I'm not really familiar with the layout, but the PI (12AT7) is normally the second-from last tube in both early Hiwatts and Sound City amps. If you want to post a picture of the socket (from the wired side) I can confirm this.
Thank you so much for the fast response. That is where is it seated. A Mullard, no less.
Attached is the shot from underneath with the new caps and such.
If I could trouble you with one more Hiwatt newbie question: on some amps it is said that you only need to put your "best" pre-amp tube in slot #1. But this baby has four inputs. So I assume, there are at least two tone circuits? So perhaps there is a second slot which might benefit from a better tube? Which might be best suited for a 5751 rather than a 12AX7? Not that I'm all that obsessed -- I play bass!
happyface wrote:
I put a nice 5751 in V1. Is that sensible? Is there any reason to put a "fancier" 12AX7 in any of the sockets?
I run a 5751 in V1 of my 1980 SA112 (to tame its rather hot front end). If your amp has enough gain and you've found a non-microphonic 5751, no harm in using it. Otherwise, try your best 12AX7/ECC83 in that socket.
I haven't owned a Hiwatt with a V5, but I've found V2 and V3 to be less demanding and my amps seem happy with modern production tubes there.
Being a bass player, it has been a while since I have used a multi-channel tube amp. And this is my first Hiwatt.
Sorry for the newbie questions. I switched to bass from piano in 1966. Those were tube amp days and I even built some amps from kits back then. But that was just "paint by numbers" stuff = I never learned the theory behind what I was soldering in. Maybe when I retire....?
