12AT7s

[greiswig]

My non-HRM build with low plates has always seemed to like the OD trimmer set lower than what I hear about typically here. My sweet spot seems to be around 12k to ground instead of 22k. If I set mine at 25k, things start sounding muddled.

I have some old Mullard AT7s, and just for kicks I decided to try one in V2. I set the OD trimmer to 25k to start with on it, and it sounded pretty good! Sweet spot for it seems to be closer to 30k. It sounds to me like a little more of the raw string sound is getting through, but there's still a nice girthy overdrive on it. And I like the fact that NOS AT7s are so much less expensive.

[angelodp]

Hmmm... gotta try that

[talbany]

-g

My 2nd Generation 100w also sounds pretty good loaded 12AT in OD side..Although that amp doesn't have the trigger entrance I have to compensate on the drive side around 1:00.. I still get some decent amount of sustain and feedback..Like you say the tone is meatier w/less hair on the top and real articulate and smooth..Tube I used was a Mullard pull and sounded pretty sweet to me...Good Luck

Tony

[angelodp]

Which AT7's aside from Mullards are going to be a good choice for this?

Ange

[greiswig]

Tony,

Is it me, or is it just a tad less touch sensitive though with the AT7? Seems like once you get the gain dialed up to where you have about as much OD as an AX7, you've also lost a bit of touch sensitivity.

I don't understand enough about it to know what the increased transconductance would do to the tone and feel.

[talbany]

Which AT7's aside from Mullards are going to be a good choice for this?

Ange

Ange.. I hope you are good..
My faves in order are Mullard/RCA/.Amphrex in this amp
Try to pick one with some good gain..

Tony

[angelodp]

Who do you go to for these tubes The Sarge?

[Structo]

Who do you go to for these tubes The Sarge?

Fort Knox!

[talbany]

Tony,

Is it me, or is it just a tad less touch sensitive though with the AT7? Seems like once you get the gain dialed up to where you have about as much OD as an AX7, you've also lost a bit of touch sensitivity.

I don't understand enough about it to know what the increased transconductance would do to the tone and feel.

-g
Yeah I would say so too..Perhaps the lower gain is to blame or like you say the OD side isn't really set up for the AT's perhaps if they were it may become more responsive..Iv'e never went there so?
BTW I recently modified a 50w low plate classic to accept a 6SL7 in the OD as it had similar characteristics as the AT less fuzz/hair and added some nice meat..kinda cool but it too lacked in the touch sensitivity area and didn't take to kindly to the larger signals in an OD circuit not to mention wild tone swings going tube to tube.. Too Finicky.. Still Kinda cool


Tony

[David Root]

FWIW I just went thru this, but in a 5E7 Bandmaster modded for blues harp. I had a 12AT7 in V2, a '71 Mullard, and a '60 GE JG-5751 in the PI, V2 was wired in parallel, PI is a cathodyne not a LTP, then I switched the two tubes and preferred them that way, with the 12AT7 in the PI.

It worked I think because I had the same value plate resistor in both spots, and it was all much lower gain than in a guitar circuit.

In Dumbles, I have a 12AT7 in the PI in my '70s ODS 50W and it definitely works well there.

In addition I use a 12AT7 in Normster's buffered FX loop, which I now add to a D-build without thinking about it.

And yes, gourmet NOS 12AT7s that would kill your bank account if they were 12AX7s are very affordable in comparison.