Princeton Reverb Bass/Midrange Dual Pot Mod

[p2pAmps]

So on my PR #4 build I decided I wanted the midrange knob up front but did not want to drill another hole and mess up the faceplate.  Here is what I came up with...  Worked out great for me.

[alerich]

Very clever! I like it.

[kagliostro]

Nice idea


Franco

[sluckey]

Looks good. How is the top hat "brim" attached to the shaft?

[p2pAmps]

Looks good. How is the top hat "brim" attached to the shaft?

The Brim is a nice pressure fit and holds really good.  The top knob I had to drill another hole for a second set screw.  Takes 2 knobs to make one. 

[HotBluePlates]

Are you considering painting a line on the reflector to indicate the Mid setting, or will you keep it a "tricks of the ninja" secret weapon? 

[tubenit]

Remarkably innovative!  BRAVO! 

What values do you come up with for the pots?  Just curious.

With respect, Tubenit

[p2pAmps]

Remarkably innovative!  BRAVO! 

What values do you come up with for the pots?  Just curious.

With respect, Tubenit

I used a CTS Stacked Concentric Pot, 500K/250K.  Tied in a 220K and a 27K to get values of 100K and 25K on the pot.  It worked fine and sounds exactly how I wanted it to sound...

[Fresh_Start]

SWEET!

What a nice touch!

Chip

[p2pAmps]

Are you considering painting a line on the reflector to indicate the Mid setting, or will you keep it a "tricks of the ninja" secret weapon? 

I think I will just leave it alone as I tune it by ear anyway.  "tricks of the ninja" LOL  thanks

[mresistor]

Cool idea and implementation! What did you use to make the cuts?

[p2pAmps]

Cool idea and implementation! What did you use to make the cuts?

I actually used my big disk/belt sander and just ground down two knobs.  Seems like the easiest tool in the shop to get it done fast and smooth...

[HotBluePlates]

I think I will just leave it alone as I tune it by ear anyway.  ...

What!!?! You set your tone controls by listening to the tone coming out of the amp?? That's probably the most ludicrous thing I've heard this weekend... 

I really had in mind whether you were going to draw attention to the fact there's a Mid control. But if it's your amp (or a customer amp & they know about it), then you already know it's there...

[sluckey]

Just something to think about...

If you use a SPST to disconnect that 27K from your MID control, it becomes a RAW control. Maybe could even use a VOL pot with a pull switch.

[uki]

Cool stuff man !!!

[tdvt]

I used a CTS Stacked Concentric Pot, 500K/250K.  Tied in a 220K and a 27K to get values of 100K and 25K on the pot.  It worked fine and sounds exactly how I wanted it to sound...

A very elegant solution.

Could you explain the added resistors for the simpletons?

Thanks, TD

[shooter]

Very nice!

You set your tone controls by listening

As a non-player I'm still amazed at the number of musicians that get all *hung-up* on what number the dial is on!

[p2pAmps]

I used a CTS Stacked Concentric Pot, 500K/250K.  Tied in a 220K and a 27K to get values of 100K and 25K on the pot.  It worked fine and sounds exactly how I wanted it to sound...

A very elegant solution.

Could you explain the added resistors for the simpletons?

Thanks, TD

Ok, so the pot is a 250K/500K guitar pot.  In order to get it too 100K for Bass and 25K (my preference) for mids you need resistors to bring the values down.  I was worried about taper but it was fine.  I use a 220K and a 27K as you can see in the pic.  About 3 O'Clock it measures out at 6.8K, or the original Bass value.  So I can get either more mids or less too.  It works for me