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Anyone using a DBX Drive Rack PA2 or Venu 360 crossover?

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Jazzman53

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If anyone is bi amp'ing their ML's with a Drive Rack PA2 or Venue 360; I have some questions about the setup.
 

Jazzman53

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I'm currently using a Behringer DCX crossover with my hybrid ESLs, but I'm considering a Drive Rack.

A friend who I built speakers for is using a Drive Rack PA2 to bi-amp them. The Drive Rack has a wonderful user interface and I really want to get one for myself. The downside is that we couldn't figure out how to get the auto-EQ function to stop changing the crossover frequencies. The Drive Rack's Auto EQ adjusts not only the EQ, but the crossover points also-- and it does it automatically.

We had the system setup for a three way crossover with subs crossing in at 65 Hz to the midbass woofer, and the midbass woofer crossing over to the panel at 265Hz. The problem is that the Drive Rack interprets the electrostat panel as a tweeter (apparently), and when we attempted to use the auto-EQ function, it adjusted the panel's crossover frequency all the way up to 2,700Hz!

So; my question is:
Is there a way to lock in the crossover points so that auto-EQ leaves them where we set them?
 
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JonFo

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Is there a way to lock in the crossover points so that auto-EQ leaves them where we set them?
Well, yes, do not use auto-EQ ;)

Seriously, it's best to do REW runs, and manually adjust the parametric EQ's, then re-measure. Auto-EQ is going to be confused by the dipole nature with all those delayed reflections and comb-filtering, it might over/under shoot targets.

With AudioArchitect software and Venue360, you might also be able to define a 'speaker' with pre-set XO values, and Auto-EQ might respect that.
I think the PA is too focused on it's DJ/PA role to be an effective permanent speaker processor. It can be made to work, but has quirks, as you are finding out.

In my 15+ years using DriveRacks, I have gotten to love them more and more. They are built like tanks, and the firmware is rock-stable. My 4800 is now 13 years old, stays on 24/7, and is functionally perfect. Never needs a reboot (like the DCX did).

So I recommend you you look at the Venue360, and use AudioArchitect software, there is even a nice used one for $400 on ProAudio Star right now,
 

Jazzman53

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Update: I've purchased a DBX Venu 360 and spent most of the weekend tweaking on my system. And it was quite easy to lock-out the crossover points from the auto-EQ. My system now sounds better than ever and I'm loving the Venu 360. I got the 360, and not the PA2, only because the 360 has a digital input, which I am using. This thing is fantastic!

I had been tri-amp'ing my system with a Behringer DEQ2496 EQ in tandem with a DCX2496. The Venu 360 replaced both of these.

Behringers get a bad rap but both of mine were dead quiet and worked perfectly for many years. However; I was never able to use their computer interface because their outdated serial ports wouldn't connect to my laptop, and using the front panel interfaces was downright tedious and clunky compared to the marvelous interface on the DBX, which I control in real time from the sofa using an Ipad.

I highly recommend the DBX Driveracks!
 

Jazzman53

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Congrats!

As you become more familiar with the UI, you'll like it more and more. Extremely flexible.

What kind of delay settings did you wind up with between panel and woofers?


Same here.
I will probably feel silly when I figure out how easy it would be to have the DBX automatically adjust the delays—but it wasn’t immediately apparent to me how to do that, so I did it manually, the old-school way:

  • Set the mic about 3 feet away and about equidistant height between panel & woofer.
  • Reversed the woofer connections to invert the phasing.
  • Played a test tone at the crossover frequency (265Hz), while eyeballing the response on the RTA.
  • Then manually adjusted delay until the RTA showed a max dip at the crossover frequency (max destructive interference from the phase inversion). I find it easier to find the dip with phasing reversed, than finding the center of the peak with drivers in phase.
I think I ended up with about 0.3ms difference between the panel and woofer.

What I really like was how easy it was to do the auto-EQ thing, compared to the Behringer DEQ2496. No more loud, obnoxious pink noise-- just a few 2-second frequency sweeps and it instantly overlaid about eight parametric EQ’s, which sounded wonderful right off the bat.

Later I was playing an old song by the Supremes and I could hear in the recording the studio reverb applied to the voices. For kicks, I turned off the delay and I could no longer discern the reverb and Diana Ross’s voice sounded kind of flat… but then came back to life when I turned the delay back on—the difference was amazing.

And then I discovered the sub harmonic synthesizer—marvelous for older recordings with anemic bass!

LOVE this thing!
 

JonFo

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I will probably feel silly when I figure out how easy it would be to have the DBX automatically adjust the delays
No worries, there is no auto mode for that. Your process is fine, and the results as I would expect. Funny how really small (relatively speaking) delay adjustments can make a noticeable difference.

I proved that to myself all over again adjusting the delays for the MidBass Modules, as a fraction of a millisecond, even with a baseline of 17ms, made a measurable and audible difference.
I used the Group Delay metric in REW to fine-tune, as the distances and room effects made other approaches more challenging.

Your approach of flipping polarity and looking for the dip is ingenious, well done.

And then I discovered the sub harmonic synthesizer—marvelous for older recordings with anemic bass!
Ah yes, a nifty feature, the DBX 120 rises from the dead in DSP form!
As a '70's Prog Rock fan, it comes in very handy on certain original recordings that were mastered for LP and the limitations of stereos of the day.
I had an iPad panel that allowed me to toggle the sub-synth on/off, but it was for an ancient version of an App Harmon published, but they dropped support of it back in 2017 or so.
Need to see if there is WebUI variant that might work.
 
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