going to make it brighter if anything. People don't realize that there's a lot different besides just gain between 12AT7s and 12AX7s.

For lower gain consider a 5751 or 12AY7.

And don't forget about speakers. I they use the gold label Jensens in there that could be why the amp is "brittle".
 

StompBoxBlues

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20,573
In general but my response was based on your "brittle" description.

12AT7s are going to make it brighter if anything. People don't realize that there's a lot different besides just gain between 12AT7s and 12AX7s.

For lower gain consider a 5751 or 12AY7.

And don't forget about speakers. I they use the gold label Jensens in there that could be why the amp is "brittle".

Thanks, that is a good point about the 12AT7's, that was what I was a fixin' to do, but I do have some 5751's I think.

You probably missed it, but I mentioned I have the head version. I wish I had the combo, but when I went looking the head was all that I could find.
 

myles111

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2,954
You mean specifically for Prosonic, or just in general? The reason I ask, I think the prosonic is quite different than many other amps in its voicing, and easily gets brittle...am even thinking of changing maybe to 12AT7's or something lower...the gain is off the charts, but not in a good way at the moment.

I feel the 12AT7 is a terrible and harsh tone generator. It is a reverb driver or phase inverter.

If you want the gain of a 12AT7 but smooth tone use an NOS 5751. That is an old SRV trick by the way in his Fender blackface amps.

NOS-JAN-GE-5751-%281967-69%29.jpg


These are GREAT in the first stage of a Prosonic whether it is the head or combo with reverb. Takes the edge off and with the cascaded gain of these amps you will still have more gain than anybody could ever ask for.

http://www.kcanostubes.com/products/485/NOS-JAN-GE-5751-1967-69.htm KCA has these and they are cheap too.
 
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Pardon the thread necromancy, but in case it's of use to anybody looking for pre-amp tube suggestions to take the harsh top end edge off the Prosonic's gain - I can vouch for Myles's suggestion of the 5751. I put a Phillips 5751 in there and it removed that edge.

Also he's right about the 12AT7 being pretty harsh and awful in the V1 position - I tried that before the 5751 and yup, he's right.
 




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