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Old 22nd April 2008, 04:04 PM   #1
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Default Coax input deq2496

Have anyone add coax input to the deq2496.

I think it would be possible to tap into the ak4114 RX0/RX1 input for the coax in. Refer to page 22 on ak4114 datasheet for the optical receiver input (with 470R) which is same as the optical circuit in deq2496.
It looks it I can solder a coax wire on input side of the 470R resistor (connected to the RX1 pin of ak4114) and put a 75R across the coax wire and put a BNC at the wire end and I am done.

Anybody done this yet?


...chuck
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Old 22nd April 2008, 04:11 PM   #2
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Refer to the pic, that would be R8 (470ohm) which is tie to RX1 (pin 44) and goes through pin 32 in the cable to the optical input.

R9 would be the digital balance input and has a 0.1uf cap connect to the RX0 (pin 42).
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Old 23rd April 2008, 02:00 AM   #3
rossl is offline rossl  United States
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Are you using the XLR input?

It may be easier to convert the XLR into a coax input. It is transformer coupled. Your plan would not be.

Build a special cable with coax on one end and XLR on the other, then change the 110R terminator resistor to 75R.
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Old 23rd April 2008, 03:45 AM   #4
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Quote:
Originally posted by rossl
Are you using the XLR input?

It may be easier to convert the XLR into a coax input. It is transformer coupled. Your plan would not be.

Build a special cable with coax on one end and XLR on the other, then change the 110R terminator resistor to 75R.
I will bypass the XLR and the 110ohm tranny of cause.
Converting 110R to 75R won't be very good for jitter, I believe.

I want a clean path if possible.
I see 2 digital input,
1. XLR->tranny-> 470R-> 0.1uf->AK4114 RX0, or
2. Optical in-> 470R -> AK4114 RX1

It would be great if someone confirm this and can be replaced by

BNC-> (75ohm across) -> digital tranny -> 0.1uf-> AK4114 RX0 or RX1

TIA.
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Old 23rd April 2008, 05:51 PM   #5
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It works. It is very simple. I solder a coax cable with signal to C15 and ground is C16, add a 75ohm and bnc or rca and I am done.
I believe the R9 (470ohm) will need to be remove too for correct 75ohm.

My 2nd deq2496 is making sound now using coax input (I kill the 1st one a while back).

Next mod, bypass the opamp for direct out!
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Old 28th April 2008, 03:45 PM   #6
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Here's a pic of the spdif direct mod.
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Old 28th April 2008, 03:48 PM   #7
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The 470ohm is removed.
I would say this is a really worth while mod for those that uses spdif.

The aux out is removed for the bnc connector. A C&D DA101 tranny added.
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