BP-25DA/BP-1.5 Questions

kristian85 · « **on:** 29 Dec 2003, 06:20 pm »

Hello,

I'm excitedly headed toward BP-25DA ownership, and am wondering if any owners care to comment on it's sound?

Same question regarding the BP-1.5 phono stage.

Thanks

jethro · « **Reply #1 on:** 29 Dec 2003, 09:50 pm »

kristian85,

I think there are some BP-25DA owner reviews on the Bryston website - www.bryston.ca. The quality of DACS have come up a few times on this circle so a search on this site might yield some additional comments.

I have heard that the BP-25DA dacs are even better than the DACS in the SP-1.7. I do not own a BP-25DA yet so I can't give firsthand feedback. I do own a SP-1.7 and I have found the SP-1.7 DACS are much better than the DACS in my Rotel RCD-971. While the RCD-971 is not "high-end", it has gotten some good reviews. The SP-1.7 DACS have a much much higher bandwidth. I base this on some A/B tests I did on my system. I can't listen to my RCD-971 anymore except as a transport for my SP-1.7's DACs. (I apologize to long time circle members for repeating this info again). I hope to get my BP-25 converted to a BP-25DA in the future so I can use it as a standalone DAC into the bypass mode of my SP-1.7.

I'm not a vinyl person so I can't help with the BP1.5.

thomaspf · « **Reply #2 on:** 31 Dec 2003, 12:15 am »

I thought the DACs and the amplifier stage in the DA version of the BP25/B60 are the same as in the SP1.7.

Crystal Sound 43122

As far as I understand the main difference is that for these 2-channel only devices there is an independent stable clock to drive the DACs which is jitter decoupled from the incoming S/PDIF stream via an asynchronous sample rate converter. Depending on your digital source this should give you a better sound. I have my SP1.7 connected to a computer sound card which are known to have quite a bit of jitter in their digital outputs.

My understanding is that this is actually one of weak points of the SP1.7. Most other processors in this price range do support a dejittering stage. I am running mine with an external dejitter device and while I can not hear a difference it makes me sleep better.

I might of course be all wrong on this but then James or Shane can set me straight.

Happy new year

Thomas

James Tanner · « **Reply #3 on:** 13 Jan 2004, 06:27 pm »

HI All,

Sorry I am late answering this but I was in Vegas at the CES show.
The Dac,s in the BP25 differ only from the SP1.7 in that we reclock everything coming in to 96/24.

james

nicolasb · « **Reply #4 on:** 15 Jan 2004, 09:55 am »

So are we ever going to get that feature on the SP1.7?

James Tanner · « **Reply #5 on:** 15 Jan 2004, 01:19 pm »

Maybe in the next update it would be something we could look at. I will check with Shane.

james

nicolasb · « **Reply #6 on:** 15 Jan 2004, 06:23 pm »

That would be cool. (Especially if it's buffering and reclocking in a way that doesn't depend on the input signal for timing information).

James Tanner · « **Reply #7 on:** 15 Jan 2004, 06:27 pm »

Have a look at my Newsletter on the DAC.
http://www.bryston.ca/newsletters/81_files/vol8is1.html

james

nicolasb · « **Reply #8 on:** 16 Jan 2004, 04:29 pm »

Well, James, having read the newsletter, we clearly don't have to sell you on the benefits of up-sampling and jitter removal. (And, while it's clearly true that the analogue components in the BP25-DA are making a big contribution to sound quality, I believe I'm right in saying that the analogue capabilities of the SP1.7 are at least close to this). So that would seem to make implementing upsampling and jitter removal in the SP1.7 an eminently logical next step.

afblaster · « **Reply #9 on:** 16 Jan 2004, 08:15 pm »

I'll second that, nicolasb. Plus a Firewire input - PLEASE!!

nicolasb · « **Reply #10 on:** 17 Jan 2004, 12:13 am »

Firewire could be very neat: if I understand correctly, it also eliminates jitter because the timing information is actually encoded in the signal rather than being deduced from the signal timing. But I suspect that Bryston will want to wait until the industry as a whole decides on a standard for high-bandwidth digital audio, and that's not going to happen any time soon because of perceived copy-protection issues. Even when it does, Firewire may not be the choice.

James Tanner · « **Reply #11 on:** 17 Jan 2004, 12:35 am »

Hi,

Yes I agreee - it would be really nice if this connection issue regarding the hi-res connection got sorted out sooner than later.

james

thomaspf · « **Reply #12 on:** 18 Jan 2004, 09:43 pm »

Firewire actually supports both an isochronous as well as an asynchronous mode. The question is, what is written in the A&M standard for hires music transport.

As far as I can tell from the 1.0 version of the standard, isochronous mode is mandatory. (section 4.3 protocol stack in the document below)

http://www.dvdforum.org/images/Guideline1394V10R0_20020911.pdf

which means you still have to recover the clock from the input stream and are susceptible to jitter unless you invest into a dejitter stage. At the end of the day you will still want this anyhow for your S/PDIF inputs.

Unfortunately with A&M still in the early adoption phase the industry has already started the next wave with HDMI. I still hope Bryston will support a 1394 interface and a properly designed dejitter stage in the SP1.7 successor.

Cheers

Thomas