DAC Showdown: AQVOX USB 2 D/A vs. Benchmark DAC1 vs. Lavry Black DA10 - Page 5

Lavry Email

What is the return policy with you and your distributors on the DA-10? Are any upgrades being made to the unit before the next batch is shipped? Thank you

Brian


Brian,

We have finished software upgrade which corrected a few bugs. This software was put in all the units that were returned from the first build.

Amazing software even fixes incorrect screen printing or can swap sides on the analog outputs on the PCB.

-Ed

A tremendously good write Iron_Dreamer!

Despite the DAC1's third place, purely audio showing, I can see myself upgrading my redbook playback but holding on to the DAC1 primarily for the jitter issue (questionable transports) and it's ability to handle the audio of DVD and DVD-Audio (I'm 2CH only). I've found those features very handy indeed.

I was not telling you that you were telling me...I was just telling you I liked the write ( ) and tie in easily with "the DAC1 certainly still has a few niches" part is all. I didn't notice where you mentioned DVD & DVD-A compatibility. I guess it was understood to be standard on all three items.

Question about Lavry DA10:

When Dave Lavry states that it may take up to four minutes for the change from narrow to wide to take does that imply that he has a four minute data buffer that he uses to query for the clock to eliminate jitter?

Anyone have any ideal?

I'm on my way to order that DA10 for myself within the month.

Yes, the CrystalLock system uses a large buffer. A buffer alone isn't enough though, as you may be aware (a buffer with a fixed clock will always be either full or starved), so the clock itself is steerable slowly within a small range. There's a good description of how CrystalLock works on the Lavry website.

You are right, I didn't count the simple old approach, and now I have to eat my words.
I've spent the best part of the weekend reevaluating the Aqvox DAC.
Integer ratio upsampling/bypass mode indeed sounds better in many cases.
Unfortunately I'm not sure anymore to which degree I'm fooling myself.I've spent many hours critically listening, I'm totally exhausted and need a break.

Could anyone explain why to me integer ratio upsampling seems to make a difference to plain Redbook?
I mean, the PCM1796 is oversampling anyway.

Hi Iron Dreamer ... what a competent review. Well done !

Cosmopragma also added another view on AQVOX usage. This is a unit I had been considering against a DAC-1, but now that the small Lavry has turned up - my attention changes.

I agree that a remote volume control would be most worthwhile on a DAC if possible, but also, in this computer age, USB sourcing could also be usefully selectable.

AQVOX make great claims for op-amp-less single ended class-A amplification and load effect free output driving, which I take to be a cascode-like arrangement, as often favoured for RF stage isolation.
Actually these are the very claims that put me off, because I cannot see single ended class-A being as dynamically accurate as a properly implemented integrated push-pull output driving stage: I am thinking of the throughput of dynamic but assymetrical music signals as compared to balanced and steady audio frequency sinewaves, and the possibility of small degrees of lower frequency zero level shifting developments, from mid range crescendos, that can accompany and thus muddy low frequency output.
Also, the load effect free arrangement would only protect the internal control loop from reactive load induced change, while the output phase relationship of harmonic content might be more free to alter through frequency with load impedance, this being relevent to higher frequencies where reproduced left and right harmonics must retain original relationships for correct image placement.

Iron Dreamer, your review makes me think of these possibilities, especially as you comment that the mid-frequencies (which automatically become the aural reference) reproduce well. Thus the AQVOX resolution might be more sensitive to signal dynamics and output loading than the other two are with more conventional amplification; thus further improvement might be possible via modification.


Cheers ........ Graham.

Here's a little more information about AQVox from their e-mail reply to me.

AQVox DAC is not DC-coupled. It does use discrete, single-ended class A output stage, but it is AC-coupled using polypropylene output coupling caps, which are the big blue caps near the output jacks. They believe that proper AC-coupling is less stressful to downstream components and also advise against trying to "upgrade" the caps b/c they were selected after extensive listening.

Also, unfortunately, AQVox uses PCM2906 chip for USB, which does not have any I2S outputs. Therefore, PCM2906 generates an spdif stream from USB and sends it to the DAC chips. I'm still looking for USB solutions using PCM2706/2707 that use I2S to DAC that I don't need to assemble from kits...

I just hooked it up a new Lavry DA10 to my system. I am using a Pioneer DV-414 as transport through rca spdif to the Lavry and XLR outputs to a Stax 007t amp / Senn HE-60 headphone.

I'll post impressions after a bit but after about a half hour of listening I'm excited about it. I look forward to comparing it to the high price one box players like the Meridian G08 at the New Jersey meet this coming weekend.

Yes, interesting.
The use of series capacitance assists in reducing low level shifts in single ended amplifier designs. Those shifts are channel specific, and thus not coherently related in a L-R sense.
Following amplifiers and loudspeakers might be less stressed without the amplitude response being notably affected ( ie. sub-bass driver cones don't slowly 'breathe' as much at sub-audio frequencies in response to overall audio throughput ), but there can then be a sub-bass phase linearity impact upon the reproduction of good source material, where the likes of kick drum pressure waves, auditorium ambience and outdoor recorded distant sounds become less realistic sounding.
The result is much more like 'good tube amplifier bass' which some folks actually prefer, and if reviewed in isolation or on lesser systems, this behaviour might never become apparent.
My comments are based upon amplification experience, not via AQVOX observation.
Anyone watch for sub-bass cone 'breathing' whilst being AQVOX DAC + good SS amplifier driven ?

The Lavry continues to impress with its balance and depth. Thanks again Iron_Dreamer!