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Potentiometers for Preamps - Which is Best?
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Author:  gofar99 [ 04 Jul 2011, 22:25 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

Hi, I just stumbled on this thread and have some concerns as well. I use ALPs pots regularly . The ones I have say Alps Japan 013G .100KAX2. They have rings not pins, but when opened up are the plastic wafer design. Another one from the same bunch has 912G in stead of the 013G. I suspect they are either date codes or batch codes. I have seen the ones with pins in other gear, but I am not sure that just the fact they have wire loops is a sign they are bogus. In operation they are fine, track well, noise free and smooth operating. Let's see if someone out there can come up with some definitive answers. I certainly would not be surprised that there are copies floating around. I doubt that the name brand suppliers would sell any though. Ebay and such - sure.

Good listening
Bruce

Author:  dtsup1 [ 05 Jul 2011, 06:48 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

ALPS pots are really great and affordable. Tracks well.

One of the finest stepped attenuator is made by TKD. Very hard to get now as they are sold out.
Managed to find one supplier - thlaudio that carries them.
This pot is used in John Curl's Blowtorch preamp (USD $15,000).

The ultimate pot ? Maybe a DACT with Vishay bulk metal foil SMD resistors! :hot: :hot:

Of course the best pot is no pot at all, with a digitally controlled volume on the source :mrgreen:

Author:  mach1 [ 06 Jul 2011, 21:17 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

http://www.jaycar.com.au/productView.as ... ATID=968#1

In another league to the Alps blue at a fraction of the price.

Author:  Geek [ 06 Jul 2011, 22:41 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

mach1 wrote:
http://www.jaycar.com.au/productView.asp?ID=RP8760&form=CAT2&SUBCATID=968#1

In another league to the Alps blue at a fraction of the price.


I tried a few of those on BoZ preamps. I was happy with them. Then my wholesalers in .ca dropped them all of a sudden like a hot potato, citing "obsolete part" :confused: :confused: :confused:

Cheers!

Author:  ILoveHiFi [ 17 Dec 2017, 22:52 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

I own a alps rk27 100k.
I also own a bourns 91 10k.

Comparison of both used in a pre amp.
The bournus 91 sounds better overall, more clean and more clear.
The 91 is a conductive plastic, with research done online they said conductive plastic is good for hifi, better than carbon or metal flim.

The rk27 is a carbon film pot, I took appart the one I own, it has a all metal conatct and a black carbon track.

The disadvantage of the 91 is low force required to move the pot, it is harder to adjust volume. Another disadvantage is the impression of being less rugged, the sharft seems to be easy to break, however I treat my components with care, I owned two 91 pots and used for 2 years+ no plorbem.
Another disadantage of the 10k pot is poor matching of left and right channels at very low volumes.
However no plorbem with matching at mid low vollumes up to max volumes.

I would recomend the 91 because it says to have virtually infinity circuit resistance between left and right channels. It also sounds better than rk27.

Author:  Geek [ 18 Dec 2017, 00:18 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

I've switched to Bourns 91 series and dropped the PEC KKA series (aka Alessandro). All carbon pots, Alps, PEC, whomever *will* go noisy. Physics is physics.

After lots of blind testing with some valued customers, 91 is in! :D

Author:  M. Gregg [ 18 Dec 2017, 15:09 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

I think one of the issues is current and leakage in the pot,

If the leakage current is very low then the only other wear is the mechanical parts (wiper and track).
Leakage current even slight will make a pot noisy very quickly no matter what make it is.

Bourns are good pots, TKD are very good. Never liked the Alps but that's a different story.
I like carbon pots (Tocos) as well but it depends what you want.

Here is an interesting thought for you, how many guitar pots have you changed even though they use violin twiddling?
Probably used and twiddled like no other pot I can think of.

Vishay also made some good audio pots. Their Sfernice pots used to be excellent and very long lasting.
Conductive plastic will always be quieter, and perhaps more reliable.
However I find pots in audio are very variable from a sound point of view, even in pre-sets for bias.
For preamps its probably better to stay with conductive plastic lower noise floor.
Some people argue that a linear pot with a resistor to give a log bias is better than a log pot but that's an audio thing, because you can choose the resistor type. :)

Regards
M. Gregg

Author:  gofar99 [ 18 Dec 2017, 18:07 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

Curious, I have used the ALPS both DIY and in commercial products and as long as youkeep DC off them they behave just fine. None of mine even in the earliest projects (over 10 years old now) have experienced any issues of noise or mistracking. Just my experience.

Good listening
Bruce

Author:  laurie54 [ 19 Dec 2017, 01:18 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

Bruce you have hit the nail on the head. DC is the big pot killer. (electrolysis). For years i thought it was humidity that would do the most damage making pots noisy. But now that i have lived in very dry environments (central northern Canada) and very humid environments (rain forest) i see no difference. I have working pots that are open to the environment (alpha) and sealed (Bourns). In both cases some fail others work for 10's of years without a scratch.
The rotary switches with fixed value resistors are more accurate and can be tailored for any curve but also the switch contacts themselves must be considered. Noisy or corroded contacts do a noisy pot make.
I just tried using a top of the line, hermetically sealed pot from Bourns. Brand new and the noisiest pot i have ever come across. Go figure.

Author:  Geek [ 19 Dec 2017, 02:41 ]
Post subject:  Re: Potentiometers for Preamps - Which is Best?

I think humidity is a bit of a factor. Here on the west coast where 80% humidity is a "dry day", all pots are getting noisy regularily. Vintage less so than modern ones, but still....

Had this one Counterpoint come in three times in a year with noisy pots. Measured the leakage current each time and it was zero. Last time I recapped it anyway and changed all the pots (one PEC, one Alps). Lo-and-behold six months later.... :eek:

Since that one, I've been using Bourns 91. None of those have come back :thumbsup:

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