RE: The best pot ?

Tom Gorr · From: Three Hills, Alberta

OK. No pot jokes.

I have to replace the gain pot on a tube preamp. Its not that its scratchy - worse - it disconnects entirely in certain positions - so its full on gain. Not pleasant when I try to find that sweet spot between clean and crunch.

Since I need to invest the time, I may as well get the best pot available. 100 M audio taper.

Recommendations ?

Thx.

Bob Metzger · From: Waltham (Boston), MA, USA

Get a pot that will fit and mount like the previous one, with the same taper. There are lots of good quality pots made today, just not for steel guitar volume pedals. Unless the stock pot that came with the unit wasn't very good, I would probably just get another one of those.

Bob M.

John Daugherty · From: Rolla, Missouri, USA

Tom, if that amp ACTUALLY IS going to max gain when moving the pot, it is not a bad spot on the pot. It has to be the connection breaking on the ground side of the pot.
Before you change that pot, check the solder connections to the board and tighten the shaft nut. If that doesn't fix it, the ground-side terminal on the pot has a loose rivet. In that case, it is best to replace the pot,although, I have reset the rivet with a center-punch (with the pot removed from the panel).
The gain pot in an amp is not worked nearly as hard as one in a pedal. I wouldn't worry too much about brand names here.
Good luck...... JD

David L. Donald · From: Koh Samui Island, Thailand

Dang it, i LOVE a good straight line.

John Daugherty · From: Rolla, Missouri, USA

Hey David.... kind of scares you,doesn't it. There are way too many comedians and not enough jobs....... JD

[This message was edited by John Daugherty on 11 August 2004 at 05:15 AM.]

C Dixon · From: Duluth, GA USA

ALL of the above

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Well, we need to know a few things first to make a good recommendation. Is it point-to-point wired? How much room is there where the pot is? What kind of shaft do you want?

And...are you sure it's 100 megohms?

Blake Hawkins · From: Florida

Donny,

On some parts the "M" denotes 1000.

So it is probably a 100,000 ohm pot.

Blake

Tom Gorr · From: Three Hills, Alberta

Good eye Donny ! It is 1 Meg.
Point to point wire.

This is a "true" 2 channel preamp with clean/crunch on channel A, and Lead 1 and 2 on Channel B. Mesa calls it a 3 channel. Channel A or B is selected by a relay (RY1) right at the input (pre-input buffer).

Channel A (rhythm) post-buffer gain pot also has "pull boost" which is somehow linked to a relay that opens up the gain circuit a bit more, and looks like it bypasses some of the eq circuit.

Maybe I'm mistaken, but the pull boost seems to have its own resistive 'track' stacked with the unpulled (normal) pot 'track'. However, both brushes are fixed to the pot's shaft. (not concentric pot).

It would be a great improvement if I could put a concentric pot in there, so I can optimize the setting of both the clean and boost settings, rather than having to compromize on the one-shaft system.

Also, since ALL of the sweet spots (cleans and leads) occur with the master volumes on all channels full on. However, this makes the rhythm channel about 5 times louder than the Lead Channels.

To solve this, it would be a big improvement if I could somehow link up RY1 to also engage a relay at the "overall output" level control stage to level match between Ch A & B.

OK - as I look into this more - my "want list" is growing fast.

I have a reasonable conceptual understanding about electronics, but my practical experience is negligible.

(Single line diagrams for a three way light switch is about the depth of my capability.)

So, also tell me how NOT to electrocute myself...

[This message was edited by Tom Gorr on 05 August 2004 at 10:12 PM.]

Tom Gorr · From: Three Hills, Alberta

Don't give up on me yet !

Tom Gorr · From: Three Hills, Alberta

I have been abandoned :<

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