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Author Topic: I need some help deciphering what this person is talking about...  (Read 2208 times)

Thomas W. Bethel

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We sold this person a Lexicon LFI-10 Digital Audio Interface on Ebay.

Here is the message I received from him

Recently I purchased this item from you which was delivered to me on June 6th without problems. The device worked well in terms of format conversion between AES and S/PDIF.

However, it appears that the SDIF-2 output does not work well: always sending noisy signal to the DAC which is capable of receiving SDIF-raw and SDIF-3 data (Mytek Stereo 192 DSD DAC) from DSD-able ADCs (PCM4222EVM from Texas Instruments and AX-WD from a Japanese maker) with DSD clock via a clock generator/distrbutor (iD from Mutec, Germany).

I tried SDIF-2 phase adjustments provided by the device without success.

My main purpose to purchase this item was to resolve the phase shift problem deriving from the the SDIF-2 audio signal and word clock when sending data from ADC to DAC but I think I could not make it with this device.



I talked to my mentor who is very knowledgeable in such matters and he is completely lost.

Anyone have a clue or how to fix the problem???? Thanks in advance...
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Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 23 years in business in 2018

pmx

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Re: I need some help deciphering what this person is talking about...
« Reply #1 on: June 12, 2012, 03:15:37 am »

so he's trying to use the sdif outputs (word clock) to clock his dac, and he says the signal is no good. no idea why he's talking about phase adjustments. it sounds a bit like an audiofool to me, who's creating a very unstable clocking loop :)
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Paul Matthijs Lombert | The Mastering Factory

Waltz Mastering

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Re: I need some help deciphering what this person is talking about...
« Reply #2 on: June 12, 2012, 10:50:03 am »

I agree,.. seems like a clocking issue and he's saying the LFI 10 specifically the spdif 2 out is not compatible with his rig.

Who knows..  The LfI 10 is about 15 years out of production.

Maybe you could have him contact the company in Germany who makes his clock generator and see if they have any suggestions.. also find out  what the system is used for and what sample rates he's running etc.

Thomas W. Bethel

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Re: I need some help deciphering what this person is talking about...
« Reply #3 on: June 12, 2012, 11:23:02 am »


I am trying to help this guy out and save the sale.

This is what I am going to send him

You of course can return the item to us for a full refund minus the shipping. I would first like to maybe help you get the item to do what you want it to do so you don't have to return it.

I am a mastering engineer and the person who we are selling the item for is also an audio engineer. Between us we have over 80+ years in audio. I guess we are both having trouble understanding what your usage is and why you are having problems. I guess the first question is would be are you sure that everything is properly terminated with 75 ohm terminations where needed? The second question is what types of “phase problems” are you having? The third question is why are you trying to adjust the phase? I am familiar with most of the equipment you are working with but have never had any phase problems using it. Can you tell me more about what the problems are so I can help you.Thanks in advance. Here is what I have been able to find on the WWW.

DSD
Selecting DSD will default to 44.1kHz reference. If no sync is available it will use the internal crystal
reference.
The interface requires a minimum of two BNC cables (DSD L and DSD R) to the DSD DAC.
The DSD output is switchable between SDIF2 and SDIF3 with the rear panel dip switch. SDIF2
requires a 44.1kHz sync signal to be passed to the DAC and this should preferably come from the
1073DPD sync output via a third BNC cable. SDIF3 transmits the DSD signals with clock
information included and should not need the sync signal.
Refer to your DAC for compatibility information.

That shows that:
- SDIF-2 is a 3-wire transmission, with a 44.1kHz wordclock (while the ESS waits for a bit clock) => a PLL is needed
- SDIF-3 is biphase encoded, thus doesn't need an external sync line. A PLL will be needed to extract the clock from the datastream.

This interface is based upon 75ohm BNC, unbalance transmission, 1channel in one cable and
externalwordclock(WCK).And its bitrate is 5.6448MbPS( f sdsd=2.8224Mbps) or
11.2896Mbps(fsdsd = 5.6448Mbps). Transmission is 1channel unbalance transmission and it
uses word clock as synchronization technique.



Thanks for the all the help so far.
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Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 23 years in business in 2018

Dave-G

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Re: I need some help deciphering what this person is talking about...
« Reply #4 on: June 12, 2012, 02:55:51 pm »

"as-is" terms on eBay sales are useful for not having to wade into these waters.  His problems may well be beyond the scope of this unit's functionality, and it hardly seems worth the headache to figure it out for him.

That email is plenty enough due-diligence, I'd make it a clear threshold of "keep it or send it back", and if he sends it back, re-list it "as-is" for the next round.

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Dave Greenberg
Sonopod Mastering

bkuijt

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Re: I need some help deciphering what this person is talking about...
« Reply #5 on: June 13, 2012, 06:10:31 am »

I agree with Dave-G here.
Don't go into details.
The person is trying to solve DSD over SDIF-2 interface issues with a PCM device.
Who knows, it could work.... but that's not your concern at all.

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Bastiaan Kuijt  //  BK Audio  //  www.bkaudio.nl

Thomas W. Bethel

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Re: I need some help deciphering what this person is talking about...
« Reply #6 on: June 13, 2012, 07:24:17 am »

Here is his reply

First of all, I'd like to thank you for your sincerity trying to help me.

> I guess the first question is would be are you sure that everything is properly terminated with 75 ohm terminations where needed?

No problem. The peripheral end of the BNC cable for word clock is well terminated just before connected to the DAC. Basically my SDIF-2 aka SDIF-raw connection between the DAC and ADCs is always okay but is lost when this LEXICON device is in between.

> The second question is what types of ?phase problems? are you having?

Well, it is well described in the manual of this LEXICON device. It is quite sorry for you to sell the item without knowing it. For your reference, just go to the URL below and please check the section of "SDIF phase adjust".

http://media.musicalplanet.com/pdf/LEX015.PDF


> The third question is why are you trying to adjust the phase?

Because of occasional (not so frequent) bit shift problem between the word clock and DSD-data signals as I wrote before. My ADCs send DSD data set to either 64x or 128x the word clock rate (44.1kHz), i.e. fsdsd of 2.8224Mbps or 5.6448Mbps. So decimation of fsdsd is required for extraction of the word clock rate and this is done by iD from Mutec, Germany as I already wrote before.

> I am familiar with most of the equipment you are working with. Can you tell me more about what the problems are so I can help you. Thanks in advance.

Many thanks for these words. But I'm afraid to say that there must be some mechanical problem in sending and receiving SDIF-2 signals with this LEXICON device, that you might not have noticed before selling.

Finally, I'm so sorry to say that I decided to return the item back you. Thank you for your trying help me.

Issue closed and my last posting on this matter. Thanks for the help and suggestions. :)
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Thomas W. Bethel
Managing Director
Acoustik Musik, Ltd.
http://www.acoustikmusik.com/

Doing what you love is freedom.
Loving what you do is happiness.

Celebrating 23 years in business in 2018
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