ADC for DEQ2496 input - Page 3 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd October 2012, 03:38 PM   #21
Ryssen is online now Ryssen  Sweden
diyAudio Member
 
Ryssen's Avatar
 
Join Date: Dec 2003
Location: Sweden--> Here
Quote:
I'm making a website to sell my DEQ and DCX mods for analog inputs and outputs at the moment
Please post the adress to the site when it´s finnished.
__________________
Regards Åke
  Reply With Quote
Old 24th October 2012, 04:47 PM   #22
diyAudio Member
 
Shadydave's Avatar
 
Join Date: Jun 2012
Location: Appalachia, in the middle of nowhere.
Default DCX2496 outputs, voltage divider for level control?

A little off topic, but as the OP I thought this may be a good place to post as it gives me continuity.
If i need to start a new thread, please let me know.
.
I presently am using the digital output from my satellite receiver to feed the DEQ's S/PDIF input.
I also can hook up my CD player to the AES/EBU input, but my DVD player has only analog outs (figure that out later).
The DCX is fed from the DEQ with an AES/EBU cable and then the analog outputs to my amps.
I presently have to control levels at each amp
I will say that using the full output voltage from the DCX, and then attenuating at the amps does not sound all that bad.
It is however a pain in the.... .
I am trying to decide whether to buy the Pilgham 6 channel volume control or just do a cap output and some PS upgrades.
.
It really would be nice to have a 6 channel volume control.
It would also be nice if the volume control did not require major mods to the DCX so when the DCX inevitably smokes I can easily transfer the volume control to a new unit.
A capacitor output mod can be rather easily transferred but the Pilgham 6 channel volume control is not all that easy to transfer.
.
I am running 2 top/midrange boxes, 2 mid bass boxes and plan to have 2 subs (only one now), so I will use 6 channels out of the DCX.
.
I found a 6 gang, motorized, remote controllable ALPS potentiometer that was manufactured as a Hi-Fi volume control.
Does anyone see a problem using this as a voltage divider to control the output levels of the DCX 2496 ?
.
The obvious way to do this would be to use it single ended, wiring the pot between + and ground, shunting - and taking the signal from the wiper of the pot.
I realize that I may have to use some (high quality) buffers to prevent the amp input impedance from entering into the equation.
.
I was thinking of making a 1 space rack mount box housing the volume control with XLR pigtails coming out to plug into the DCX and 6 chassis mount connectors for connecting amps.
I could also install some trimming potentiometers to balance all the channels.
.
I believe the DCX 2496 can tolerate the 10K load with no problems.
.
Any comments?

Dave
  Reply With Quote
Old 24th October 2012, 05:12 PM   #23
Davey is offline Davey  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Bremerton, WA.
Dave,

Would this interest you?

MSB DACs

This is a terrific unit that I've been using with my (unmodified) DCX for many years.

Dave.
  Reply With Quote
Old 24th October 2012, 05:48 PM   #24
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
MSB looks good at the new price.

Where did one find the 6-gang ALPs??
  Reply With Quote
Old 24th October 2012, 06:52 PM   #25
diyAudio Member
 
Shadydave's Avatar
 
Join Date: Jun 2012
Location: Appalachia, in the middle of nowhere.
Default attenuators

Davey,
That MSB attenuator looks very interesting.
I have been all over the internet looking for stuff like that, I guess Google doesn't work well.
.
RNMarsh,
EBAY, from a store called "Familygate"
No it's not about that incident with my family

6 10K pots with stepper motor, IR remote driver available
Click the image to open in full size.
It has a D-log taper but who cares as it is not a fader, just a volume control.
Hope I can figure out how to wire it......Doh
.
Also, here is the analog equivalent of the MSB

Click the image to open in full size.

Or should I buy 3 of these bad boys. Only $771 Each.
What people wont do for SQ.

Click the image to open in full size.

Davey, thanks for the MSB link,

Dave
  Reply With Quote
Old 26th October 2012, 07:57 PM   #26
diyAudio Member
 
Join Date: Jan 2008
I’ve got a DEQ2496, date code: 0303. I bought it used, never been inside it. Its capabilities as a live device are of some merit, but all the filters may be generated in software elsewhere.

Referencing is all about absolute levels.

Single sine wave signal as digital is normalized to full bit depth, FFT spectrum is referenced to 0 dBFS. A two sine signal full scale signal will have two peaks at –6dB.

In your DacMagic, DEQ2496, to M-Audio Fast Track Ultra loop an IMD sideband –95dB could only be excessive from an electrical engineering standpoint. This is completely beyond limits of human perception, and orders of magnitude beyond performance of speaker transducers.


I’ve got an E-MU 0404 USB box that serves me fairly well. Manufacture specs are easy to duplicate/beat using loopback of analog out to analog in, microphone gain set to 0dB.

The output pot is adjusted for –1.0dB peak using 1kHz full scale sine fs 96kHz 24bit wave file. Resultant spectrum:

1 1kHz sine fs96 spectrum.jpg

Zoom:

1 1kHz sine fs96 spectrum zoom.jpg

On surface E-MU is in same ballpark as DacMagic:

Click the image to open in full size.

Fig.10 Cambridge DacMagic, Steep filter, balanced output, HF intermodulation spectrum, 19+20kHz at 0dBFS peak into 100k ohms, 24-bit data (left channel blue, right red; linear frequency scale). Stereophile pictures and captions



E-MU for comparison:

2 IMD emu 19k 20k.jpg

Zoom:

2 IMD emu 19k 20k zoom.jpg

E-MU side bands aren’t much higher than DacMagic, but getting close to Davey’s excessive point!

With E-MU and DEQ2496 it is possible to set up ditital loop, and demonstrate bit perfect behavior, so it is possible to look at E-MU analog out, DEQ analog input pair, and look at DEQ analog output, E-MU analog input pair separately from E-MU, DEQ, E-MU analog loop.

The results are scary:

3 IMD DEQ analog input.jpg

DEQ2496 analog input fed is by E-MU output, with same levels as for E-MU loopback with itself.

Digitally fed DEQ with analog output to E-MU: DEQ2496 output levels are higher, and lowering output from DAW and from DEQ utility menu produce similar results:

4 IMD DEQ analog output.jpg

Not pretty.

Regards,

Andrew
  Reply With Quote
Old 31st October 2012, 06:08 PM   #27
Tenson is offline Tenson  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: Kent
Thanks for the posting Andrew. It's good to see your results show the same shortcomings as mine do for the DEQ.

Anyway, as I said I have made some boards to improve the analog inputs and outputs of the DEQ / DCX and I've set-up a website to offer an upgrade service. Behringer Mods Home
  Reply With Quote
Old 1st November 2012, 05:52 AM   #28
diyAudio Member
 
Join Date: Jan 2008
Standard v Modified picture of 1kHz sine show power line issues that I don't have:

Click the image to open in full size.

My DEQ2496 as analog insert:

1kHz no imd.png

Evident in your setup are intermodulation components riding 1kHz. Likely present in original, but hidden by plot of mod results.

Two tone IMD doesn't reveal odd order components.

Three tone IMD (Bob Cordell) provides slightly more challenging signal, and more in band components:

IMD 2 tone v 3 tone clean power.png

Regards,

Andrew
  Reply With Quote
Old 1st November 2012, 02:13 PM   #29
Tenson is offline Tenson  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: Kent
Hi Andrew,

The power line issues are to do with grounding between the PC + soundcard and the DEQ. It will change in each persons setup. I think how well an output stage isolates itself from that noise is interesting to see though. The superior CMRR of the modded output stage is likely making the improvement.

The 1KHz side bands are interesting as I've seen them on all the DEQs I've measured, modded and un-modded. I think they are jitter. I'd like to know why yours doesn't have them!
  Reply With Quote
Old 1st November 2012, 03:20 PM   #30
diyAudio Member
 
Join Date: Jan 2008
Side bands in your pictures appear about +/-150Hz; Could be 3rd harmonic of power supply. Yes, given Behringer, I am amazed that I don't have them.

Is DEQ2496 SMPS?

On another note; with DCX2496 how hard to get digital out, and clock synching instead of SRC input? Gotta be some DAC heads that would like this.

Andrew
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
4 spdif input adc? paleorama Digital Line Level 6 10th December 2010 05:56 AM
Coax input deq2496 ChuckT Digital Source 6 28th April 2008 03:48 PM
DEQ2496, then input info into a DCX2496? mazeroth Digital Line Level 1 21st September 2005 05:25 AM
Suggestions on nonlinear ADC input CeramicMan Digital Source 2 11th February 2004 09:41 PM
ADC input stage, using transformers instead Mark Hathaway Digital Source 17 4th May 2003 10:12 AM


New To Site? Need Help?

All times are GMT. The time now is 05:33 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2