Mr White's "Opus", designing a simple balanced DAC

[4real]

Originally posted by jleaman

I agree, fire-wire is for speed/data intence hardware. A audio device such as a DAC will never even closely use the amount of bandwidth need that Fw400-800 can supply.

Fire-wire is not just build for speed. The whole technology is far better than USB. It has decent timing control, better bandwidth allocation, and much more fun stuff. Oh well, who cares, USB works just fine..

Speaking about that: the USB board also has a SPDIF output. Would it be smart to link that to the new Wolfson SPDIF receiver, let it decently reclock there, and then let the data go to the DAC from there, in stead of directly linking the USB receiver to the DAC? My guess is that jitter might be reduced even further (the PCM2707 doesn't really say a lot about that though).

An added bonus might be that switching the SPDIF signal might be a lot easier that switching I2S.

[thomaseliot]

Firewire evolved because of USB 1.1 speed limitations. Latency is not an issue when using ASIO drivers.

Today USB 2.0 has better performances than Firewire and some sound cards using USB 2.0 appeared:

MOTU 828mkII USB 2.0
E-MU 0404 USB 2.0
EDIROL UA101 USB 2.0

It exists Firewire II faster than USB 2, but not so diffused.

However there is not an analogue to PCM2707 based on USB 2.0, but it will be needed (and maybe released) wnen, and if, we will have plenty of 24bit/192 khz music to play.

[4real]

Originally posted by thomaseliot
Today USB 2.0 has better performances than Firewire and some sound cards using USB 2.0 appeared:

Yeh, as if those 80 Mbits will make a difference in real life... Fact is that with most devices Firewire performance is still better that USB 2, and needed CPU power is far less.

However there is not an analogue to PCM2707 based on USB 2.0, but it will be needed (and maybe released) wnen, and if, we will have plenty of 24bit/192 khz music to play.

Actually, 24/192 might even work with USB 1.1 it's about 8.7 Mbit/second, so there is still some room for signaling an packeting

[thomaseliot]

Originally posted by 4real
Fact is that with most devices Firewire performance is still better that USB 2, and needed CPU power is far less.

MOTU 828mkII is sold either with USB 2.0 or Firewire. The manufacturer states that performances are identical.

That could be marketing, of course, so it would be nice to know why Firewire data transfer would be better than USB.

[planet10]

Originally posted by thomaseliot
Firewire evolved because of USB 1.1 speed limitations. Latency is not an issue when using ASIO drivers.

Firewire was developed completely independently of USB 1.0 and in the same time frame. USB had nothing to do with FireWire

Today USB 2.0 has better performances than Firewire and some sound cards using USB 2.0 appeared:

This is not true at all. Firewire was developed from the get-go as a transport for high-denity media and when used with video, large amounts of data, or even audio Firewire 400 handily out-classes USB 2.0 (check out posts by Fast Eddy for technical reasons)

Anyone who has used an external drive with both Firewire & USB connectivity can attest to the difference (the USB cables for my drive iare stored away).

I don't know about Windows (where drivers can be a real pain -- actually that pretty much applies to most of Windows) but on a Mac Firewire is native & just works.

dave

[Spartacus]

Hi Russ/Brian,

do you have an ETA for the Wolfson based receiver?

Ta,
Dan

[BrianDonegan]

Did we mention that we will not be doing a firewire board? (at least it's not on the roadmap....)

[Russ White]

Originally posted by Spartacus
Hi Russ/Brian,

do you have an ETA for the Wolfson based receiver?

Ta,
Dan

We will probably receive the boards in the next 2-3 weeks. So sometime soon after that.

[Variac]

Actually, 24/192 might even work with USB 1.1 it's about 8.7 Mbit/second, so there is still some room for signaling an packeting

So it appears that USB 1.1 is more than fine for standard CD data rates then.


Knowing the minimum requirements is quite helpful since I have a lot of old stuff laying around.

I have three computers not used so much, with only USB 1.1 connections:

- a Blue/white Mac G3 with a 350 mHz processor
Could be updated with a USB 2 card

- a 450 mhz Mac iMac - the kind with the CRT screen in a lovely strawberry color.. tough to update the USB, unless there's a Firewire/USB translator box? cause it does have Firewire of course..

- a PC with a 1.2 mhz Athlon. I still kinda use this for work, so more a future thing


Anyone care to opine on how will each of these work with Russ's USB DAC? And maybe more generally, what processor speeds will work with CD bitrate audio and 24/192.

[jleaman]

Originally posted by Variac


So it appears that USB 1.1 is more than fine for standard CD data rates then.


Knowing the minimum requirements is quite helpful since I have a lot of old stuff laying around.

I have three computers not used so much, with only USB 1.1 connections:

- a Blue/white Mac G3 with a 350 mHz processor
Could be updated with a USB 2 card

- a 450 mhz Mac iMac - the kind with the CRT screen in a lovely strawberry color.. tough to update the USB, unless there's a Firewire/USB translator box? cause it does have Firewire of course..

- a PC with a 1.2 mhz Athlon. I still kinda use this for work, so more a future thing


Anyone care to opine on how will each of these work with Russ's USB DAC? And maybe more generally, what processor speeds will work with CD bitrate audio and 24/192.

It should work just fine, if the mac is running osx it will be fine too. OSX = compatible