marshall mg 10 cd pot replacement

[blttlive]

i picked up a used marshall mg10 amp. the 2 volume pots  and the gain pot were broke and need replacing. the clean channel volume had a 5k log. pot .A5k . gain had a 1M but the volume on the overdrive channel had a 5k linear pot B5k. shouldnt it be a log. pot  on the overdrive volume ?

[DrGonz78]

It's a cheap lil Marshall practice amp and I remember replacing some broken pots on that amp. That was the 3rd amp that I bought to fix. Sure a Log is much better for Gain and Volume type controls but on this amp it really does not make all that much difference. I have all these pots still too... I went to Tayda for replacements... $1 pots free shipping! For this amp that is what is practical. I am sure they have the Log version of that pot, but if they are harder to find then that explains why it is linear.

[Enzo]

Harder to find???

Marshall, like all the other factories, has their pots made for them.  Which taper they get is a simple matter of which one they ask for.  The schematic specifically calls for the audio on the clean channel and the linear on the dirt chanel.  This is not because Marshall couldn't find them, it was designed that way.   I'd stick with the linear it came with, unless I found the control did not operate smoothly in terms of function.

[blttlive]

It's a cheap lil Marshall practice amp and I remember replacing some broken pots on that amp. That was the 3rd amp that I bought to fix. Sure a Log is much better for Gain and Volume type controls but on this amp it really does not make all that much difference. I have all these pots still too... I went to Tayda for replacements... $1 pots free shipping! For this amp that is what is practical. I am sure they have the Log version of that pot, but if they are harder to find then that explains why it is linear.

I ordered some pots from tayda on there web site. they were only 50 cents each.but the min. purchase is 5 dollars .so i ordered like 10 different pots  they do sell on ebay but there 99 cents. i ordered 2 log and 2 linear 5k yeah i didnt think it would matter much which one i used.

[blttlive]

Harder to find???

Marshall, like all the other factories, has their pots made for them.  Which taper they get is a simple matter of which one they ask for.  The schematic specifically calls for the audio on the clean channel and the linear on the dirt chanel.  This is not because Marshall couldn't find them, it was designed that way.   I'd stick with the linear it came with, unless I found the control did not operate smoothly in terms of function.

oh ok . That's what I thought, just making sure. Thanks alot for the help. I appreciate it.

[blttlive]

Harder to find???

Marshall, like all the other factories, has their pots made for them.  Which taper they get is a simple matter of which one they ask for.  The schematic specifically calls for the audio on the clean channel and the linear on the dirt chanel.  This is not because Marshall couldn't find them, it was designed that way.   I'd stick with the linear it came with, unless I found the control did not operate smoothly in terms of function.

Oh yeah one more thing .the gain pot was a G1m i know its a 1m . I have a A1m log. pot will that work ? I couldn't find a G1m anywhere

[Enzo]

A wrong taper will never hurt anything, the only thing it will do is make the knob settings less friendly - for example, the useful range of some control may wind up all scrunched over near one end.   If you donlt have what it should be use what you have.   If the difference becomes annoying, then find the proper part.  If it works to your satisfaction, then who cares if it is "wrong"?

I for one am not sure just what a G taper is.   Goggle is telling me it means graphic taper.  Well OK, that would mean a taper going from center towards both ends.   But why a gain control would want that, I can't imagine.  On the other hand, maybe it worked for Marshall.

[DrGonz78]

Sorry to spew out that silly line about "Harder to find..." Did not think enough on that one...  :duh

However, perhaps a G1M was used in the circuit as it looks in parallel to the diode clipping circuit? What do you think?

[J M Fahey]

In that position, what you need is an Audio taper pot.
It's an inverting Op Amp configuration, and gain is directly proportional to pot resistance, so a log pot will give you the needed Log response .
You *can* use a Linear there, but at "1" or "2" you'll have practically 90% of perceived distortion.

EDIT: "why" they label it "G"?
Don't know, but I've seen others (Fender/Peavey) add some extra letters which usually refer to mounting type ("wings", etc.) or shaft shape/length or whether they have a threaded collar or not.
"Mechanical" differences, not "electrical".

[Roly]

"G" taper, (from way back in the mists of distant memory) might be an anti-log-log. A.k.a. "W", apparently also used in the Tube Screamer as the tone pot.  This would seem to make some sort of sense where this pot is situated in the NFB loop.

Would have been really nice if they hadn't decided to make a total mess of the letter coding system with many manufacturers just doing their own thing.

See also;

http://www.ozvalveamps.org/pots/bending-the-law-of-resistance1-ewww-091201.jpg

and

http://www.ozvalveamps.org/pots/bending-the-law-of-resistance2-ewww-091201.jpg

[blttlive]

well  i used the a1m log pot on the gain and the b5k linear on the overdrive volume and it works fine. thanks for the help everyone i appreciate it . so it only cost me 20 dollars. i paid 15 bucks for the amp and 5 for the pots .