Metropoulos Forum

How would you add a push/pull pot for a 5TH gain stage and have it switch on by pulling it out?

Bump, cause I would be interested in it too..

Lots of ways of doing this. Depends where you want to add the gain, whether you will make it adjustable etc... I was actually experimenting with this today. I wired up an ef86 gain stage (thru a 500k a pot) then with a dual throw quad pole switch made it switchable from before or after a 2203 preamp. It sounds pretty great and totally different both ways. With the ef86 before the first 12ax7 you can cascade your gain over two gain knobs before you hit the master. You can get very high gain in this mode. Simialar to my bradshaw but squishy. Or... I actually prefer the extra stage in between the master and the phase inverter. It let's you run the master up real high into the ef86 stage simulating a crushed phase inverter sound while turning the stages 500 k pot down and hitting the power amp at a low volume! I then got really geeky and added a six way adjustable tone switch for the gain stage after the tube before phase inverter . Basically a second eq stage. I'm still experimenting but I can post some photos so you can see how it works. It is a VERY versitile setup. Now I'm trying to figure out how to make it switchable between just the ef86 stage for clean ch 1, 2203 preamp alone for ch 2, 2203+ef86 as ch3.

Sorry if this is confusing
Bill

As for the how to wire it to a push pull master, you would just wire the exra stage into series after master, before phase inverter ( adjust volume boost with resistor to suit) or with gain pot as push pull (more distortion)have it insert it into the signal chain either before v1 or after depending where you like the sound. It will be a lot of tweaking to get the values right without using a separate pot but well worth the effort for how clean it would look in the amp. I haven't messed with push pull pots much, but it would be a kinda expensive pot to get the swigging right. I will try to draw it out.