Solid State Volume controls

[Bonsai]

I've been doing sopme research for my pre-amp, and considered using a PGA2310/20 integrated volume control and amp.

I came across quite a few remarks on the forum about the aove device, iao comment s about it being garbarge. Then, at the site below, I discovered that AR use a solid state potentiometer on their $5000 LS25 preamp . . . . and its highly rated.

http://www.arcdb.ws/LS25/LS25.html

Here is the digital pot they use . . . .

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2747

Pavel claims the PGA2310 does not sound good . . . . but CJ Sonograph used it and so does Jeff Rowland on a few of their products. I've also heard that there are PGA2310's ALL over studio mixing consoles (along with loads of op-amps in the signal chain as well).

So where does this leave us?

[thespeakerguy]

There is neither a spec or a graph for changes in RDSon as a function of voltage.

They don't tell you if the analog conduction is through PMOS, NMOS, or both in parallel, which is likely the case.

Buffer the output with a FET input amp, is my suggestion if you chjoose to use this.

[janneman]

I'm using the CS3318 in my 6-channel control for the Behringer DCX. I have had only positive reports about it.
Basically it is a switched resistor network implemented on a chip with a buffer amp. 0.25dB step size, from -96 to +22 dB or so. Distrotion better than -120dB.
Specwise it runs circles around all those other PG's and SS switches.
There is also a 2-channel unit, I believe the CS3308.
Worth to consider.

Jan Didden

[analog_sa]

Originally posted by Bonsai
I discovered that AR use a solid state potentiometer on their $5000 LS25 preamp

They also use the same in the LS26 and likely in the REF. I use the same and like it. No, it does not sound as good as a Seiden switch with even simple metal films but i prefer it to any pot i've tried. And it makes balanced/multichannel a breeze. It also sounds much better than the PGA2310, probably because it doesn't include a cheap opamp in the chain.

I would place the DS1666 as the best price/quality compromise volume control i've ever tried; it just doesn't cut it for a statement preamp.

[Bonsai]

The point of my post was I hear all these claims about fancy pots, switched resistor netwrks etc, and see a lot of negative 'press' about solid state pots, and yet these same solid state pots get used in 'statement gear'. As Thespeakerguy says, the DS1660 does not even show a distortion plot. do they even measure it in production? How linear is it? etc etc.

What is it that makes a switched resistor network sound 'better' than a PGA2310/20/CS3308 when the measuarable non linearity, cross talk etc for both are below the measurement threshold of all but the very best test gear?

Lets not forget the point about the PGA23xx's in many studio consoles as well.

I think a lot of claims are being made for and against without any decent AB testing to prove the case either way.

[Juergen Knoop]

see my comment at the elektor pga2311 circuit.
http://www.diyaudio.com/forums/showt...92#post1582192
How much of the bad rep is due to questionable implementions?
regards

[analog_sa]

Originally posted by Bonsai
Lets not forget the point about the PGA23xx's in many studio consoles as well.

The main problem of the 2310 is the horrible output opamp. If you can swallow an OPA2132 you'll have no issues with the 2310. And yes, many studio consoles use worse.

A lot of the so called "statement" gear is simply mid-fi inside stunning cases using a couple of boutique components. A badge with history and recognition. Whatever keeps the average audiophile happy.

[Bonsai]

hve you tried and compared it to other volume control methods? What were your findings?

[Bonsai]

hve you tried and compared it to other volume control methods? What were your findings?

[analog_sa]

As mentioned above i have tried DS1666 and PGA2310 against ordinary Alps pots, 6-bit relay attenuators (Nais DS2Y-S-5v) and switched attenuators using Seiden, Elma and Daven switches with both high quality and generic metal film resistors. I don't do any blind tests (life is too short, mine in particular) and any A-B comparisons as that is not the way i listen to audio. So, yes, highly subjective but i really have no point to prove.

The mechanical switched attenuators are simply in a class above the rest, even when using cheap fixed resistors. Followed by the relays and the Ds1666. The relays i tried are probably not of particularly high quality and i find something difficult to express but not very pleasant in their sound.

The Alps pot and the 2310 are at the bottom. They are not similar at all but equally objectionable.

Until recently i also used a transformer volume control. While it had some positive sonic qualities, transparency wise i would rate it below the DS1666 or the relays.