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Old 16th February 2011, 06:56 PM   #2981
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Quote:
The problem is that the DCX is basically a pro-audio positioned piece of equipment. Pro audio input and output levels are up to 14dB higher than home audio equipment. So if you mod your player, you have to keep on modding any other source you'll be using.
The output level is also too high so you'll have to turn it down more than ususal, and hopefully you don't overload your preamp/level control.
To use the DCX in an easy and flexible way in home hifi there's a lot to say for modding the DCX rather than the rest of your system.
Jan;
Thanks for your input. This system is a dedicated PA sound system for outdoor pyromusicals. The player will be the only source ever and the outputs will drive QSC amps. The only missmatch I have is with the player. With this applicashoin I think it best to mod the player not the DXC. I could use a level converter but would rather not have another box on a portible system.
Any thoughts on modding the CDMP-1400 player?
Andy
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Old 16th February 2011, 07:09 PM   #2982
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Quote:
Originally Posted by 4pyros View Post
Jan;
Thanks for your input. This system is a dedicated PA sound system for outdoor pyromusicals. The player will be the only source ever and the outputs will drive QSC amps. The only missmatch I have is with the player. With this applicashoin I think it best to mod the player not the DXC. I could use a level converter but would rather not have another box on a portible system.
Any thoughts on modding the CDMP-1400 player?
Andy
Yes of course, depends on the app. Just wanted to give my 2eurocents.
I don't know that player, but a schematic of the post DAC analog part should make it clear if/how that gain can be increased. Do you have any?

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Old 16th February 2011, 07:42 PM   #2983
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Jan; I am working on scaning a hand drawing, please stand by. Andy
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Old 16th February 2011, 07:59 PM   #2984
_Wim_ is offline _Wim_  Belgium
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Default Improve crosstalk on active output mod

Hi,

Over on the DCX yahoo forum I was discussing strange cross talk measurement result when measuring the DCX2496 (see also request of Jan some posts ago) with the acitve output mod from Jan

As it turns out, the lowered crosstalk is caused by the last low pass filter stage after the DAC (on the active outputboard). This filter stage can be easily removed by removing C29 to C31, and bypassing R45 to R50.

Results without low pass filter removed:

Test</STRONG>Digital Out / Analog in (out 1&2) @ 96kHzDigital Out / Analog in (out 3&4) @ 96kHzDigital Out / Analog in (out 5&6) @ 96kHzFrequency response (from 40 Hz to 15 kHz), dB:+0.10, -0.07+0.13, -0.08+0.14, -0.08Noise level, dB (A):-102.2-102.8-103.2Dynamic range, dB (A):102.0102.4103.0THD, %:0.00540.00530.0048IMD + Noise, %:0.00920.00910.0089Stereo crosstalk, dB:-59.8-59.6-59.6

Results with low pass filter removed:

Test</STRONG>Out 1 & 2 with C29 to C31 removed and R45 to R50 bypassedOut 3 & 4 with C29 to C31 removed and R45 to R50 bypassedOut 5 & 6 with C29 to C31 removed and R45 to R50 bypassedFrequency response (from 40 Hz to 15 kHz), dB:+0.09, -0.07+0.12, -0.08+0.14, -0.08Noise level, dB (A):-91.9-101.1-101.0Dynamic range, dB (A):91.9100.8100.8THD, %:0.00470.00440.0040IMD + Noise, %:0.0120.00910.0089Stereo crosstalk, dB:-97.8-98.8-99.9

This makes stereo image even better. Definitely worth a try!

P.S: don't mind the lower noise rating of out 1 & 2, probably some test wires were picking up some noise.
Attached Images
File Type: png original.png (11.1 KB, 282 views)
File Type: png low pass removed.png (12.8 KB, 281 views)

Last edited by _Wim_; 16th February 2011 at 08:23 PM.
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Old 16th February 2011, 08:53 PM   #2985
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Jan; Here is the output Section of the CDMP-1400 player and what I think will change the gain. Andy
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Old 17th February 2011, 08:57 AM   #2986
AndrewT is offline AndrewT  Scotland
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What are the supply voltages to the output opamps?
What is your existing maximum Vpk from the player?
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Old 17th February 2011, 11:35 AM   #2987
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Quote:
What are the supply voltages to the output opamps?
+/- 12 VDC
Quote:
What is your existing maximum Vpk from the player?
.15 VRMS into the output Section and .3 VRMS out
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Old 17th February 2011, 02:52 PM   #2988
AndrewT is offline AndrewT  Scotland
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+-12Vdc as the supply will limit your maximum peak output voltage to ~10Vpk if the loading is light.
Are you confirming that the peak output voltage of the player is 0.3Vrms ~ 0.424Vpk?

But if 0.3Vrms is an average reading or meter scaled to read out rms from an average then it is not the peak output of the player, unless you feed in a fixed test voltage and adjust the test signal until the output shows signs of clipping.
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Old 17th February 2011, 03:37 PM   #2989
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May I ask who knows a CD digital output, how to connect two DCX2496? I intend to use every DCX2496 mono. Simply engage in a "Y" cable to connect if not run properly, thank you!


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Old 17th February 2011, 03:46 PM   #2990
AndrewT is offline AndrewT  Scotland
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This appears to be the same question that was asked and answered a couple of weeks ago.
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