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Misconception of "neutral / accurate"
Aug 15, 2011 at 1:46 PM Post #106 of 292
16kHz to 20kHz is less than a half octave. 20Hz to 60Hz is an octave and a half. Most people are happy if they can get their bass controlled down to 30 or 35Hz. There's buffer at each end of the spectrum of a half octave or so.
 
Aug 15, 2011 at 2:22 PM Post #107 of 292
I don't know why some people keep on insisting that most music don't have much sub-bass information. That is simply not true, and it's so grossly misunderstood that it kind of boggles my mind. People who keep claiming that needs to learn how to use a spectrum analyzer properly, and needs to listen to a wide range of styles of music. If you do that, you'll see just how much information is present in the sub-bass region from 60Hz all the way down to 30Hz. We're not talking about just hip-hop or electronic music here--plenty of acoustic and conventional musical styles all have lots of sub-bass information.
 
Aug 15, 2011 at 7:06 PM Post #108 of 292
Quote:
lunatique said:
I don't know why some people keep on insisting that most music don't have much sub-bass information. That is simply not true, and it's so grossly misunderstood that it kind of boggles my mind. People who keep claiming that needs to learn how to use a spectrum analyzer properly, and needs to listen to a wide range of styles of music. If you do that, you'll see just how much information is present in the sub-bass region from 60Hz all the way down to 30Hz. We're not talking about just hip-hop or electronic music here--plenty of acoustic and conventional musical styles all have lots of sub-bass information.
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X2! Any idea how difficult it is for a headphone to 'give a good image' of the heavy percussion that you can find in recordings of symphonic orchestras? Even instruments like the harp can go lower than expected. 
 
If you want serious bass, dynamic at that try the recordings of the Japanese percussion group Kodo. Back to listening...
 
 
 
Aug 21, 2011 at 11:50 PM Post #109 of 292
Some interesting and generally very accurate information. I certainly agree with the proposition of aiming for transparency in a system.

I think though the use of EQ for room correction has been given undue weight. I'm reasonably knowledgeable about acoustics (having built two recording studios and a dubbing theatre) but not an expert, although I have a couple of friends who are leading experts. The general rule in professional recording studios should be used to solve 90% of the acoustic problems using construction/acoustic treatment, with EQ accounting for no more than 10%. The problem of course is with room modes and and reflections, phase cancellations are a particular problem, which no amount of EQ'ing can fix. Think of a 100Hz sine wave, the peak is say 60dB, which means the trough is -60dB, when 180deg out of phase (due a room reflection) 60dB + (-60dB) = 0dB. Let's say we raise the level of that 100Hz frequency and boost the EQ by 30dB, we now have 90dB + (-90dB) = 0dB. Now it's extremely unusual to to find a room with total phase cancellation but you get the basic idea, that EQ is of only limited benefit. Just to be clear, all rooms have room modes and in more than one plane (tangential room modes).

Room acoustics are hugely important to speakers. Once you get into the roughly $2,000+ range for speakers, room acoustics are the most important factor in determining performance. I've seen $5,000 monitors in a room with no treatment. That's like buying a F1 racing car and driving it round a dirt track, you just aren't going to get a fraction of the performance out of it in the wrong environment, you'd get better performance from a Ford Explorer! Better to buy $1,500 monitors and spend $1,500 on treating the room, you'll get better overall performance and save yourself $2,000.

Lunatique, I found your claim that your room is completely flat to within 1-2dB from 30Hz to 20kHz very difficult to believe. This puts your studio up there with the very finest studios in the world and I just can't see how you could achieve that using your construction techniques and the fact that you have reflective surfaces all over the place. Even using double shell construction, perfect ratios, no parallel surfaces, helmholtz resonators, the latest in quadratic diffusers and absorption materials, etc., etc., it would still be difficult to achieve your quoted figures. Are you sure you are measuring accurately? Here's an example of a state of the art mastering studio which might just about match the figures you have quoted for your studio:



I don't want to scare people off, the studio above is extreme and acoustics is like anything in the audio world, the law of diminishing returns and you can spend virtually unlimited amounts of money if you really want the best. But you can get amazing improvements to an untreated room for a bit of effort and relatively little money.

Hi Bigshot, long time no speak. I agree with you generally but I think you're underestimating the importance of room treatment. Of all the top studios I've ever been to or worked in, they have all, without exception, spent huge effort (and sums of money) on acoustic design. Also, I agree that 5.1 creates even more acoustical problems but the method of increasing the size of the sweet spot and reduce some problems is by using diffuser systems, IE., Splitting the load of speakers amongst several smaller speakers. This is what they do in cinemas. Have a look round next time you're in one, there won't just be two big speakers in the rear left and right of the cinema, instead there will be quite a number (depending on the size of the cinema) of smaller speakers evenly spaced around the back and sides.

Just as a by the way, here's a picture of my current studio (dubbing theatre):



G
 
Aug 22, 2011 at 12:38 AM Post #110 of 292
gregorio - Awesome post.
 
My method of measuring probably isn't totally accurate, but it's close enough that I don't worry too much about it, since it's not supposed to be a  mastering studio. It's a personal home studio where I do composition, recording, and mixing, and if the project won't be using a mastering facility, then I'll have to do that too (these are of course, small projects). 
 
The way I measure is simple--I just use the IK Multimedia ARC System's measuring mic in my listening spot, play pink noise and log sweeps and test tones at important intervals. The signals picked up by the measuring mic is then fed into spectrum analyzer where I scrutinize the frequency response. Wherever I see peaks and dips, I tweak with an additional layer of EQ on top of the ARC System. I also double-check with two different SPL meters and try to get as flat as possible. So it's not that my room alone sounds that flat--it's just the audio output with the ARC System and custom EQ in the signal chain. 
 
My method is more DIY and improvisational than conventional/standardized, so I wouldn't be surprised if someone came into my studio with high-end calibration/measuring gear and find the audio output in my listening spot isn't as flat as I have measured with my own gear. But I'd assume even then, it shouldn't be off by any significant amount. After all, I'm only targeting my listening position and that's it, so it's relatively easier to tweak for a flat response in just one specific spot. I almost never record acoustic instruments or voice, and when I do, the rear half of my studio is a bit livelier than the front half (on purpose), and the spots I record in sounds good enough that I have no problems.
 
 
 
Aug 22, 2011 at 1:12 AM Post #111 of 292
A living room is not a recording studio. Real people don't want to live on the bridge of the starship Enterprise. And real houses aren't built with acoustics as the sole requirement. A listening room in a home makes concessions that studios don't have to make. That's why equalization is more of an option for a lot of people than radical room treatments.

In my own case, I have a theater/listening room where I entertain small groups of people. I can't design it for one focused sweet spot, because it needs to sound good in several locations. I have to have couches for people to sit on and the placement is dictated as much by livability as acoustics. The room is panelled in beautiful midcentury knotty pine. I'm not going to start hanging black mesh panels up all over it. Thankfully the panelling does a pretty darn good job of minimizing reflections. I did as much as I could with placement of speakers and seating and optimizing the surfaces for the floor. The rest is up to the EQ and it does a fine job.

I had to split my mains into two sets to get the soundstage wide enough to span my ten foot projection screen without gaps between the mains and the center channel. You're right that larger spaces require that. It doesn't complicate things as much to have two sets of mains in phase with each other as trying to balance the fronts with a totally separate set of rears. To be honest though, I haven't found 5:1 to be consistently enough applied to spend time really fine tuning it. I'm more concerned with the sub and mains.
 
Aug 22, 2011 at 1:42 AM Post #112 of 292
lunatique said:
gregorio - Awesome post.
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Thanks, I was impressed by yours too.

I'm not familiar with the ARC system, at a very rough guess I would be very surprised if you didn't have some dips and peaks in your room of less than 6dB. That sounds quite alarming but in reality the way that room modes work is that these peaks (and/or troughs) are spread over very narrow frequency bands, so represent really quite small amounts of energy and are usually not very noticeable. But as I said before, there is only a limited amount EQ can do to solve room problems. Even the odd 6dB peak or trough would still put you in line with some of the better professional recording studios. My first studio had a lot worse acoustic problems than that but I still managed to use it successfully for a number of years.

You've obviously done your homework, the Owens Cornering 703 is great stuff, a fraction of the price of commercial bass traps and virtually as efficient. You can probably expect trapping down to 80Hz or so with those, depending on how far away from the wall you have mounted them. In my experience the real problems are always in the bass, 20Hz - 200Hz. You get problems higher in the spectrum of course but they're relatively easy to absorb or diffuse, but with the low freqs you run out of options real quick. If you have a phase cancellation at 40Hz (for example), to absorb that you'd probably have to fill a sizeable percentage of the room with rock wool, just over 7ft! My studio I pictured above had a standing wave at 19Hz, that was a nightmare to sort out but a peak is a lot easier to deal with than a trough!

Keep up the good work though, there seem to be a lot more people here now who know what they are talking about than when I was here last time (just over 2 years ago). There is more marketing BS and uniformed opinion in the audio world than I've seen in just about any other industry and the best weapon to combat this BS and protect the consumer from some of the virtually fraudulent BS is, in my opinion, accurate information.

G
 
Aug 22, 2011 at 2:39 AM Post #113 of 292
bigshot said:
A living room is not a recording studio. Real people don't want to live on the bridge of the starship Enterprise. And real houses aren't built with acoustics as the sole requirement. A listening room in a home makes concessions that studios don't have to make. That's why equalization is more of an option for a lot of people than radical room treatments.

I've got a home too and like most people I don't have a dedicated listening room, just a sitting room. So, I'm not talking about radical room treatments. The law of diminishing returns works in reverse, meaning that to start with a little time and money makes a big difference. For example, a couple of well placed rugs hung a few inches away from the wall where the speakers are pointing can be both decorative and surprisingly efficient. Better still, some thick (backed) curtains covering the back wall can be fairly unobtrusive when not in use by pulling them into the corners but again can dramatically improve room acoustics. There are a number of things you can do with a bit of imagination depending on budget and how unobtrusive you want any treatment to be.

In my own case, I have a theater/listening room where I entertain small groups of people. I can't design it for one focused sweet spot, because it needs to sound good in several locations. I have to have couches for people to sit on and the placement is dictated as much by livability as acoustics. The room is panelled in beautiful midcentury knotty pine. I'm not going to start hanging black mesh panels up all over it. Thankfully the panelling does a pretty darn good job of minimizing reflections.

Really, are you absolutely sure about that? Most concert halls are wood panelled specifically to maximise reflections in the mid lows to mids. All materials have an absorption co-efficient, a softwood is likely to absorb the high mids and higher, the lows are likely to pass right through and everything else would be reflected. Have a closer look at the mastering studio picture above, the walls are covered in wood, arranged as a quadratic diffuser, the idea being that the wood reflects the sound from the speakers but the different mathematically calculated depths of the wooden pieces randomise the reflections so they don't interact and cause standing waves or phase cancellations. And, I'm not saying that EQ should not be used, just that using some relatively unobtrusive acoustic treatment and then EQ as a last resort is far better than using EQ as the first and only resort. Like with pretty much everything else in audio, in practice it's a trade off, in this case between what's practical for a living room and the limited ability of EQ to deal with acoustic problems.

I had to split my mains into two sets to get the soundstage wide enough to span my ten foot projection screen without gaps between the mains and the center channel. You're right that larger spaces require that. It doesn't complicate things as much to have two sets of mains in phase with each other as trying to balance the fronts with a totally separate set of rears. To be honest though, I haven't found 5:1 to be consistently enough applied to spend time really fine tuning it. I'm more concerned with the sub and mains.

I'm not sure I understand exactly how your system is setup. I was talking about using diffuser speaker arrays for the surround channels (in cinemas) to widen the sweet spot. You should be getting good imaging without gaps just from the 3 front speakers. You should only run into problems with gaps between the centre and L/R channels in really large cinemas and then they will often use a 7.1 systems which is 5.1 plus a Left Centre and Right Centre speakers but generally we're talking of screens of about 15m+.

G
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Aug 22, 2011 at 3:04 AM Post #114 of 292
clclubhouse.jpg


The screen comes down across the fireplace in the center. I had problems with the soundstage being too tight to the edge of the screen, so I added the cabinet speakers on the side to open it up a bit. Now the sound comes from the full width of the wall. The woodwork is from 1951. It is very soft wood and with the high ceiling, the sound doesn't reflect much. The room goes further back behind the couch so the speakers are too far to reflect off the back wall. The floor is hard so it keeps the bass moving forward.

The mains are JBL towers and custom JBL studio monitors from the 70s. I have piso tweeters that are pointed upwards on the back of the studio monitors. The sub is a 12" top of the line Sunfire. My rears are just Klipsch bookshelves and I forget the brand of the center. I don't care much about those. I spent a week experimenting with placement and determining how many speakers I needed, and then another couple of months EQing. It sounds very good and very consistent now. Most of the work was the EQing.
 
Aug 22, 2011 at 4:56 AM Post #117 of 292
bigshot said:
The screen comes down across the fireplace in the center. I had problems with the soundstage being too tight to the edge of the screen, so I added the cabinet speakers on the side to open it up a bit. Now the sound comes from the full width of the wall.

OK, I see. So you feed the Left Front channel to both the left tower and the left cabinet speaker? Why not cut down the complexity, reflections and probability of some phase issues between the two right (and two left speakers) by just feeding the front left channel to the left cabinet (or move the towers wider apart and just feed them the front channels and get rid of the cabinets)? I know that you know enough about sound to have obviously considered this and the problems of having two identical sound sources at different locations. There must surely be a better solution?

The woodwork is from 1951. It is very soft wood and with the high ceiling, the sound doesn't reflect much. The room goes further back behind the couch so the speakers are too far to reflect off the back wall. The floor is hard so it keeps the bass moving forward.

As a general rule, the softer the material the higher the freqs which are absorbed (rather than reflected) and your vaulted ceiling will probably be aiding diffusion. Nevertheless, I can't imagine that you're not still getting some fairly significant reflections and at the very least a quite smeared soundfield. If possible, I'd also recommend some soft furnishings hung on the wall where the speakers are pointing. I can't really tell from this angle but it looks like the front right cabinet is pointed at the surround left speaker. If so, that's another potential problem, you don't want any speakers pointing at any other speakers. In 5.1 cinema sound the left and right front speakers are rarely toed in very much (unlike studio stereo systems).


The mains are JBL towers and custom JBL studio monitors from the 70s. I have piso tweeters that are pointed upwards on the back of the studio monitors. The sub is a 12" top of the line Sunfire. My rears are just Klipsch bookshelves and I forget the brand of the center. I don't care much about those.

Obviously for stereo the centre is irrelevant and sometimes with surround music mixes the centre is not utilized much (or sometimes at all) but in 5.1 film sound, of all the six channels the centre is the most important! All the film's dialogue is panned almost exclusively to the centre, much of the Foley is exclusively in the centre, the SFX usually have some centre panning and the music soundtrack may or may not utilize the centre channel.

G
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Aug 22, 2011 at 5:05 AM Post #118 of 292


Quote:
gregorio said:
Thanks, I was impressed by yours too.

I'm not familiar with the ARC system, at a very rough guess I would be very surprised if you didn't have some dips and peaks in your room of less than 6dB. That sounds quite alarming but in reality the way that room modes work is that these peaks (and/or troughs) are spread over very narrow frequency bands, so represent really quite small amounts of energy and are usually not very noticeable. But as I said before, there is only a limited amount EQ can do to solve room problems. Even the odd 6dB peak or trough would still put you in line with some of the better professional recording studios. My first studio had a lot worse acoustic problems than that but I still managed to use it successfully for a number of years.

You've obviously done your homework, the Owens Cornering 703 is great stuff, a fraction of the price of commercial bass traps and virtually as efficient. You can probably expect trapping down to 80Hz or so with those, depending on how far away from the wall you have mounted them. In my experience the real problems are always in the bass, 20Hz - 200Hz. You get problems higher in the spectrum of course but they're relatively easy to absorb or diffuse, but with the low freqs you run out of options real quick. If you have a phase cancellation at 40Hz (for example), to absorb that you'd probably have to fill a sizeable percentage of the room with rock wool, just over 7ft! My studio I pictured above had a standing wave at 19Hz, that was a nightmare to sort out but a peak is a lot easier to deal with than a trough!

Keep up the good work though, there seem to be a lot more people here now who know what they are talking about than when I was here last time (just over 2 years ago). There is more marketing BS and uniformed opinion in the audio world than I've seen in just about any other industry and the best weapon to combat this BS and protect the consumer from some of the virtually fraudulent BS is, in my opinion, accurate information.

G
Click to expand...

 
I think the worst offender I had was a 60Hz dip, and after experimenting with speaker placement, listening position, and using the ARC System with additional EQ, I managed to flatten it to within 2~3 dB. It would've been much worse had I not consulted the engineers at Klein + Hummel. They advised me to place the speakers flush (soffit mounting), or right up against the wall if possible, and since I didn't have the option to punch holes in my wall, I pushed them against the wall, which eliminated comb filtering against the front wall at a more critical frequency. 
 
I try to shoot for deviations within 3dB for what I consider acceptable. 6 dB would make me pull my hair out, since I'm a bit obsessive and picky. I can't find the screencapture, of the final measurement I made (of Voxengo's SPAN) when I decided I was close enough--it was a pink noise measured by the ARC System measuring mic, centered in my listening position, with the ARC System correction engaged, as well as my custom EQ curve picking up what the ARC didn't. I was pretty happy with that measurement, and I knew I couldn't get any closer short of moving to someone else's studio (or completely re-construct the room), and that's when I put my foot down and said, enough is enough. No more endless hours of measuring and tweaking--I'm done. I'm sure if I used a higher block sizes, such as 4096 or higher, then I'd see less forgiving readings, but at around 2048, (using (3 dB slope) it looked pretty good to me. If I have time, I'll try to setup another test session and make sure to save the screenshot this time. 
 
If you are ever in my neck of the wood, I would totally invite you over and take a listen at my listening position through the signal chain I spent countless hours testing and customizing. I'm sure I'll learn some cool tips and tricks from you.
 
BTW, I have an insane amount of bass trapping in the form of superchunks in my studio. The entire ceiling/walls corners are lined solid with the 703's cut to triangular shapes, as well as all the wall/wall corners. I also have a storage closet that doubles as a large bass trap (the door to the storage closet is actually an acoustic panel) You can check out the plans and construction photos of my studio here: http://www.ethereality.info/ethereality_website/about_me/images/workspace/cloud_pagoda/cloud_pagoda-design_construction.htm
 
I don't worry about anything below 30Hz since that's beyond my concerns as mostly a MIDI and DI recording composer (but if I were a sound designer or sound FX/dubbing person, or I worked more with recording of instruments through mic's, I'd be more concerned with stray low rumbles from trains and planes accidentally recorded). If I see stuff out of the ordinary below 30Hz in what I'm working on with the spectrum analyzer, I'll just low-self EQ and kill it completely. 
 
 
 
Quote:
cee tee said:
Some interesting discussion here on the ARC.
 
http://thewombforums.com/archive/index.php/t-5582.html
 
 
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Be careful with anything Ethan Winer posts. He sells acoustic treatment first of all, and second of all, he has the habit of cherry picking replies and information, and conveniently not mentioning ones that aren't beneficial to his business. I used to be on his side, until I witnessed his behavior first hand in a thread about the ARC System on gearslutz.com. While I respect some of his views, I don't fully support the manner in which he conducts himself.
 
What I have maintained, is that the ARC System works best when you already have acoustic treatment, since the two working hand-in-hand is better than either one on their own. But the fact of the matter is, if a room cannot be treated for whatever reasons (spouse, budget, available space), the ARC System will go a long way to help it sound much better, and even if it still won't be ideal, it'll be much improved. I suspect Ethan is threatened by this, as he should be. He keeps repeating the point that ARC isn't a magic bullet, but he conveniently glosses over the fact that an overwhelming percentage of acoustic treatment solutions are not either, and most rooms that's been treated still have issues (as gregorio stated in his awesome posts), and the ARC System can address some of the problems acoustic treatment couldn't take care of. If you scour the internet for discussions and reviews regarding the ARC System, you'll see that the people who dismiss it are almost always the people who have never even used it, or they used a similar product and assume the ARC is identical to that product, and the people who have actually used it are largely impressed by it--including all the reputable pro audio reviews. 

 
Aug 22, 2011 at 5:24 AM Post #120 of 292
^Very good...I love this discussion and if anyone is like me and hopes for technology to do all of the "heavy lifting"- this might keep keep things in perspective.
 
(Also, I noticed Bob Ohlsson in that thread I linked to as well.)  
 
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