TKD pots

We all start somewhere
User avatar
Thermionic Idler
Old Hand
Posts: 1018
Joined: Sun Apr 22, 2012 8:22 pm
Location: Southsea

#1 TKD pots

Post by Thermionic Idler »

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?
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#2 Re: TKD pots

Post by IslandPink »

I don't like the bit about " Their conductive tracks are made from laser-trimmed conductive plastic taper"
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Thermionic Idler
Old Hand
Posts: 1018
Joined: Sun Apr 22, 2012 8:22 pm
Location: Southsea

#3 Re: TKD pots

Post by Thermionic Idler »

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.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#4 Re: TKD pots

Post by IslandPink »

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.
"Once you find out ... the Circumstances ; then you can go out"
Ant
Shed dweller
Posts: 2332
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#5 Re: TKD pots

Post by Ant »

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
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8867
Joined: Mon May 21, 2007 9:42 pm

#6 Re: TKD pots

Post by Paul Barker »

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.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
Ant
Shed dweller
Posts: 2332
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#7 Re: TKD pots

Post by Ant »

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
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
User avatar
Ray P
No idea why I do this anymore
Posts: 6294
Joined: Thu Nov 22, 2007 5:18 pm
Location: Somerset

#8 Re: TKD pots

Post by Ray P »

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.
Sorry, I couldn't resist!
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8867
Joined: Mon May 21, 2007 9:42 pm

#9 Re: TKD pots

Post by Paul Barker »

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.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
User avatar
Ali Tait
Eternally single
Posts: 4374
Joined: Fri Jun 08, 2007 8:10 pm
Location: Galashiels

#10 Re: TKD pots

Post by Ali Tait »

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.
User avatar
Thermionic Idler
Old Hand
Posts: 1018
Joined: Sun Apr 22, 2012 8:22 pm
Location: Southsea

#11 Re: TKD pots

Post by Thermionic Idler »

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.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#12 Re: TKD pots

Post by ed »

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.
There's nowhere you can be that isn't where you're meant to be
User avatar
Ray P
No idea why I do this anymore
Posts: 6294
Joined: Thu Nov 22, 2007 5:18 pm
Location: Somerset

#13 Re: TKD pots

Post by Ray P »

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.

Image

Image

works with the rotary encoder or IR remote control.
Last edited by Ray P on Sun Dec 05, 2021 12:19 am, edited 1 time in total.
Sorry, I couldn't resist!
User avatar
Ray P
No idea why I do this anymore
Posts: 6294
Joined: Thu Nov 22, 2007 5:18 pm
Location: Somerset

#14 Re: TKD pots

Post by Ray P »

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,

Image
Sorry, I couldn't resist!
User avatar
Thermionic Idler
Old Hand
Posts: 1018
Joined: Sun Apr 22, 2012 8:22 pm
Location: Southsea

#15 Re: TKD pots

Post by Thermionic Idler »

Wow - if those really are transparent then they might be worth looking into.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
Post Reply