Digital volume control.

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pre65
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#1 Digital volume control.

Post by pre65 »

I was exploring Ebay for passive pre's and things and came across this.

It's a digital volume control. Anyone ever used anything like this, or similar ?

https://www.ebay.co.uk/itm/Digital-Elec ... Swwvtbzpra
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#2 Re: Digital volume control.

Post by ed »

the item doesn't mention which chip it uses but...I've got a bit of experience playing with these, one of which may be in there:

AD5204/6
CAT5113
DS1882
MCP4241
MUSES72320
PGA2311

I had mixed results and none of them really stood out. Some were noisy, some had audible click, and some were just plain cloudy.

That's really not much help I know, and my experience goes back to 2014 so things may have improved dramatically since then. The reason I was interested was because it was easy to introduce remote IR control.

From the little experience I have I can recommend you build a Pass B1, with or without the Korg double triode. Even with a £2.50 maplin pot it shone at Owston/Eggborough when I brought it.

edit: On reflection I recall that our man in Bedford also built a B1 and he didn't like it....you going to have to put your hand in your pocket and let us know what it's like.
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#3 Re: Digital volume control.

Post by pre65 »

Seems the PGA2310 or PGA2311 are "high quality " chips, so I'm looking at those now.

I'd also prefer remote control if possible. :)
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#4 Re: Digital volume control.

Post by pre65 »

Life is what happens to you while you're busy making other plans. John Lennon

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#5 Re: Digital volume control.

Post by ed »

yeah, that looks to be good value....please report back.

bear in mind that the PGA23xx are not digi pots so you wont be getting a passive pre. That is a complete volume control with gain.

go for it!

edit: that may be better value than I thought at first...the chips are now $11(in pin form) and the last time I bought an apple controller I think it was £15 so factor in the transformer and case and control chip and it doesn't look bad at all.
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#6 Re: Digital volume control.

Post by JohnG »

I am fortunate to have listened to the Korg B1 Pre Amp.
I also have one that is to be assembled for me.
I have heard a basic Korg B1 build which sounds very good, and was good enough to make me realise my Slagle AVC was to be replaced.
I have now heard three other variants of the basic build and one of these variants has shone out as much more improved and is a design I hope to achieve.
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#7 Re: Digital volume control.

Post by Ray P »

JohnG wrote: Sat Apr 04, 2020 8:59 pm I am fortunate to have listened to the Korg B1 Pre Amp.
I also have one that is to be assembled for me.
I have heard a basic Korg B1 build which sounds very good, and was good enough to make me realise my Slagle AVC was to be replaced.
I have now heard three other variants of the basic build and one of these variants has shone out as much more improved and is a design I hope to achieve.
John, I think you're comparing apples with pears. The Slagle AVC is a superb passive volume control and will be much better than the potentiometer that the Korg B1 typically uses - maybe what you're liking with the B1 is the active gain stage.

I think I would be inclined to build a Korg B1 with the Slagle AVC as the volume control.

BTW, there are loads of reports about how microphonic the Korg device can be so you really need to pay attention to mitigating it in your build. There's lots of info on the Korg B1 thread over at DIY Audio.
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#8 Re: Digital volume control.

Post by Ray P »

This looks like an interesting volume control development, though I expect them to cost significantly more than £20-40 when they're released;

https://www.tortugaaudio.com/new-epot-v ... ased-soon/

Of course, they're not actually digital volume controls as they use LDRs (it's just the control element that uses a microprocessor).

I think that applies to all of the chip based volume controls Phil is looking at too.
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#9 Re: Digital volume control.

Post by Nick »

as they use LDR
Arrgh, the thing that just won't die.

"Total Harmonic Distortion LDR Attenuation Module - typically less than 0.5%"
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
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#10 Re: Digital volume control.

Post by steve s »

John, many of us on here tried an ldr pre, one did the rounds and many reported an improvement - sort of a brighter sound. When I tried it there was noticeable distortion heard, my speakers showed what it was doing to the music. Both myself and Scott had the same opinion of it. My view is some speakers don't resolve what is does to the signal, but I've heard them and they do make some systems.,,, 'improve ' ! Many on the AOS use them.
Just my opinion of course.
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#11 Re: Digital volume control.

Post by vinylnvalves »

I first I was getting concerned, that digital volume control was actually being discussed. :roll: I know some DAC’s can do it but it’s digital sound processing.. unnecessary in most people’s books. Then reading further it’s digital controlled analogue attenuators, being discussed, so here’s my experience. In my Nadja Preamp/DSP. The volume control is done using IC. CS3308 https://www.cirrus.com/products/cs3308-18/ the collective opinion is that it’s very transparent, some on DIYaudio have gone into elaborate ways to put TVC’s etc into the path to better it, without much tangible benefit. Sometimes IC’s are the best approach......
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#12 Re: Digital volume control.

Post by Ray P »

steve s wrote: Sun Apr 05, 2020 7:55 am John, many of us on here tried an ldr pre, one did the rounds and many reported an improvement - sort of a brighter sound. When I tried it there was noticeable distortion heard, my speakers showed what it was doing to the music. Both myself and Scott had the same opinion of it. My view is some speakers don't resolve what is does to the signal, but I've heard them and they do make some systems.,,, 'improve ' ! Many on the AOS use them.
Just my opinion of course.
Steve, it was me that posted about the LDR volume control modue, not John. As you know, I have a high-resolution system and have tried an LDR-based volume control in the past - I found it transparent and didn't hear any distortion affects - horses for courses I guess.

I posted the LDR link for general interest seeing as the thread is about microprocessor controlled analogue volume controls. I find myself leaning towards the Slagle AVC approach, which is why I suggested to John that, if he liked the sound of the Korg B1, he might try the B1 active stage (there are, of course, other active stages available) after his AVC. The AVC is just a passive, but very high quality, attenuator so my presumption is that it would be superior to a potentiometer equipped B1. You can, of course, control the switching of AVCs with processor controlled relays or motorised rotary switch if remote control is a requirement.
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#13 Re: Digital volume control.

Post by Ray P »

vinylnvalves wrote: Sun Apr 05, 2020 8:12 am I first I was getting concerned, that digital volume control was actually being discussed. :roll:
Why 'concerned'?
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#14 Re: Digital volume control.

Post by ed »

Nick wrote: Sat Apr 04, 2020 11:36 pm
as they use LDR
Arrgh, the thing that just won't die.

"Total Harmonic Distortion LDR Attenuation Module - typically less than 0.5%"
+1

Ray, if I'm reading you correctly then you're about eight years behind the curve. There are a number of threads on these devices dating around 2012-2014. I personally did a few prototypes after the George Stantscheff exposure on diyaudio and decided that the channel balance went to pot after a while(in my case about 6 months) so I gave up.(swidt)

If memory serves the whole thing got very political with the EU ban on cadmium in domestic product and Richard Dunn became uber vocal on many fronts about the illegality of the NZ products.

edit.also...The B1 that I demo'd at Owston or Eggborough was an original....It has no gain.
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#15 Re: Digital volume control.

Post by Ray P »

ed wrote: Sun Apr 05, 2020 11:14 am Ray, if I'm reading you correctly then you're about eight years behind the curve.
You're not Ed and I'm not - for a start lots can happen in eight years so maybe you're behind the curve relying on old threads for your baseline?

I linked to the LDR site because it was kind of on the theme of microprocessor controlled volume controls. One of the interesting things about it is that it carries a 'fingerprint' of the LDRs and that's used by the microprocessor to calibrate the behaviour of the volume control so the balance problem you experienced might have been solved? I say 'might' because, whilst I've had personal experience (less than 8yrs ago BTW) of a very transparent LDR attenuator, as I posted previously, I've none of the Tortega LDR volume controls and I only posted the link for interest not to advocate them. As I posted earlier this morning, I'm inclined towards the AVC approach.

Politics, Richard Dunn and the B1 are irrelevant to this.
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