REW with my Mac - Home Theater Forum and Systems -

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post #1 of 6 Old 12-05-13, 04:51 AM Thread Starter
Join Date: Aug 2013
Location: the Trinity Alps, CA
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REW with my Mac

I finally got REW working properly on my Mac, and thought I would share my experiences and what it took to make it work. This thing runs on OSX 10.5.8 Leopard. This summer I bought an SVX SB12 plus sub to add to my Paradigm Studio 80's, Studio C/C, and Mini-monitor's. The SVX has a single band of parametric EQ and I read on this forum that it is difficult to adjust without a way to measure its response. So this summer I ordered a UMIC-1 usb calibrated mic from mini-dsp. Now that the sun is hiding behind the mountain ridge next to my house and the yard stays frozen all day, I have some time to play with my system.

I downloaded REW and booted it up with the mic plugged in, it did not recognize it as advertised. After some searching around here I found that I needed at least beta 13 for that to work. I thought that I had loaded the newest version. No, you have to come to the REW forum and find the latest beta release to download, I found beta 17. I got the mic to work but could not get any output to send a sweep to my amp. After lots of fiddling around with midi settings I got it to work. I am just using my headphone output with an RCA adapter. I am concerned with the accuracy of the sweep it puts out. Tomorrow,I should receive a 12ft toslink cable to try outputting digitally. The results looked OK, but I was down 20 db from around 100 to 250 Hz and the top end would drop off and sometimes truncate at some higher frequency's. I started wondering if my speakers had a bass driver with a lead reversed internally. If I slowly turned up the gain on the sub, it would suddenly bring that bottom section up, but it would be way too high below 80. I would keep running sweeps making the smallest adjustments I could but it would still be either way up or way down. Then, I noticed that a low frequency sweep ending at 200 was up, and a full sweep had the 20 db dip. This was without adjusting any gain. It was fully repeatable.

Then, I tried using Wayne's method of creating a house curve by comparing an 80Hz tone to a 30, I started slowly moving the tone up and discovered I had a 7 db peak at 45 Hz, It did not show up on the graph! So, I started reading some more. I found where some people had used the calibration file for the mic and also had it entered for the sound card, I had also done that, so I had been doubling up on the calibration correction. I started paying more attention to the error messages I had been receiving while taking readings. Like the one about the impulse response not being where expected, or that there might be some corruption in the file. But it looked OK right? I still don't know what an impulse response is for. Anyway, I reread the section about using soundflower, and line-in to make REW work on a Mac. I had searched my hard drive for soundflower when I first installed REW and could not find it. It turns out you have to download it off the net. What is a big flag that you need it? the impulse response error message! With a usb mic running at 48 kHz and the system running at 44.1 kHz things get out of whack. Soundflower and line-in works in between to make it work right.

I had to look for a legacy version of line-in, the new version won't work on Leopard. Once I downloaded the programs, and set them up as described in the link, no more error messages! and more accurate data, there was my 45Hz spike, and the highs roll off nicely at the top end as described in a proper house curve. I found I have a huge node in my room, that is where the boominess in the sub comes from. The roof angles up to a peak in the center with a fake beam there (it is a modular home). I have carpet spikes on my main speakers to keep the floor from resonating. I adjusted the subs parametric, it took all of the level it has with a high Q to tame it. It is still up a couple db over 30 Hz but sounds the best it ever has. I put out a 45 Hz tone and walked around the room, just below the roof peak/beam it gets a lot louder, I'll bet something like 20 db all the way across. I wonder if that would be the place to treat it? I have one more place to try putting the sub. My smallish room does not leave me lots of choices. The next step will be a full parametric.

I want to thank you John for creating REW and taking the time to support it on this forum. Wayne, I think you are a great asset, I enjoy your posts, and tutorials on house curves, and sub placements ect. I actually bought a Yamaha YDP2006 off ebay for $50 but then the schmuck did not send it, I had to file a claim to get my money back. Anyway, I still have a lot to learn, but i am proud of the way my system sounds now, thanks to everyone who posts on this forum. Dave
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post #2 of 6 Old 12-05-13, 02:07 PM
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Re: REW with my Mac

Great post Dave, thanks. Treatment in the roof space might well help, but it would be worth getting some opinions from the Home Audio Acoustics forum where the folk who are knowledgeable about treatments hang out.
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post #3 of 6 Old 12-05-13, 06:13 PM
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Great post. Thanks for sharing it with us. It will really help me out when I get my theater done.
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post #4 of 6 Old 12-06-13, 08:22 AM
Join Date: Dec 2013
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Thanks for the info I'm glad you find the right fix for your problem.

I'm also using a Mac (mini) with Mavericks through hdmi, but my problem was with the input, not output. and after trying to get everything setup yesterday, I couldn't fix a low level input problem and when checking for levels, calibrating spl or measuring I was getting -487.xx dB. (I went into the midi menu and selected 44.1 kHz for input and output and set my default input to the umm-6 and output to the hdmi and it didn't fix it). So I will download line-in later tonight (apparently sunflower was already installed) if I have some spare time. I finally connected my system yesterday (will have to fix the bfd HUM problem later) and I'm planing to start playing with REW for the first time ever this weekend.

Not trying to take over your thread, just venting out my Mac hiccups I had.
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post #5 of 6 Old 12-07-13, 03:15 AM Thread Starter
Join Date: Aug 2013
Location: the Trinity Alps, CA
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Re: REW with my Mac

No problem. I could have done it the easy way and dug out one of my PC laptops with windows, but I have been trying to learn more about this Mac, I have never owned one. In researching ways to figure out this thing I found out that the headphone and microphone jacks double as mini-toslink digital in/outs, which is pretty cool. So today, I received a 12' digital cable, I plugged it into the front panel jacks on my AVR and ran a couple of sweeps to compare it to the headphone to RCA output I was using. It looks like the higher frequency's extend flatter. Then the old lady came home early due to snow so I had to suspend my tinkering. It is definitely addicting making sweeps, then trying adjustments then more sweeps to see what changed. I tune motors for a living so this is just an extension of that, I am just listening to different sounds, searching for that ideal that is in my head.
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post #6 of 6 Old 12-07-13, 08:51 AM
Join Date: Dec 2013
Posts: 7
I had My first Mac about 6 years ago and haven't looked back. They are not perfect by way easier and more reliable than windows and have good resale value so updating them doesn't hit your wallet as bad (compared with the new price tag of course).

Anyway, y learned about the mini digital out but didn't know about the microphone serving as a mini toslink as well. I wonder if the mini dvi on the wife's 12' mb pro can be converted to hdmi so I don't have to use the Mac mini and tv for rew and having to sit on the floor so I can see what's going on on the tv (now computer monitor) that is 12' from the couch.

I found the instructions for Mac on another post that explains the setup for USB mic's and Mac's using sunflower and I hope I can try them later today, I also found out that I needed a spl meter to calibrate it after I bought it, but I realized they have an ANSI certified meter at work that comes with a calibrator and they let me borrow it for the weekend.

I'm looking fwd for start using rew and find some spare time to do it when the house is relatively quiet (not an easy task). I'm a mechanical engineer doing projects for a chemical plant and my usual graphs are pump curves, enthalpy of dilutions, and some other boring stuff so playing with this thing will make looking at graphs finally a fun thing.

This is an awesome forum btw. I usually don't participate on forums because it seems impossible to get answers without digressing or the usual trolls but this is definitely a great source of information.

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impulse response , mac , rew , soundflower

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