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Shadydave 24th August 2012 02:21 PM

ADC for DEQ2496 input
 
I recently acquired a Behringer DEQ2496 and a DCX2496.
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I will use the AES/EBU cable to connect the EQ to the crossover.
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I was thinking it may be better to use an external ADC for the input to the DEQ, thereby bypassing all the (supposedly noisy or low SQ) analog circuitry in the DEQ's input stage.
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What I do not know is how high the quality (and I assume price) of the ADC would need to be, to improve on the SQ of the Behringer analog circuitry.
Obviously it should be at least 24 bit (2496, this means 24 bit 96 kHz, correct?).
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I see ADC's on EBAY for less than $100 and some for way less, but are they good enough to make any difference.

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It would also be nice to use the ADC for level matching as most of my sources (digital satellite TV, CD and DVD/Blu ray) seem to be -10 dBV (0.3 Vrms).
I also have several synths (Roland MC-303 groovebox, Korg Poly 61, Ensoniq ESQ-1) and all my sources have been compatible with both amps which drive fully at +4 dBU (1.3 Vrms).
But, all of my sources go through a mixing board before the EQ and crossover so I may have been doing all of my signal level matching with the board.
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Any info on the level of quality for an ADC that would improve on the DEQ2496 analog inputs would be appreciated.
I would assume that others are taking this approach, what works for you.
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I will worry about changing the DCX crossover outputs at a later date, but plan on either transformers or caps eventually.


Thank you very much,
Dave

Davey 24th August 2012 02:31 PM

The DCX2496 already has considerable EQ capabilities. Why do you need both?

Cheers,

Dave.

DorinD 24th August 2012 03:07 PM

Dave,
You could simply consider an SRC2496 as ADC. I'm using one and seems to me the best option for what you already have.
Regards,
Dorin

Tenson 24th August 2012 03:34 PM

The SRC has the same basic input circuit as the DEQ and DCX. The ADC in all is superb, it is an AKM AK5393. However as you said, the analog circuit is rather poor and introduces excessive IMD.

IMO the best thing to do is replace the analog circuit.

Ryssen 24th August 2012 03:43 PM

Are there any DIY ADC´s ?

Shadydave 24th August 2012 05:16 PM

Quote:

Originally Posted by Tenson (Post 3138249)
The SRC has the same basic input circuit as the DEQ and DCX. The ADC in all is superb, it is an AKM AK5393. However as you said, the analog circuit is rather poor and introduces excessive IMD.

IMO the best thing to do is replace the analog circuit.

I was thinking that using a separate ADC would be an easy way to bypass all the analog circuitry in the DEQ input.
But that assumes that the separate ADC has good analog input circuitry.

Quote:

Originally Posted by Davey
The DCX2496 already has considerable EQ capabilities. Why do you need both?

I didn't realize that. I will have to look into it some more.
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Either way, it would be nice to bypass the analog input section of whatever I use.
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I will look into the SRC2496.

Thanks,
Dave

Tenson 24th August 2012 05:23 PM

The DCX has some parametric EQ functions that can be applied to the outputs per channel or to the input channels. If you use a lot of EQ it will run out of memory though.

Ignore the SRC, it is worse.

Ryssen 24th August 2012 07:35 PM

AD24QS - Audio Analog to Digital Converter 24 Bit / 192 kHz

Shadydave 25th August 2012 03:20 PM

It looks like the AD24QS Kit is unavailable at this time.
I guess I am going to look much more closely at improving the DEQ's input stages.
I see that there are several people offering either kits or several levels of input stage services up to, and including entire new input/output boards.
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That is probably my best option at this time, that is upgrading the DEQ analog input stage.
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The DEQ to DCX interface is in the digital domain AES/EBU, I already have the cable.
At some point I will have to deal with the DCX output stages, and there seems to be numerous approaches for that.
A remote controlled volume or even remote muting control would be great.
I guess I will see what is the best way to go at a later date concerning the crossover output electronics.
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I am starting to get the idea that if both of these units are used at the signal levels they are intended for (Pro level +22dBU) then the signal to noise ratio is fairly low and SQ is not all that bad (I know that SQ is a subjective thing, but I am not all that discriminating of a listener).
One step at a time.

Thank you everyone for your input.
Time to read those long DEQ/DCX mod threads again.
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One question.
Allot of the posts in the mod threads are as much as 8 years old, and I have heard that the DEQ has gone through many generations of small changes.
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Has the SQ of the input stages been improved since the flurry of mods that seemed to start in 2004?
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Thanks again,
Dave

Shadydave 28th August 2012 12:55 PM

A bump for this question
 
I read all the threads (that I could find) here and elsewhere on the input/output stage mods for the DEQ/DCX series, but allot of the info is from 2003 thru 2006.
so,

One question.
Allot of the posts in the mod threads are as much as 8 years old, and I have heard that the DEQ has gone through many generations of small changes.
.
Has the SQ of the input stages been improved since the flurry of DIY mods that seemed to start in 2004?
.
Thanks again,
Dave


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