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In Reply to: RE: managing system via a tablet / measuring it with one? posted by Timbo in Oz on August 28, 2014 at 18:39:22
A few years back my college organised a conference in the sports hall. The sound was appalling. Afterwards I looked round the web and found some free room measurement software and ran it on my laptop. I then switched in a crappy Radio Shack equaliser to take out the worst boom peaks. It all worked well. It was windows software so if your tablet runs the FULL version of windows 8 it should work. If the tablet runs the cut down win8 implementation (more like an android OS) then no chance.
The laptop I ran it on is only an old Lenovo T60 Centrino Duo so it's not too demanding.
Hope this helps
Dave
Follow Ups:
I will do some more research.
I'd want to use it on a new biamped (line level xovers) 3 way vertical array? bass, wide ranger, bass. 150 Hz HP and LP.
i) to maximise the xover cancellation dip (when on side flipped) to get close enough to time / phase alignment. I'll be trying 1st order slopes initially, or 3rd if I have to.
ii) to Eq the bass / below 150 Hz. I have two 1/3rd octave eq'rs for that. There's also a third one which I will use on the HT's single sub. Gifts, now serviced. BSEGrin.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
If you're using REW to time-align drivers, it's helpful to use a mic/soundcard combo that allows for a loopback timing reference. Generally this involves an external USB sound "card" with an XLR measurement mic.
Nowadays, USB mics are popular, but they don't allow for a loopback timing reference. What REW does in this case is to always shift the peak of the impulse response to t=0, which then removes any actual delay differences between drivers.
If you only care about the combined response and don't care about getting accurate delay information for each driver individually, then a USB mic is fine. For more information, see the thread Can REW predict 2sub performance from single sub measurements? . It's about subs, but the ideas are the same. The poster JohnM is John Mulcahy, the author of REW.
Can you accomplish the loopback timing reference capability with a external sound card that has an usb input for a usb mic?
I hope so because I don't want to buy another mic.
Hi,
Sorry for the late response. I don't read or post to this forum much.
I'm not aware of anyone who's gotten loopback working for a USB mic. In this thread , someone tried a workaround using a software loopback, but it did not work.
The HolmImpulse software uses a single-input, single-output method and is still able to get a timing reference using the so-called "time locking" feature. So it might appear that this could be made to work with a USB mic. But in the HOLM Impulse - Timelock, creeping offset?? thread, Bill Waslo, author of the OmniMic measurement software, explains the reason why it doesn't work with some sound devices:
"That kind of thing can happen if the record (ADC ) clock isn't locked to the play (DAC ) clock of the soundcard. Some audio soundcards (for instance, the ones using TI PCMxxxx chips such as the Behrengers) use entirely separate timing sources for the two functions."
--Bill Waslo
In the case of a USB mic, the A/D clock is in the mic itself, while the D/A clock is in the sound device, so these can't by synchronized.
Bill has some workarounds whereby one can calculate the delay offset that needs to be added in an indirect way. You might check the XSim thread for more info. XSim is his free passive crossover design software.
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