type of potentiometers

[rafaelctt]

What type are these HD or J-terminated potentiometers?
Thank you

[mresistor]

It seems that J means a J-taper.  Don't know what HD means yet.   






J taper is a softer audio taper where you have around 30% resistance at noon, as opposed to the 10 to 15% found in more conventional audio taper pots.  You could think of it as an in-between the linear and audio taper.  I've seen it in some Fender amp schematics.

If you are familiar with Duncan's tonestack calculator, you'll see there are two kinds of audio taper in the program, "A" and "B".  The former corresponds to the "J" taper, while the latter corresponds to the sometimes called "A" or log or audio taper.


Logged

STM
runoffgroove.com

[pdf64]

The few 999k HD late 70s / early 80s pots from Fenders that I’ve checked are basically 1M linear.

It seems a strange choice, but the justification may be that these are loud stage amps, and also it makes them stand out on the shop floor. eg if they’re this loud on ‘2’ then think how loud they’ll be at ‘10’.

[d95err]

(rant warning!)

Fender’s obsession with linear taper colume controls is just wierd.

When I’ve had the misfortune to encounter a Hotrod Deluxe on stage, I’ve found them virtually unusable. If you even breathe in the direction of the master volume knob, the level changes to either inaudible or frickin’ way too loud. Almost impossible to get a balanced level.

I would never buy an amp with that kind of design flaw.

(rant over, sorry!)

[rafaelctt]

And being of volume, wouldn't it be better to replace it with 1 M Audio (logarithmic)?