Recent content by Nordo

I recently did some speaker testing (for crossover design) using a UMIK-1 and the latest version of REW. SPL graphs were normal and what was expected - i.e. no anomalies. Make sure all your settings in REW are correct. Read Making Measurements in the REW help In particular, don't use the...

I think at one stage I researched exactly what the speed of sound would be in my situation, but ended up just adopting 344m/sec. I'm just about to offset all my t=0 locations and export to VituixCAD. Even if the t=0 offset doesn't effect the essential part of my design data, doing the offset...

Sorry - I just confuse myself when I over think things. Thanks again.

Sorry to be so naive, but are you saying that the first image does not have the correct offset, and the second image does? The notes that REW added to the original measurement (first image) states that it recognised a 2.4ms delay - and that's what's confusing me.

Oops, sorry everyone. The difference is obvious. Not sure why I didn't see it before??? :rolleyesno:

Thanks guys. Can you check my IR images below. I think I might already have the correct t=0 offset. The first image is "as measured", and the 2nd image is after I went into Control and applied "Offset t=0". I can't see any difference.

I've had a play around with my measurements in REW and can see how altering the Windows Ref Time in the IR Windows (diff between Ref and Test distances) aligns the t=0 with the peak of the impulse. My only concern with my measurements was that I didn't use the Timing Offset in the Measurements...

Thanks again. I've added your comments to the notes I have in front of me when I'm measuring. I just want to be 100% certain of all the correct settings (particularly when using my USB mic) before I re-measure. I'll have to re-measure instead of just adjusting my current IR results, as I'm not...

I haven't read it yet, but I understand what you are saying. VituixCAD has a lot of built-in apps that are as good any stand alone program. John has developed REW to be fully featured as well, going well beyond is original intention of evaluating in-room responses. I think my main problem now...

I have used Kimmo's REW guide for all my driver testing measurements, but as he (understandably) has an aversion to USB mics, his guide only includes instructions for loopback reference, which makes it hard for me to realise what settings/instructions are relevant when using acoustic timing...

That's great. Thanks John. I've read everything I could find relating to acoustic timing reference that you have written, but didn't come across that one.

The more I learn, the more confused I become. As I am using a UMIK-1 usb mic, I will be using acoustic reference timing. I understand that in the Measurement window, I need to add the necessary adjustment in the Timing Offset window. In my case, the difference in distance between the...

Thanks again. Maybe the cone touches the phase plug at some point? Not sure what to look for in the FR graphs when checking for the effect of early reflections in my measurements. The test speaker doesn't have a tweeter. Maybe I'm making a mountain out of a mole hill. But that's what I want...

Still can't figure out what's happening with my measurements. I have added seperate screen shots of my on-axis Impulses of my two drivers (7" RS225 and 2.5" TC9FD). If the early spikes I was seeing in the RS225 Impulse were due to early reflections off something, I should see them in the TC9FD...

The first tests I ever did, approx 30 years ago, was in an open paddock with a SPL meter on a tripod. I also wrapped the tripod legs in a big thick feather doona. The Mic surrounded by acoustic material sounds like an interesting approach. But I think most acoustic materials would reflect...