mimicing an audio taper pot with linear taper pot...

[louped garouv]

http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

Is this a **good** idea --

I have a piece of equipment (electronic crossover) that originally had audio taper pots. Some of the techs that currently work on this piece of gear seem to think that a linear taper in the unit is fine, that is what they have been spec'ing in their jobs yada yada yada, they talk about the protection factor afforded the drivers from ppl unfamilar with the units, etc....


OTOH there are others who believe that Audio Taper is the way to go. that the sound and responsiveness of the units change with the change in taper...

It does not help that this particular unit used pots that are NLA.

Despite the lack of availability of the parts, I managed to source some NLA carbon composition pots for the unit (and spares), however they are linear taper and I **needed** the audio taper ones. which brings me to the link provided above. Will using the "tapering resistor" present other problems?


Does any of this **really** matter? what differences should I expect between using linear and audio taper pots?

thanks for any insight.

[scott fitlin]

You can order Audio taper Conductive Plastic Pots, same pinout as the Bourns or AB,s from Clarostat!

The Clarostat CP,s sound good, beefy sound!

Clarostat bought the rights to manufacture the modpot line from AB back in 1990, so thats the thing to get, and ive used them, they are good, a bit pricey!

[louped garouv]

no offense Scott -- But I already knew where you stood on this issue ;)



But since youre here..... why do some of the others sing the praises of linear tapered pots in these kinds of units?


and what about using the "tapered resistor" to mimic a log/audio taper?


has anyone here done this?

excerpt....
If we set up the easiest, simplest pot to get, a linear taper pot of resistance R, and then connect a "tapering resistor" across the wiper and CCW lug, we get the situation shown in the following diagram. For clarity, I've separated the resistance above the wiper and the resistor below the wiper into two separate resistors. It makes the calculations much easier.

We're assuming the total pot resistance R is split into an R1 at the CW side and R2 on the CCW side, with R3 paralleled with R2. We'll let "a" represent the fraction of the total resistance R that the wiper has turned, and "b" be the fraction of R that R3 is. When we get out the algebra books and do the math, we find out that we can show that the ratio of output voltage to input voltage is that odd looking fraction in the picture. When we calculate out the results, we find that the divider ratio of Vout to Vin is shaped something like a true logarithmic tapered pot if we pick the right value for b. If b happens to be 1/4 to 1/5, the resulting voltage division is remarkably close to a true logarithmic pot, probably closer than a two segment approximation that we could buy! Wow! No more waiting for volume control pots!

[scott fitlin]

Who sings praises about putting linear tapers in a unit originally designed with audio tapers?


I have read about using a resistor to alter the taper, but I have never done it, nor do I know anyone who has!

[subwoof]

I have a box of modpot parts, elements and hardware from my service days. What value do you need??

sub

[scott fitlin]

I have a box of modpot parts, elements and hardware from my service days. What value do you need??

sub10K audio taper dual gang pots PC mount! How many do you have, I will buy whatever you have. And Louped Garouv needs some too!

The original AB part number was 70P1N048F103A.

[toddalin]

10K audio taper dual gang pots PC mount! How many do you have, I will buy whatever you have. And Louped Garouv needs some too!

The original AB part number was 70P1N048F103A.


You mean these guys??? Two for $1 or 100 for $40. Is that cheap enough for you?



http://www.goldmine-elec-products.com/prodinfo.asp?number=G13281&variation=&aitem=1&mitem=41



http://www.goldmine-elec-products.com/images/G13281B.jpg

These came from an audio equipment manufacturer making high end systems. Standard 3/8" panel mount bushing dual potentiometer features 1/4" dia. x 1/2" long shaft to mount your knob. Size of pot (excluding shaft) is 0.62" W x 0.70" T x 0.60" D. High quality audio taper dual 10K pot made by PIHER. Brand new with mounting nut. Package of 100. G13281A

[Ian Mackenzie]

http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

Is this a **good** idea --

I have a piece of equipment (electronic crossover) that originally had audio taper pots. Some of the techs that currently work on this piece of gear seem to think that a linear taper in the unit is fine, that is what they have been spec'ing in their jobs yada yada yada, they talk about the protection factor afforded the drivers from ppl unfamilar with the units, etc....


OTOH there are others who believe that Audio Taper is the way to go. that the sound and responsiveness of the units change with the change in taper...

It does not help that this particular unit used pots that are NLA.

Despite the lack of availability of the parts, I managed to source some NLA carbon composition pots for the unit (and spares), however they are linear taper and I **needed** the audio taper ones. which brings me to the link provided above. Will using the "tapering resistor" present other problems?


Does any of this **really** matter? what differences should I expect between using linear and audio taper pots?

thanks for any insight.

You will find it more difficult to control the require level with a linear Pot.

As to sound quality, its very subjective thing.

Have you thought about a Shunt attenuator with a class A buffer input and output buffer or a 24 postion swith attenuator.(like DACT or Gold Point)

The difference if anything is that a quality dual gang pot will track both channels for accurately!

Ian

[scott fitlin]

You will find it more difficult to control the require level with a linear Pot.

As to sound quality, its very subjective thing.

Have you thought about a Shunt attenuator with a class A buffer input and output buffer or a 24 postion swith attenuator.(like DACT or Gold Point)

The difference if anything is that a quality dual gang pot will track both channels for accurately!

IanUnfortunately, Ian, there is no room inside the unit Louped talks about to fit a stepped attenuator!

[scott fitlin]

You mean these guys??? Two for $1 or 100 for $40. Is that cheap enough for you?



http://www.goldmine-elec-products.com/prodinfo.asp?number=G13281&variation=&aitem=1&mitem=41



http://www.goldmine-elec-products.com/images/G13281B.jpg

These came from an audio equipment manufacturer making high end systems. Standard 3/8" panel mount bushing dual potentiometer features 1/4" dia. x 1/2" long shaft to mount your knob. Size of pot (excluding shaft) is 0.62" W x 0.70" T x 0.60" D. High quality audio taper dual 10K pot made by PIHER. Brand new with mounting nut. Package of 100. G13281AThis is a similar pot but the pinout is slightly different! The AB,s have two pins across, and one in front instead of three across.

You can hardwire these into the board though!

[louped garouv]

10K audio taper dual gang pots PC mount! How many do you have, I will buy whatever you have. And Louped Garouv needs some too!

The original AB part number was 70P1N048F103A.

my thoughts exactly...

and i had seen those other audio tapered pots on goldmine, but I would like to stay as true to the original as possible, with the exception of an upgrade to the carbon AB mods from some Bourns that are in it now... (but the ABs were a factory option at the time); but like I said I keep hearing that linear taper is not a bad thing with these crossovers.

Ideally I would like to hear the unit both ways I guess... then I can really know what I am talking about...

[boputnam]

You will find it more difficult to control the required level with a linear Pot.:yes:

Ain't this the issue with Fender amps? The dang gain pot is twitchy...

[louped garouv]

I don't understand the difference between the crossovers in question (RLAs) and the ones made by Rane and some smaller boutique operations then -- I had a Rane AX30 (showed a pic in another thread...) and I have heard reviews of other similar units that had used linear tapered pots...


what gives? I am kinda dense sometimes :banghead:

[louped garouv]

10K audio taper dual gang pots PC mount! How many do you have, I will buy whatever you have. And Louped Garouv needs some too!

The original AB part number was 70P1N048F103A.

I think they will look like this... but with the number Scott mentioned on it

[Ian Mackenzie]

To be honest I doubt the pot change woud make a significant improvement.

The signal goes through all sorts of parts that have a more pronounced effect on the sound than you might think.

Ian

[scott fitlin]

To be honest I doubt the pot change woud make a significant improvement.

The signal goes through all sorts of parts that have a more pronounced effect on the sound than you might think.

IanYou`d be surprised at HOW much influence the pot does have on the sound!

I used to believe what you believe, UNTIL I heard it for myself!

Just as the capacitors have much to do with a units sound character, the pots are also influential!

[scott fitlin]

I think they will look like this... but with the number Scott mentioned on itThat pot has solder lugs, the pot for the RLA has pins to fit right into the board! The body is the same, you could hardwire those in, and its the same electrically!

[louped garouv]

That pot has solder lugs, the pot for the RLA has pins to fit right into the board! The body is the same, you could hardwire those in, and its the same electrically!

you have good eyes for an old guy :D

Just kidding! and yes the Bourns I have in the unit now have pins that go right through the board... I should have just posted a pic of the actual board...

[scott fitlin]

you have good eyes for an old guy :D

Just kidding! and yes the Bourns I have in the unit now have pins that go right through the board... I should have just posted a pic of the actual board...The Bourns were pretty good, they didnt wear out like the AB,s, so if you have them, why do you want to change them?

They sound clean, and good!

[louped garouv]

I hooked the crossover to drive a wharfedale box I had laying around -- they are really noisy (scratchy); figured I would start fresh again...

when I emailed Al to see about a bench test, he indicated to me that he didn't have any pots on hand for the unit.

and so the quest began...

[toddalin]

There's also these guys, but still may not be up to your quality specs.




DUAL 10K AUDIO POT, PC MT W/THREADED BUSHING
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