Cheap Chinese DACT type attenuators

Anyone tried these things? They're like $15 on ebay. I'm trying them out just for shits and giggles since they're cheap.

I just swapped out an ALPS blue for one of these on a second amp and immediately recognize the same very specific difference in sound as on the first. Compared to the ALPS these things have less of a haze, they're "sharper". I'm trying to decide which sound signature is more "correct".

 

The valab brand is very well made. I had another and it just fell apart. Like any pot, there will be a frequency curve depending on the resistor in use. There should be a sweet spot that you should try to stay in. An interesting discussion on the subject is here by AtomicBob https://www.superbestaudiofriends.o...echnical-measurements.7324/page-3#post-351148

 

Yup, you're talking about the load on the DAC and the input impedance the amp sees. That's a different topic (a big part of matching preamps to amps properly). I'm talking about just replacing ALPS with el-cheapo stepped attenuators while keeping resistance the same.

On two different amps I hear the same change - like a haze is removed. However, it also comes with some crunchiness. I'm having a hard time deciding which is more "correct" (not to be confused with more "pleasant").

 

maybe get another inexpensive one with better resistors?. The quality of the switching does matter. Some of the vendors let you choose various resistors. Resistor nervosa is a thing.

 

What I'd do to get the most 'pure' signal path for comparison is to substitute both attenuators for an equivalent voltage divider created with fixed resistors. Set a comfortable volume for test tracks, measure the pot resistance across the different wipers, and try to match it exactly.

I expect the stepper is most accurate. The Alps Blue is reasonable, but reports of it being hazy go back as long as I've been in the hobby.

But depending on the design, a stepped attenuator might have several resistors in the signal path. And the switches might be of questionable quality. Both might contribute to 'crunch'.

 

Well, these guys don't spec the resistors used (no brand, series or, tolerance) so kind of hard to know what I'm comparing against. Also I haven't seen "better" and inexpensive. The Goldpoint and Khozmos are easily over $100. You got a link to something else?

Honestly this is more of an educational exercise to see if a low number of steps (21 in this case) is reasonable rather than a search for SQ. I have an AVC waiting on me to wire it up for that purpose. I'm just really surprised at the amount of difference between the ALPS and these guys. I expected a lot less. And I'm starting to think that these things are more accurate than the ALPS (at half the price).

 

Brilliant! Hadn't thought of that, thanks.

Yup I've read this, I just didn't expect it to be this blatant.

Noted. I really need to do what you suggested with just a pair of primo resistors and get a baseline to compare with.

 

Pots typically have a higher temperature coefficient which means the resistance changes more with varying current. In effect, the signal modulates the resistance. Sometimes you can see this on an ohmmeter.

 

Don't even need primo resistors, I don't think. Cheapo carbon film might replicate the Alps. The DACT clone might be cheapo thick film if it's SMD, cheapo metal film if it's through hole. Any decent metal film popular with DIYers like Xicon or Vishay is probably better (i.e., more transparent) than them both in this application.

FWIW, I hated stepped attenuators the few times I used them, 24 steps for the standard models simply wasn't enough control. I'm sure the Goldpoint and Khozmo with 47-48 steps are better, but they are stupid expensive. I very much like TKD CP-2500 series. I very much like my 256-step relay-based attenuator. I did like my previous digital volume control. I would use any of these over and above an Alps Blue in a new build.

 

Going a bit OT, sorry - I haven't seen these at Digikey or Mouser, but Parts Connection now has them at what's claimed to be a discount (top row):

https://www.partsconnexion.com/tkd-potentiomters.html

And now that I'm here - for a simple amp build, would you guys consider the TKD 601 series (bottom row at link above) at ~$CAD 52 to be a significant upgrade over the equivalent Alps Blue at ~$CAD 34? I already have an Alps, so it'd be an additional spend not an alternative.

 

No worries, I'm curious what the brain trust thinks about the 601 series as well.

 

Ha! I bought TKD from PCX 11 years ago, I didn't even know anywhere else that sold them. And that current price is really good, I paid CA$95 all that time ago.

Interesting comparison, I've never really thought about it. The contrast was always between similar sized pots, the RK11 and CP-601, then the RK27 and CP-2500.

Never used one myself, but gut instinct says the CP-601 would win out over the RK27, for conductive plastic vs carbon film.

 

Interestingly, the 601 series has "S" versions as well which are stepped. Sadly though, regardless of version, they only offer 10K and 100K resistances.

The 2500 series add a 50K pot. Would really like a 25K in addition to the 50K.

 

Mechanical steps tho, not fixed resistor...

https://www.hificollective.co.uk/potentiometers/tkd-2cp-601s-potentiometer.html

...so not equivalent to the DACT clones.

 

Ah, I see. That's....a bit pointless lol.