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Old 10th September 2012, 01:26 PM   #3331
yoke is offline yoke  Croatia
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o.k...
I have read some, but not all the tread...
and since this tread starts couple years ago...I start to think about replacing DCX2496 dac's with new ones...something up to 100$ for two channels ?...

Is it posibile...
just to take I2S of the DSP and connect some exterenal DAC with I2S interface ?
or is it just to complicated ?

I'm new at this...
I have found service manuals for DCX...
And I'm just thinking out loud

I have search net but didn't see that any one owercome internal DAC of DCX
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Old 10th September 2012, 02:01 PM   #3332
SY is offline SY  United States
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What's wrong with the DACs? They are far and away not the weak point which is why people have been concentrating on the things which are. #1 is the output analog electronics. #2 is the input analog electronics. #3 is the digital receiver. #4 is the clock.

Take care of 1 and 2 and you're 99% of the way there.
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Old 10th September 2012, 02:09 PM   #3333
puppet is offline puppet  United States
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But it is. If you put voltage amplification after the DAC, as Behringer did, the levels will be too high for home use unless they're digitally attenuated. This compromises S/N and audibly so. Gain structure is just wrong for home use.
You've lost me here SY ... suitable levels for the DSP are dependent on the source/preamplification before signal processing. With the Behringer, using a digital source (PC for instance), attenuation would still need to be done at the source (manipulating the file levels if/as required). If other program sources don't produce a satisfactory result (such as a CD player), then analog conversion, allowing attenuation, would be called for prior to this particular DSP.

Neither of the above workarounds require attenuation within the DCX. One shows it's lack of flexibility though.

Amplification/attenuation post DSP just manipulates the speaker level signal(s) ... and that would be done in analog. Once again though, the Behringers lack of flexibility would necessitate separate amplifier channel attenuation here (worst case driver sensitivity mismatches) or some other multichannel solution prior to amplification.

I agree with you about the digital attenuation ... but I think a guy would be OK here with the DCX provided they added the extra work (digital file prep) and/or equipment needed (analog attenuators).

The only question remaining then is how well the DCX performs as a DSP (internally ... is it noisy?)? Looks to have some nice features.

phil

Last edited by puppet; 10th September 2012 at 02:12 PM.
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Old 10th September 2012, 02:11 PM   #3334
yoke is offline yoke  Croatia
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Thanks SY
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Old 10th September 2012, 02:16 PM   #3335
SY is offline SY  United States
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Quote:
Originally Posted by puppet View Post
You've lost me here SY ... suitable levels for the DSP are dependent on the source/preamplification before signal processing. With the Behringer, using a digital source (PC for instance), attenuation would still need to be done at the source (manipulating the file levels if/as required).
With a digital source, you have to attenuate the outputs, but you shouldn't attenuate the digital source or you lose S/N. With an analog source, the input gain has to be run at max and that's where the noise problem starts.
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Old 10th September 2012, 02:53 PM   #3336
tvrgeek is offline tvrgeek  United States
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'cause the transformers sound better. I did blind tests, I preferred the transformers. RC is much better than what's in there, tho.
For domestic use as single ended is preferred anyway, how about just better analog output buffers? The only thing I have against transformers is good ones are expensive. No surprise. They may not fit inside the chassis, no surprise there either.
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Old 10th September 2012, 02:55 PM   #3337
tvrgeek is offline tvrgeek  United States
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Originally Posted by yoke View Post
o.k...
I have read some, but not all the tread...
and since this tread starts couple years ago...I start to think about replacing DCX2496 dac's with new ones...something up to 100$ for two channels ?...

Is it posibile...
just to take I2S of the DSP and connect some exterenal DAC with I2S interface ?
or is it just to complicated ?

I'm new at this...
I have found service manuals for DCX...
And I'm just thinking out loud

I have search net but didn't see that any one owercome internal DAC of DCX

DAC's are not the biggest problem IMHO. I would hit the power supplies first, then the analog quality. Look up Jan's work on this.
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Old 10th September 2012, 02:59 PM   #3338
tvrgeek is offline tvrgeek  United States
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Originally Posted by SY View Post
Not necessary. See this thread:

Help in choosing a potentiometer as a "Passive preamplifier"

For a 5k pot, worst case source Z is about 1.3-1.5k. Aleph has 47k input impedance. Pots have linear source impedance.
I confirmed that is it not this simple in some SPICE simulations. Noise and distortion are factors. I am not going to argue with the lessons I got over in the lounge by some folks we both respect.
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Old 10th September 2012, 03:13 PM   #3339
SY is offline SY  United States
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Actually, I think it is that simple. If you run SPICE assuming a 1.3k resistor in series with the output of your preamp and a 47k load with whatever the input capacitance is of the Aleph in parallel with the 200pF or so from the interconnects and you see something significant, I'm all ears. Noise of a 1.5k resistance is buried.
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Old 13th October 2012, 07:13 PM   #3340
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related: last nite, my deq2496 blew itself up. it was powered-on for months at a time (probably half a year or more) and just always left on, along with the dcx2496.

powering it off to swap in some new equipment in my main rack, then powering it on causes this cap to blow enough to stop the unit from coming on. cap is bottom/left. just bulged enough to not work.

sigh.

luckily, the damage was not far and it seems that by replacing this bad cap the unit powers on, the display comes alive, filters work and aes3 in and out work. that was a close call!

just about a year after buying it, brand new, too.

oh, and the top sticker that had its production date or code said '9/11' on it. (uhm, lol?)

anyway, if you are outside your warranty period, its probably a good idea to just replace ALL filter caps in your behringer boxes. I don't trust their parts selection (not that I ever really did).
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