Jazz-tonestack layout

[scaesic]

i knocked up a tonestack layout for vero based on the polytone jazz amps. It's unverified as im waiting for a delivery.

layout:



schematic:

[Dragonfly]

cool...a "standalone" Bax tonestack is definitely a useful thing to have around...especially for recording....it would be cool to build this into a Bass DI, maybe adding a cabinet sim to the end of the circuit.

[Ben N]

As I recall there was a long thread a while back about how to incorporate a mid control into a bax--here is one way. That thread had a few schems by stm, IIRC.

Ben

[scaesic]

if you're using it in a stompbox remember to stick a capacitor on the input.

i'l submit this to my gallery once i verify it (once the post arrives...)

[Dingleberry Electronics]

That looks nice!

My friend had one of those polytone jazz-amps with spring reverb.
It was very nice sounding little box. Sadly, last year when we were on tour it got stolen.
Need to build him one, so he can use it as preamp pedal before his current amp.
Maybe he's able to get the Polytone vibes back.

It would be nice to try to combine that stack with the Ruby-amp.
Nice small jazz sounding amp for practice purposes.

-T

[scaesic]

well this is only a very small part of the polytone schematic, but that is the kind of idea i had.

combine mosfet boost with this and a tda2050 power amp.

id be surprised if it sounded exactly like a polytone, but at least its a right start for the kind of toneshaping the polytone employs.

il get back to this once iv finished my amp project....(probably at least a few months)

if you really wanted a jazz tone id stick a clean tube pre either before or after this, and then think about what kind of poweramp to use (chip amps might brighten things up a little too much).

http://www.murchmusic.com/Polytone%20Info/Schem1.JPG  - from what i can tell this is the section you need to preclude the power amp (if you remove the distortion and reverb sections)

if you're intrested in getting into power amps i found this http://diyaudioprojects.com/Solid/ZCA/ZCA.htm - i wanted something a lot more powerful but it sounds like it could be a winner in terms of pure audiophile sound.

[Ben N]

if you really wanted a jazz tone id stick a clean tube pre either before or after this, and then think about what kind of poweramp to use (chip amps might brighten things up a little too much).

If so, the why not skip the opamp and put the bax either between two halves of a 12a_7,like an Amppeg Gemini, or in the feedback loop of a tube stage (with reverse pots, of course).

Just a thought.

[aron]

COOL! I forgot about the Polytone!

[scaesic]

if you really wanted a jazz tone id stick a clean tube pre either before or after this, and then think about what kind of poweramp to use (chip amps might brighten things up a little too much).

If so, the why not skip the opamp and put the bax either between two halves of a 12a_7,like an Amppeg Gemini, or in the feedback loop of a tube stage (with reverse pots, of course).

Just a thought.

im not an expert, but the op-amp is just really being used as a buffer to split the signal and then to sum the components on the other side, isnt it?
i dont know if you can use tubes like that, but then again, tubes are completely out of my league.

also, i think you'd lose some clarity by putting it in a feedback loop, but again, i have no idea about how tubes work.

[scaesic]

new layout (previous one had r8 missing) - still unverifived

[Zben3129]

Im not sure if this is correct because my computer has aweful contrast, but...arent you missing the 4 trace cuts under the opamp?

[scaesic]

Im not sure if this is correct because my computer has aweful contrast, but...arent you missing the 4 trace cuts under the opamp?

hey! i think you're right! good thing i added them to the real thing