Alpha 8mm pots and 3/8 holes

[galtjunk]

The 24mm Alpha pots all have an 8mm (actually about 7.75) bushing.
It's a sloppy fit for a chassis with 3/8" holes.
Are there any bushings available that will provide a better fit?

[ToneMerc]

The 24mm Alpha pots all have an 8mm (actually about 7.75) bushing.
It's a sloppy fit for a chassis with 3/8" holes.
Are there any bushings available that will provide a better fit?

http://www.allparts.com/Pot-Adapter-Bus ... 00-000.htm

TM

[Structo]

I never knew such a thing existed.
Is Allparts the only dealer with those?

And of course they don't have a picture of the item.

Over $1 each?

[ToneMerc]

Tom, it's a clear plastic bushing which also works well for isolating the pot from the chassis. Also, I've had good sucess by just putting an 8mm ext washer tooth (the large coarse teeth) next to the pot body. If you get the center of the shaft aligned with that .375 hole once the washer bites into the inside of the chassis that pot won't ever move again.

TM

[Structo]

So it's just a shoulder washer like jack isolation washers.

Do you think there is a problem if the can of the pot is not grounded?

I have often wondered about the different schools of thought on grounding where you will see guys solder the buss wire across the back of the pots.

To the type where you float the buss wire above the pots and just connect the lug that needs ground to the wire. (Dumble way)
Yet he did solder the shields of the coax to the cans.

Does it make a quieter amp to have the pot cans grounded by the buss wire verses mounting the pots in the holes and connected via the chassis?

[martin manning]

I thought that if I ever ran into this bushing diameter problem I'd just get some skinny O-rings and use them to fill the gap.

Technically if you run a bus and use the pot cases for a ground you have a loop, and of course you are relying on the bushing for a ground path. If that develops resistance then it could become noisy. For the shielded runs I don't do it, just ground the shield pigtail to the buss. No hassle or danger of overheating a pot.

[Structo]

That's the way I do it as well Martin.
Thanks for the confirmation.

[martin manning]

I guess I'll amend my comment about creating a loop in the case of the shield grounds. They are only grounded at one end and are otherwise not connected to the circuit. I'd think that you'd still want the least possible resistance to ground though.

[galtjunk]

It seems that a wrapping of stripped 20awg centers it nicely.

[Structo]

Clever!

[Chris333]

The 24mm Alpha pots all have an 8mm (actually about 7.75) bushing.
It's a sloppy fit for a chassis with 3/8" holes.
Are there any bushings available that will provide a better fit?

I know that some pot values are hard to find, but if I remember right, everything but the presence pot is pretty much available with a 3/8" bushing, no?

[M Fowler]

Yes I have no problem finding 3/8 Alpha pots.

[galtjunk]

I don't see any 3/8 Alpha pots at Mouser.
Do you have any part numbers?

[husky]

I don't see any 3/8 Alpha pots at Mouser.
Do you have any part numbers?

The Bourns are a little nicer and have 3/8

[ToneMerc]

I don't see any 3/8 Alpha pots at Mouser.
Do you have any part numbers?

AFAIK, Mouser only carries the 8mm bushing versions. I've gotten 3/8's bushing Alphas from Mojo, Watts Audio, Tubesandmore and Tube Depot.

TM