DAC volume control conundrum

[cat6man]

I know you have resolved your issue. I just noticed this thread so I could offer my experience with the totaldac.

I think you may have to do some "gain matching" whenever you decide you want to use digital volume control. This is a system thing so you have to consider how the entire system gets better or worse with a specific implementation. My experience with digital volume control is that dithering is an artform, not just a number of bits game. I think it's best to listen carefully and decide what it is that you are losing by attenuating -20 or -30db. I don't think it will be naturalness or spaciousness when it comes to how Vincent does his volume control. If anything, you would hear a loss of system dynamics. However, unless your room has something north of 100db of dynamic range, you will not hear any loss of dynamics. Most rooms don't have any dynamic range north of 90db. This is easy to measure with a microphone. It's simple math.

However, not all dithered volume controls sound the same. I know Bob Katz has dealt with this topic extensively and I've done my own blind ABX comparing totaldac's digital volume control against the Jriver 64bit dithered volume control. My local dealer could pick out the totaldac volume control everytime when only attenuating -11db in my ABX tests.

It's funny because the folks that like to criticize digital volume control don't seem to acknowledge the loss of transparency that even the best pre-amps will introduced when interposed between a DAC with a GREAT analog output stage (like the totaldac). I've done my homework. I compared super nice pre-amps against the totaldac direct, and the difference is pretty big in favor of the totaldac.

Thanks. I think we are violent agreement.

Gain matching here is the key and my vtl deluxe 300 monoblocks have too much for my new nola metro grand speakers, while they were well matched for my old 801s.

Actually, I'm running at -30 (very loud) to -40dB or more (background) and that just doesn't cut it. I (and others) hear a loss of detail and the sound gets flatter, both with speakers and Stax 009/BHSE. On the other hand, Vincent has listened to 009s with a Stax amp and found he like the dac attenuation better than the Stax attenuator.............which I find fascinating. I'm sure the load seen by the DAC (either BHSE or VTL) has a big impact...........ah system matching again and everything matters.

I agree that dither is a black art (I'm an engineer) and everyone's implementation is different. However, a 30-40db attenuation is 5 to 6.5 bits no matter how things are done. Consider the case where I want to reduce the volume by factors of 2, then all I'm doing is a shift with no loss of precision. Using 60+ bits is a good way to approach volume control to avoid additional degradations but it doesn't save those LSBs. Subtracting 5 or more bits from a 24 bit DAC is a reduction in resolution. Whether or not we can hear the difference or not and whether or not this is preferable to or worse than a pre-amp is a function of multiple implementations including the output stage. If you believe that 24 bits is better than 19 bits and audibly desirable, then the digital volume control is suspect. If the resulting 19bit resolution for hi-rez is the resolution limit of the rest of our systems, then it won't matter. So we are really in agreement here, I think, as it is the overall end-end result that matters. With my D1-dual ==> BHSE ==> Stax 009, the results are fully in favor of the BHSE attenuator over the digital volume control. I agree also that the output stage of the DAC sounds superb driving my BHSE.

I'm intrigued that others have found that -30 or -40dB is not readily audible. Can you describe the system configuration you are using, dallasjustice?

By the way, I've been lurking and reading your posts here for a few years. Nice to actually talk/type to you.

 

[agisthos]

Steve from Empirical Audio is kind enough to not toot his own horn, so I will mention his Overdrive SE DAC. It has an interesting volume control that is not digital attenuation

http://www.empiricalaudio.com/products/overdrive-dac

Volume control is accomplished without any added parts to the line-output signal path. It is not an entirely digital or entirely analog volume control. It is a little of each actually. The volume is changed by adjusting the reference voltage of the D/A. It does not adjust attenuation of a resistor divider, change the gain of an amplifier stage or truncate bits in the digital data. All of these would add noise and/or distortion to the signal. This technique is unique in the industry. Unlike other volume control methods it has the characteristic of reducing the S/N ratio as the volume is decreased - an ideal situation.

 

[Alrainbow]

I pm catman6 about it. And Steve is a frontier guy in this industry. I own an offramp 5 with All the goodies it makes any DAC I use with sound way above it without it.
Al