REW discrepancy

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Hi all, i've been messing around with room eq wizard and a berry ecm on an old hifi speaker. i'm getting considerably different hf response between using 2 sweeps and 8 sweeps for measurement . |Blue icicle mic stage and generic usb card which i have calibrated using rew. Please see images below. any ideas why? (2 sweeps has better response).

Edited by soundchippy - 15 November 2011 at 1:02am

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soundchippy Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 September 2011 Location: Tavistock Status: Offline Points: 770	Post Options Post Reply Quote soundchippy Report Post Thanks(0) Quote Reply Topic: REW discrepancy Posted: 15 November 2011 at 12:38am
	Hi all, i've been messing around with room eq wizard and a berry ecm on an old hifi speaker. i'm getting considerably different hf response between using 2 sweeps and 8 sweeps for measurement . \|Blue icicle mic stage and generic usb card which i have calibrated using rew. Please see images below. any ideas why? (2 sweeps has better response). Edited by soundchippy - 15 November 2011 at 1:02am

soundchippy Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 September 2011 Location: Tavistock Status: Offline Points: 770	Post Options Post Reply Quote soundchippy Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 1:12am
	swapped for a different cab. 2/8 sweeps (new cab black(2) and purple(8)) Edited by soundchippy - 15 November 2011 at 1:13am

soundchippy Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 September 2011 Location: Tavistock Status: Offline Points: 770	Post Options Post Reply Quote soundchippy Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 1:16am
	1st cab - mordaunt short festival 2, 2nd cab b&w dm601 s1 mic and cab position same each measurement Edited by soundchippy - 15 November 2011 at 1:17am

Tony Wilkes Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840	Post Options Post Reply Quote Tony Wilkes Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 8:26am
	Mr. S Chippy, I have been using REW for quite a while now, dabbling with it for a few years but now getting quite deep and dirty and can honestly say that I always get repeatable results. Will have a play later with exactly the number of sweeps that you used. Tony p.s.What version are you using? Edited by Tony Wilkes - 15 November 2011 at 8:26am
	www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)

soundchippy Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 September 2011 Location: Tavistock Status: Offline Points: 770	Post Options Post Reply Quote soundchippy Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 5:50pm
	Plots were made using REW V5.0

Steve_B Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 29 September 2007 Status: Offline Points: 1587	Post Options Post Reply Quote Steve_B Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 7:04pm
	If I remember correctly you have to sign up to their own forum to download the software. It might be worth asking there. Now with the disclaimer that I don't use REW that much and my copy is not likely to be up to date.... Multiple sweeps use synchronous averaging, so if anything causes an interruption or break in the generated or captured signals the averaging will fail. If your soundcard supports ASIO drivers it is worth trying them (assuming you are not already). A mismatch in the sample rate settings can also cause problems. Of course if your Berry mic is un-calibrated you might as well guess what the response is anyway.

soundchippy Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 09 September 2011 Location: Tavistock Status: Offline Points: 770	Post Options Post Reply Quote soundchippy Report Post Thanks(0) Quote Reply Posted: 15 November 2011 at 7:53pm
	In the fullness of time I will make a calibration file for the ECM. Luckily i'm not using it for critical measurements, just playing around trying to get to grips with the program. I dont appear to have the option of selecting ASIO drivers for my soundcard. Thanks for the post, at least now I can surmise that the 8 sweep plot is more likely incorrect.