Add predicted filter response to REW measurement data ???

mamba76

New Member
Thread Starter
Joined
Sep 9, 2017
Messages
38
Location
SE London
More  
Preamp, Processor or Receiver
Lenovo M8 FHD tablet
Main Amp
JL Audio XD600/6 (front end)
Additional Amp
JL Audio XD400/4 (midbass)
Other Amp
JL Audio XD1000/1 (sub)
Front Speakers
Focal Utopia (2003 model) (6W2's + TN51's)
Surround Back Speakers
JL Audio ZR800s (pair)
Subwoofers
JL Audio 13W3 4ohm
Streaming Equipment
miniDSP 2x4HD feeding C-DSP6x8
Hi all. Iv been using REW for tuning my cars 7 way system for about 2 years now so have a fair bit of experience but there are some things I want to do that REW doesn't quite seem to be able to do.
Basically I modified the data in a psychoacoustic measurement text file so that all gain is set to 70db and and all phase is set to 0deg. This gives me, what I call, a 'Flat Line' graph I the import back into REW. I want to be able to add the predicted response of a filter set to this 'flat line' FR plot so I can manipulate the resulting graph with the trace arithmetic tools. That's it! Sounds simple but I can't find anything on the web that can do this unless you want to pay £300 for software like Acourate Convolver which I briefly looked at. Not even sure if that will do what I want.

Im doing my own maths for balancing the FR at both ears for my cars two main speakers. I have the data I need now but just need this last tool so I can work with the results to create an equal correction filter set that I will add to the individually EQ'd speakers. I'm sure plenty of people can gauge what I'm trying to achieve here but I will keep it to myself until I can prove it works lol, if not I'm another step closer to madness!!

In the pictures I want to add each of the 4 filter sets to the 'flat line' measurement data to create 4 new measurements I can use in All SPL main window.

Thanks

ps I use a Minidsp cdsp6x8
 

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John Mulcahy

REW Author
Joined
Apr 3, 2017
Messages
7,326
You can export the impulse response of a filter set as a WAV file then reimport that WAV file as a measurement to use in trace arithmetic. The level at which a response sits can be set using the offset adjustments in the graph controls.
 

mamba76

New Member
Thread Starter
Joined
Sep 9, 2017
Messages
38
Location
SE London
More  
Preamp, Processor or Receiver
Lenovo M8 FHD tablet
Main Amp
JL Audio XD600/6 (front end)
Additional Amp
JL Audio XD400/4 (midbass)
Other Amp
JL Audio XD1000/1 (sub)
Front Speakers
Focal Utopia (2003 model) (6W2's + TN51's)
Surround Back Speakers
JL Audio ZR800s (pair)
Subwoofers
JL Audio 13W3 4ohm
Streaming Equipment
miniDSP 2x4HD feeding C-DSP6x8
Haha, Urika! I thought there must be a way! Iv got to say John this is a great product and thanks to you and any team for the hard work it must have taken to make this product and for making it available to people like me. ))
 

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mamba76

New Member
Thread Starter
Joined
Sep 9, 2017
Messages
38
Location
SE London
More  
Preamp, Processor or Receiver
Lenovo M8 FHD tablet
Main Amp
JL Audio XD600/6 (front end)
Additional Amp
JL Audio XD400/4 (midbass)
Other Amp
JL Audio XD1000/1 (sub)
Front Speakers
Focal Utopia (2003 model) (6W2's + TN51's)
Surround Back Speakers
JL Audio ZR800s (pair)
Subwoofers
JL Audio 13W3 4ohm
Streaming Equipment
miniDSP 2x4HD feeding C-DSP6x8
As expected the overall process I was trying didn't work as well as expected but I learnt a bit more this time round.
I would be interested in methods others have used to balance the perceived output from both the front main off-axis car speakers. I consider this the hardest challenge in car audio. Getting a good center stage with all the reflections / cancellations etc, especially the comb effect round 180-200 hertz. The dip from left speaker at 500hz Iv accepted as cannot be changed without negligible or detrimental effects. (a piece of board orientated correctly can boost this easily 6-8db!) but Im not driving around with a piece of board in the passenger foot well lol.

On the RTA graph it always seems to be tilted down compared to the actual measurement making it hard to visualize. I also have to offset the measurement in RTA mode about -30 / -40db to get it imposed behind the RTA. Would be good if you could use 2 microphones (in my case one at each ear) and see a dual trace RTA with a target curve imposed behind it. Then when you alter one side you can see the effect on the other at the same time.
Thanks again
 
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