I2S over a longish cable

5th element · 15th February 2006, 03:50 PM

In my other post regarding my DIR1703 I said I would try taking the I2S off my M audio revolution and feeding it into my DAC. Of couse this was not entirely succesful!

The Maudio uses an AKM AK4381 for the main two channels. Pins of importance 1,2,3,4.

MCKL - Master clock
BICK - Bitclock input
STDI - Data
LRCK - Clock set at sample frequency

On the PCM1798 pins 4,5,6,7

LRCK - Clock set at sample frequency
DATA - Data
BCK - Bitclock input
SCK - Master clock

Now I have soldered into the soundcard wires to the important areas and have the serial data available. This wire is unshielded and when connected to the Soundcard but not anything else creates zero problems. If I place the DAC next to the computer case and plug this wire in directly to the various pins of the PCM1798 it seems that a HUGE amount of noise/interference is picked up somewhere and apparently onto the masterclock as the soundcards input goes wild, im assuming the masterclock feeding the A/D on the soundcard is the reason behind this.

I am little confusing by this.

When the cable carrying the serial data stream is placed within the DAC but not connected to anything everthing is great, the analog output on the soundcard is clean as is the input.

The DAC works with the DIR1703 so I know its not picking up any noise anywhere enough to cause issues.

Plug the two together and we get issues. Insane noise, now the analog out from the DAC - noise basically, but it does follow the music and you can hear it behind the fuzz.

Is it just I2S isnt suitable for carrying over large distances? Ive seen it done elsewhere with no problems.

As far as I am aware the data is transmitted in I2S I dont think the VIA Envy24HT can output left justified or other.

I wish I had a scope so I could see whats happening.

Jocko Homo · 15th February 2006, 04:10 PM

I think if you had a 'scope it would answer 99.98% of your questions. Capacitve loading making the wavform unusable..........reflections bouncing back and forth...........

Get a 'scope, 'cuz you are going to need it. I saw some Tek 465s on eBay in the UK.

Jocko

5th element · 15th February 2006, 04:21 PM

Yeah it probably much easier to get my dad to ninja one for a few days from his work -.-

However im a total digi newbie and wouldnt even know how to make it stable. I know how to design digital on PCB. How would one go about making sure the I2S was stable? Or is this just a bad idea to start with.

Jocko Homo · 15th February 2006, 05:04 PM

You can't just hang 2 m of cable onto the existing I2S lines, and expect it to work. You need to make a buffer/cable driver. Elso posted something that works..........just a bunch of followers. If you bug him about via e-mail, I will deny giving you the idea.

(Even though it is here in print.) So don't bug him.

Jocko

rfbrw · 15th February 2006, 05:30 PM

Quote:

Originally posted by 5th element

As far as I am aware the data is transmitted in I2S I dont think the VIA Envy24HT can output left justified or other.

What is the basis for this ?

5th element · 15th February 2006, 05:43 PM

Quote:

Originally posted by rfbrw

What is the basis for this ?

I read a review of the soundcard which had a bit of information on the VIA chip stating it can output two types of data I2S and some other thing I have never heard of. Now as the AKM dacs can only accept the I2S listed I assumed the data would be transmitted in I2S.

I had thought about buffering the signal next anyway.

rfbrw · 15th February 2006, 06:03 PM

Quote:

Originally posted by 5th element

I read a review of the soundcard which had a bit of information on the VIA chip stating it can output two types of data I2S and some other thing I have never heard of. Now as the AKM dacs can only accept the I2S listed I assumed the data would be transmitted in I2S.

I had thought about buffering the signal next anyway.

The AK4381 will accept 5 different formats and the default is not I2S.

5th element · 15th February 2006, 08:58 PM

Quote:

Originally posted by rfbrw

The AK4381 will accept 5 different formats and the default is not I2S.

Yes I am well aware of that, but the VIA chip can only output two formats. One of which the AKM cant use.

chris719 · 15th February 2006, 09:16 PM

PM me if you need the Envy24-HT datasheet, it's too large to attach.

5th element · 15th February 2006, 10:21 PM

Jocko I assume you are refering to this?

Buffer choice for IIS Direct

15th February 2006, 03:50 PM	#1
5th element diyAudio Member Join Date: Oct 2002 Location: England	I2S over a longish cable In my other post regarding my DIR1703 I said I would try taking the I2S off my M audio revolution and feeding it into my DAC. Of couse this was not entirely succesful! The Maudio uses an AKM AK4381 for the main two channels. Pins of importance 1,2,3,4. MCKL - Master clock BICK - Bitclock input STDI - Data LRCK - Clock set at sample frequency On the PCM1798 pins 4,5,6,7 LRCK - Clock set at sample frequency DATA - Data BCK - Bitclock input SCK - Master clock Now I have soldered into the soundcard wires to the important areas and have the serial data available. This wire is unshielded and when connected to the Soundcard but not anything else creates zero problems. If I place the DAC next to the computer case and plug this wire in directly to the various pins of the PCM1798 it seems that a HUGE amount of noise/interference is picked up somewhere and apparently onto the masterclock as the soundcards input goes wild, im assuming the masterclock feeding the A/D on the soundcard is the reason behind this. I am little confusing by this. When the cable carrying the serial data stream is placed within the DAC but not connected to anything everthing is great, the analog output on the soundcard is clean as is the input. The DAC works with the DIR1703 so I know its not picking up any noise anywhere enough to cause issues. Plug the two together and we get issues. Insane noise, now the analog out from the DAC - noise basically, but it does follow the music and you can hear it behind the fuzz. Is it just I2S isnt suitable for carrying over large distances? Ive seen it done elsewhere with no problems. As far as I am aware the data is transmitted in I2S I dont think the VIA Envy24HT can output left justified or other. I wish I had a scope so I could see whats happening. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

15th February 2006, 04:21 PM	#3
5th element diyAudio Member Join Date: Oct 2002 Location: England	Yeah it probably much easier to get my dad to ninja one for a few days from his work -.- However im a total digi newbie and wouldnt even know how to make it stable. I know how to design digital on PCB. How would one go about making sure the I2S was stable? Or is this just a bad idea to start with. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

15th February 2006, 10:21 PM	#10
5th element diyAudio Member Join Date: Oct 2002 Location: England	Jocko I assume you are refering to this? Buffer choice for IIS Direct __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Anyone using microphone cable in making their phono cable?	rich121	Analog Line Level	8	10th September 2010 12:50 AM
cheap cat5e cable for speaker cable	fishline	Full Range	6	19th May 2009 07:42 PM
New in package Component Video Cable and Toslink Cable for sale cheap	jainbaby	Swap Meet	1	30th December 2007 05:18 PM
problems with speaker cable as power cable	pjpoes	Parts	11	14th January 2007 08:24 PM
Plinth isolation: longish	pixpop	Analogue Source	5	20th January 2006 08:37 PM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

15th February 2006, 04:10 PM	#2
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	I think if you had a 'scope it would answer 99.98% of your questions. Capacitve loading making the wavform unusable..........reflections bouncing back and forth........... Get a 'scope, 'cuz you are going to need it. I saw some Tek 465s on eBay in the UK. Jocko

15th February 2006, 05:04 PM	#4
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	You can't just hang 2 m of cable onto the existing I2S lines, and expect it to work. You need to make a buffer/cable driver. Elso posted something that works..........just a bunch of followers. If you bug him about via e-mail, I will deny giving you the idea. (Even though it is here in print.) So don't bug him. Jocko

15th February 2006, 09:16 PM	#9
chris719 diyAudio Member Join Date: Jun 2004 Location: Connecticut	PM me if you need the Envy24-HT datasheet, it's too large to attach.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read