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Author Topic: Replacing my DSP  (Read 5488 times)

Rob Spence

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Re: Replacing my DSP
« Reply #10 on: July 18, 2019, 12:22:38 am »

Today I fired up the dbx Venue360 and started configuring.
Of course it didnít have my speakers in its library but it did have similar amps (I use plx3402, 1602 & I chose 3602, 1802). I picked SRX722 as similar to my QRX212s and ran the configuration wizard. I then edited the crossover, PEQ & Limiter according to settings I got from EV (thanks for the email... it bounced but included the correct one - Technical.Support@us.bosch.com. They replied within a day!). I then compared it to the settings Evan K posted years ago and tomorrow will compare to what I had loaded into the Sabine (rebranded Xillica). Then, I will hook up my SMAART rig and compare the two and adjust as needed.

One thing I noticed on the dbx unit was a reduced level of precision on PEQ and crossover settings from what I am used to and the numbers EV gave me for an Ashley Protea.

It sure was nice to sit in my easy chair with my MacBook and connect via WiFi to do the configuration.
« Last Edit: July 18, 2019, 12:25:17 am by Rob Spence »
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Rob Spence

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Re: Replacing my DSP
« Reply #11 on: July 18, 2019, 12:29:03 am »

Why stop there? Use a dual channel analyzer and really verify -- magnitude and phase. An all-pass filter, or any non-minimum phase behavior, won't show up on an RTA. I would always want to do a final verification, including an acoustic one with a mic, no matter how sure I am of the settings. All the info may be perfect but I can still find a way to screw it up. Check the limiters with a voltmeter while you're at it.  And then sit back, play some nice music, and have a beer (or something) for the final verification  8)

--Frank

Yes, using the dual channel analyzer is the plan. Setting the rig up to listen will be a big job but you are right, it has to be done.
Perhaps left channel through old DSP and right to new and pan back and forth or something like that?

The beer, yup!
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David Sturzenbecher

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Re: Replacing my DSP
« Reply #12 on: July 18, 2019, 01:36:06 pm »

Yes, using the dual channel analyzer is the plan. Setting the rig up to listen will be a big job but you are right, it has to be done.
Perhaps left channel through old DSP and right to new and pan back and forth or something like that?

The beer, yup!

No, not like that. You donít need to set up the speakers either.  You need to take the transfer function of just the two DSP boxes. So your reference channel is what is going into the DSP and your measurement channel is what is coming out of each DSP output.
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Rob Spence

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Re: Replacing my DSP
« Reply #13 on: July 18, 2019, 02:38:51 pm »

No, not like that. You donít need to set up the speakers either.  You need to take the transfer function of just the two DSP boxes. So your reference channel is what is going into the DSP and your measurement channel is what is coming out of each DSP output.

What I did today was put pink noise (via SMAART) into the inputs of both DSPs.
I then used my old one for a reference and the new one as the measurement channel (I have a 2 channel SMAART setup with V7) on a MacBook.

The LF section looks great. Flat with good coherence. The HF is good to 2KhZ but then wacky after that. I am not sure how to move on from here.

My ignorance and lack of experience with SMAART is showing.

I have a screen shot of the HF capture. I will try and post it.
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Rob Spence

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Re: Replacing my DSP
« Reply #14 on: July 18, 2019, 02:44:06 pm »

Here is (I hope) a screen shot of the HF as seen in SMAART.
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Marc Sibilia

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Re: Replacing my DSP
« Reply #15 on: July 18, 2019, 02:52:22 pm »

Here is (I hope) a screen shot of the HF as seen in SMAART.

To me, that looks like a difference in latency between the two processors that is showing up in the phase plot.  You could adjust a delay in the faster processor to eliminate the shifting phase.
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Russell Ault

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Re: Replacing my DSP
« Reply #16 on: July 18, 2019, 03:03:55 pm »

To me, that looks like a difference in latency between the two processors that is showing up in the phase plot.  You could adjust a delay in the faster processor to eliminate the shifting phase.

Yup, a "stepped" coherence in Smaart is a tell-tale sign your measurement delay isn't set properly (as is, for the most part, the fact that it's set to 0.00).

-Russ
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Rob Spence

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Re: Replacing my DSP
« Reply #17 on: July 18, 2019, 03:06:30 pm »

Yup, a "stepped" coherence in Smaart is a tell-tale sign your measurement delay isn't set properly (as is, for the most part, the fact that it's set to 0.00).

-Russ
So, you are saying it should be zero?

I didn't check and it might have been from whenever I used it last.
« Last Edit: July 18, 2019, 03:09:25 pm by Rob Spence »
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Russell Ault

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Re: Replacing my DSP
« Reply #18 on: July 18, 2019, 06:21:40 pm »

So, you are saying it should be zero?

Sorry, no, that was unclear of me. Unless you're measuring cables or analogue gear, 0.00 means you've forgotten to set it/auto-find it.

The measurement delay in Smaart is there to make the measured and reference signals "line up" in time, i.e. it delays the reference signal to compensate for delay in the measurement signal. (When measuring something with a microphone, this delay is often largely caused by distance; when measuring a DSP, this delay is caused by latency.)

When the delay isn't set properly, the two signals don't line up, and Smaart goes a little nuts. Magnitude information may or may not survive this, but the phase trace will go haywire, and your coherence will drop in steps as each subsequent time window is further and further away from where it wants to be.

TL;DR - use the delay finder to find and compensate for your measurement's delay.

-Russ
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Tim McCulloch

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Re: Replacing my DSP
« Reply #19 on: July 18, 2019, 09:54:50 pm »

To expand a little, Rob, Russ is saying that without applying a delay to the reference signal, it will be "ahead" of the measurement signal by virtue of AD/DA conversion and latency created by the processing of the DR.

Use the delay finder.
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Re: Replacing my DSP
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