Fender Frontman 65R volume mod

[themusic]

Looking for a volume mod for this frontman 65R. Something with a little more control. Seems to jump to full vol. at 4 or 5.
I remember seeing something a couple of years ago...thanks

[Jazz P Bass]

I doubt that it will be as 'easy' as simply changing to a diggerent potentiometer (taper/ resistance)

The one currently installed is a 50K A taper.

The problem is that it is part of an opamp circuit.

fender frontman 65R Normal Volume Control.pdf

[themusic]

I doubt that it will be as 'easy' as simply changing to a diggerent potentiometer (taper/ resistance)

The one currently installed is a 50K A taper.

The problem is that it is part of an opamp circuit.

[ATTACH]33457[/ATTACH]

I found this but you know better than I...
https://sites.google.com/site/robertotricks/home-1/home

[Jazz P Bass]

Thanks for the link.

If you take note, there is a lot more that is done to the circuit than 'simply changing a pot'.

[themusic]

Thanks for the link.

If you take note, there is a lot more that is done to the circuit than 'simply changing a pot'.

[ATTACH=CONFIG]33458[/ATTACH]

Yes, I realize what he's done, but I thought I'd run it by you to see if it makes sense...don't what to give it a shot
and then not really accomplish anything...thanks

[J M Fahey]

Fender, like many others, uses a grounded wiper pot as if it were two, the right half attenuating passive and the left half NFB/active gain .

The perfect pot would be one with an "S" curve, made of unobtanium (I had to pay in advance for 5000 tracks to get them although I only ordered 500), 90% manufacturers use a linear pot there.

Fender uses a Log one, but way too high value, so as soon as you rotate it a little the right half stops attenuating .

Replacing R15 with 10K will give you a much smoother "start", try it, no need to mod anything else.

The Mod suggested disconnects the NFB side, sets first Op Amp gain to full all the time (which will cause problems with hot humbuckers or pedals) and wires the pot like a conventional volume pot.

Smoother? .... no doubt, but the input stage becomes prone to overload (what does not appear in the simulation )

The 33 ohm resistor is not needed, he might as well have used a wire link.

He also lost the bright cap effect created by C8 for 2 reasons:
a) he disconnected it from the volume pot.
b) anyway he shorted it with the 33 ohms resistor (which bto boot should be a wire link).

[themusic]

Fender, like many others, uses a grounded wiper pot as if it were two, the right half attenuating passive and the left half NFB/active gain .

The perfect pot would be one with an "S" curve, made of unobtanium (I had to pay in advance for 5000 tracks to get them although I only ordered 500), 90% manufacturers use a linear pot there.

Fender uses a Log one, but way too high value, so as soon as you rotate it a little the right half stops attenuating .

Replacing R15 with 10K will give you a much smoother "start", try it, no need to mod anything else.

The Mod suggested disconnects the NFB side, sets first Op Amp gain to full all the time (which will cause problems with hot humbuckers or pedals) and wires the pot like a conventional volume pot.

Smoother? .... no doubt, but the input stage becomes prone to overload (what does not appear in the simulation )

The 33 ohm resistor is not needed, he might as well have used a wire link.

He also lost the bright cap effect created by C8 for 2 reasons:
a) he disconnected it from the volume pot.
b) anyway he shorted it with the 33 ohms resistor (which bto boot should be a wire link).

Thanks I'll give it a shot and let everybody know how it turns out...thanks again

[themusic]

Thanks I'll give it a shot and let everybody know how it turns out...thanks again

Drop in a 10k last night...way better...thanks everybody

[Jazz P Bass]

Good to know, good to know.

Thanks for the update.

[Five Aces]

Fender, like many others, uses a grounded wiper pot as if it were two, the right half attenuating passive and the left half NFB/active gain .....

Replacing R15 with 10K will give you a much smoother "start", try it, no need to mod anything else.

etc...etc....

Thanks I'll give it a shot and let everybody know how it turns out...thanks again

Drop in a 10k last night...way better...thanks everybody

So as I see it, all you had to do is replace R15 with a 10K and the volume control is way improved in its response? I'm curious about this because my 65R has the similar issue where it increases volume so rapidly (but not jumpy) from 0-2, and although the schematic calls for an audio taper pot, reading it with an ohm meter says its acting like a linear taper! I suspect replacing the pot with the correct 50K audio taper would fix it, but would the 10k (R15) further improve it as well?

[Jazz P Bass]

As far as I can see from the post, that 10K change did the trick.

[Five Aces]

Great! I'd like to give this R15 change a try when I have a chance.

Any chance you would know if a similar resistor change can be done on the Gain Channel? (The Gain pot only, not on the volume pot... that one seems ok).... If so, which resistor & aprox. what value would do it?

My preference would be nice to calm down the Gain Control pot so it increases at a less rapid rate, too.

Thanks....

[Honk55]

Juan, you're damn right. I put the Roberto trick in some weeks ago and at first sight it seemed to work. But when I was practising with my spouse last week (she's playing tenor sax) i noticed the amp was cranking all the time, regardless which volume I'd choosen. It did even not calm down when I turned down the guitars volume. So I dismounted this "trick" and gave the 10K a try. And it works! Hallelujah! It is not that one can now turn the volume pot from 1 to 10 with a linear "curve", but between 1 and 3 you can regulate the volume quite nicely and, more important, absolutely controlled with no unexpected jumps in it. Thank you so much

[Five Aces]

Finally got around to doing that volume mod on my Frontman 65R (changed R15 to 10K) and forgot to report back.

I'm glad to say it did indeed do the trick! It gives you a more controlled volume in the 0-3 range instead of jumping out at you!

Thanks ! ! ! ! !

[curryman86]

Fender uses a Log one, but way too high value, so as soon as you rotate it a little the right half stops attenuating .

Replacing R15 with 10K will give you a much smoother "start", try it, no need to mod anything else.

Hi J M

Interesting but where can you get these pots Fender (uk) don't do them and Fender (us) don't do them and even when they did they were charging approx $7- $8 each plus p&p for something that cost then less than a $1 to buy.
You seem to be the man with the knowledge can you help, it's a Frontman 65r (Type PR 557)
I would have just fitted normal 16mm pots but there is no room, any ideas?
Many thanks
Stephen