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Old 9th December 2003, 10:43 PM   #101
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Default XLR

I use XLR all over the signal path, so I do not use adapters, but I can offer this information:

1-Converting "XLR OUTs to RCA" is easyly done, if you are dealing with short interconects.(short cables).
You just need to use only one of the differenctial outs (pin 2)and Pin 1 and then lower the level by around 11 something db. This is easyly done with a pair of resistors. Ther's a lot of schematics in the net that shows you cleary how to do it.And is not expensive at all! Do a Google search.

2-Converting "RCA to XLR ins" is no that easy. You need to apply gain by the same amount.Either electronically with an active gain stage or using good quality transformers. That's going to be more expensive.
You can live without increasing the gain, but your signal to noise ratio will suffer almost 12 db!

3-Many DCX2496 owners use the digital in and then siimply atenuate the output to go to the amps and that works reasonable ok.

cheers

Ric
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Old 10th December 2003, 12:52 AM   #102
Davey is offline Davey  United States
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br,

For digital input you can use the input sliders to reduce the level if required. It can be a bit confusing however because the level indicators don't reflect this change and might still be bouncing up into the red even though the unit is not clipping internally.

If you have any equalization programmed that is boosting levels above 0db then you risk clipping. I would suggest set the input sliders no higher than -3db, and even lower if there is some EQ boost programmed. The clipping indicators may still be flashing, but it's probably okay. You need an oscilloscope and test CD with some 0dFS recorded tracks to really confirm this.

RCA/XLR adaptors are available from many outlets for cheap. Check MCMelectronics.com.

Some of the Behringer units adjust the gain automatically if using unbalanced interfaces so there really isn't any penalty for doing this. The 12db reduction in SN ratio mentioned by Ric is actually a different subject. Pro units generally operate at a level 12db higher than consumer units. It's good to take advantage of this extra headroom if you can, but if it means interfacing with transformers and/or outboard active devices it's probably not worth the trouble.

The most important thing to consider with the DCX is volume control implementation. If you're using a digital input then you need a good quality four/six channel attenuator or VCA or something similar.

Cheers,

Davey.
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Old 30th December 2003, 06:45 AM   #103
dkxdn is offline dkxdn  Denmark
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Iam using a 6 channel NLE attenuator in front of my Poweramp. The Behringer gets the digital signal from a Teac vrds 10 but now I have regornize some new strange sounds and it is not when the input clips - has set it to -4dB. The sounds comes and goes on some CDs - Its some "Clicks" sound.
The Firmware is ver. 1.14 I will today try to upgrade it to 1.15 dont no the difference.

If I use the analog input it works fine but that was not the setup I wanted.
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Old 30th December 2003, 11:53 PM   #104
Thunau is offline Thunau  United States
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Quote:
Originally posted by Davey
br,

For digital input you can use the input sliders to reduce the level if required. It can be a bit confusing however because the level indicators don't reflect this change and might still be bouncing up into the red even though the unit is not clipping internally.

If you have any equalization programmed that is boosting levels above 0db then you risk clipping. I would suggest set the input sliders no higher than -3db, and even lower if there is some EQ boost programmed. The clipping indicators may still be flashing, but it's probably okay. You need an oscilloscope and test CD with some 0dFS recorded tracks to really confirm this.

....

Cheers,

Davey.
Yes, in a 24 bit unit the penalty for lowering the gain of a 16 bit signal is somewhat lessened, but you should know where in the signal path the gain change is least harmful. I think that lowering of the output is the best way to do it. Trimming the input results in processing of a lower resolution source.
As to clipping, the SHARK processor is a 32 bit floating point device. You can hardly clip it internally. The internal dynamic range is huge - about 1500dB. As long as you lower your signal in the digital domain before it hits the DA converters to compensate for any processing related signal boost you are fine.

I think that the best way to adapt the Behringer to a ha-fi setup would be to lower the output gain of the buffer amplifiers. I know, it probably would be hard due to use of surface mount components, but the resulting headroom would be most welcome.
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Old 31st December 2003, 12:22 AM   #105
Davey is offline Davey  United States
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Jan,

Yeah, I understand your suggestion and the internal dynamic range of the processor, but in this case the clipping problem is not related to the SHARC unit....at least I don't think so. More likely the input is maxed somehow because level reduction applied in the digital domain will not fix the problem. I'm unsure how the architecture allows this, but it does. Hmmmm.

Lowering the gain of the output amplifiers also won't correct the problem since the waveform they see is already clipped. It will just result in lower amplitude clipped waveforms.

On my unit the output waveform is clipped with 0dbFS recorded information on the digital input if the input sliders are set anywhere higher than -1db. This holds true regardless of EQ, level shifting, crossover effects, etc, that are programmed downstream.

I've investigated other setup configurations to try and work around this "problem," but have been unsuccessful so far.

Cheers,

Davey.
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Old 31st December 2003, 12:49 AM   #106
Thunau is offline Thunau  United States
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Pretty much all of the modern popular music is "maximized" to the point of clipping in the mastering process, but a lot of it comes to the mastering house already clipped in the recording process. It's is very hard to remove clipping especially if the client won't have it 1 dB lower than another popular CD used as reference during mastering. I have been guilty of doing such damage in the past, but since I got out of the recording world I learned to hate it. Now to me it's just grotesque, and is one of the reasons why I don't listen much to modern rock and pop.

What music are you listening to?

Your input meters are showing the digital input level before the digital attenuator. Most likely they are preset to trigger the red LED a couple of dB's below 0dBFS. After all this is a pro audio unit, meant to be fed output of a mixing console. If you put in clipped material the clipping will be preserved through the signal path. Not much you can do about it, other than use analog inputs and feed it the signal at "safe" levels.
Maybe the digital output stages of your CD player have some kind of interpolating circuit that reduces the audible effects of clipping. Some do. If you insist on using the digital input, find CD's that are not clipped, or just accept the fact that your favorite music is recorded poorly.
If enough people complain, maybe something will change in the world of music production. Quite a few mastering engineers are already outspoken about it. Most notably Bob Katz of Digital Domain.
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Old 31st December 2003, 03:29 AM   #107
Davey is offline Davey  United States
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Jan,

I'm using a test CD with 0dbFS recorded sine waves and monitoring the outputs with an oscilloscope. I've analyzed this test disk with other means and there are no clipped samples on any of the tracks. I've also generated some of my own CD's using CoolEdit.

I may have overstated the "problem" here....it's not really a problem as long as the input sliders are set to -1db. Everything comes through clean as a whistle in that case. However, as you mentioned, the triggering point for the red LED's appears to be significantly below 0dbFS since they are illuminated constantly with this level input even though the waveforms look good.

My concern is for less experienced users who don't have the testing capabilities I have to identify this effect. The level indicators do not reliably indicate a clipping condition so it's possible to have a significant effect added to "hot" CD's and not realize it. It would only be severe if the input sliders were bumped up considerably...not a typical situation. However, it's something to be aware of.

Cheers,

Davey.
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Old 31st December 2003, 08:00 AM   #108
dkxdn is offline dkxdn  Denmark
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I have now upgraded it to 1.15 and the problem are still there.
The problem is very stable when I play the old Dire Strasits CD from 1978 - Vertigo 800 051-2.
Track 4 - "Six Blade knife"
The level is only comming up to -5dB

The click sounds and phase distortions is very clear on that track.

Iam a little confused could it be my ZapPulse Amp that makes the problem instead ???

But to day its new yearsday so Ill wait to next year.

Happy new year out there

- Dion
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Old 31st December 2003, 02:14 PM   #109
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Default Clicks?

I'd like to know if anybody else are experiencing those clicks. I don't, but I'm feeding the unit from a digital mixer and not a CD player.
Also I didn't upgrade to 1.15 firmware. Is there's somethhing new? Does it fixes something?

cheers

Ric
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Old 1st January 2004, 03:48 PM   #110
Thunau is offline Thunau  United States
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Quote:
Originally posted by dkxdn
I have now upgraded it to 1.15 and the problem are still there.
The problem is very stable when I play the old Dire Strasits CD from 1978 - Vertigo 800 051-2.
Track 4 - "Six Blade knife"
The level is only comming up to -5dB

The click sounds and phase distortions is very clear on that track.

Iam a little confused could it be my ZapPulse Amp that makes the problem instead ???

But to day its new yearsday so Ill wait to next year.

Happy new year out there

- Dion

The clicks are most likely due to scratches on the surface of the CD. CD Red Book spec calls for a certain amount of data redundancy and the error correction is built in the data format. But once the number of errors reach certain level they become non-recoverable. There is just not enough good data to figure out what the missing bits are. Some CD players will interpolate the data, some will output silence in those moments. In your case it sounds like the digital stream has moments of digital silence where the data is missing. The next sample might be at fairly high level and the instantanious jump from 0V to maybe 1V results in a audible click.
Few suggestions.
1. Clean the CD . Sometimes it's just dust or dirt that causes errors.
2. Try a different transport
3. If you don't have a different transport try ripping the CD using EAC. It will reduce the number of errors dramatically, then make a CDR and see if the clicks are still there.
4. Double check your S/PDIF connection. Are you using 75Ohm cable, is your wiring correct?

Hope this helps.
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