Home » Forums » Specific Product Questions » DAC1 PRE / DAC1 HDR

connecting DAC1 HDR to 3 way active crossover

connecting DAC1 HDR to 3 way active crossover

Submitted by tangofish on Fri, 2012-01-27 13:41
Hello!
Can you please help me with some technical advice? I intend to conenct my DAC1 HDR to a 3 way active crossover.
 
I am wondering if better performace/device matching may be achived by conecting the DAC1 BALANCED outputs to the DBX Unbalanced inputs rather than by simply connecting the unbalanced output to unbalanced input?
 
If so, what cable and DAC configureation/wiring would be need?
 
 
The my crossover is a dbx 234 (unbalanced) and the input specs are as follows:
 
Connectors: 1/4” TRS
Type: unbalanced, RF filtered
Impedance: > 25 kΩ
Max Input Level: +22 dBu typical
CMRR: >40 dB, typically > 55 dB at 1 kHz
 
 
In my setup the DAC crossover input/output cable interlinks would about 30cm max.
 
Thank you!

 

‹ question for some budget monitor speakers for dac 1 pre DAC1 HDR REMOTE CONTROL ›

Sub integration

Submitted by compcond on Mon, 2012-01-30 19:25.

I'm in kind of the same boat.  My Hsu "High-End Crossover" doesn't like the HDR so I'm kind of stuck.

I purchased a pair of XLR to RCA cables from BlueJeans Cables (pin 3 floating, thank you) so I have the RCA outputs going to my CJ amp and the XLR outputs going to the sub.

I also purchased a pair of Harrison Labs 12db/100Hz in-line passive crossovers which I should have in a few days and hope they won't screw up the mains too much.

Keeping in mind I have no idea what I'm talking about, I doubt you'll hear much of a difference between running balanced as unbalanced and just running unbalanced.  I suspect you're going to have far more degredation due to the dbx than anything else

 What sort of problems did

Submitted by EliasGwinn on Thu, 2012-02-02 12:54.

 What sort of problems did you have connecting the HDR to the Hsu crossover?  

Best,

Elias

Hsu

Submitted by compcond on Thu, 2012-02-02 13:01.

There were not so subtle scratching noises, first only on the right channel and then on both.  As soon as I pressed the "bypass" button on the Hsu the noises stopped.

Mine was 10 years old so I ordered a new one and had the same problem.  The Hsu had no issues with the C-J SC26 preamp but just didn't like the Benchmark.

 Tangofish, From your specs,

Submitted by EliasGwinn on Thu, 2012-02-02 12:53.

 Tangofish,

From your specs, it seems that your crossover will take balanced (TRS) inputs.  So you can simply use a XLR-to-TRS cable like this:

http://store.haveinc.com/c-1651-xlr-female-to-trs-male.aspx 

Best,

Elias

Dear Elias, Thank you for

Submitted by tangofish on Thu, 2012-02-02 14:40.

Dear Elias,

Thank you for your enlightening reply; today is a red letter day for me! Seems I've misread the specs on the crosover & I was under the impression it was an unbalanced unit (as this is what I was told when I bought it) now I see that this may not be so...

The "TRS differentially balanced" specs on the crossover are:

impedance > 50 kΩ / max level input +22 dBu typical

With the XLR-TRS cable you've mentioned will I need to do anything special with the impedance attenuators on the DAC XLR outputs?

Thanks again!

 

DAC1 Attenuator Settings - feeding DBX 234 Active Crossover

Submitted by JohnSiau on Thu, 2012-02-02 15:44.

The DBX 234 will perform best when driven at nearly +20 dBu.  This is a high signal level, but the DAC1 converters are well suited to this task.  The maximum output level from the DAC1 converters is 27 dBu in variable made, and +29 dBu in calibrated mode (attenuators set to 0 dB).   The 10 dB pads will be required when driving the DBX 234.

If you are using the front-panel volume control on the DAC1, set the attenuators to 10 dB.  This will reduce the peak output of the DAC1 to +17 dBu at full volume.  This will leave about 4 dB headroom in the DBX.  Excessive headroom will reduce the SNR through the DBX, so we want the headroom to be reasonably close to 0 dB.  You should be able to set the input gain of the DBX to +4 dB to remove the excess headroom.

If you are using the "calibrated" (fixed-gain) mode on the DAC1, set the attenuators to 10 dB.  This will set the DAC1 outputs at +14 dB peak (if the trimmers are still at their factory calibrated settings).  This will leave 7 dB headroom in the DBX.  You should be able to set the input gain of the DBX to +7 dB to remove the excess headroom.

The DBX is equipped with output gain controls.  If possible, set these near 0 dB and reduce the gain of your power amplifier.

will be using the front-panel

Submitted by tangofish on Mon, 2012-02-06 18:17.

I am using the front-panel controls on the DAC1. The DBX input gain can be set to +/-12 db so setting to +4 db was trivial, your advice is sound (no pun intended).

I've made my own set of XLR-TRS cables and set the HDR XLR output pads to -10db. The system works just fine and sounds much better (for whatever that means) than the line outs did with the dbx.

Custom XLR->TRS interconenctors.

Submitted by tangofish on Mon, 2012-02-06 18:18.

It may be interesting to note, when I made up the inteconnectors, I've connected the cable shild to pin 1 on the XLR and the sleve on the 1/4" plug. Many standard cabling charts reccomended leaving the sheild unconnected on the 1/4" plug (signal exit side of the cable) but I was getting very light hum. I connected it on both sides and the system is totally dead quiet now.

 Thank you very much John and Elias!

 

Crossover

Submitted by compcond on Mon, 2012-02-06 18:28.

Now that you're all done you may want to toss it all.

I purchased a set of 100Hz 12db/octive high-pass crossovers from Harrison labs and they sound amazing.  Virtually no loss compared with running direct.  Beats the living snot out of the HSU and ran $39 with shipping. ($459 for the Hsu)

I also purchased a pair of 10' XLR to RCA cables from Blue Jeans Cable for the sub and they left pin 3 floating, as per Benchmark's directions.  The HDR feeds both outputs simultaneously and the sub already has a 24db/octive low-pass built-in.

Total cost was $110 not including the 1M MIT AVT1 cables, I lost a box, there are no turn-on thumps, and the clarity will absolutely blow away your dbx crossover (it's an active device... there has to be some loss)

I'm a very picky SOB when it comes to audio; a very happy one at the moment.

Hex-Amped.

Submitted by tangofish on Tue, 2012-02-07 15:04.

Hi Compcond,

Unfortunately my system is a Hex-Amp setup (I have 6 independent mono block amps) so passive corossovers would introduce a load of inductors into the signal path and would be contrairiy to my efforts to reduce any and all uneccesary weird loads (and parts) between the amps and my drivers. Not the cheapest way to go, but this is the way I'm going.

I noticed you mentioned that your sub has a 24db/octive lo-pass filter, I can't help but mention this sounds like it may actually be an active device (passive devices seldom cut-off steeper than 12db/oct)?

Power on thumps are not a problem for me if the crossover comes 'on' before and 'off' after the amps.

best,

Tangofish.

 

Actively weird

Submitted by compcond on Tue, 2012-02-07 15:58.

You are correct.  I am running XLR to RCA cables to the sub which has a built-in active 24db/octive crossover.

The Harrison 12db/octive filters are high-pass to the C-J main amp.

I still suspect, however, that the dbx crossover may be thwarting your efforts to audiophile nirvana.  The Hsu completely destroyed the Benchmark magic.