audio-talk

So... TKD pots. I hear they are quite special : https://www.hificollective.co.uk/potent ... meter.html

Now I've seen them described variously as a shunt or a ladder type attenuator. I do know that shunt stepped attenuators can have significant variance of input impedance, the minimum value of which is determined by the fixed value of resistor that sits between input and output.

However, looking at the drawings for how the things work, I see a long resistive element which the wiper contacts through the adjustment range, with a series of short resistive elements connected along it to ground. To me it looks like a sort of hybrid ladder / series attenuator.

If the datasheet matches reality, then as far as I can see, the input impedance that a source would see, would be determined by that circuit of resistive element and resistive connections to ground, which would remain fixed - I can't see how the position of the wiper would change the input impedance any more than it would with a conventional wiper-based pot. Have I missed something?

I don't like the bit about " Their conductive tracks are made from laser-trimmed conductive plastic taper"

Would a series stepped attenuator still be superior though, with that long chain of resistors?

This is just a thought experiment at the moment, I'm considering a scenario where I don't have enough real-estate to accomodate a whole lot of relay boards for volume control.

Stepped attenuators would be good if using the right sort of resistors - surface mount ones should be good, I know these are good as grid-stoppers, and I believe are made from tantalum.
Some of the others you can buy ( OK, years ago.. ) with the brown metal-films were not that good.

The conductive plastic is in most of pots these days, including the Alps Blue, and I associate that stuff with a poor sound - much inferior to older carbon-track pots.

Ive used the 2511 extensively and the 601, the 2511 measures very strangely if you measure between the in and out of the pot as the reading doesnt change as you rotate the pot. I thought it was broken until i looked at the datasheet.
Ive tried loads of pots and steppers for customers and found that smt steppers tend to be hit and miss, some are good and some are rubbish, series ones are fine, shunt ones are not much different. Ladder ones seem to sound abit better but to me but they are more costly.
The tkd pots are rather good in my opinion, and the 601 is tiny so really good for tight spaces
Getting a decent new carbon track pot is abit difficult as most half decent ones are condictive plastic. so i prefer to look for nos carbon ones.

Alps blues are rubbish imo, i just fit them if folks ask

Can you remember what’s in my preamp Ant?

Right now on the Nightingale 801a I’m from dac to Panasonic pot, which sounds good. I found two no’s Allen Bradley 50k carbon pots, so if I can be bothered with having to watch the balance, I might try those against Panasonic.

I think yours has a khozmo stepped attenuator in it if i remember paul, iirc the 3575s were after it to make the balanced out for the barbarik
I think its a 10k shunt version

I'm just putting together a switched attenuator for my SIT amplifier project - I picked up a really good NOS 25way MBB switch on ebay for a few pounds and I'll build it as a shunt type with a 25K Charcroft in the main position and the rest using PSP metal films. To step up from that type I would go for some of Dave Slagle's Intact Audio autoformer volume controls - very transparent but take up a bit of estate.

I have a HiFi Collective 25K shunt attenuator (Takman metal film/Elma version) in my 300B HPA and it sounds and feels great - very happy with it.

Ant wrote: ↑Fri Dec 03, 2021 9:23 pm I think yours has a khozmo stepped attenuator in it if i remember paul, iirc the 3575s were after it to make the balanced out for the barbarik
I think its a 10k shunt version

Yes seem to remember something like that.

Ray P wrote: ↑Fri Dec 03, 2021 9:35 pm I'm just putting together a switched attenuator for my SIT amplifier project - I picked up a really good NOS 25way MBB switch on ebay for a few pounds and I'll build it as a shunt type with a 25K Charcroft in the main position and the rest using PSP metal films. To step up from that type I would go for some of Dave Slagle's Intact Audio autoformer volume controls - very transparent but take up a bit of estate.

I have a HiFi Collective 25K shunt attenuator (Takman metal film/Elma version) in my 300B HPA and it sounds and feels great - very happy with it.

The Slagles are very good and a bargain. I was lucky enough to pick up a pair of Tributes, which Ant put in a nice case for me. They are even better then the Slagles imo.

The Khozmo stepped series attenuator was another consideration - it has to be remote-controllable basically, that's a must-have. The question in my mind was whether the TKD could offer close to the same performance for considerably less outlay - they do seem well-regarded.

a thought just occured...as you've been messing with the soc critters lately, had you considered a muses digipot or similar. I still haven't got round to implementing mine yet, but I do plan to when I get some space back on the work bench...they do get high praise from some quarters.

if automation is required there's also the added benefit of using IR instead of a rotary encoder.

there are also mas6116 and cat5113 which also seem to be well regarded.

I built a buffered passive volume control using the Academy Audio Muses kit - works really well and seems transparent, The buffer uses vintage BUF-03 devices and has plenty of current to drive the input of an amplifier, in fact sufficient to use it as a heaphone amp. Power supply is a SilentSwitcher.





works with the rotary encoder or IR remote control.

I'm also using another Muses implementation, this time based on some boards from DIY Audio, in a 2P29L preamp I'm slowly putting together,

Wow - if those really are transparent then they might be worth looking into.