Room Measurement & Treatment - Page 2 - AVS Forum
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Dedicated Theater Design & Construction > Room Measurement & Treatment
fotto's Avatar fotto 06:52 AM 12-14-2011
Quote:
Originally Posted by aackthpt View Post

The bottom line is that you want to reduce the strength of the arrival on the ETC, right? If I can do that, regardless whether I know the acoustical center of the speaker or not, I am done. You understand the tool, you did it once, you can do it again. Good enough, assuming once you listen to your reference material you like the sound.

Very true aackthpt! At this point, I think the alternate methods of measuring and resolution are more out of "morbid curiosity" than anything else. This is supposed to be "simple" right?

aackthpt's Avatar aackthpt 08:40 AM 12-14-2011
longshorejl's Avatar longshorejl 01:12 PM 12-14-2011
What mic should I buy for REW? I assume there is a standard off the shelf mic that is cheap that everyone uses.
fotto's Avatar fotto 01:58 PM 12-14-2011
Quote:
Originally Posted by longshorejl View Post

What mic should I buy for REW? I assume there is a standard off the shelf mic that is cheap that everyone uses.

You can use a standard Radio Shack SPL meter connected through a low cost USB sound card such as Beheringer UCA202 (which is my set-up), but this is really only good for testing bass response and up through around 3KHz due to inaccuracy of the SPL meter. For full range measurements/greater accuracy many people are using Dayton EMM-6 or Behringer ECM-8000 mics. The set-up using those mics is a bit more involved as they require phantom power, but not a lot more overall in terms of cost. There is a LOT more information on set-up options over at the REW forum.
aackthpt's Avatar aackthpt 04:14 PM 12-14-2011
Quote:
Originally Posted by fotto View Post

You can use a standard Radio Shack SPL meter connected through a low cost USB sound card such as Beheringer UCA202 (which is my set-up),

Technically if the computer has a line-in on the soundcard you can dispense with the UCA202 also. Mic-in won't do it though, which disqualifies most laptops. But those with an HTPC can typically just get the right adapters and things and go.

Personally I don't trust the RS meter even at LF. The EMM-6 is generally a better and less expensive choice than the Behringer mic but there are a few sources for it, the choice between I'm not going to go into. Suffice it to say choice of mic can quickly become an in-depth subject.
longshorejl's Avatar longshorejl 04:39 PM 12-14-2011
Thanks. I'll check out that forum. It sounds like regardless of what mic I use a laptop isn't going to cut it. My laptop does have an hdmi input though... Hmm I'll do some more research . Thanks again.
aackthpt's Avatar aackthpt 08:21 PM 12-14-2011
Quote:
Originally Posted by longshorejl View Post

Thanks. I'll check out that forum. It sounds like regardless of what mic I use a laptop isn't going to cut it. My laptop does have an hdmi input though... Hmm I'll do some more research . Thanks again.

It doesn't disquality the laptop, it just disqualifies using the sound card in the laptop. That's why you get an external soundcard like the UCA202 if using an RS meter, or one containing a mic preamp and phantom power if using a mic like the EMM-6. A computer is a computer is a computer! Almost any machine, including a netbook, is plenty powerful for REW.
longshorejl's Avatar longshorejl 08:25 PM 12-14-2011
Would a mic like the Dayton EMM-6 and a Behringer XENYX 302USB and a laptop be enough to take the measurements? This would allow for a USB connection to the laptop's sound card.
fotto's Avatar fotto 09:13 PM 12-14-2011
I haven't seen a lot on the Xenyx 302USB, but the ART Dual USB Pre seems to be a popular option.
aackthpt's Avatar aackthpt 06:35 AM 12-15-2011
Quote:
Originally Posted by longshorejl View Post

Would a mic like the Dayton EMM-6 and a Behringer XENYX 302USB and a laptop be enough to take the measurements? This would allow for a USB connection to the laptop's sound card.

The Xenyx would probably work, and I've looked at it briefly as an interesting option. However since mixers have a lot of knobs and buttons, it's also a bit needlessly complex for this application - and also prone to error for a novice. It would be about the same price and simpler (though less flexible) to use the Dual Pre that Floyd mentioned. I gave some hints on how to get a discount on it here, although the same info could apply to the Xenyx, in case you decide to go that way, assuming they sell it.
krabapple's Avatar krabapple 02:21 PM 12-28-2011
Quote:
Originally Posted by aackthpt View Post

The Xenyx would probably work, and I've looked at it briefly as an interesting option. However since mixers have a lot of knobs and buttons, it's also a bit needlessly complex for this application - and also prone to error for a novice. It would be about the same price and simpler (though less flexible) to use the Dual Pre that Floyd mentioned. I gave some hints on how to get a discount on it here, although the same info could apply to the Xenyx, in case you decide to go that way, assuming they sell it.

FWIW, REW setup using ECM8000 plus a Behringer preamp/mixer like the UB802 or Xenyx is explicitly described on the HTF REW tutorial thread, with pictures. The Xenyx 502 is now the recommended unit there (only because it's low-cost and simple, and still has phantom power) if this is your chosen connection strategy :

http://www.hometheatershack.com/foru...on-basics.html

But these use an analog, not a USB, connection.
Michal - Poland's Avatar Michal - Poland 07:24 AM 07-28-2013
I appreciate accuracy of Your measurements and conclusions. I did simmilar measurements in past for my two speakers but not with not so clear outcome as Yours. Great and educative job for sub. In my research I used to use "mind evaluation" to overcome "data mess" form measurements outcome.. Anyway my conclusions of this my evaluation were not optimistic - my measurements did not replace or even compare to hearing sense so I used it to proof my arised to system suspisions, to proof opinion and to descreen phase shift between bands. . It gave me more orientation about complexity of sound transmission. What may be interesting I observed with measurements the fact of impact from left enclosure to right and vice versa - just the way bass traps do it. Or I was upset about unexpected pik at 17 kHz form my speakers untill I didn't notice that my TV was muted and switched "on" passing horizontal trafo job - I find it enyoable also smile.gif. I observed that accurate measurements to one speaker cannot be obtained when ithere is no silence in room - due to microphone effect of the drivers. . What disappointed me was that when I was introducing changes to sound of my speakers , sure I could recognize them in measurement diagramm but only because I knew where to look for them because they were so slight . I couldn't measure or separate them from unchanged to analize as I wondered. Coming back to your room : by my experience I think You have good quiet room except as You mentioned main sub resonance. For this resonance I wouldn't accept the placement of sub - in case of ideal side channels You may experience masking of main material. This placements is always kind of compromise due to when one frequency is nivelated another arises or disappears.May be two separate subs in different places would do better? . After many years when I had build superlow tone transmission line speakers I avoid high level of low bass which was introducing to me some impairment to ears. But this speakers were moving tables one level below in radio studio smile.gif. Generally if speaker is really good then sounds "normally" also through a thick wall . I wish You to acquire this because unfortunatelly almost all average speakers deliver only narrow bass. Rgds.
fotto's Avatar fotto 08:39 AM 07-28-2013
Thanks for your comments Michal. As this thread has been stale for a while, I should provide an update on where things are. I have recently added a ceiling cloud to address the ceiling reflections I found during my ETC experiment. You can view that (and results) here: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/3840#post_23485395

In terms of the bass response/ringing, I think I'm at a point where I'm not actively chasing more improvement. Not to say I won't consider another sub in the future, just that I'm pretty pleased with how things are now, and would really need some justification for spending the money and time. Following are current measurements. Note that although I have not SOLVED the ringing at the 20Hz area, but it is essentially very low at 500ms and isn't something that bothers me.

Sub and fronts no smoothing:


Sub and fronts full range 1/6 smoothing:


Sub and fronts waterfall:


Sub and fronts spectrogram:


The other thing that I worked on recently was trying to solve my x-ver splice dip. I got that pretty well resolved via a combination of changes to x-over point and sub distance settings. I think I would have more interest in tweaking that further vs. the 20Hz ringing at this point. smile.gif
Michal - Poland's Avatar Michal - Poland 10:36 AM 07-28-2013
I do agree with You - 20 Hz is almost not present in music - sorry - I did not analyse picture but just read something that seemed to me as your complain. I even don't care for 30 Hz.if it's more or less - that is life smile.gif. The final opinion should always be based on one's impression - I have the same point. That is the biggest problem of measurements by mics- they often show clearly what is not even heard. Our sense of hearing is formed on basis of it's phisiology which means that power is in fact loudness and this shows that in reality our attention in listening is taken not only by the limits but most charming is middle range in complex with them .

All best Michal
Nightlord's Avatar Nightlord 05:45 AM 07-29-2013
There's plenty of music that goes to 20Hz and below. Sometimes on quite surprising pieces, they are not all dubstep...
Michal - Poland's Avatar Michal - Poland 04:47 PM 07-31-2013
. Any natural sound has 20 Hz incorporated but what I was pointing is that in 99% the level is below noticing. Mostly my notes are regarding sound of classic instruments, percussion, human voice and nature . Music has different meaning.- is in milions pieces what is plenty of plenty :)and always 20 Hz one may mix up to his satisfaction:). Even from synth. My interest is all around sound reality compare to original - may be it is different point of interest.. Check my web : Michal Czabajski D.I.Y. Nonfatigue Sound System
Rgds. Michal
Nightlord's Avatar Nightlord 10:41 PM 07-31-2013
Well, plenty for me means that the spotify-list with collected <20Hz music will keep me occupied for hours if I'm to listen to all in one go, and I think the owner of the list has restiricted the number of entries per artist/band or it would be even more substantial.

I also listen to much more than just classical music. But I have dropped the notion of that the music should sound like my idea of what the music sounded like when it was recorded, as I have no possibility to know how it was processed before it landed on media. So today my goal with my setup is to accurately reproduce what's on the media, which makes go od recordings shine and bad ones sound exactly as such. I'll check your page later.
Michal - Poland's Avatar Michal - Poland 10:33 AM 08-01-2013
Quote:
Originally Posted by Nightlord View Post

Well, plenty for me means that the spotify-list with collected <20Hz music will keep me occupied for hours if I'm to listen to all in one go, and I think the owner of the list has restiricted the number of entries per artist/band or it would be even more substantial.

I also listen to much more than just classical music. But I have dropped the notion of that the music should sound like my idea of what the music sounded like when it was recorded, as I have no possibility to know how it was processed before it landed on media. So today my goal with my setup is to accurately reproduce what's on the media, which makes go od recordings shine and bad ones sound exactly as such. I'll check your page later.

THat is right about difficulty to know how instruments should sound - directly from listening to them it is no way because nobody has this knowledge based on few recordings of them. . . I use many tricks with pink noise.- too much to say . Hopefully in past years I could manage to create step by step this sound. How many steps is needed depends on long term satisfaction with all possibile sound material I may say it supposed to be minimum 6-12 months of changes and familarization to them. There are indications of "proper" sound if we know how to look for them one of them is as You said no matter the quality of analogue source, poor or studio, always sound should be real and natural. It's like art of painting and photo - no matter of details both are real, both give right emotions. With digital it's another problem.
I also listen not only to classicals but my priority is reception in that way that what I hear makes me to feel it's presence - even through all the walls, sounds like coming from out of windows.. It's direct consequence of reality to all instuments. Finest test is noise sound and it is incredibile. According to my experience there is very special condition of harmonics which allows to feel the presence of event in quite shoking way - unfortunatelly with commercial speakers I think 100% not posssibile to obtain . Then even electronic experimental music seems with all it's power to be hanging in the air. This condition I would describe as natural continuity of transmitted frequencies. It makes that each instument sounds with it's born low tones foundation, own instrumental and outside added reverbation most important middle part and all higher details with no any exceed or depression. One out of line resonsnce destroys all.. For this I invented special kind of LC circuitry allowing to get almost unlimited accuracy of tunning.of three way speaker in main hearing range. Of course also even very good headphones can't stand such impression. Hmmm - itn't it developed full blown addiction?smile.gif. I hope in my age it should be forgiven.eek.gif
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