Yes I had heard there are fakes, fortunately I haven't come across any. I am not saying the Blue is a poor pot in terms of matching, they are generally very good. The problem is any pot isn't 100% transparent, I appreciate many will not have heard the difference but it is there when better alternatives are put into use.
Which leads me nicely to stepped attenuators. I replaced the Alps Blue in the KIN preamp with a quality stepped attenuator (SA) and the difference was marked, much better detail and transparency.
The problem really with cheap SA's is that they are based on 21/23 or 24 step switches and don't offer enough fine steps.
The problem with expensive SA's is just that, they are expensive. However it is debatable that there is anything better than the Khozmo or Acoustic Dimension.
This is the Acoustic Dimension SA in my preamp, it takes more room than the Alps Blue but fortunately it is electrically a straight drop in.
More to follow.
Did you need to move anything around? As my holiday is probably cancelled, and Brexit means I probably won’t be able to insure my toy car, I will probably buy the SA at the end of the month, assuming I don’t get infected before.
Are you referring to a Digitally controlled Analogue chip? Such as the PGA211A?
Funny you should mention that, it is the subject of investigation.
With my long time involvement in electronics I was still under the impression that analogue multiplexers or chips that included them were very inferior, with very imperfect 'on' resistances that were far from linear with varying signal levels.
How things have come on now with modern CMOS processing . The Burr Brown digitally controlled analogue volume chips PGA2310/2311 have staggeringly low published distortion figures of 0.00002%
I have acquired a slightly older ready made volume control unit from Mshow:
Construction is reasonable but one omission is a mute relay, as there is a pronounced click at turn off.
This is the internal shot after certain modifications:
To glean the ultimate performance from these chips needs consideration of the operating conditions with regard to noise and impedances. Both regulators feeding the supply to the chip have been replaced with low noise regulator modules and a buffer stage has been fitted driving the input pins.
The buffer stage can be seen in the foreground and the mute relay has been fitted directly to the output sockets. The unit came without a remote control but I have been able to adapt one to work.
Leading on from the Mshow experiments I ordered a new unit along the same lines, this time under the Weiliang Audio name. It is from China of course so availability now may be a bit delayed due to the current situation.
The pcb is very well done with some quality caps fitted, Elna and Silmic. It also has a mute relay included on board. I have fitted a buffer stage which improved on the as built performance but am still waiting to receive some low noise regulators.
Compared to the Mshow it is only a few percent behind, hopefully with low noise regulators fitted it will have equal performance. The soundstage and spacial clues come though exceedingly well, this is in use at the moment.
I think it's only fair to give a nod to the fella who kicked off the thinking about this approach........me lol
Just kidding, The real instigator was Tony of Coherent Systems.
After his visit, i was particularlty taken with the spatial presentation and the almost boundless soundstage his Liquid Music preamplifier delivered. We chatted about the approach he had taken and one of the things i felt were of interest was th fact his preamplifier used a Digitally controlled Analogue chip. Now, obviously Tony isn't using off the shelf bits and designed his own DCAC.
Hoewever, China being the home of everyhthing electronic you can imagine, Alan identified the Weilang as interesting.
Inbetween this being ordered and arriving, the Mshow popped up on ebay and Alan snapped it up.
Funnily enough, i was there when this arrived and straight out of the box it delivered an alarmingly familiar experience of what happened when Tony put his preamplifier into my system. And before someone suggests otherwise, NO i am not saying it is as good lol
It just delivered a similar effect in Alans system, that Tony's had in mine. Just to a slightly lesser magnitude.
So go and buy one now?
Well, not quite.
The modded Mshow didn't fare quite as well in my system vs the Neurochrome from a tonal perspective. I felt it sounded slightly rolled off Vs the Neurochrome. However, when we substituted the 286 in for the 686, it sounded a little sharper. This investigation is far from over but it shows great promise as a volume control, regardless of price.
It's been a bit of a mad project but i have a few ideas i'd like to try but i have other things to sort out first, like a Torroid PSU for the 686.
I realised I had some spare OCC speaker cable so I though 'why not upgrade the cable on the sub?' So I upended the sub to disconnect it and found lots of web, spider sort.
During dis-connection I found a loose terminal, plus the legs weren't that tight either. Those of a certain speaker persuasion might recognise where the legs came from. Upon removing the baffle I discovered the culprit:
There were a few dead carcasses as well as more spider web so the live one went outside and the rest up the vacuum. After the clean up: