Room Tunning Questions ~ REW

[College_Records]

I recently aquired a ton of 703 :]]]]]] In an effort to tune my room and get the most out of my gear, I purchased a Nady cm100 referance microphone which I plan to use with REW. My questions are:

1. Does the preamp I'm using (onboard RME FF800 pre's) affect the signal??
2. Do I need 2 mics to make sure that the sound being heard by my left and right ear are even?
3. What is the best setup/methods to conduct these tests and adjustments?

P.S. I've looked into the specs of the the Nady cm100 and even though the spectrum claims to be accurate from 30hz-2k (within +or- 1db) recent tests from various gearslutz members suggest the mic is really only accurate from 50hz-1k. My focal cms 50's only go down to 55hz, and I'm packing my small room with 703 (making it as dead as possible) so I'm not really worried about the high frequencies. I'm mainly worried about 50hz-1k; the other frequencies will have minimal impacts on my mixes.

[DanDan]

REW is a Java app.
Apple doesn't do Java to spec.
Between that and Firewire issues, you are unlikely to have luck with the RME.
You may however be able to get a Direct Out signal from one of the Preamps. If there is no dedicated one, try the Send on the hardware Insert, if there is an insert.

Use the onboard Apple I/O. It is surprisingly good. I tested it.
Minijack to whatever leads. Same as iPod ones. The headphone output is useable as Line Out.

Mic anomalies are likely to be tiny compared to the 20 and 30 dB nulls you will find in your room!

If you drive one speaker at a time and place the mic at the corresponding ear position, you get most of the effect of a two mic binaural measurement.

http://www.gearslutz.com/board/studi...er-v2-1-a.html

DD

[College_Records]

Originally Posted by DanDan

REW is a Java app.
Apple doesn't do Java to spec.
Between that and Firewire issues, you are unlikely to have luck with the RME.
You may however be able to get a Direct Out signal from one of the Preamps. If there is no dedicated one, try the Send on the hardware Insert, if there is an insert.

I am a pc and my rme interface has never given me any problems. I have one of the most stable firewire 800 cards for windows, so I think I should be ok.

Originally Posted by DanDan

Use the onboard Apple I/O. It is surprisingly good. I tested it.
Minijack to whatever leads. Same as iPod ones. The headphone output is useable as Line Out.

Is there a windows alternative to the apple I/O?? I have an iPhone 4, but somehow I don't think it'd be accurate if I ran it on my tiny phone...

Originally Posted by DanDan

Mic anomalies are likely to be tiny compared to the 20 and 30 dB nulls you will find in your room!

Nulls? Won't any modes be eliminated or atleast decreased by coating my room with 4"-8" thick of 703?? As long as I have a sweet spot of a watermelon, I'll be overjoyed.

Originally Posted by DanDan

If you drive one speaker at a time and place the mic at the corresponding ear position, you get most of the effect of a two mic binaural measurement.

http://www.gearslutz.com/board/studi...er-v2-1-a.html

NICE!! This is super helpful!

[DanDan]

Sorry I presumed Mac. REW should work fine for you using either the RME or the PC's internal card.
There is nothing special about the Apple I/O, just decent sound quality generally.
There are iPhone apps but go with REW, it is superb.

Take your time, start simple, no calibration, no loopback correction.
Just start measuring and learn as you go.

Large Superchunks are great. They can be square too, like Glenn's Soffit Traps.
You won't be cladding the whole room, maybe half of it at most. Focus where it matters first. Corners Corners Corners. Then Cloud and a Zone Without Reflections around the listener. A good eye for snooker and a mirror will help you place the Reflection killing panels. When you get going on REW the ETC is kinda like an EchoGraph.

For state of the DIY art My Experiment with a Metal Panel Absorber

4 inches of 703 with a 4 inch airgap is a good general purpose trap.
8 inches of fibre is slightly better, so if you have tons to spare, go for it.
Laths scattered over the fabric layer look good and stop drummers falling into the fibre.....

DD

[College_Records]

Originally Posted by DanDan

Sorry I presumed Mac. REW should work fine for you using either the RME or the PC's internal card.

Thank goodness! I was a bit nervous there. Ok, last question and then I'm off to start testing...

Is there a particular referance preamp that I can use to optimize my results? Would clean be classified as referance? ~ grace m101, dmp3, or an fmr rnp are contenders... Should I just use the stock rme preamps? Which preamp or type of preamp do room tunners usually use? I found some "referance preamps" online for around 2 grand per channel... are there any budget alternatives that produce great results?

[Glenn Kuras]

Originally Posted by College_Records

Thank goodness! I was a bit nervous there. Ok, last question and then I'm off to start testing...

Is there a particular referance preamp that I can use to optimize my results? Would clean be classified as referance? ~ grace m101, dmp3, or an fmr rnp are contenders... Should I just use the stock rme preamps? Which preamp or type of preamp do room tunners usually use? I found some "referance preamps" online for around 2 grand per channel... are there any budget alternatives that produce great results?

Most any kind of clean pre will work. Looking at your list any of them should be fine.

[Papanate]

Originally Posted by DanDan

REW is a Java app.
Apple doesn't do Java to spec.

I have a new iMac and haven't had any issues with Java or REW being inaccurate. Do you have any info to match this claim?

Between that and Firewire issues, you are unlikely to have luck with the RME.

Again I'm using a Mac with Firewire HD's and Apogee Gear and have zero issues. I've also have a RME Fireface 800
- I have used that a considerable amount and have had zero issues. Do you have experience with Mac firewire?
And has your experience been repeatable amoung other firewire owners?

Mic anomalies are likely to be tiny compared to the 20 and 30 dB nulls you will find in your room!

You don't know his room - so how can you assume 20 - 39db nulls before you've been in it and tested the space????

And please don't take these comments wrong or as snarky...I am challenging them because they sound
like rumor more than fact.

[DanDan]

JohnPM has said that there are issues with Firewire Mac and REW.
Check out the REW forum for details.
He also explained the Java issues directly to me.
I have experienced the Java problems myself, I had to sell on a lovely Lexicon iONIX because it was unworkable.

I am glad you are having success. I have not seen a multichannel interface work properly with REW on a Mac.
But again, the onboard I/O is quite good.

My point was not at all about nulls, it was that the anomalies of a room are much much larger than say the 0.3dB variation I measured on a Mac's onboard I/O. Ditto small variations between pres. Even cheap mics are smooth compared to any normal room curve.

Nulls do achieve that sort of depth everyday in every room.

This is why. Created two aux tracks in a DAW. Sine Wave Generator on both. Sum them +6dB. Reverse phase of one, (delay compensation may be necessary if the phase reverse plug causes a delay)
The null will be minus infinity.

Similar things happen with destructive reflections in actual rooms, but of course infinity doesn't happen. -25dB is absolutely common.


DD

[College_Records]

Originally Posted by DanDan

My point was not at all about nulls, it was that the anomalies of a room are much much larger than say the 0.3dB variation I measured on a Mac's onboard I/O. Ditto small variations between pres. Even cheap mics are smooth compared to any normal room curve.

Nulls do achieve that sort of depth everyday in every room.

This is why. Created two aux tracks in a DAW. Sine Wave Generator on both. Sum them +6dB. Reverse phase of one, (delay compensation may be necessary if the phase reverse plug causes a delay)
The null will be minus infinity.

Similar things happen with destructive reflections in actual rooms, but of course infinity doesn't happen. -25dB is absolutely common.

Thanks for all the input guys, but Whaaaaaaaa???

What are these nulls you speak of and why the heck would I invert the phase of an aux track???

My room is an A-symetrical pentagon about 10 ft along each wall. I have my mixing space in one of the corners, monitors positioned to shoot down the further length of the room. I have absorbed first reflections with 8" of 703 and a 16" air gap. the rest of the control room in front of me has 4" of 703 and a 1" air gap. Almost every single corner is trapped. If you have any suggestions I'd love to hear them.

I apologize if I should already know this. I've read the seactions of rod's book describing control room construction and general acoustics, but I may be confusing the "nulls" you're talking about with room modes and standing waves.

[DanDan]

The aux inputs was meant to be an analogy or a model showing how sine waves add.
In phase they only add up to +6dB
Out of phase they cancel each other, or very nearly so.

My point is...take note of the nulls, they are much deeper and thus more important than the peaks.

Take a speaker, a floor, a listener. Sound will travel from speaker to listener. It will also travel to the floor, bounce back up and partially cancel the direct sound from speaker to ear. See Flush mounting to wall
DD