K&K Audio / Lundahl Transformers

Welcome! Need support, you got it. Or share youe ideas and experiences.

Return to K&K Audio / Lundahl Transformers

K&K Audio / Lundahl Transformers

Re: USB input for RAKK DAC?

209.29.50.252

[ Follow Ups ] [ Post Followup ] [ Thread: Display All Email ] [ K&K Audio / Lundahl Transformers ]

In Reply to: USB input for RAKK DAC? posted by shane. on November 22, 2004 at 21:38:45:

Just out of curiosity, what is your motivation for the request?
How many transports have USB output, and are there any high-end DACs with USB input? And would the USB interface offer any technical advantage over the standard interfaces. Just wondering. Most I have seen are SPDIF, AES/EBU or proprietary arrangements like Meitner's that send the DAC clock to the transport seperately for ultimate jitter reduction.

Follow Ups:

USB is the bomb apparently... - Bas Horneman 07:48:06 11/23/04 (18)
currently you have the Wavelength Cosecant and Twindac from bd-design that I know of.. Jim de Kort a dutch tube-o-phile is also convinced...why is it the tube guys "seem" to be at the forefront of this technology heh? ;-)
Has massive tech. advantage over SPDIF. In any case the technical advantages are secondary to the result no? The sound is very good apparently.
Dave, you can put my name on the list of interested.
Cheers,
Bas
To infinity and beyond!!!
- Re: USB is the bomb apparently... - divo 09:54:07 11/23/04 (6)
  yes, sometimes technical advantages have positive repercussions. But as an engineer, I like to understand whether the hype is justified. Is USB a faster pipe that has inherently lower jitter? A fast pipe is not necessarily a jitter reducer of itself, unless a clock signal goes with it. And which transport do people intend to use? Their PC? Just trying to understand what is truly behind this enthusiasm.
  - Excellent questions! - KevinC 10:15:04 11/23/04 (5)
    Is this a fad or are there benefits to be had other than cutting out the sound card digital output?
    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com
    - So it's both...it's a fad and there are advantages.. - Bas Horneman 10:36:31 11/23/04 (0)
      No fancy transports costing ten's of thousands of dollars because a 500$ pc can better it in technical terms... And 300 cd's onto one system is also pretty neat.
      The cd's are compressed in a LOSLESS compression..such as AIFF.
      Then again just putting on a cd has a charm of it's own...but LP had an even greater charm.
      Have I ever heard such a DAC? Nope. Do I want to find out for myself? Yes.
      
      To infinity and beyond!!!
    - Some answers - Bas Horneman 10:25:11 11/23/04 (3)
      From Wavelength Audio
      Basically the DAC has a single digital USB input. USB unlike SPDIF is bidirectional and therefore has error correction and buffering on both sides. This happens automatically so the data on the disk is identical to what is going out all the time. Also since this interface is asynchronous the clocking problems associated with SPDIF go away.
      From Jim de Kort's site
      Looking at it technically you could see why this would bring an improvement. A "normal" CD transport runs it's data synchronously into the DAC; if there is a read error, you will hear it or the error correction equivalent. Not much time to go back and see what it was supposed to be.
      With the PC and USB2.0 (running at 480Mbs, no longer at 44kHz!) the data parity (or CRC) is regulated by the USB device on the other end. If something is suspect, it is sent again. As the transfer rate of USB and the PC are a factor 100 or greater than your CD transport, the PC almost has all the time in the world to resend any suspect/corrupted data.
      Another benefit of this system is that jitter is a non-issue, again because of the USB. The only jitter introduced will be between the USB-SPDIF converter and your DAC chip. You can use a 10 meter cable now without any penalties in the form of jitter. USB seems to win out on two fronts here. Almost seems TOO perfect...
      The ears say this is a real improvement, if the technical side is actually right I don't know... but I trust the first over the second.
      I have to point out that the music is not being played from the CDROM transport, but the complete track is read from the hard-drive and buffered completely into memory. No moving parts involved at all.
      Once you have your music ripped on to your drive, you will want to hook up your PC to the stereo system, right? Besides the music and the PC, you will need two items to make full use of this setup. These are a DAC bearing a USB-to-SPDIF converter and appropriate software on the PC to play the files.
      End of Jim's text
      My own experience is from listening to wavs ripped onto my hard drive...just sounds too good to come from a pc.
      To infinity and beyond!!!
      - Re: Some answers - Cappy 10:50:03 11/23/04 (2)
        
        In Reply to: Some answers posted by Bas Horneman on November 23, 2004 at 10:25:11:
        
        I do read some hype into the above information.
        For example, Bert Doppenberg has mentioned that he can hear the difference between USB cables. So no jitter penalties -- I doubt it.
        On the other hand, enough smart people with good "ears", such as Bert and Gordon, have commented on improvements so it would be cool to experiment with it myself, using my RAKK DAC as a platform.
        Also, I've heard Bert's TwinDac and thought it sounded quite good.
        What I don't understand is why asynchronous mode on USB can be good for jitter reduction. I don't claim to really understand it but would like to learn more. Clearly the asynchronous packets are chock full of jitter when they are going over the wire so there must be more going on.
        Some of my questions: 1) Where is the clock coming from in this case? Is it somehow imbedded in the packet stream? 2) Is it because the USB receiver chip is good at buffering, or is there more to it than that?
        
        I would have to refer you to - Bas Horneman 11:38:57 11/23/04 (0)
        
        In Reply to: Re: Some answers posted by Cappy on November 23, 2004 at 10:50:03:
        
        http://www.audioasylum.com/forums/pcaudio/bbs.html
        ;-) for more answers.....
        To infinity and beyond!!!
        
        Now I'm out of my depth... - Bas Horneman 11:36:23 11/23/04 (0)
        
        In Reply to: Re: Some answers posted by Cappy on November 23, 2004 at 10:50:03:
        
        since I too wonder where the clock is....and if Bert can hear the difference between USB cables...I too have would have to question if there is no jitter.........
        
        To infinity and beyond!!!
- Re: USB is the bomb apparently... - Dave Davenport 07:50:45 11/23/04 (10)
  Hi Bas,
  Okay, you are on the list. Anyone else out there interested?
  Dave
  - Belated YES as well please! - jusbe 14:12:26 12/08/04 (0)
    Late to the game as ever.
    
    Big J.
  - USB RAKK in a heartbeat! - soulcargo 05:40:16 11/26/04 (1)
    That would be super cool!!
    Would it be possible to do A to D and record lps onto a hard drive sans digital sound card??
    Even cooler!
    Kjell
    - Re: USB RAKK in a heartbeat! - Dave Davenport 06:15:49 11/26/04 (0)
      Hi Kjell,
      Well, I guess that you could, but that is another question better posted over on Digital - PC Audio.
      But then it is a question of quality. I would guess, and it is only a guess, that sound cards do a mediocre job of converting Analog to Digital. I don't know if an audiophile-quality sound card exists.
      Dave
  - USB. Yes! - mourip 13:31:34 11/25/04 (0)
    Hi Dave,
    I have been looking into the DaKKit for several months. While waiting I spent $180 to add an M-Audio Audiophile USB to my system so that I could try using my PC as my source feeding my aging DAC. I am really happy with it and looking forward to ripping my CD's and also exploring streaming Audio.
    I think that before too long USB will be found on many DACs. The perfect combo in my own mind would be two inputs: one SPDIF and the other USB, with the USB getting it's power from the DAC, not the PC.
    Please put me on the interested list...
    Best,
    Paul
  - I am interested too, especically if... - Ed Sawyer 17:54:24 11/23/04 (1)
    ...it can be retro-fitted to an existing RAKK DAC. ;-) Would be nice to not have to get a whole new board... or if there was some trade-in value to the old one, if a new one for USB was needed...
    just some thoughts.
    -Ed
    - Re: I am interested too, especically if... - Dave Davenport 18:03:28 11/23/04 (0)
      Hi Ed,
      It is a wonderful thought, but, unfortunately,,,,,, well it just ain�t possible. I have looked at the problem enough to see what it would take to implement a USB interface and it is a totally different design, that is, assuming that I didn't convert to SPDIF. Converting to SPDIF is the easy way to go but it gives up much of the advantage of the USB interface.
      Sorry.
      As for recouping your SPDIF RAKK dac investment, well I would hope that one the RAKK dac gets known there would be a ready market for used units.
      Dave
  - Re: USB is the bomb apparently... - AnandR 09:35:59 11/23/04 (0)
    Add me to the list.
    Anand.
  - Re: USB is the bomb apparently... - Cappy 07:59:49 11/23/04 (2)
    Sign me up too.
    - Re: USB is the bomb apparently... - shane. 18:08:17 11/23/04 (0)
      add me to the list, if it doesnt convert to S/PDIF.
      playing from a hard-drive makes so much sense. you know how many scratched CD's I got?.
    - Although I should add... - Cappy 08:29:26 11/23/04 (0)
      ...that I am interested in a USB solution that doesn't convert to SPDIF.

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

You can not post to an archived thread.