Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: worth on August 24, 2012, 08:38:10 am

Title: mid pot.. linear or audio taper ?
Post by: worth on August 24, 2012, 08:38:10 am
Which one do you guys usually use , and why ?
Title: Re: mid pot.. linear or audio taper ?
Post by: John on August 24, 2012, 09:11:29 am
I think normally, tone pots are linear, volume pots are audio. I'm also betting there's exceptions all over the place.  :laugh:
Title: Re: mid pot.. linear or audio taper ?
Post by: alerich on August 24, 2012, 01:33:30 pm
I have never built an amp entirely from my own design so I can only say I would probably rely on tried and true ideas as a starting point. My 1972 Fender Super Reverb had all audio taper pots in both tone stacks. I built a clone of a Marshall Studio 15 that uses audio taper Mid and Bass controls and a linear taper Treble control (see pic below). It's a little bit different from the usual tone stack layout.

I know this is obvious but it just depends on the surrounding circuitry and how the control interacts with it. One spot where I always sub in an audio taper pot for a linear taper is on the reverb control on Fender amps. To this day I do not understand why Leo Fender used a linear pot for that function. An audio taper pot gives you so much more control of the effect on the lower end of the control sweep.

(http://www.alerich.com/tonestack.gif)
Title: Re: mid pot.. linear or audio taper ?
Post by: tubeswell on August 24, 2012, 06:55:34 pm
Which one do you guys usually use , and why ?

Depends what sort of mid control you have.
Title: Re: mid pot.. linear or audio taper ?
Post by: plexi50 on August 24, 2012, 07:03:21 pm
When i first starting learning about tube amplifiers and there part values i used Audio mid pots until i starting looking at some of the layouts from dougs library and other sites like Thundertweaks/Sonicdeli. Thundertweaks had a lot of great PDF layouts and that made it much easier for me to understand different values and why. I have all the layouts TW ever put out online. Most of them are gone now so im glad i got them all when they were available. Then i got the understanding that most mid pots used were Linear. But it is this forum unlike any other on the planet that is like a family even though most of us have never met in person. Talk about a meeting of the minds. This is the site to get the best education you will ever dream of. And it's all free. Doug should charge at least a few dollars for membership to help with the cost of website and just the serious amount of work it takes to keep a site up to date and running. (oh shit) But seriously this site is priceless bar none

I was wrong about the sonicdeli. All those PDF amp layouts are still there or back. I couldnt find them last year. Oh well
Title: Re: mid pot.. linear or audio taper ?
Post by: PRR on August 24, 2012, 09:09:01 pm
> it just depends on the surrounding circuitry and how the control interacts with it

+1.

> why Leo Fender used a linear pot

Small reverb is subtle. When SELLING an amp in a noisy showroom, a linear gives a WOW! reverb over most of the dial.

Also Reverb generally needs to be "similar" to dry signal. You don't usually go 1% or 2% wet; I've rarely used under 10%, and I have (on DAW) used 140% (to put a too-close-mike track "in a room"). I do agree that if you favor ~~~10% wet, a linear is too twitchy; OTOH a classic 10% Audio will be "dead" 0 to 4. Most modern "Audio" tapers are less dramatic.
Title: Re: mid pot.. linear or audio taper ?
Post by: alerich on August 25, 2012, 05:12:24 am
Small reverb is subtle. When SELLING an amp in a noisy showroom, a linear gives a WOW! reverb over most of the dial.

Also Reverb generally needs to be "similar" to dry signal. You don't usually go 1% or 2% wet; I've rarely used under 10%, and I have (on DAW) used 140% (to put a too-close-mike track "in a room"). I do agree that if you favor ~~~10% wet, a linear is too twitchy; OTOH a classic 10% Audio will be "dead" 0 to 4. Most modern "Audio" tapers are less dramatic.

That's as good of an explanation as I have ever read. I am in the "splash of reverb" camp. Anything more seems to swamp the tone to me. A linear pot in that application might as well just be a switch.  :smiley: