Mitch - Beware replacing a good active pre with a volume control in a DAC. Most of them are substandard and will be a step down.
On the other hand, a few are excellent and will probably beat your active pre. Depends on the technology and implementation. It varies widely. I would read the reviews. If they say it beats good preamps, then its probably a good candidate.
Some are based on variable gain control of an active buffer stage. Others are based on resistive attenuation combined with a gain stage. Some are based on using an integrated chip to digitally control the gain of an analog stage. Two of them are based on controlling the reference voltage to the D/A conversion.
The last 2 generally deliver the best SQ, but again it depends on the implementation, the design details. Controlling the D/A reference voltage is the only one that actually reduces distortion as the volume is decreased.
You can also use purely digital volume control, but I dont recommend it. More than about 9 dB of attenuation will start to reduce sound quality.
Another option is to use a passive transformer based volume control (TVC). You basically cannot lose doing it this way and it beats pretty much all active preamps.
Steve N.
Empirical Audio |
I" can't help but wonder what my savings would be if there were no preamp attached to those units."
It's not about saving money. Its about removing a serious number of veils. Nothing quite like it.
I used a highly modified Levinson pre for years. Mostly wired with silver wire, point-to-point and lots of Black Gates etc.. Nothing like the stock ML. I though it was really transparent, until I developed a DAC volume control. The pre has been gathering dust for years now. Not even close.
The only thing I have found that approaches the tranparency and air of this is a good transformer linestage, such as the Music First. I actually use a transformer buffer now, using the Finemet transformer technology from Feastrex. Even better.
The only requirement for a transformer linestage is that the output drive on the DAC be sufficient. Op-Amp outputs can stay at home.
Steve N.
Empirical Audio |
"The reason remains somewhat unclear but to the ones I spoke with it was the challenge of the circuit. I somehow doubt that is why, I think it more an economical one and we need a frank discussion of that."
I can speak to why I did it in my DAC. It was strictly because there was an opportunity to leverage the D/A technology to create a superior volume control with lower noise, distortion and no compression. It's all about performance. My volume technology can only be done within a D/A converter and cannot be adapted for analog circuits. If it was inferior to other active analog volume technologies, I would not have done it.
I believe other manufacturers typically add inferior volume control circuits because their competition adds this feature, so they have to add this feature. Their marketing depts decide for them. This all got started by one DAC manufacturer IMO.
Steve N.
Empirical Audio |
"Wonder why no one has build this"
Empirical Audio and Weiss both have it, at least variations.
Steve N.
Empirical Audio |
All good tube active preamps probably do improve the behavior of the amps, particularly dynamics, because they have sufficient drive compared to resistive passive linestages or op-amp DAC outputs.
However, and this is a big however, removing them from the signal chain is even better.
What you must understand is that some DAC volume control technologies do not "replace" the active preamp, they actually eliminated it. There is actually no preamp circuitry in the signal path at all. It is exactly like connecting the line-out of a DAC directly to the amps.
When you do this, the distortion, noise and compression that is in every active preamp, even the most expensive, is eliminated. Sound quality is a LOT better IME, particularly when the drive of the DAC is sufficient, like the drive (current) of an active pre.
Steve N.
Empirical Audio |
Mapman - there are only two DACs that I know of that use the reference voltage to control volume (which actually connects the DAC line-out directly to the amps):
Empirical Audio Overdrive SE
I believe the other is a dCS DAC that is out of production
Steve N.
Empirical Audio |
"So far in my listening experiences premium quality tube preamps are an asset and clearly improve the sound quality."
I agree. For MOST systems, the tube pre is an improvement. However for well-designed DACs with volume controls, even these will be crushed. There are only a couple out there that accomplish this BTW, so it is likely that you have not heard them.
Steve N.
Empirical Audio |
"Even if you choose to go "no preamp"... there is still a preamp involved!! It's just a lower quality preamp, tagged onto the digital circuitry, sharing the same power supply as the digital section. No thanks!"
This is where you are dead wrong. You evidently missed some of my posts. There is actually "no preamp".
Steve N. |
"It makes a lot of sense to bundle preamp and dac these days much like pre-amp and phono pre-amp have been bundled into some pre-amps for years. The fact is digital is the norm now, not phono. So it is a natural thing to do. May not be the best/right solution for all. THat is why there are still separates for purists who care, like me."
The distinction that needs to me made is between the DACs that just add a simple volume control in order to add the feature, and others that actually improve upon existing volume control technologies by using the infrastructure only available in a DAC.
Like so many preamps, active and passive, the devil is in the details.
Steve N.
Empirical Audio |
"Steve, DCS latest gear has an all digital VC. Why would they have moved to all digital if they had a better mousetrap before?"
I believe it was probably abandoned because it is very difficult to implement. It puts another layer of complexity and linearity concerns on top of the architecture.
It has some limitations, such as no ability to go to zero volume. It can go really low, but not zero typically. I dont see this as an issue.
Steve N.
Empirical Audio |
"However, my ears are telling me otherwise now, and the fact that a number of >$20 DACs use them suggest they can't be all that bad."
Well even the best S/W DSP volume controls seem to cause audible artifacts at more than about -9dB of volume reduction. No amount of dithering and resampling will help IMO.
The besst overall solution is to use a good volume system to reduce the volume to listening levels and then adjust finely for each track using -0 to -9dB of digital volume. Works like a champ.
Steve N.
Empirical Audio |
Mapman - Look, I have used a few digital volume controls, including the one in the DEQX, iTunes and Amarra. By far, Amarra is the best sounding volume software so far, and it starts to affect the SQ at more than -9dB. I can hear this because I have on of the most resolving systems on the planet. I clearly hear lyrics in tracks that noone else can make-out.
In most peoples systems they will probably not hear this effect until maybe -20 dB or more. This is due to the fact that there is so much other noise, distortion and compression in the typical system that these effects are masked. This masking can be caused by jitter from the source, active preamps and even poor amplifiers.
Steve N.
Empirical Audio |
"the reviewer preferred Bel Canto, which has Digital VC"
I read this review. I think the digital volume they are talking about is a digitally controlled analog volume chip. I dont believe it is DSP. They also used a certain low-jitter USB to SPDIF converter to drive the DAC BTW.
Steve N.
Empirical Audio |
Mapman - sure, my system comprises:
2009 Mac Mini with SSD and 8Gbytes DRAM (better than newer versions IME). Amarra rev 4318 used for playback - 3 EQs are used in Amarra to flatten the speakers and room. Tuned with calibrated mic Earthworks M30 and iTunes Audiotools. Music Files are all .wav format uncompressed.
16-foot Polestar USB cable
Short-Block USB cable filter
Empirical Audio Overdrive SE DAC - used for volume control and D/A
Empirical balanced "bare-wire" silver cables
Empirical Audio Final Drive transformer buffer for galvanic isolation and achieving true-balanced signals (2 chassis). Also switches in the Home Theater
More Empirical balanced "bare-wire" silver cables
Empirical Audio modded Parasound JC-1 monoblocks - power cables are top of line silver Tekline.com
Empirical Audio Clarity7 speaker cables
Custom 4-foot ribbon speakers with 10" bass-box underneath. Custom crossover with Jensen Capacitors air-core inductors, V-Cap Teflons, non-polar Black Gates and low-inductance planar resistors. All wired with silver-plated copper wire in multiple twisted-pairs.
I also have a Sonos connected with cheap S/PDIF cable to an Empirical Audio Synchro-Mesh reclocker that feeds the S/PDIF input on the Overdrive DAC for more casual listening.
I dont sell the cables anymore BTW.
Steve N. |
Ed - I'm sure your system is resolving. You may have one of the few.
Maybe we should exchange some tracks and find out how resolving.
Steve N.
Empirical Audio |
Ed - I think this is possible. I have some old tracks that recently I noticed new lyrics and background singers that I never heard before. The challenge will be to distinguish the lyrics and understand them.
Steve N.
Empirical Audio |
