Tonepad - Ross/Dynacomp

[keysandguitars]

I'm building a tone pad Ross compressor with the MXR Dyna mod. I've attached an image I drew to see if I'm understanding the instructions for wiring the 4PDT switch. Did I get it right, or am I way off?

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[jkokura]

Close. The empty lug needs to go to ground for each pole. So your left most lug.

Jacob

[Jamiroking]

As far as I remember, the schems actually call for you to omit the caps for the dyna mod rather than jumper them to ground which means I think wiring system would work

[jkokura]

*edit* Looks like I need to look more closely. Yikes I jump to conclusions too quickly. Hang on I'll see if I can describe what I think needs to happen...

Jacob

[keysandguitars]

Close. The empty lug needs to go to ground for each pole. So your left most lug.

Jacob

So I'll have two ground wires, or the cap's negative lead and one ground wire soldered to each negative pad as drawn?

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[jkokura]

Close. The empty lug needs to go to ground for each pole. So your left most lug.

Jacob

So I'll have two ground wires, or the cap's negative lead and one ground wire soldered to each negative pad as drawn?

Dang, I think I'm making this more complicated than it needs to be. Sorry Jamiroking, I was contradictory but I didn't need to be, you were correct and I had misspoke (mistyped?).

I put some more research into this. I looked more closely at the schematic. I don't think this Mod is worth doing, and it seems like the real experts (namely Mark Hammer and R.G Keen) agree with that sentiment.

Those caps are there to improve the power supply for the circuit. It looks like that has nothing to do with the tone of the compressor at all. In fact, I don't think I would build a Dyna comp - the Ross is a better version but the exact same sound! To compare, it's like the 'improved' version of the SHO circuit - it used to not have power protection diode, now it does. Why build it without one? No tone change, but more risk to the circuit.

If you really want to see the difference, what I would do is wire up the circuit but leave those caps out. Use a breadboard and see what the sonic differences might be!

If you're determined to try this, I would look into doing it slightly differently than everyone else. 4PDT switches are expensive and uncommon, and while your first drawing you had was correct, I would do it differently just to see if it can be done. I've whipped something up in Inkscape I think might work.

Basically, there's only one pole instead of 4 and the caps all mount on the PCB to keep them from 'floating' around inside the enclosure. The - lead of the cap's goes to the outside of the switch pole and the middle lug goes to ground. The - ends of the cap aren't always connected to ground though, so I'm not sure if it will create popping or not. I think what might happen is that the caps get charged up while in use and since they aren't connected to ground at all that might not be a good thing for them.

What you could then is solder the Caps right into the PCB, then cut the connection between the - lead and ground. once cut, you can connect those - leads to the switch, even jumpering them so that you only have one wire running to the switch, and one wire connecting to ground. Makes for MUCH less wiring. We need to look into whether or not it would be detrimental to the circuit to have the Caps charged up and not connected to ground.

The problem with this mod is that the resistor changes honestly change the dyna mode into something that isn't a dyna comp. It's not a true Dyna comp without the right resistors, and the cap changes may actually be better for you to have than not.

Again, my apologies. Hopefully you'll try this on a breadboard and let us know what you find.

Jacob

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[keysandguitars]

If only I had a breadboard...and a brain like yours!

In all my googling last night and today for answers and wiring diagrams, I continued to find opinions similar to yours, that the mod isn't worth doing and that the Ross was an improvement on the circuit. I'm glad I was able to draw the wiring correctly as I thought I had it making sense in my head, albeit on a simpleton's level.

I'm going to save your post and maybe revisit it at a later date. I've got a lot of pedals I want to build and I haven't picked up my guitar for more than a 10 minute span in a month! I need more time in the day.

Thanks to you both. I'll hopefully have it boxed and rocking soon enough.

[Jamiroking]

Sorry Jamiroking, I was contradictory but I didn't need to be, you were correct and I had misspoke (mistyped?).

No worries at all. I'm glad to see this mod get some attention by smart guys like you. This pedal was the second one I ever built and I had absolutely no idea what was going on when I did it so seeing you give a different answer made me think that newbie me wired it up wrong and THAT's why I don't really hear the difference between the two modes.

Basically, there's only one pole instead of 4 and the caps all mount on the PCB to keep them from 'floating' around inside the enclosure. The - lead of the cap's goes to the outside of the switch pole and the middle lug goes to ground.

I was wondering why this wasn't done in the original mod and thought that it might do something funny if all these caps were wired together when disconnected.

I can give testimonial that I really don't hear much difference (other than what I convince myself I'm supposed to be hearing) when toggling between the two. Jacob knows way more than me about how these circuits actually work so I trust him when he says that it's not working on the tone signal at all. I'd say youll be happy just building the stock ross specs. If you have the 4dpt already, from what Jacob says, maybe switching resistor values might make a bigger tone difference.

[jkokura]

Yeah, as Mark Hammer says, there are other and better mods to do to this circuit than this one. But if it can be done, a smaller switch would be better.

Jacob