Getting more control over the volume with resistors

[Exist1214]

Hello,
I recently built my Bottlehead Crack, and would like to make a modification to get more use of the volume knob.
Right now, a comfortable listening level is at about 15%, and the channel imbalance only stops at around 10%.

I read about adding some 33k and 75k resistors in-line with the pot, but I'm still not quite sure what I need to do exactly.
In my attached image, some someone please explain the number of resistors I need and the exact connections I need to make?

Much appreciated!


Side note: I also have an Alps RK27 pot that I might add sometime soon. Would that install (with resistors) basically go the same way?

[Paul Birkeland]

There's a photo at the end of the FAQ post here:
https://forum.bottlehead.com/index.php?topic=4295.0

The RK27 complicates this a little bit because you also need to add a PC board to that pot in order to use it with wires, but the resistors will function the same way with that pot that they do with the stock pot.

[Exist1214]

There's a photo at the end of the FAQ post here:
https://forum.bottlehead.com/index.php?topic=4295.0

The RK27 complicates this a little bit because you also need to add a PC board to that pot in order to use it with wires, but the resistors will function the same way with that pot that they do with the stock pot.

Ah, thanks! So it should be:

• 75K at 1U
• 75K at 1L
• 33K between 1U and 3U
• 33K between 1L and 3L

For the RK27, that's actually what was keeping me from installing it right away! Well, other than cutting down the length of the pot shaft.
I bought this and I'm waiting for delivery: ebay.com/itm/275031067565
Should be OK I think.

[Paul Birkeland]

I would get RN55D resistors (not on cut tape, just loose ones) for the RK-27 install.  They have really long leads and should stretch across that PC board without giving you a ton of trouble.

[Exist1214]

I would get RN55D resistors (not on cut tape, just loose ones) for the RK-27 install.  They have really long leads and should stretch across that PC board without giving you a ton of trouble.

Oh I already purchased some of these standard metal film ones. About 1 inch lead length on each side.
Might be too short?

[Paul Birkeland]

You'll know soon enough when you get those PC boards.  They may fit just fine, but certainly they'll work well on the stock pot.

[Exist1214]

You'll know soon enough when you get those PC boards.  They may fit just fine, but certainly they'll work well on the stock pot.

Thanks! I'll do the stock pot tonight

[Natural Sound]

Hi Paul, Will this padding scheme work with the S.E.X. amp as well? The amp I use in my my home office is always playing in the background. Often times it takes a lot of fiddling to find a good low volume/channel balance position.

[Paul Birkeland]

Sure, you could put these on the SEX amp.