overdrive amps and guitar volume swells

[lowell]

My custom amp overdrive channel has an annoying side effect. My guitar volume has to be in a SUPER specific spot before you hear any change in volume and overdrive. Its really hard to do swells and to clean up the sound via the guitar volume knob. Im thinking that theres so much clipping in my circuit which is causing this. Anyone know if dumbles and soldanos have this problem? Fyi it's not something im goona fix via the guitar volume.... as that works great on the clean channel.

[defaced]

soldanos

The SLO 100 lead channel has this problem big time (I have built the Avenger preamp, which is the lead channel from the SLO 100 with some very minor changes). You can't clean it up. The Fryette Deliverance has a great ability to clean up, but I'll be honest, I'm not sure why or how it works so I can't explain it.

[d95err]

From what I read over at Ampgarage.com, the Dumble OD should clean up well with guitar volume. I haven't tried any such amp myself though.
What taper volume pots do you have on the guitar? Log or linear? Is it just as difficult to clean up when using other guitars?

[pdf64]

I'd guess that you've got a linear taper pot on your guitar volume. They work fine on clean, but are too sensitive (at 0-30% end) with overdrive. There are other tapers available (20 or 30%, 10% audio), it's a case of finding the best compromise for your needs. A 10% audio taper (the most common type) might cut down too quickly for you between 100-70% on clean.

[Chuck H]

Provided you do have a proper taper on your guitars volume control... If your preamp is breaking up before your power amp it's impossible to get good clean volume compared to the OD volume. Unless your using some kind of master volume circuit and both channels are run through the same master volume. In that case it's still the same story except that it's about each preamp stage remaining cleaner than the one ahead of it if you ever want to reach max volume by cleaning up the input. Not that this was your specific complaint, but it could make things hard (or impossible) to adjust so it could be part of the problem.

JM2C

Chuck

[J M Fahey]

I think it's the combination of two problems.
1) High gain amps, specially Soldanos and their derivatives, do have too much gain (duh!) and clipping, which is good (or you wouldn't be using it), which is beyond the range controllable with a simple volume pot.
Besides, even if you could, the preamp stays at very high gain and hisses/hums/crackles/pops, etc.
That's what channel switching was invented for !!!
Medium "natural" distortion, such as used in classic hard rock as in Purple, Zeppelin, Kiss, Cream, etc. that's to say a Plexi on 10 and good humbuckers, can be easily controlled.
Even lighter, sweeter natural overdrive, "Blues and Rock'n Roll" type (Humbuckers, Soapbars or Strat/Tele pickups and a Twin or Super Reverb on 7 to 10), can easily be controlled by a skilled guitarist without even using the volume control, just by varying how hard or light he plays.
2) Traditional volume controls are log, which allow for an easy 20dB range; newer (cheaper) guitars often save 10 cents by using cheaper more available linear pots, which allow easily only about 6 to 10 dB range.
The -20dB point is there, of course, but it becomes very hard to set and the slightest knob movement sets you off, either too high or too low.
3) If you need on-guitar control, besides replacing your pot with a real 10% audio taper pot, you may do some of the following:
a) a mini-switch somewhere with a fixed 20dB attenuation
b) going the other way, technically better: you build a clean boost in your guitar, you set your distortion sound with it engaged, you kill it for clean(er)sound.
You avoid a lot of hum, noise, and troubles.
3) If you do not want to modify your guitar you can build a small floor mounted clean boost or even clip a smaller one to your guitar strap.
A comparison of pot tapers.
Setting it on 5, an easy thing to do while playing, the different tapers will provide the following attenuations:
Linear (which means 50% taper): -6 dB . The -20dB point lies between "1" and "1.1", very hard to set, huge change with the slightest knob movement.
True Audio or Log taper: (10%): -20dB (excellent range) Little audible change between, say, "4.5" and "5.5", very forgiving.
"Impress the kids" taper (as in : "gosh, it's on 5 and it's SO loud") , a.k.a. 30% taper: -10dB.
As you see, this sounds much louder than a true Log taper, good as a volume pot on an amplifier, but a poor choice as a guitar control.
NOTE: on a BASS guitar, where you do not use that much adjustment , where you set your basic level from your amplifier and use the Bass volume only for minor trimming, as setting the Bass-to-Drums-Ratio onstage, a linear pot can be the best bet.

[lowell]

Ok all good info, thanks guys. My guitar is a '07 Les Paul Antique Classic. Anyone know what taper stock Gibson volume pots are?

[J M Fahey]

Well, it *should* be LOg, but you can answer that question much better than any of us: as Nike says: Just do it !!!!!!!
Which in this case means: measure it.
Leave only the ground lug connected, both others free (momentarily), set it on "5" and measure resistance center lug to each end.
Supposing it has 1M end to end, you'll get the following readings (within10%)
500k/500k : Linear
900K/100K: Log (10%) <-- you *should* have this one.
700k/300k (or 250K) 30% Log (it would be *very* unusual)
That's all that there's to it.
Of course, most posters on zillions of Forums (not this one) will talk cr*p and insult each other for ages instead of wasting 60 seconds measuring.
Oh well !!!

[Chuck H]

My personal amp has a ton of gain (ala Trainwreck-ish). It's MY circuit that I designed ten years ago (before the TW circuit was public knowledge) but I fear anyone seeing it would think I was spring boarding from the TW circuit. I just wanted to say that for defensive reasons I guess. Anyway...

I need to change my volume pot on my main guitar (30%). I've actually gotten use to it but the threshold between 'not enough volume', 'loudest possible clean' and 'starting to get gritty now' is all between 1 and 1.5. A proper A10 pot would sure help. But to be sure I can go from clean to nearly metal OD levels on the volume control with only a small difference in volume. So it is possible to cover a huge range if the amp and guitar are set up correctly.

Chuck

[lowell]

Ok JM thanks for that. I've never known solid figures in regards to Log pots and the % rating. Helps alot. Do manufacturers always state the %?

[J M Fahey]

Hi lowell.
Not as a clear % number, but today's most usual coding is:
"A" = Audio / Log 10%
"B"= Linear 50%
"C" = Reverse Log 90% (or more exactly, 10% but starting from the other end of the pot) Used as Gain/Distortion controls in MXR Dist+ and their clean preamp. They are also used as input gai controls (*not* volume controls which are log) in PA and Recording consoles.
"S"= start as Log up to 5, then they become antilog. Used in equalizers to provide a sort of linear scale in dB.
In my wonderful Argentina, industry is advanced enough as to have potentiometer (and many other parts) factories and small enough as to let them hear my crazy demands.
I can have potentiometers made almost in any value and with any curve, ordering only 100 of each type, although they prefer 300 each.
I can also have dual pots made, with different tracks if necessary (Log/antilog, or both halves different resistance).

[d95err]

The taper coding is different for different pot manufacturers. I have linear pots marked "A", etc. So, the only way to be sure is to measure, or check the manufacturer datasheet.

[Chuck H]

today's most usual coding is:
"A" = Audio / Log 10%
"B"= Linear 50%
"C" = Reverse Log 90% (or more exactly, 10% but starting from the other end of the pot)

That's a little bit of a misnomer... Only because the most common pots used by builders here in the US are the Alpha brand pots sold by Mouser. Which are marked "A" and are certainly 25 or 30% taper. I mention it because I wouldn't want anyone unaware of this to think that "A" means 10% taper. It doesn't. It just means it's a log pot with a slower activation than linear. At least one MFG (Bournes) does put a number next to the "A" designation like A10, A,15, etc. This is the taper percentage. It's not indicated in the spec sheet though, only on the pot itself. IMHE getting specific info on a MFG's pot taper can be near impossible. So when you buy "audio" or "A" pots you put down your $$$ and you take your chances.

I can have potentiometers made almost in any value and with any curve, ordering only 100 of each type, although they prefer 300 each. I can also have dual pots made, with different tracks if necessary (Log/antilog, or both halves different resistance).

That's nifty. I've had MANY design ideas that required dual gang pots with different tracks but no good source for them. There use to be pot "kits" that would do it but I don't see them around any more. Too bad I'm never likely to need 100 of a given design.

Chuck

[Ronsonic]

I don't think the problem is the guitar pot, rather the gain structure of the amp. Some amps are like that, enough level to overdrive them is like flipping a switch and it's almost impossible to get them to balance on the guitar volume.

[Usable Thought]

I don't know how to "fix" your specific problem[/url]

But you do know how to spam ads on this & other threads? I have "reported" this post & hopefully the super moderators will revoke your membership. Whoever you are, you are off base doing this on a forum.