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External sweep with REW

21K views 59 replies 22 participants last post by  StanDingwave 
#1 · (Edited)
Feature Request: External sweep with REW

EDIT: Modified title to feature request.

Is it possible to play a sweep externally from CD or another computer when taking a REW measurement?

Reason why I want to do this is that I want to confirm the digital EQ parameters I have applied in my audio playback software have flattened out the freq response as REW has predicted.

Thanks
 
#3 ·
Sorry I was not clear enough in my first post.

I have measured my system with REW, found some peaks in the 20-100hz region, and have then created filters to flatten them.

On my playback system (macmini running PureMusic) I then apply these filters using a VST EQ plugin, and all music played back on the macmini through the PureMusic playback software has the EQ applied and the 20-100hz region sounds alot better. The modes seem to have been tamed.

But I now want to confirm - to see the frequency response of my system, with the digital EQ applied. Running a sweep in REW would not include the digital EQ so I would just get the same result. What I would like to do is play a recorded sweep (WAV file) through PureMusic (with the EQ VST active) and then have REW simply record and show my the data. I.E. REW would 'wait' for the sweep to come and simply process and display the measurement data. In theory this should now look the same as the 'predicted' result from within REW when making the filters.

Hope that makes sense!
 
#11 · (Edited)
I'm curious about this as well. My problem is measuring my system in 5.1 configuration. The fronts and sub is ok, but I'm having trouble measuring the center and surround channels, one by one.

When using the multichannel inputs on the AVR (Yamaha RXV767) all eq and other DSP-curciuts are bypassed. With an external sweep source, one could use a multichannel calibration disc.

EDIT: seems JohnM managed to write a reply before me. Looking forward to the new functionality :)
 
#18 ·
Perhaps a quick and easy way to implement this would be to allow a set of parametric EQ filters to be loaded (or manually entered) in the 'Measurement' dialogue window which would then be applied on the sweep? If the resulting measurement is then flat it would confirm proper setup of EQ filters...
 
#22 ·
Would that work? I.e. hit 'measure' in REW and then play a sweep of the same length externally? Would it matter/affect the result if there was a 1 or 2 second delay in the playback of the external sweep?

WAV files of sweeps can be found in many places. The measurement settings in REW could be set to mirror the sweeps properties (volume and length)? Perhaps the external sweep just needs to be of shorter length than the REW sweep settings so that the full sweep plays during the measurement period? Wonder if this would work... JohnM or other developers could you please comment?
 
#23 ·
JohnM or other developers could you please comment?
You would need to capture the exact sweep REW produces to get a valid result and match the timing within a second or so, tricky to achieve. I'll get around to providing solutions in time, but this is a development team of one I'm afraid.

REW's predicted EQ responses are generally very accurate (I made them that way to save the bother of lots of redundant verification measurements), but the RTA check already suggested would provide a quick check of whether the predicted responses are correct - make sure to measure from the same location as used for the uncorrected measurement.
 
#24 · (Edited)
- An "open front end" would be somewhat intriguing ( but it's not a game-changer as far as I'm concerned ) .

- ( OTOH ) , I'd like to see REW have the ability to host VSTs for convolving EQ exports ( just before the signal leaves the program on the way to the soundcard ) .

- In lieu of that ever happening , here's my work-around ( to see the consequences of applied EQ filters ) ;




- One can see ( in the second pic ) a convolved sweep of the EQ filters ( as created by REW & then exported as a mono wave file ) .
- "Green" is the speaker response as captured ( by someone over at GS ) , "Orange" is what the EQ filter itself looks like .
- "Orange" was captured using the SoundCard calibration ( loopback ) protocol .

- This setup ( software-wise ) is reasonably stable & costs less than $100.00 ( for both VAC & ConvoBoy ) .

:sn:

Oh ( I almost forgot ) , here's the REW side of it ( ie; the preferences window ) .

 
#33 ·
Hi, i am just starting to approach measurment...
I have Jriver 19 and Audiolense, plus REW in a Wint 64 bit PC equipped with Lynx AES 16 soundcard and extenal Lucid DAc
I am just at the step of configuring biamplifications of the speakers (7.2 with fronts and back surround biamped for a total of 11 channels out of 16 being used in lynx AES) using Jriver crossovers...it seems to work well
Now i am wondering which is the best way of making measurments with REW and AUDIOLENSE considering i need to have all the audio routed by Jriver
Starting from REW....connect calibrated mic to analog input of Lucid DAC, converting to AES, recording trough Lynx aes in 1+2 i should be able to have ASIO loopback (or using the new feature of Jriver as ASIO driver)
in JRIVER (or wasapi) of REW's sweeps
Same for Audiolense (after ebnabling different play and recording)


Is this correct approach?

Thanks
 
#48 · (Edited)
Looking at the jRiver 'loopback' option. I just cant see how you get the REW sweep to run through jRiver when it's going from my REW/preamp/processor
the jriver asio line in or WDM option means the signal chain is

REW -> jriver -> DAC

you don't go out to a prepro and then back into jriver (well you could if you really wanted to and had the appropriate hardware)
 
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