Modify behringer DEQ2496?

[stef1777]

Originally posted by ChuckT
Hi Stef,

I thought c33 decouples the ak4524 (although it shares the same 5V as ak4393).
I think it might be better to put a cap as close to the ak4393 as possible.

Also for the opamps output, only 2 of the opamps will be used if you don't use the "higher db output" button.

I should check this. I may be made a mistake. I just used my multimeter to check circuit.

Datasheet say 10uF/100nF between 16/17, and 18/19 from AK4393. C11 is the one between 16/17 (no 100nF). C32 is the 100nF between 18/19 (no 10uF).

Stef...

[stef1777]

Originally posted by stef1777



I should check this. I may be made a mistake. I just used my multimeter to check circuit.

Datasheet say 10uF/100nF between 16/17, and 18/19 from AK4393. C11 is the one between 16/17 (no 100nF). C32 is the 100nF between 18/19 (no 10uF).

Stef...

Sorry, C11 is for the DEQv1. With DEQv2, it is C15.

[stef1777]

Ok, I restarted the circuit as the v2 seems different from v1 DEQ.



The missing parts are the 100nF/10uF between pins 18 and 19, and 10uF between pins 1 and 2.

[DorinD]

Hello guys, I have a specific question on DEQ2496's features and I'm thinking maybe here I'll get the answer.

I intend to use the AUX analog out to delay a subwoofer with about 15ms. But, in the same time, I want to be sure that the digital out remains undelayed.

My concern is generated by the fact that AUX and digital outs are treated everywhere in the user manual as one block. And the Main analog out as the second block. Any of the first or the second block can be delayed one after the other but it is not clear if the delay is refering only at the analog outs or include also the digital out.

Hope you've got my point. Thank you very much!

[Yo_Azazel]

Hi,

Unless I remember wrongly, on the I/O menu, thrid page delays, you can choose to apply them to AUX (default) or MAIN.

When I choose MAIN, if I use the analog (main) outs I can hear the changes when changing delays settings, but when I use the digital outs, I have to choose AUX for the delay settings to be heard (and working).

So, as far as I see, and if I have got the point , you need to do it the other way around: plug your SW to the MAIN outs, delayed, and main system to the AUX (digital) out, undelayed.

Btw Stef, I am a fan of your work on the Behringer
I have one of mines now open (for whatever reason it had a DC output over 200mV on one channel and blew my Beta22 amplifier and my K701 headphones the damn thing) and will do some modding to it... I have some Lundahls around and looks like this will be the starting point (passive DAC out, this will keep me far from DC outs too).

[DorinD]

Thank you very much Azazel!

Not too bad in fact, I just need some cable adapters to switch between the two analog outputs.

Best regards,
Dorin

[Bernie7]

Just got a DEQ2496 with firmware v2.4 and I have been very pleased with the new-found control it gives me.

I have it connected between my preamp (Denon Pro DNA-7100) and power amp (Hypex UCD400HG) using the analogue XLR connections.

I find the output of the DEQ too high, so that at max listening levels, the input signal peaks are barely hitting -25dB on the VU meter. As I understand, this is way below the level for ADC to work at its best (ideally close to 0dB). I've already reduced the Gain setting in the Utility by -15dB and set the back button to 12dB

I've been able to reduce by a further 15 dB or so by turning the gain setting on the DYN menu for both channels to -15dB (with Threshold and Ratio at minimum). Does this in any way affect the audio beyond gain reduction?

Is there any other way to reduce the DEQ's voltage output by 20dB (including simple hardware changes that will not degrade audio quality?).

[sendler]

Originally Posted by Bernie7

Just got a DEQ2496 with firmware v2.4 and I have been very pleased with the new-found control it gives me.

I have it connected between my preamp (Denon Pro DNA-7100) and power amp (Hypex UCD400HG) using the analogue XLR connections.

I find the output of the DEQ too high, so that at max listening levels, the input signal peaks are barely hitting -25dB on the VU meter. As I understand, this is way below the level for ADC to work at its best (ideally close to 0dB). I've already reduced the Gain setting in the Utility by -15dB and set the back button to 12dB

I've been able to reduce by a further 15 dB or so by turning the gain setting on the DYN menu for both channels to -15dB (with Threshold and Ratio at minimum). Does this in any way affect the audio beyond gain reduction?

Is there any other way to reduce the DEQ's voltage output by 20dB (including simple hardware changes that will not degrade audio quality?).

The easiest thing you could do, at least temporarily to find out how it would sound, is to put the DEQ before the preamp. This would also allow you to try it with the digital in. Having volume control after the DEQ is the key to getting the best sound out of it so as to get the input level to just peak the meters at your desired listening level in order to maintain the maximum resolution in the analog to digital conversion. You may also need volume control before it as well to get the right input level. I use the SRC2496 in front of my DEQ as it has an analog input level control that the DEQ lacks but then again, I don't listen to my turntable or tuner much any more so analog source quality isn't a big priority for me. I mainly use the digital in. Beyond this you would need circuit mods inside the Behringer.

[Bernie7]

Originally Posted by sendler

The easiest thing you could do, at least temporarily to find out how it would sound, is to put the DEQ before the preamp. This would also allow you to try it with the digital in. Having volume control after the DEQ is the key to getting the best sound out of it so as to get the input level to just peak the meters at your desired listening level in order to maintain the maximum resolution in the analog to digital conversion. You may also need volume control before it as well to get the right input level. I use the SRC2496 in front of my DEQ as it has an analog input level control that the DEQ lacks but then again, I don't listen to my turntable or tuner much any more so analog source quality isn't a big priority for me. I mainly use the digital in. Beyond this you would need circuit mods inside the Behringer.

Scott, thanks for your suggestions. I've yet to hear how the set sounds with the DEQ pre-preamp so I'll give it a try one day - my gear is snuggly nestled in my sideboard and re-connections are not to be lightly attempted

Yes there are advantages to having the DEQ between the source & preamp. This way it can do its work entirely in the digital domain too without doing the ADC thing.

However, my preamp is actually a 7.1 pre pro so I have several digital sources to be EQ'd - a CDP, NMT (media server), DVDP and digital radio tuner. Or maybe get a multi s/pdif selector box (is there such a thing?)

There's yet a third way - I've connected my pre pro's optical O/P into the DEQ and used the DEQ's Gain Setting as volume control! The volume levels are actually quite feasible for my setup - moderately loud, louder or deafening This could eliminate the preamp for a single digital source stereo setup

I'd still like to know what the hardware mod would be like to attenuate the DEQ's ouput.