Music Player Network Home Guitar Player Magazine Keyboard Magazine Bass Player Magazine EQ Magazine
Topic Options
#2768809 - 03/31/16 10:41 AM Using Room EQ Wizard to test hardware (preamps, etc)
musichascolors Offline
Member

Registered: 03/30/16
Posts: 3
I tried using Room EQ Wizard to test hardwaretwice. The first time was my desktop PC at work, I ran a 1/8" patch cable from the headphone out to the mic input. I got a flat frequency response, but a decent amount of harmonic distortion, which made sense (to me).

The curious thing though was when I tried doing the same with my interface. This time there was much less distortion, but the frequency response wasn't flat (to a db or so). Could that have something to do with timing? (Or maybe the interface being on it's way out?; two channels have died already, but the input I was using seemed to be working fine)

I'm planning to do another test with a regular sine sweep and seeing if it comes out flat.

But yeah, is REW a decent tool for measuring frequency response and THD of hardware?



Edited by musichascolors (03/31/16 10:44 AM)

Top
#2768816 - 03/31/16 11:07 AM Re: Using Room EQ Wizard to test hardware (preamps, etc) [Re: musichascolors]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
Yes, REW is useful for measuring hardware, though I use an audio editor (Sound Forge) most of the time for that. Sound Forge has an FFT display that shows the level of every frequency.

What brand and model interface do you have at home? Most are pretty flat, but being a dB or so down at the frequency extremes isn't uncommon.

--Ethan

Top
#2768821 - 03/31/16 11:17 AM Re: Using Room EQ Wizard to test hardware (preamps, etc) [Re: Ethan Winer]
musichascolors Offline
Member

Registered: 03/30/16
Posts: 3
It was a Focusrite Saffire Pro 14. The deviations were throughout the response, not just at the extremes, it was very strange and unexpected, I probably was doing something wrong. I'll do further testing as well.

It seems efficient to do it in REW as it automatically calculates the THD levels/percentages


Edited by musichascolors (03/31/16 11:25 AM)

Top
#2769129 - 04/01/16 11:59 AM Re: Using Room EQ Wizard to test hardware (preamps, etc) [Re: musichascolors]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
If you get strange peaks and dips, that's probably due to the input and output being mixed together somewhere, which in concert with the latency delay creates comb filtering.

--Ethan

Top
#2769348 - 04/02/16 09:40 AM Re: Using Room EQ Wizard to test hardware (preamps, etc) [Re: Ethan Winer]
musichascolors Offline
Member

Registered: 03/30/16
Posts: 3
Found the issue... I had forgotten to clear the calibration file. Whoops, lol.

Top
#2775269 - 04/26/16 01:58 PM Re: Using Room EQ Wizard to test hardware (preamps, etc) [Re: musichascolors]
Arnold B. Kruege Offline
Senior Member

Registered: 05/07/14
Posts: 40
Originally Posted By: musichascolors

The curious thing though was when I tried doing the same with my interface. This time there was much less distortion, but the frequency response wasn't flat (to a db or so). Could that have something to do with timing? (Or maybe the interface being on it's way out?; two channels have died already, but the input I was using seemed to be working fine)

But yeah, is REW a decent tool for measuring frequency response and THD of hardware?


Other competitive freeware alternatives:

Audio Rightmark
Arta (demo mode)

Try your tests with several alternatives. The ones that agree with each other the most closely and probably the most accurate and reliable.

Top


Moderator:  Ethan Winer