Behringer DCX2496 digital X-over - Page 38

sfogg · 21st September 2005, 03:26 AM

"I think that might have something to do with 75 ohm S/pdif and expecting 110 ohm XLR connection."

I tend to doubt that. The difference in impedance isn't going to change just the samples for the high end... it doesn't work like that.

The non-audio data pre-amble bits in a frame of S/PDIF have different meanings between consumer and pro formats. I think one of the bits that is different is the bit for pre-emphasis. Possibly the Behringer is getting confused and applying/not applying pre-emphasis which would screw up the high end of the signal.

Shawn

EC8010 · 21st September 2005, 09:12 AM

It could be a problem of mistermination because the pulses will not be totally absorbed in the 110R load, causing a reflection to bounce back to the 75R source where it will be totally absorbed. However, the cable is quite short (<1m), so I doubt that a slight mistermination will have very much effect on pulse shape. I think the problem is far more likely to be that S/PDIF is typically only 0.5Vpk-pk unbalanced whereas AES3 is typically 5Vpk-pk balanced, so AES3 enjoys greater immunity from induced noise spikes.

Agreed (consumer) S/PDIF has a bit for invoking 50/15 equalisation, but it's highly unlikely that the (professional) Behringer is designed to act upon it. No, the occassional loss of HF is a symptom of it getting its knickers in a twist, no more, no less.

Madmike2 · 21st September 2005, 11:46 AM

soooooo. what you are saying is that the S/PDIF cable into an XLR adapter will make my behringer DCX2496 accept digital input ?

sfogg · 21st September 2005, 11:54 AM

"Agreed (consumer) S/PDIF has a bit for invoking 50/15 equalisation, but it's highly unlikely that the (professional) Behringer is designed to act upon it. "

Pro format has pre-emphasis available on it to and has more available settings for pre-emphasis then consumer S/PDIF.

For Pro format S/PDIF transmissions it is configured with pre-amble bits 2,3 and 4 of byte 0.

Bit 2 is emphasis not indicated so it defaults to no emphasis but allows over-riding that setting based on bits 3 and 4.

In the consumer format pre-emphasis is also in Byte 0... however it is encoded in bits 3,4 and 5. Bit 2 (the start of the pre-empasis bits in Pro) is Copy Protect status.

It very well may be the Behringer is just flipping out but I have heard other times converting from Consumer to Pro caused a loss of treble in totally different equipment.

Shawn

thylantyr · 21st September 2005, 03:37 PM

Quote:

Originally posted by Madmike2
soooooo. what you are saying is that the S/PDIF cable into an XLR adapter will make my behringer DCX2496 accept digital input ?

Don't mess around and buy that stuff I posted

Madmike2 · 22nd September 2005, 01:10 AM

Thanks Thy but i am going to buy a used Ultramatch they have at the pro shop for 63 bucks. that will kill two birds with one stone as it has a gain control on it so viola' i now have a pre amp

Only bad part is that it is NOT 192 capable

EC8010 · 22nd September 2005, 01:26 AM

Quote:

Originally posted by Madmike2
Thanks Thy but i am going to buy a used Ultramatch they have at the pro shop for 63 bucks. that will kill two birds with one stone as it has a gain control on it so viola' i now have a pre amp

Um, what you actually have is an expensive means of converting S/PDIF to AES3. The volume control is a means of increasing distortion.

The ideal solution is to convert your source to produce AES3 and to use stepped attenuators at the outputs of the crossover to ensure that the DACs are operated at their optimum level.

Madmike2 · 22nd September 2005, 01:33 AM

hmmmm ... i dont know about expensive. The adapters he is speaking of come out to pretty much the same thing. And how would i introduce distortion to digital feed ?

Right now Winamp is my volume control

ANYTHING will be better then that.

EC8010 · 22nd September 2005, 09:51 AM

Quite apart from whether the gain calculations and subsequent dithering are done correctly, if you send a signal to the DACs that has been adjusted to be a produce a quieter analogue signal, then you must have increased the distortion compared to operating the DACs at full resolution. Given that DACs aren't perfect, the optimum place for a volume control is after the DACs.

oehlrich · 23rd September 2005, 09:24 AM

Quote:

Originally posted by Madmike2
Only bad part is that it is NOT 192 capable

Madmike2,
look here, (http://freerider.dyndns.org/anlage/B...ut-Stage-E.htm) I built a 192Khz Interface. Works great!

Charly

21st September 2005, 09:12 AM	#372
EC8010 diyAudio Moderator Emeritus Join Date: Jan 2003 Location: Near London. UK	It could be a problem of mistermination because the pulses will not be totally absorbed in the 110R load, causing a reflection to bounce back to the 75R source where it will be totally absorbed. However, the cable is quite short (<1m), so I doubt that a slight mistermination will have very much effect on pulse shape. I think the problem is far more likely to be that S/PDIF is typically only 0.5Vpk-pk unbalanced whereas AES3 is typically 5Vpk-pk balanced, so AES3 enjoys greater immunity from induced noise spikes. Agreed (consumer) S/PDIF has a bit for invoking 50/15 equalisation, but it's highly unlikely that the (professional) Behringer is designed to act upon it. No, the occassional loss of HF is a symptom of it getting its knickers in a twist, no more, no less. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

21st September 2005, 11:46 AM	#373
Madmike2 diyAudio Member Join Date: Apr 2005 Location: Toronto	soooooo. what you are saying is that the S/PDIF cable into an XLR adapter will make my behringer DCX2496 accept digital input ? __________________ Persistence is better then intelligence. Unless persistence kills you.

22nd September 2005, 01:10 AM	#376
Madmike2 diyAudio Member Join Date: Apr 2005 Location: Toronto	Thanks Thy but i am going to buy a used Ultramatch they have at the pro shop for 63 bucks. that will kill two birds with one stone as it has a gain control on it so viola' i now have a pre amp Only bad part is that it is NOT 192 capable __________________ Persistence is better then intelligence. Unless persistence kills you.

22nd September 2005, 01:33 AM	#378
Madmike2 diyAudio Member Join Date: Apr 2005 Location: Toronto	hmmmm ... i dont know about expensive. The adapters he is speaking of come out to pretty much the same thing. And how would i introduce distortion to digital feed ? Right now Winamp is my volume control ANYTHING will be better then that. __________________ Persistence is better then intelligence. Unless persistence kills you.

22nd September 2005, 09:51 AM	#379
EC8010 diyAudio Moderator Emeritus Join Date: Jan 2003 Location: Near London. UK	Quite apart from whether the gain calculations and subsequent dithering are done correctly, if you send a signal to the DACs that has been adjusted to be a produce a quieter analogue signal, then you must have increased the distortion compared to operating the DACs at full resolution. Given that DACs aren't perfect, the optimum place for a volume control is after the DACs. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...


	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

21st September 2005, 03:26 AM	#371
sfogg diyAudio Member Join Date: Jan 2004 Location: MA	"I think that might have something to do with 75 ohm S/pdif and expecting 110 ohm XLR connection." I tend to doubt that. The difference in impedance isn't going to change just the samples for the high end... it doesn't work like that. The non-audio data pre-amble bits in a frame of S/PDIF have different meanings between consumer and pro formats. I think one of the bits that is different is the bit for pre-emphasis. Possibly the Behringer is getting confused and applying/not applying pre-emphasis which would screw up the high end of the signal. Shawn

21st September 2005, 11:54 AM	#374
sfogg diyAudio Member Join Date: Jan 2004 Location: MA	"Agreed (consumer) S/PDIF has a bit for invoking 50/15 equalisation, but it's highly unlikely that the (professional) Behringer is designed to act upon it. " Pro format has pre-emphasis available on it to and has more available settings for pre-emphasis then consumer S/PDIF. For Pro format S/PDIF transmissions it is configured with pre-amble bits 2,3 and 4 of byte 0. Bit 2 is emphasis not indicated so it defaults to no emphasis but allows over-riding that setting based on bits 3 and 4. In the consumer format pre-emphasis is also in Byte 0... however it is encoded in bits 3,4 and 5. Bit 2 (the start of the pre-empasis bits in Pro) is Copy Protect status. It very well may be the Behringer is just flipping out but I have heard other times converting from Consumer to Pro caused a loss of treble in totally different equipment. Shawn

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

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