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Old 18th September 2010, 12:26 PM   #2781
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Default DCX Fried???

I have been doing some mods on my DCX2496. This is the digital input and clock change from Frank Oettle. At this point I have removed the digital input/sample rate converter chip and disabled the crystal oscillator. I just tried to power up as is and the LCD display just goes blank or sometimes random stuff. I'm sure all the cabling is OK. This is with no new input board attached yet.

Have I already hurt something or is the 24MHz clock needed.
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Old 18th September 2010, 05:23 PM   #2782
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Got my answer, the 24MHz clock is needed to get things working.
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Old 27th September 2010, 03:55 AM   #2783
WT is offline WT
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Default analog output for dcx2496 with opa1632

I need some help. I would like to mod the analog output of dcx2496 and this circuit is what I come up with. Could anyone comment on the circuit if this will work and what improvement should I made.
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Old 27th September 2010, 06:15 AM   #2784
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Quote:
Originally Posted by WT View Post
I need some help. I would like to mod the analog output of dcx2496 and this circuit is what I come up with. Could anyone comment on the circuit if this will work and what improvement should I made.
Can't see anything wrong with the circuit as such but the resistor values are not optimal.

On the input side, you have those 300 ohms loading the DACs. That's much too heavy; I think the datasheet says min 1k or so.
Then on the output side there's some 10k's; I'd think that's too high. The OPA can easily drive a few 100 ohms and you want low impedance to drive the output cable and its capacitances and keep low impedance to limit interference etc.

jan didden
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Old 27th September 2010, 10:57 AM   #2785
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@Jan Thanks so much for your reply. So, change R input to 1K. May change R feedback to have some gain like 2+.

On the output side, I would like to do volume control with LDR that is why I put 10K there and 10K variable resistor is my LDR. I can lower them to 5K but lower them less than 3K would be tricky. If I use 5K and drive cable with no more than 3 meter long, will there be problem.

I get confuse with akm4393 datasheet, is there dc at the output of this DAC?
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Old 4th October 2010, 05:58 PM   #2786
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Hello all.

Has anybody succeeded feeding the DCX with a I2S signal?
By removing the 8420 that is!

Flemming Bay
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Old 4th October 2010, 06:38 PM   #2787
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Originally Posted by WT View Post
@Jan Thanks so much for your reply. So, change R input to 1K. May change R feedback to have some gain like 2+.

On the output side, I would like to do volume control with LDR that is why I put 10K there and 10K variable resistor is my LDR. I can lower them to 5K but lower them less than 3K would be tricky. If I use 5K and drive cable with no more than 3 meter long, will there be problem.

I get confuse with akm4393 datasheet, is there dc at the output of this DAC?
All DACs with +5V (unipolar) analog supply always have DC at the output, otherwise they can't give out ac signals.
Generally the 'zero signal' level at these outputs is half the supply, 2.5V. Each output swings around this 2.5V, up to the supply and down to ground, so about 2.4V peak or 2.4*0.7 or less than 1.7V RMS.

BUT because there is 2.5V on each balanced output, if you put it into a difference circuit like the OPA1632 there will be NO output DC because the difference between 2.5VDC and 2.5VDC is, errr, zero.

The only thing left to do now is to make sure that the two OPA1632 outputs are nicely around zero so you can chuck the output coupling cap(s). Those smart engineers who designed the OPA1632 foresaw that you would want that and provided an 'output common mode pin'. The DC output will be whatever you connect that OCM pin to. Just ground it and both outputs sit at ground with zero signal.
Neat huh?

jan didden
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Old 6th October 2010, 07:42 AM   #2788
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@jan Thanks so much

that is really neat feature. I will grap some part and start building some prototype now.
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Old 6th October 2010, 03:05 PM   #2789
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Hello Eivind.

Do you have any of the Freeraider PCBs left?

Flemming Bay
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Old 7th October 2010, 03:36 AM   #2790
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Default DCX2496 digital input seems dead

I've had a DCX2496 in a triamp setup for about 2 years, with no problems. Thinking myself clever, I sold my Musical Fidelity CD player, and bought an E-mu soundcard with an AES/EBU digital out. But no amount of fiddling has caused the DCX to show in any way that its reading the digital signal, despite telling it to use AES for A and B in.
In frustration, I bought a DVD player and tried running the digital coax via a 10 inch cable - no luck at all. Ive searched all over this forum for a similar problem, but I cant find anything. Has anybody had any similar problems getting the digital input to work? At what point should I head to the nearest authorized repair depot?
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