Comparison of Bryston DAC with Benchmark USB DAC models

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ian.ameline

Re: SRC arithmetic precision
« Reply #100 on: 17 Mar 2009, 04:29 am »
The CS4398 DAC specs for distortion+noise relative to a full scale 997 Hz sine wave is -107 dB, which is (107-2)/6 = 17.5-bit resolution.  At -20 dB the distortion+noise spec is -97 dB, which implies resolution relative to full scale of 117 dB, which is 115/6 = 19-bit resolution.

Since the DAC chip has only 19-bit resolution (add another half-bit for two DAC's used in balanced mode), it is unclear whether a difference between 27 and 28 bit precision in the SRC interpolation filter will be audible.  I expect a difference in the SRC algorithm would be more important than the 1-bit difference in precision.

let me discuss your second point first -- you are correct in saying that float has 1 fewer bits of precision then the input or output samples from the sample rate converter, but if you use single precision float, the problem is exacerbated by the fact that there are no guard digits to preserve numerical accuracy through the calculations of rate conversion -- this is exactly why the 4392 has 4 extra bits of precision in its data paths and ALUs. So I'm talking about a 23 to 28 bit difference. This increased precision in the 4392 could certainly be matched (and exceeded) by the CPU were it to use double precision floats, or even keep things fixed point and use 32 bit integers for the calculations. But this is not how I understand that core audio works on the mac.

I agree with you that the choice of algorithm is probably more important than these precision nit-picks (but picking numerical precision and stability nits is part of what I do for a living, and I like it :-). It is also unlikely that Apple is using the same algorithm -- as the one the SRC4392 uses is patented by TI. (I've had a read of that patent, and I like their algorithm -- I think it's quite elegant.)

As to the first point -- the spec sheets disclose minimum and "typical" numbers. (page 39 of the spec sheet defines their measurement terms, but gives little detail on what circumstances under which these were obtained (temperature, power supply stability etc) -- there is a weak implication that they were obtained using the CDB4398 reference board). Yes, you are right that adding a second dac in balanced mode adds 1/2 bit of effective precision. But I wonder how bryston measures 140db s/n (unweighted) with an AP2700 (implying 23 bits). Could they be selecting DACs? (They've been known to hand select components before.) Perhaps they have a more stable power supply than Crystal assumes when giving "typical" specs.

For speculation; They could be measuring differently, say -- not just at 997 hz (nice and prime :-). The measurements given by Crystal are assuming a 1kΩ, 10pF test load, and I bet that is not the same as what bryston's discrete op-amps are presenting (I believe they're in the 20kΩ to 50kΩ ballpark) -- I suppose they could have screwed up the measurements, or the AP analyser could be wrong -- both of these seem unlikely to me given the reputations of the companies involved. 

Back to you :-)

-- Ian.

/In case you couldn't tell, I like a good debate :-)

mountaineagle

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #101 on: 2 Jun 2009, 03:44 pm »
Meanwhile back at the ranch... :duh:

I would like o know whether the Bryston BDA-1 would be the optimum purchase with my Rega Apollo or whether I should just get, say, an Ayre Cx-7e cd player?

...or maybe another DAC?

I have read the thread and my head hurts  aa

Greg

werd

Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #102 on: 2 Jun 2009, 04:24 pm »
Meanwhile back at the ranch... :duh:

I would like o know whether the Bryston BDA-1 would be the optimum purchase with my Rega Apollo or whether I should just get, say, an Ayre Cx-7e cd player?

...or maybe another DAC?

I have read the thread and my head hurts  aa

Greg

Hello Greg

Get the dac unless you are a dedicated to cd only. The dac is more source versatile. I use my dac as source selector and barely touch my pre. Even if cd is only what you want the dac lets you  change out transports for different sounds/tastes and not to mention its very musical.

Dilbert

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #103 on: 2 Jun 2009, 05:15 pm »
After listening to my new BDA-1 for some three weeks now, (it has been left powered up), I couldn't agree more with Werd. I have three CD players connected, Sony SCD-777-XA, CDP-707 and a semi pro CDR. Plus, I have my cable box connected - I listen to the CBC satellite stations (which are awesome, by the way at 48Khz).

It's darn nice to have the digital switching capability at a central location and the sound quality is unbelieveable, too.




wkatzir

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #104 on: 2 Jun 2009, 05:26 pm »
Hello Greg-

     I agree with the rest and would definitely purchase a DAC over a new CD player.  I love my Bryston BDA-1 and would recommend it to anyone.  I am very curious to hear the new Ayre DAC as well as the Wavelength's, but other then those, I would go for the Bryston as it is simply fantastic for the money.  It will even work with Blu-Ray caliber recordings 192/24 (Neil Young is coming out with a 10 disc set).

Hope that helps

-wkatzir

mitcho

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #105 on: 6 Jun 2009, 05:14 am »

BDA-1 does not sound the same on all inputs, it sounds like crap on USB, thank God for that.  :D


Lull ...... do u even know what jitter sounds like Sasha?, i didnt until i started seriousily listening with my laptop.

The USB on this dac is superb and outperforms all the other inputs due to my harddrive source. Take a serious read to Gordon Rankin's reply on the other BDA's thread and his take on jitter. He claims that Jitter is best dealt with at the source than with the dac and i agree. Proof is all there u just have listen to it.

that is exactly the same reasoning used by a number of digital designers including Ed Meitner.   He dealt with Jitter at the source / transport NOT the DAC whether it was red book with his BIDAT or later with DSD (SACD)

wkatzir

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #106 on: 6 Jun 2009, 05:40 am »
Mitcho -

     I think the next few years will prove very interesting as different companies will try to tackle the jitter issue wether it be via better control at the source or better control via asynchronous data flow management or whatever new method they come up with.  I guess it all comes to budget of the end user.  EMM Labs is great, but their newest DAC is well over $7000.  I am curious as to what you would suggest for people in the market for a $2-3000?

-wkatzir

mitcho

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #107 on: 6 Jun 2009, 07:27 am »
Ed's equipment has been priced a little over the top for quite awhile.  I am not recommending anything other than give the BDA-1 a try for newer DAC's.   There are a lot of older DAC's I would recommend over the Benchmark which would be in the same price range-  Altis, Timbre TT1 are a couple.  I have owned both of these and they are still superior in sonics to the Benchmark.

I have only had the BDA-1 for a couple of days with limited usage so far and I would take it easily over the Benchmark which I owned as well.

At today's prices, I would not recommend any of Ed's DAC's including his older DAC's  -Bidat, IDAT44, Bitstream etc.- owned pretty well all of them.  John Wright has priced himself out as well for his "upgrades".

Who knows how they will deal with jitter, but it seems that a large number of designers have tackled the issue via the transport vs the DAC.   

wkatzir

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #108 on: 6 Jun 2009, 07:32 am »
Mitcho-

     Thanks for the reply.  What is your opinion on utilizing a computer as the source?

-wkatzir

mitcho

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #109 on: 6 Jun 2009, 08:30 am »
I started using a Squeezebox a couple of weeks ago.  Growing more fond of it daily.  Still in the process of transferring my CD's to it.  Have not connected a DAC directly to my PC or MAC as yet.

I have used outboard DAC's for quite awhile and like Werd, use the BDA-1 as my input switching box using the remote that now comes with the BP26.  I have found an outboard DAC allows you so much flexibility in picking sources.  It allows you to use a cheapy transport and still have excellent sonics.

I used to have a GAMUT CD1 and Audio Aero Capitolle players.  When I switched to an outboard DAC and transport, it was amazing that I lost little if anything over the mega players.  I have yet to miss either player.

I presently use the following with the BDA-1

1-  Squeezebox Duet
2-  Playstation 3  (DVD/SACD/CD/BluRay)
3-  Oppo DV981   (DVD/SACD/CD/DVD audio)
4-  Star Choice HD PVR receiver
5-  FTA HD PVR Receiver (Audio and video including Digital Radio)

So I get a varied amount of sources.  Each sounds great with a good outboard DAC

I have only had the BDA-1 for a couple of days and I am pleased with the unit.  It is improving with each play as it breaks in.  It replaced my long time Timbre TT1 DAC.   I would recommend either to all.  The BDA-1 is the first newer DAC that I have heard that I have preferred over the older DAC's.   Found a lot of them, including the Benchmark sounded a little dry and clinical.   

A number of years ago, I had all of the Meitner DAC's and used them for a number of years.   Later I strayed away from the outboard DAC, getting mega players.  I went back to the outboard DAC's/ transports and have not missed the all in one players.   I don't think I would consider going back to just a CD player UNLESS you could use it's DAC with other sources.

I think Bryston really has nailed digital down.   Quite a strong showing with just getting into digital.  Would love to see a separate transport come out in the future.   That would interest me quite a bit.
« Last Edit: 6 Jun 2009, 02:35 pm by mitcho »

Stu Pitt

Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #110 on: 7 Jun 2009, 02:21 am »
Greg,

I have the Apollo and love it.  It may not be the last word in 'Hifi' stuff like resolution, soundstaging, imaging, etc., but it just gets the music right.  It grooves better than so many CDPs and DACs that cost multiples of its price IMO.

The BDA-1 and BCD-1 have all its groove and then some.  They're better in every single way to my ears and are an unquestionable upgrade.  I'm saving up my pennies for a BDA-1.  $2k is a lot of money for me.  Its going to take me a little longer than most people, but its the only thing currently out there that'll replace my Apollo.  Its that good.

wkatzir

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #111 on: 7 Jun 2009, 02:43 am »
To Stu and All-

     I just thought I would mention, $1995 is "suggested" retail.  Most retailers that you have a relationship with will have some wiggle room to help you out, especially in these times.  Everyone deserves to make a reasonable profit, your retailer included, but don't think that MSRP is the last word in final cost.  You can get this product for a good discount just don't be afraid to ask.  Might be preaching to the choir, but I just thought I would mention.
     I love the BDA-1 and would second all the praise that I have read about it.  If you have a great CDP like the Apollo, I am sure the BDA-1 will breathe a new life into it. 

-wkatzir

mitcho

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #112 on: 7 Jun 2009, 03:04 am »
I have owned a large number of DAC's over the years and I can vouch, the BDA-1 from what I have now heard is state of the art.   I am really impressed with it.

I have no doubt the Rega will benefit from the DAC.

Stu Pitt

Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #113 on: 7 Jun 2009, 03:11 am »
wkatzir,

I have a very good relationship with my Bryston guy and he will take a bit off the MSRP.  Not that I expect it.  Everyone needs to make a living.  Everyone has to take a bit of a hit during these economic times, one way or another.  But a discount isn't going to make or break the deal for me.  He's got an excellent product and excellent service.  If I wanted to save a few bucks bad enough, I'd take my chances with an unauthorized dealer or buy from Audiogon.

My dealer charges an honest price for an honest product and service.  If it takes me an extra couple of months to support him, so be it.  I'll sleep better at night.

If we were talking about disposable products sold by guys I cared nothing about, it would be a different story.  Not that I think you were implying anything like this.

As great as the Apollo is, the BDA-1 is a very big upgrade worth every penny.  I just don't have enough pennies yet :D

wkatzir

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #114 on: 7 Jun 2009, 03:42 am »
Stu-

     I am all for supporting the authorized dealers (mine was purchased via an authorized dealer).  You get their expertise and a valid warranty, win - win.  I just wanted to mention that there are deals to be found, us consumers have to help each other when times are tough.
     I hope that the penny saving goes fast, I know you will love the DAC when you get it.

-wkatzir

mountaineagle

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Re: Comparison of Bryston DAC with Benchmark USB DAC models
« Reply #115 on: 13 Jun 2009, 11:36 am »
Thanks Guys, It seems the addition of the Bryston DAC is the next proper upgrade on my Rega Apollo. If anyone thinks anything else is a better upgrade on the Apollo please say.

Greg