Coloradan Tries Various Pot(s) - An Audio Nervosa Story

You might remember my recent amp comparison. Well, I was feeling a bit rebelious, a bit insane, and wanted to experiment with pot to see how it subjectively changed what I was hearing.

I am, of course, talking about volume potentiometers in amps. How much of a difference can they make in an amp's sound? I fully blame @MisterRogers and officially label him as a bad influence for giving me what he calls "the itch." Do not let his kind, laid-back nature fool you!

If you can recall my thoughts on the ECP Black Diamond, I later saw some "low hanging fruit" when I peeked inside. What if I swapped out the input and output wiring as well as the potentiometer? It seemed easy enough. I won't go into the how-to details, nor do I encourage anyone to mod their amps without knowing full well the consequences! (Bye bye warranty, possibly safety risks, further encouraging insanity and nervosa, and all other sorts of bad things. No amp engineer, creator, designer, manufacturer, etc. will say positive things towards you if you do this.)

Parts Details​

New Wiring: I replaced the input wiring (RCA jack to pot) and output wiring (PCB to HP jack) with this stuff (24 AWG). Damn, look at all those buzzwords and audiophool marketing speak! Still, I didn't need much for this project, so this was relatively cheap.

Pots: Stock Alps (RK27? Albeit with stock wiring), PEC Carbon, TKD 2CP-2511, Chi-Fi 21-Stepped Mini Attenuator DACT-Type Something or Other off eBay at about $12, and a Tocos Cosmos carbon pot. All 50K like stock.

Note 1: The new wiring alone could have affected the amp's sound more than the pots. All pots except the stock Alps were using the new wiring. Keep that in mind. You can at least get a good comparison feel for every other pot besides the Alps.

Note 2: Subjective impressions in this case have the downside of time taken to remove and resolder each pot, which could highly skew results due to the listening time gap.

Impressions
​

Alps and Stock Wiring - See amp comparison thread. Lacked a bit in low-end power and sustain, was a bit bright and sharp sounding in some situations.

PEC Carbon Pot - Hilariously bad channel matching. I figured given the specs it would be no worse than the Tocos Cosmos, which I have in my modded Super 7. And, you know, mil-spec. C'mon! Nope. Unusable. The two spots on the pot I could find that were decently matched gave the BD a more full, powerful, dynamic, and wider, airier sound. More organic. Slightly warm. But still worthless. Dang.

TKD 2CP-2511 - Amazing channel matching, as it should be for the price and reputation. Very smooth sounding, no hints of nasty issues. Fairly even and balanced sounding. Effortless sounding and good with detail despite this. Doesn't pop out and wow you or say, "Look at me!" in an way. Downsides are a somewhat 2D, flat stage. Slightly warmer sounding than Alps but still lacked a sense of dynamics, power, and sustain. It sounded like it was constrained and holding back a bit (yet somehow effortless, a bit contradictory, I know). Biggest issue was that it was sort of soft and fuzzy sounding around the edges. Kind of boring.

Mini, 21-Stepped Attenuator - I personally thought this was a surprisingly good sounding pot/attenuator. Tight but full, powerful, and dynamic sounding low-end. Resolution seemed on par with the other pots, though everything had a very nice balance of clarity and sharpness without much in the way of additional brightness, glare, or other nastiness. I really felt this was the most lively and dynamic of the pots I tried without sacrificing much else. If I had to nitpick, it could sound a hair hard at times and did not quite match the stage of the Alps or carbon pots. Oh, and the actual steps. Dialing in that exact volume isn't always possible. I will say this particular attenuator has an interesting curve to it, in that it has a lot of fine-grained steps until it gets loud, at which point the steps are fairly large. How well the curve works will depend on the amp and headphones. For sensitive headphones, it was great. HD650, not as much.

I get that some of you don't liked stepped attenuators, especially the series kinds, whether that be the idea of adding so many resistors in the signal path or simply due to how they sound. Or, perhaps you like the pricey attenuators, series or not, but have had bad luck with the cheapo ones. All fair points. I figured for a tiny attenuator, the only one I could fit in the BD, at $12 or so, and with SMD resistors, it was worth the cost of entry for experimentation's sake. Attenuators are polarizing and, thus, should be tried by each individuals to see what they think, IMO.

Tocos Cosmos - These had a lot in common with the PEC, though physically much smoother to turn the knob. See notes below about channel matching. Not as powerful and dynamic as the attenuator above, but better than the Alps or TKD in this regard. Closer to the attenuator than the Alps or TKD. Actually put the BD in a very good spot, I think. Seems to excel at staging, layering, and air. Not quite as articulate as the Alps or attenuator down low, but very slight. Slightly warm sounding, but balanced. Not only is this sort of my sound, it seemed to mesh really well with the BD as a whole. Downsides are that I think this pot can be a little gritty sounding in comparison to the others, but as a whole, it's something you can overlook in the grand scheme of things.

Again, this is what @MisterRogers stuck in my Super 7, and what he had in his as well (now in the hands of @jexby). I bought these in bulk, wired them up with alligator clips, and found the best of the lot through listening. My guess is if you buy them from the "right" sellers on eBay, they're not as poorly matched as you'd expect. Some aren't particularly good, but nothing laughable like the PEC. I'd say over half were more than usuable, with a couple in particular that stood out. It's a risk you take with these...may or may not be worth it.

Overall Findings, Thoughts, Conclusions, and Recommendations​

Pots/attenuators and wiring affected the sound of the BD more than I expected. I would say the differences were not far behind that of tubes and caps in other amps, for example. Just enough to tip the scale of a very nice amp closer to a preferred sound, but no revelations. The Black Diamond did not turn into a Black Widow, for example, just like adding a Christmas tree of tubes to the Elise isn't going to make it a Super 7. But it did change things regardless, for better or worse.

My Recommendation - Buy the amp that sounds like you want out of the gate. Don't buy an amp and roll components in hopes you'll all of a sudden love it. You know the Black Widow? Yeah, looks like it has an Alps pot in it, and it's just dandy like that.

Once you've hit that level where you're comfortable experimenting for the sake of experimentation, or want to tweak an amp you love (or know that you love the sound of the tweaked amp, having heard it at a meet), then maybe consider it. These sorts of endeavors are not for those fairly new to the hobby. If you're still worrying about your end-game DAC and amp, just stay far away from pot.

Another note: I cannot promise my findings will mirror yours with the same amp, and especially not with a different amp. This is a very particular, small experiment.

 

I might be a bit burnt out on pot rolling, nor did I try anything I couldn't fit in the BD. But, hey, if you buy them and send them to me, I'll have no option but to try them! Also I am an old man and need to figure out this chat business.