Panel mounted tone stack

[LeftyStrat]

I've been thinking about this for a while, and came across some photos of someone else doing something similar.

It's nice because it reduces flying wiring between the preamp board and the tone controls, and as mentioned in this blog post, makes it easy to swap out pre-made tone stack modules:

http://toboy-diy.blogspot.com/2012/01/p ... stack.html

I think I might feel safer with an insulator between the board and chassis.

[BTF]

Interesting idea. I like his veroboard layout.

In my rack-mount Marshall JCM 800 preamp, I configured the output - via DPDT switch-so you can switch between the Marshall tone stack or a Vox AC30 stack (due to the Vox's deep mid cut, players always think it's a gain switch). The concept of interchangeable modules would be neat. With some sort of 2-wire quick connect plug, you could chain a simple tone control, Baxandall, Marshall, or whatever after your preamp without the hassle of rewiring.

[ChrisM]

Cool idea, some nice fabricated PCBs with a bit nicer layout and mounting style would be fun to mess with.

Those TS wires in old Fenders can really be noisy, high impedance and shielded. I remember when I started building amps and I read one of Gerald Webbers books. He suggested mounting the TS parts right on the pots to minimize noise, went on about how sensitive those TS wires are. Always stuff with me...

[LeftyStrat]

Yeah, as long as you can standardize on pot distances, seems really useful.

A little more robust than just soldering the components to the pots. And like you say, I could have a bunch of pre-made tone stacks to swap in and out really quick.

Maybe a three pin connector for input, output, and ground. I have some two conductor shielded cable that would work.

I'm thinking it might be more useful to have the board at right angles to the pots, making it easier to sub parts. That close to the chassis might be hard to work if you are using eyelets. I guess turrets might work better in this application.

If you take this a step further, you could have tweaker modules with switches to do variants. Imagine a 'master' Marshall tone stack that had switchable 33k/56k, etc. Once you've decided on values drop in a board without the switches.

[megawhat]

Hello.

I don't post here too often but this was brought to my attention.
That is actually my blog post.

The wires underneath the vero had been insulated with teflon sleeve, but that insulation point you made was a concern of mine too.

Eventually that board was replaced with an FR4 board that had 2 turrets on it. The turrets did make me worry less about insulation from the chassis less. The new pots are wired using bus wire mainly, and using 2 turrets its possible to hole all the relevant caps (2x 22nf, 1x 470pf) and the slope resistor.

I used two separate wires off the board. One for ground and one signal. I did have an issue with the signal wire which was shielded single core coupling to the next grid and inducing some oscillation, but that was stopped with a simple 10K grid stopper.

I'm sure it could still be executed better.

I also agree about mounting the board at right angles. It would be easier to swap parts. I couldn't find any really nice PCB mounted pots that I was comfortable with using to do this. The Bourns pots I initially used were total junk. If the tags on the pots are long enough, it should be possible to solder the tags to eyelets and mount the board on the back of the pots. There are all kinds of ways once you get thinking about it.

VHT/Fryette use small boards to mount NFB and TS circuits. That's were I got the idea for this. There is also a thread somewhere on the net about someone who did a similar thing with an old fender.

[mhartman]

That's a great idea! I've always liked how Two Rock did their Opal with V1 up front and the tonestack wired point-to-point directly from the V1 socket to the pots. Of course, the disadvantage is that you have V1 upfront and thus you would have to look out for heater noise in that sensitive area of the amp.

[LeftyStrat]

Hello.

I don't post here too often but this was brought to my attention.
That is actually my blog post.

The wires underneath the vero had been insulated with teflon sleeve, but that insulation point you made was a concern of mine too.

Eventually that board was replaced with an FR4 board that had 2 turrets on it. The turrets did make me worry less about insulation from the chassis less. The new pots are wired using bus wire mainly, and using 2 turrets its possible to hole all the relevant caps (2x 22nf, 1x 470pf) and the slope resistor.

I used two separate wires off the board. One for ground and one signal. I did have an issue with the signal wire which was shielded single core coupling to the next grid and inducing some oscillation, but that was stopped with a simple 10K grid stopper.

I'm sure it could still be executed better.

I also agree about mounting the board at right angles. It would be easier to swap parts. I couldn't find any really nice PCB mounted pots that I was comfortable with using to do this. The Bourns pots I initially used were total junk. If the tags on the pots are long enough, it should be possible to solder the tags to eyelets and mount the board on the back of the pots. There are all kinds of ways once you get thinking about it.

VHT/Fryette use small boards to mount NFB and TS circuits. That's were I got the idea for this. There is also a thread somewhere on the net about someone who did a similar thing with an old fender.

Thanks for the blog post and the update.

[vibratoking]

I believe Fuchs does something similar.

[soma_hero]

For typical fender/marshall tonestack, i mount a three terminal standup strip centered at the mid control. plate/cathode to the bottom lug, slope R from bottom to top, caps from top to mid and bass, cap from bottom to treble. No circuit board, nothing extra.