Potentiometer upgrade

[ajcllc]

I am upgrading my cheap volume pot in my preamp to a TKD 2CP-2511. What differences in overall performance should I expect?

[ZAKO]

The TKD is almost as good as the Penny&Giles and at half the price....Very clean sounding....I have one in a Krell preamp....A very smooth feel to the control.

[ajcllc]

I just put the TKD in the other day, and it has been a great upgrade; the sound has more detail and the pre-amp sounds very clean as well as more open with greater clarity. This has been a cheap upgrade to my system so far for about $68 shipped with results that are quite measurable and very pleasing to listen to .

[PrestonTom]

I just put the TKD in the other day, and it has been a great upgrade; the sound has more detail and the pre-amp sounds very clean as well as more open with greater clarity. This has been a cheap upgrade to my system so far for about $68 shipped with results that are quite measurable and very pleasing to listen to .

Did you actually get a chance to measure the differences on a scope or spectrum analyzer?

-Tom

[ajcllc]

No. When I say "measurable", I mean what I am hearing. The sound is warmer, more detailed, and clearer.

[PrestonTom]

Okay, I understand now.

The reason I asked was because I was going through a similar process. In my case I was constructing a "passive pre-amp" (an unfortunate name) for a 4 channel bi-amp configuration (a pair of two-way cabinets). I had to mechanically gang a pair of stereo pots together (the alternatives either introduced noise or were too costly). The problem is that at low levels, audio (log) pots don't track very well. So my solution was to buy a dozen 10K audio pots (made by Alpha) and measure their resistance and select a pair that matched the best (both within and between pots). The Alpha pots only cost less than $3 (they are not boutique).

It turns out that the inter channel variability (within a single pot) is only true at very low levels and is not as bad as many folks claim (at least for my batch of Alpha pots, although there were a couple that were clearly outliers). Anyhow, while I was at it, I ran a sinusoid through the pot into an amp and then into a power resistor (simulated speaker load). There was not much distortion to speak of, what I did see on a scope was probably due mostly to the amp and not the pot (I double-checked this against a pair of resistors as a voltage divider, but this is not a definitive test...). As for my subjective tests, well it sounded fine to me.

Good Luck,

-Tom

[mike stehr]

I need to cobble up some sort of line-level attentuation. I've been using a 100K radio shack stereo pot. They are ok, but you need to buy several and measure between sides for best matching.

I picked up a older Pioneer CDP, a PD7100 from Craigslist for 30 bucks. This really is a pretty good player, with low use. It has the digital level control from the remote. It only attenuates -25 db, so it doesn't turn all the way down. But this isn't much of a issue.

Right from the player to the 2A3 SET amp. With remote control......

[Erik Mandaville]

I need to cobble up some sort of line-level attentuation. I've been using a 100K radio shack stereo pot. They are ok, but you need to buy several and measure between sides for best matching.

Another thing you might like to try sometime for improved channel balancing are separate input level controls for each channel, with general gain adjustment made with 'master' control. Or just use the two pots if that's preferred. It helps in situations where the are differences between not only the two sections of a stereo control, but in cases, such as a tube amplifier or preamp, where input/driver or output stage tubes may not be matched. I set my preamp up with three controls. The middle one is the main volume control that's used once the balance is set with the other two. My wife listens quite a bit, too, and she prefers the single control.

[Erik Mandaville]

The same thing I did to another forum member's Transcendent Grounded Grid preamp. Note that JM preamps products already have this feature built in, which make them, in addition to great performance, a very good value. It's a little time consuming to do this.

[Erik Mandaville]

This is another option: Fixed, close tolerance resistors for each channel in a stereo control. This is also a Transcendent kit product, and while cheaper than some other available options, is still expensive. The initial experiments with it in my Moth amp prompted a couple of minor changes in resistance values at lower rotations, and the two work well together now. The resistors are tiny things, so care is needed in soldering.

[HarryO]

"Another thing you might like to try sometime for improved channel balancing are separate input level controls for each channel, with general gain adjustment made with 'master' control. Or just use the two pots if that's preferred. It helps in situations where the are differences between not only the two sections of a stereo control, but in cases, such as a tube amplifier or preamp, where input/driver or output stage tubes may not be matched. I set my preamp up with three controls. The middle one is the main volume control that's used once the balance is set with the other two. My wife listens quite a bit, too, and she prefers the single control."

I just changed both channel volume controls yesterday and added a "master" gain for more control also. Now I'm having to make a new faceplate using an existing template. I like the control for balancing the room out as I'm not able to balance speaker placement. It's working out pretty good. It's a simple task on the McAlister. He gives plenty of room to work.

Harry

[Erik Mandaville]

I agree it helps. The dual mono control is just as good, I think, although maybe a little less convenient.

...but Harry: Orange Drops on the Dyna 70!? []

I'm kidding, of course. They sounded better to me than of all the others I tried in my Moonodogs. On the other hand, Will put Hovlands in the ST 70 I wanted to get from him (wonderful build quality), and they sound fine.

Erik

[PrestonTom]

".....

I need to cobble up some sort of line-level attentuation. I've been using a 100K radio shack stereo pot. They are ok, but you need to buy several and measure between sides for best matching.

....."

The 100K pots from Radio Shack are (or used to be) made by Alps. They are a good value for the price. However, not all pots from Radio Shack (other sizes) are made by Alps.

Good Luck,

-Tom

[Erik Mandaville]

Radio Shack also sells the Alps 100K mono pots in an audio (log) taper if you wanted to try dual mono controls. That involves extra input wiring, though, and depnding on how the shields are connected (if your gear uses shielded cable) may involve some extra wiring; which, if it gives you the flexibility you want, may be worth the extra work (if you know how to work with shielded cable). The shafts are long, though, and need to be carefully cut down with either a rotary tool or dremel.

These pots work fine, and also don't sound much different from the FAR more expensive, fixed resistor switch pot shown above.

Erik

[HarryO]

"I agree it helps. The dual mono control is just as good, I think, although maybe a little less convenient.

...but Harry: Orange Drops on the Dyna 70!?

I'm kidding, of course. They sounded better to me than of all the others I tried in my Moonodogs. On the other hand, Will put Hovlands in the ST 70 I wanted to get from him (wonderful build quality), and they sound fine."

Erik

This is the one I got from Joessportster. I haven't touched it except for bias and putting a new quad of the Mullards in it. The Mullards have hid any sins in the Dynaco. Money well spent for the quality tubes. Biggest difference I've heard just changing the amp tubes so far. No question.

I have volume control on the CDP remote and once I set the preamp controls it's as convenient as I need. The master gave me a bit extra versatility. Not all my source have remote volume control. I thought about a motorized volume control on the preamp via remote but I didn't have anything handy that would work.

Harry

[mike stehr]

Radio Shack also sells the Alps 100K mono pots in an audio (log) taper if you wanted to try dual mono controls. That involves extra input wiring, though, and depnding on how the shields are connected (if your gear uses shielded cable) may involve some extra wiring; which, if it gives you the flexibility you want, may be worth the extra work (if you know how to work with shielded cable). The shafts are long, though, and need to be carefully cut down with either a rotary tool or dremel.

These pots work fine, and also don't sound much different from the FAR more expensive, fixed resistor switch pot shown above.

Erik

The RS pots I'm using are ALP's. I agree with your last sentence Erik, there isn't that much difference. I had a 100K 23 stepped attenuator. It seemed quiet, had good balance between channels. But my main complaint was it broke before it made, making DC coupling. I hated that.......Pap! pap! pap!

I have my Aikido mono linestages. Right and left with AB type "J" 100K pots. Kinda inpractical, but you can dial it in real good....

Using the digital level control from that Pioneer PD7100 and inputing direct to the 2A3 amp works rather well. Excellent balance between sides, no noisy cables, volume control and I can run it from the remote.

Excellent ideas that I will consider, however. Thanks!

The TVC from Intact audio looks like a nice option.

Another boring Saturday......I guess I'll go listen to some Jubilees.....heh