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Quick measurements of dbx DriveRack PA2 speaker management system

pkane

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PA2 is a nice little box designed for quick and easy setup of a speaker system with adjustable crossover, automatic room correction, PEQ and GEQ, delay and gain adjustments, as well as feedback cancellation (notch filters). The box has a reasonably easy, pro-looking interface but the ability to control all its functions from a mobile phone, a tablet, or a Mac or a PC makes it really easy to use. To do this, an ethernet connection to the network is required. List price seems to be $439, but I bought mine 'open box' for less than half that.

This is a 2 analog inputs to 6 analog outputs device. Internally, input is converted to digital, processed through DSP pipeline, and then converted back to analog. All inputs/outputs are balanced on XLR.

1592335652214.png


Tested with Element24 as DAC and ADC, and REW to capture measurements.

First, no DSP selected, just straight-through ADC/DAC conversion:

1kHz sine-wave @24/96kHz:
1592332867129.png



Not a bad performance, THD is below -110dB, THD+N at -94dB.

Frequency response (red) and phase:
1592333206850.png



Distortion vs. Level:
1592334008810.png


Distortion vs Frequency:
1592334409382.png


Combination of antialiasing/reconstruction filters (ADC/DAC):
1592334671486.png



Multitone test:
1592334965417.png


And J-Test (jitter):

1592335315149.png


Overall, I find this performance to be quite acceptable for managing speaker output!
 

Blumlein 88

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Glad to see you post measurements of this. I've had one in mind for some time. So many potential uses. Could have hoped for a little better noise performance, but for many purposes it looks like it would be good enough. Looks ideal for doing 3-way digital crossover to speakers.
 
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pkane

pkane

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Glad to see you post measurements of this. I've had one in mind for some time. So many potential uses. Could have hoped for a little better noise performance, but for many purposes it looks like it would be good enough. Looks ideal for doing 3-way digital crossover to speakers.

Yeah, at -94dB the noise could be better, but it's still lower than some high-end audiophile DACs :)
 

naagratrax

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It's look really good guys and transparent ! Do you think if the Venue 360 have a better specs ? in comparaison with DEQ 2496 with analog in/out it's better ?
 

Neddy

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Thanks for the measurements!
I've been wondering the same thing.
One of the Harman support techs told me the 360 was a fresh hardware design (same UI software, it would appear, though), but didn't ask 'from what' (presumably from the 260?)
Published specs for it are a tad better than measured above, but look about the same as PA2.
I'm running my Venu360 via AES (main) outputs from the OktoDAC, so that should take the A-D part of it out of the equation.
Venu also does 96khz sample rate.
Not hard to find used ones in good condition for around $500, at least in the US.
PS. I leave the RTA mic connected, on a stand, next to my listening chair all the time - fun to be able to 'see' what's coming in and going out!
 
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pkane

pkane

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It's look really good guys and transparent ! Do you think if the Venue 360 have a better specs ? in comparaison with DEQ 2496 with analog in/out it's better ?

I measured DEQ2496 previously. Here are the analog and the digital results. Digital is clean and transparent (which is how I used it), but analog is pretty noisy and with high levels of IMD and HD.
 
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pkane

pkane

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Thanks for the measurements!
I've been wondering the same thing.
One of the Harman support techs told me the 360 was a fresh hardware design (same UI software, it would appear, though), but didn't ask 'from what' (presumably from the 260?)
Published specs for it are a tad better than measured above, but look about the same as PA2.
I'm running my Venu360 via AES (main) outputs from the OktoDAC, so that should take the A-D part of it out of the equation.
Venu also does 96khz sample rate.
Not hard to find used ones in good condition for around $500, at least in the US.
PS. I leave the RTA mic connected, on a stand, next to my listening chair all the time - fun to be able to 'see' what's coming in and going out!

Venu does look like an updated version of PA2. I like that you can bypass the analog conversion by feeding it AES digital signal. This should improve analog performance even with no other changes.
 
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pkane

pkane

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Wanted to see what the subharmonic synthesis setting really does to the frequency response. Here are a few tests.

1592410361290.png


Subharmonic enhancement turned off, test signal is 30Hz + 60Hz + 120Hz sinewaves:

1592409068861.png



Subharmonic enhancement turned on: Level=10%, 36-56Hz=10%, 24-36%=0%:

1592409195260.png


Subharmonic enhancement Level=50%, 36-56Hz=10%, 24-36%=0%:

1592409246029.png


Subharmonic enhancement Level=10%, 36-56Hz=50%, 24-36%=0%:
1592409314022.png



Subharmonic enhancement Level=10%, 36-56Hz=0%, 24-36%=50%:

1592409413211.png



Subharmonic enhancement Level=10%, 36-56Hz=50%, 24-36%=50%:
1592409434929.png



Subharmonic enhancement Level=50%, 36-56Hz=50%, 24-36%=50%:

1592409510289.png
 
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Javs

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Hi,

Thanks for doing this. I have this unit and used it to replace my MiniDSP HD units.

Am I reading that distortion vs level graph right that I really dont want to go past roughly -4dbFS on the outputs? Distortion seems to skyrocket right after that, and it looks like your measurement doesn't quite reach -0dbFS either?

Is that right?
 
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pkane

pkane

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Hi,

Thanks for doing this. I have this unit and used it to replace my MiniDSP HD units.

Am I reading that distortion vs level graph right that I really dont want to go past roughly -4dbFS on the outputs? Distortion seems to skyrocket right after that, and it looks like your measurement doesn't quite reach -0dbFS either?

Is that right?

Remember that PA2 is analog in and out, so there’s no concept of 0dBFS, just analog voltages. Since voltage was generated by Element24 and measured by Element24, the clipping was caused by it.
 
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Neddy

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Thanks for the sub-synth tests - I'd always been curious what exactly it did.
I use it for pretty much all vintage tracks that were 'mastered for vinyl'; basically anything from before the 80s, and for the most part it does a really nice job of re-creating those bottom octaves, and in a few cases really 'makes' the recording!
 

ol_mcdonald

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I’ve been using the PA2 for a few months now, creating an output
for my sub and using dsp to crossover my bi amped mains.

Nice UI (on Mac), easy to set up, does exactly what I needed.

Likewise I would liked to have seen better noise figures but I can’t say I have even noticed! Mine is totally silent as best I can tell.

I believe I read somewhere they use a proprietary dbx ADC/DAC, is that the case? If not, what does it use? How would this units numbers play into the use of an external high end DAC that would be placed before the dbx in the signal chain? (Forgive my ignorance) for instance, say Ihave a DAC with 120 db sinad, would quality be reduced to the dbx specs when output to my amplifiers? What happens? Sorry for the noob questions. Here to learn!
 
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pkane

pkane

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How would this units numbers play into the use of an external high end DAC that would be placed before the dbx in the signal chain? (Forgive my ignorance) for instance, say Ihave a DAC with 120 db sinad, would quality be reduced to the dbx specs when output to my amplifiers? What happens? Sorry for the noob questions. Here to learn!

PA2 doesn't have a digital path through it, so analog inputs are converted to digital, processed, and then converted back. There's no way to avoid the ADC/DAC cycle, which means whatever distortion and noise it adds will be added on top of whatever is there at the input. Now, these may add up in different ways, but ultimately, if you put in the output of a DAC that's fairly clean, say 120dB SINAD, you'll likely get, at best, a 94dB SINAD out of PA2. Not that this is a poor result by any means: it's better than most amplifiers can deliver. Some newer dbx models allow all digital processing, without the analog conversion. So you could use a really good DAC after the unit, if you feel that a very high SINAD is a must. Personally, I wouldn't worry about it.
 

dougi

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Thanks for the measurements. I've been considering this, the dcx2496 or another DSP crossover solution. Ended up ordering minidsp nanodigi plus topping E30 dacs. One reason so that I don't have to physically turn anything on so better integrates with the rest of the system for WAF.
 

AdamG247

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danielbaen

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Thank you, sorry for not introducing me in a post. My English is very basic and I don't trust Google translate very much.
 

KA7NIQ

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I bought a Driverack PA2, but I have yet to hook it up. I had to buy a tablet for the remote control feature. I also have a couple of Onkyo receivers, one has Audyssey XT 32, and the other has the latest AccuEQ. I THOUGHT I would have more control over Audyssey XT 32, but the Audyssey Controller App only works with Denon, not Onkyo. Does anyone know of any tests done of the Driverack PA2 vs other room correction schemes ?
 

CHOKSTARmusic

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Do you think if I get Driverack PA2 to set a crossover for my Sonodyne SM300 and Sonodyne SLF 312 Sub, will I notice any audible transparency loss?
 
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