[skunark]

But wouldn't coaxial S/PDIF and AES/EBU connections also have a non-isolated ground, requiring an optical TOSLINK connection for true isolation?

As far as combining the BDP-2 and BDA-2 in a single enclosure, I'm thinking that many people might still require additional DAC inputs to acommodate their other digital sources, and in the end there might not be enough cost savings over the separate units.

Steve

Galvanic isolation is already being done on the s/pdif based connections.     

[a1p1]

Hi Folks

I have been playing around with a version of the BDP-2 digital player which allows you to use one of the 6 USB connections to output to our new BDA-2 Asynchonous DAC. 





James,

Would this be possible with the BDP-2 as available now? or in the future with a firmware update?  I am thinking that I could use the BDP-2 into my current DAC via BNC and perhaps later with a different DAC with an asyncrhonous USB input.

Best,
AP

[James Tanner]

The BDA2 turns into a USB Audio device which is essentially the sound card.    Sadly at this point though with USB, you will lose isolation between the BDP2 and the BDA2, as far as i'm aware there's not a single USB isolation device that truly isolates the ground.   There are several USB products that claim isolation, but the fine print always indicates the ground is not...   IMO, you might as well put both the BDA2 and the BDP2 in the same chassis for more cost savings.

I assume there's no chance of considering an i2s type interface or s/pdif w/word clock?  This way you can actually maintain the isolation.

Hi

The advantage of the USB asynchronous circuit in the DBA2 is the data is transferred I2S from the USB to the DAC and does not have to go through the SPDIF conversion.

So I assume from the comments that most believe USB signal transfer is not performing at the level a sound card and AES or BNC or COAX SPDIF does?

James

[James Tanner]

James,

Would this be possible with the BDP-2 as available now? or in the future with a firmware update?  I am thinking that I could use the BDP-2 into my current DAC via BNC and perhaps later with a different DAC with an asyncrhonous USB input.

Best,
AP
[/quote]



Hi AP

Yes it would just be a simple software change for the BDP2

James

[James Tanner]

Ok, i see. Thanks James for taking time to explain. Appreciate that.

For me, it would make it a tempting offer, if this new BDP would be able to do what my Mac/pc now can do. That is, play internet radio streams effortlessly, play audio/video broadcasts like digitalconcerthall.com, etc etc, and play hdmi and DSD sources without all the hassle the user has to overcome right now.

Would make it even more tempting to have the current bdp, 1 and 2 , do those things, and still be able to use its sound-card to do its normal things....

In other words, please make the bdp mature on those things it cant do right now. Don't make it an even more niche product by leaving out the sound card, and in that way make it have even more competition and consequently a hard time surviving.

Seems to me Bryston needs to pump up the software capabilities instead of limiting the hardware.

just my 2cents.
cheers!

Marius

Hi Marius

It would be nice if it could do all that but I do not see that happening any time soon. The BDP has always been targeted at a more specific customer and performance level than the more typical computer or laptop offers.

James

[skunark]

Hi

The advantage of the USB asynchronous circuit in the DBA2 is the data is transferred I2S from the USB to the DAC and does not have to go through the SPDIF conversion.

So I assume from the comments that most believe USB signal transfer is not performing at the level a sound card and AES or BNC or COAX SPDIF does?

James

If you had i2s from the start you wouldn't have to go through the USB "conversion" either..       You now have to worry about:
* linux usb audio driver making decisions based on the USB DAC connected to it
* Does the usb audio device chip recover the clock from the USB signal and drive the i2s clock?
or does it synchronize the data and use another clock to drive the i2s clock?

Perhaps you are removing a sound card and s/pdif to i2s step, but the data will still be the same here.   USB flow, it depends on the setup, which I'm sure you can control with the BDP-2, but not with other DACs.

What is Bryston's support model with other USB dacs if the BDP-2 supports non-Bryston USB DACs?  I would expect folks to just add a BDP-2 to their AVR USB DAC input or other USB DACs.  Not all USB dacs support 192/24 audio, you the BDP-2 would have to allow the generic linux USB audio driver to downgrade the audio.    Does this open up a can of warms for support?

Jim

[James Tanner]

If you had i2s from the start you wouldn't have to go through the USB "conversion" either..       You now have to worry about:
* linux usb audio driver making decisions based on the USB DAC connected to it
* Does the usb audio device chip recover the clock from the USB signal and drive the i2s clock?
or does it synchronize the data and use another clock to drive the i2s clock?

Perhaps you are removing a sound card and s/pdif to i2s step, but the data will still be the same here.   USB flow, it depends on the setup, which I'm sure you can control with the BDP-2, but not with other DACs.

What is Bryston's support model with other USB dacs if the BDP-2 supports non-Bryston USB DACs?  I would expect folks to just add a BDP-2 to their AVR USB DAC input or other USB DACs.  Not all USB dacs support 192/24 audio, you the BDP-2 would have to allow the generic linux USB audio driver to downgrade the audio.    Does this open up a can of warms for support?

Jim

Hi Jim

Yes there would be some propriatary-ness to the interaction of the BDP-2 too the BDA-2 to optimize the performance.

james

[skunark]

Hi Jim

Yes there would be some propriatary-ness to the interaction of the BDP-2 too the BDA-2 to optimize the performance.

james

So it might just boil back down to the lack of galvanic isolation with USB, so begs the question of combining the BDP-2 + BDA-2 into a single chassis to lower the cost even more..  (and the same time preempting the issue of folks using other USB dacs you don't have control over)

On key advantage with combining the two into a single chassis... We won't have to hear folks talk about USB cables adding more air and space to the music and folks pointing out that it's a high-speed digital interconnect...        

What happened with the digital preamp discussion earlier?    Adding a BDP to the digital preamp enclosure would be much more interesting to me.

Jim

[unincognito]

Chris, seriously throw the SOTM USB card for output with or without the filter and you have got something!!! 

Think about it...an attached hard drive for PCM and one for DSD with a USB out to whatever PCM/DSD capable DAC you want to buy and wow!!!!

Take the Bryston engineering knowledge for linear PS and go with it...it will sell like gang busters for those of us who want to avoid the computer/CAPs builds.

Add a better interface via I whatever and Andriod whatever and you are in!!!

Mark

Hi Mark,

Dan, one of senior engineers is working on something that would allow us to output DSD/PCM via bnc, RCA and balanced xlr from a bdp unit.  So it is a direction we are considering just perhaps not with SOTM USB, but with our own in house equivalent.

Cheers,
Chris

[unincognito]

If you had i2s from the start you wouldn't have to go through the USB "conversion" either..       You now have to worry about:
* linux usb audio driver making decisions based on the USB DAC connected to it
* Does the usb audio device chip recover the clock from the USB signal and drive the i2s clock?
or does it synchronize the data and use another clock to drive the i2s clock?

Perhaps you are removing a sound card and s/pdif to i2s step, but the data will still be the same here.   USB flow, it depends on the setup, which I'm sure you can control with the BDP-2, but not with other DACs.

What is Bryston's support model with other USB dacs if the BDP-2 supports non-Bryston USB DACs?  I would expect folks to just add a BDP-2 to their AVR USB DAC input or other USB DACs.  Not all USB dacs support 192/24 audio, you the BDP-2 would have to allow the generic linux USB audio driver to downgrade the audio.    Does this open up a can of warms for support?

Jim

Hi Jim,

We do plan on offering options for users that either don't have a dac capable 192k 24bit or USB for that matter.  Although we have only begun testing quite recently we have found the Linux USB audio class 2 driver quite predictable and works well.  We have thought a out what type of support to offer customers and I don't think we would treat it any differently then we do now with using Dac's via bnc or xlr balanced.

Cheers,
Chris

[SGK]

Galvanic isolation is already being done on the s/pdif based connections.   

Can I ask a basic/dumb question regarding this? Is this a part of the way Bryston has designed the connections or a property of such connections generally?  If the former, where is it grounded to? (I hope this makes sense.)

(I'm also intrigued as to where the $500 saving comes from when the Juli@ sound card only costs about $150 retail?  )

[James Tanner]

Can I ask a basic/dumb question regarding this? Is this a part of the way Bryston has designed the connections or a property of such connections generally?  If the former, where is it grounded to? (I hope this makes sense.)

(I'm also intrigued as to where the $500 saving comes from when the Juli@ sound card only costs about $150 retail?  )

Hi

I will ask engineering on the grounding issue.  As for the soundcard cost it really is not a juli@ as we only use some of the parts on the original card.

james

[SGK]

Thanks James. 

On the cost side I was speaking with tongue in cheek.  I know you discard the analogue portion of the card (which is easily separable) but that you still have to pay for the whole thing.  I also understand that you need the Byston PCB to take the SPDIF and offer up AES/EBU as well. And, of course, you're entitled to make a margin on your costs.

[Napalm]

If you had i2s from the start you wouldn't have to go through the USB "conversion" either..       You now have to worry about:
* linux usb audio driver making decisions based on the USB DAC connected to it
* Does the usb audio device chip recover the clock from the USB signal and drive the i2s clock?
or does it synchronize the data and use another clock to drive the i2s clock?

Since Bryston seems to indulge in acronyms like "BIT" I'll wait until they come up with the BDA/BDP "SOFA". Standing for State OF the Art but also suggesting a comfortable cozy audition. 

Now seriously. Conservatively assuming that USB 3.0 can deliver half of its specified rate of 5Gbits/sec. This still means some 300 MBytes/sec. A full CD delivered in 2 seconds. Or one track in 0.2 seconds.

At this point it is perfectly feasible that the whole track is delivered to the DAC box at once, stored in a buffer then played from there using a high precision low jitter clock. You don't need to synchronize with some silly PC computer clock - you already know that the track has to be played at 44.1kHz sample rate.

So guys please wake me up when someone finally comes with such design. Until then I'll use just a CD player.

[Napalm]

And BTW since we still haven't figured out that we shouldn't rely / synchronize on PC clocks.

Has anyone noticed an option in the PC BIOS called "Spread Spectrum" that is enabled by default?

Ever wondered what it does?

Well, on short it helps the PC pass FCC EMI certification. It does it by intentionally introducing clock jitter (as to spread EMI on a larger bandwidth).

And there are still people making "synchronous" DACs? Muhahahahahahahahaaaa.....

[SGK]

Hi

I will ask engineering on the grounding issue. 

james

Hi James, did you ever get an answer to this?

[James Tanner]

Hi James, did you ever get an answer to this?

Sorry - No I have been off sick for the last 2 weeks.

James

[SGK]

No worries - I hope you are now feeling better!

[SGK]

Presumably galvanic isolation is achieved for S/PDIF by simply grounding the RCA jack to the chassis of the BDP?  How much of an issue is the lack of galvanic isolation with a USB connection - is this significantly reduced by not having the USB DAC draw power from the source USB bus? (Presumably this is a big negative associated with niche USB DAC designs that do not have their own clean, low noise, low ripple, power source.)

[OrangeCrush]

First post for me as new to the forum and hope to have some Bryston kit soon.

I may be wrong, but I thought it was a bad idea to have a "computer" as a music player with the source data coming in via usb and going out via usb as well.  All to do with the way the usb protocol works and confilicts.  So I have a mac mini as a player, the data is on a usb drive and the dac output is via firewire.

I think I read it on the Computer Audiofile forum.

Paul

That seems to be a common argument. What's Bryston's view on this? Anybody compared USB out yet?