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Author Topic: DSP delay testing [solved]  (Read 3759 times)

jacqlan111

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DSP delay testing [solved]
« on: July 14, 2012, 09:43:28 pm »

Hi,
Since a couple of months, I'm using the MC's DSP tools to mix 8 channel outputs, building crossovers between Sub, woofers, mids and tweeters and doing frequencies corrections, all with MC EQs.  Everything is allmost working fine, including the Asio URL allowing the Room EQ Wizard (REW) to get sweep signals through MC.
I can play with high/low-pass frequencies and slopes optimizing "XO" phases with great success.

Though, I am not able to perform any delay settings.  I don't know what I'm doing wrong here, I tried to fix several time delays without any effects on phase or IR responses?  I'm actually using the 2 EQs, 1 for frequency corrections and 1 for channel mixing and XO settings.  I tried delays in both...
Should be as simple as the other operations.. ?
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Matt

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Re: DSP delay testing
« Reply #1 on: July 14, 2012, 09:50:04 pm »

As a test, I just added a delay using Parametric Equalizer to a single channel.

Even at 50ms it's immediately obvious.  I also tested 5000ms (5 seconds), and it makes it sound like a round.

So it seems to be working for me.  Anyone else?  Any other clues?
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Matt Ashland, JRiver Media Center

jacqlan111

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Re: DSP delay testing
« Reply #2 on: July 15, 2012, 10:07:33 am »

I was WRONG, false info
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jacqlan111

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Re: DSP delay testing
« Reply #3 on: July 16, 2012, 08:29:43 pm »

As a test, I just added a delay using Parametric Equalizer to a single channel.

Even at 50ms it's immediately obvious.  I also tested 5000ms (5 seconds), and it makes it sound like a round.

So it seems to be working for me.  Anyone else?  Any other clues?

OK I found my real "BIG" mistake.

The left channel was still checked and as it is used for time reference in REW, the delays where then eliminated.

Still a significant variability in measurements, and the scale of delays in ms is not fitting with applied delays numbers.  This can be hazardous, which setting could cause these variations?.
 Is it better to use distance delays in room correction or ms delays in EQs?
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Matt

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Re: DSP delay testing
« Reply #4 on: July 16, 2012, 10:07:16 pm »

Still a significant variability in measurements, and the scale of delays in ms is not fitting with applied delays numbers.

I don't think I understand what you mean.

You can enter decimals, so there's no limit to precision (other than 1 / sample rate).


Quote
Is it better to use distance delays in room correction or ms delays in EQs?

I personally set the distances in Room Correction, and also the levels.
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jacqlan111

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Re: DSP delay testing
« Reply #5 on: July 17, 2012, 03:21:04 pm »

problem with images

I will have to come back later,
I don't know how to delete
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jacqlan111

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Re: DSP delay testing
« Reply #6 on: July 18, 2012, 10:50:11 am »

I don't think I understand what you mean.

Sorry for my delay ;)
Now I can say that the time reference channel can go through MC17 witout problem.  If the measured channel in REW has a delay variation, it will show it exactly where it should be.
Then my second mistake that produces variations in measurements was from a bad volume leveling of the reference channel, a lot to low.

The image shows  0, 5 and 10 ms delays for the right woofer.  So the rest should be OK now.

thanks for the interest
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EarlK

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Re: DSP delay testing [solved]
« Reply #7 on: July 19, 2012, 12:18:41 am »

 Jacques, I'm glad that you have worked this out !   

<> EarlK
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jacqlan111

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Re: DSP delay testing [solved]
« Reply #8 on: July 20, 2012, 08:12:18 pm »

Jacques, I'm glad that you have worked this out !  

<> EarlK
thanks  8)
 I thought it may be a good idea to show the EQ commands

EQ1 is only for frequency EQ

EQ2;
1- copy right to subwoofer
2- copy left to subwoofer  (1 and 2 brings the signals to 1 subwoofer)
3- copy left to center
4- copy right to center (3 and 4 brings signals to the time reference physical loopback "one at the time" for REW measurements)
5- copy left to RL
6- copy right to RR (5 and 6 brings the signals to woofers)
7- copy left to SL
8- copy right to SR (7 and 8 brings the signals to tweeters)
9- high-pass at 15hz (sub) 24db/oct (low cut for subwoofer)
10- low-pass at 60hz (sub) 48db/oct (high cut for subwoofer "XO")
11- high-pass at 50hz (RL-RR) 48db/oct (low cut for woofers "XO")
12- low-pass at 150hz (RL-RR) 48db/oct (high cut for woofers "XO")
13- high-pass at 120hz (right-left) 36db/oct (low cut for mids "XO")
14- low-pass at 4000hz (left-right) 36db/oct (high cut for mids "XO")
15- high-pass at 3500hz SL-SR) 36db/oct (low cut for tweeters "XO")
16- low-pass at 20000 (SL-SR)  36db/oct (high cut for tweeters "XO")
17- delay 0ms (RR)  right woofer
18- delay 0.5ms (RL)  left woofer
19- delay 9.7ms (right) right mids
20- delay 9.7ms (left) left mids
21- delay 3ms (SL) left tweeter
22- delay 6ms (SR) right tweeter

here is 2 images for sub/woofer "XO" and phase
and 2 for woofer/mids.,,,

I wish that some readers will tell me if inappropriate commands are listed.

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JustinM

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Re: DSP delay testing [solved]
« Reply #9 on: July 20, 2012, 10:51:57 pm »

Awsome!  I'm also interested in trying this type of setup. So far I've been using REW/ Babyface for measurement to tweek a mid-Hi / subwoofer (bi-amped with electonic xo) set-up. I have a bunch of Questions  :)
- My only fear in going to a completely digital xo is the fear of playing audio outside JRiver.  EG: audio from web browsing blowing a tweeter.  Have you addressed this ??
- how are your xo, delay and eq settings in JRiver used while measuring in REW ?? I'm guessing it has something to do with your "center chnl" output that your looping back in.
 - Did you start with a passive xo ? Hows the JRiver xo setup sound?? :)
I'd be interested in hearing more on your setup and gear.

cheers.
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jacqlan111

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Re: DSP delay testing [solved]
« Reply #10 on: July 21, 2012, 03:08:48 pm »

I have rearranged the format as noted
- My only fear in going to a completely digital xo is the fear of playing audio outside JRiver.  EG: audio from web browsing blowing a tweeter.  Have you addressed this ??
I addressed it in a way that I don't web outside MC17 for music, anyway no sound goes to my RME sound card but JRiver...  My tweeters are on ch 7-8 and only ch1-2 are awake when I play something on the JRiver web-media option .  I did not went further than that and I feel safe within JRiver unless I change the tweeters lower cut accidentally :o.  This question is however frequently asked.  You can search on this forum
- how are your xo, delay and eq settings in JRiver used while measuring in REW ?? I'm guessing it has something to do with your "center chnl" output that your looping back in.

Yes the URL live://asio loopback enables the REW signal to go through JRiver's and all the EQ settings you want to measure the effect on the signal.  I have to use the URL live://asio because I run on win XP.  I need the help of "VAC" virtual audio cable to complete the connection and a physical loopback from my time reference "center channel"dac output connected to the left mic input (the right input is for the MIC).  This is possible because I use 4 separate dacs, one for each 2 digital RME card output pairs. A standard sound card will allowed the physical loopback easily.  Otherwise a multi-output dac is needed.  If you are on win7 you can refer to this topic "WASAPI Loopback (experimental feature)" and use (live://loopback).

- Did you start with a passive xo ?
No I started with a Linn aktiv multi-amp system and slowly I got the Linn system cards away

Hows the JRiver xo setup sound?? :)
The sound is now much ahead of what it was in the  Linn's aktiv system because I'm using DIY open baffles for mid and tweeters which the Linn's active card where not design for, now with the complete control of XO and other parameters I  did the best tuning I could.
I'd be interested in hearing more on your setup and gear.

I guess it is not the best place to describes it and show pictures (unless "moderator" as no objection ??)  I would be glad to answer any questions.
 a bi-amp would be a lot simpler to build, however 2 or 4 makes not  much differences except for gear pricing.
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JimH

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Re: DSP delay testing [solved]
« Reply #11 on: July 21, 2012, 03:40:20 pm »

To quote text, you use these tags (without the spaces) before and after:

[ quote ]
What someone says.
[ /quote ]
Your reply

Removing the spaces, it will look like this:
Quote
What someone says.
Your reply
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JustinM

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Re: DSP delay testing [solved]
« Reply #12 on: July 22, 2012, 11:56:51 am »

Thanks jacqlan for the guidence and info !
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EarlK

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Re: DSP delay testing [solved]
« Reply #13 on: July 22, 2012, 12:41:56 pm »

Justin,

Look for my posts within the "Line-in playback: ASIO or WASAPI" thread where I explain to Jacques ( with pics ) "How to run REW through MC17's" ASIO input ( assuming you're after this knowledge ).

:)
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jacqlan111

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Re: DSP delay testing [solved]
« Reply #14 on: July 22, 2012, 01:53:31 pm »

Justin,

Look for my posts within the "Line-in playback: ASIO or WASAPI" thread where I explain to Jacques ( with pics ) "How to run REW through MC17's" ASIO input ( assuming you're after this knowledge ).

:)
EarlK your referenced reply was extremelly well done with a lot of patience, I should have mentionned it In fact I'll copy it for my personnal files
:)
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JustinM

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Re: DSP delay testing [solved]
« Reply #15 on: July 24, 2012, 06:21:45 pm »

Thanks EarlK !  I book marked the  page :)
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