Can you have a State of the Art home theater without room correction? - Page 2

You got me there. I was assuming that if you produce a soundtrack for a hugely expensive movie production that will be played in EQ'ed movie theaters, you consider the presence of EQ during playback in the sound editing process.

But, as the saying goes, assumptions are the mother of all screw ups and I could be totally off base. Come to think of it, I am not even sure all (or at least most) movie theaters have EQ, but I am sure the esteemed HT experts on the forum can shed light on this.

I am certainly willing. I auditioned the Vandersteen's and considered getting a the 5a which has EQ in the bass cabinet, but did not like the speaker.

I tried a USB DAC to replace my (network streaming) Perfectwave, with the idea I could apply EQ in Amarra on a Mac, and decided to stick with the PWD.

If a reasonably practical and affordable solution presents itself I'm all in. for now I am quite pleased with what I have, despite inevitable compromises.

What I am not willing to do however is run my mains signal through A/D/A conversion and apply EQ across the entire spectrum.

All playback venues ( movie theaters, etc. ) are EQ'd as part of the commissioning process- the EQ corrects the loudspeaker/room response to playback accurately. Large rooms still interact with loudspeakers' response.

The assumption of the sound director is that the installed venue will have relatively flat frequency response.

Dan

For Amir but anyone pls feel free to respond. I am trying to learn RC processes and becoming ever more confused. I think Dan mentioned he had to remove the theater chairs the other day for some process to work (??), and you need a pro tuning the system, not an automated process (??), and now this. If true, I think a lot of people like me ("audiophiles" who want to try) are just going to get scared from buying anything.

1. Are you saying that if my speakers don't have the "correct" power response, then none of these processes - whether Trinnov, or Dirac, or JBL, will work? My speakers are Thiel CS5i, and Thiel MCS center, how do I know if they have the appropriate power responses, that are correctable? What is an appropriate power response?

2. Reading your post, it seems the JBL process is excellent, but is tuned with JBL speakers and hence best to be used with JBL speakers only?

3. What's the point of room correction if you require 8 (or however many) subs for it to work? You are selecting out 0.05% of customers if this is true, no? This doesn't sound like room correction, but more like using electronics to determine how many more speakers to add to your room? Which is fine, but then it seems room correction process is not "that" capable of correcting electronically.

4. Did I understand correctly that some of these processes, I think Trinnov?, require a pro to listen and tune for it to work properly? That sounds quite subjective and wouldn't that mean the sound customers end up with depends on who is tuning your system and what music/movie you are using to tune? if this is the case, really, I will let no one but Dan Francis tune mine - the same concept goes for Porsche owners - no rookie mechanics is allowed to touch my Turbo. Anyway, whatever it is, that doesn't sound like room correction, which I thought was mostly an objective process? What if the sound is good with one movie but not with another? Is good to Dan's ear, but not good to Curt's, or yours?

Fair enough. The only reason I asked is because I couldn't tell whether you were against room correction in principle or just hadn't yet found a solution that met your needs.

My posts have a way of doing that sometimes .


Well, all the products being talked about are professionally installed ones. But this is not an all or nothing case. For example, we through JBL provide full turnkey optimization of subwoofer placement. Here is a bit on it from the presentation:



As the slide says, all we need is the room dimensions, possible locations of the subs and the number you will tolerate. We then come back with the subs and the nice simulations I showed earlier that tells you how smooth the response will be.

I can't speak about the systems Dan has tested but the JBL Synthesis is very automated and most of the time the single path through it does the job. No knowledge of acoustics is needed to do that although the process does require a dealer measurement kit. The same technology however will become available next year in the Lexicon MP-20 and that will be something users can do on their own.


The process works. But it cannot fix certain problems such as those caused by the power response of the speakers. Those defects remain. And you have to make sure to listen to the system to make sure it did not attempt to "fix" those issues. This is why sometimes people think they get worse sound with room eq than without.


You are asking something that requires a full chapter in a book to explain . But it is an excellent question. Dr. Toole's books cover this in great detail.

Short answer is that you probably don't know if your speakers have poor power response and no way of getting such data. Harman measures this using a special jig that measures 70 points in 3-D space, determining the sum total response of the speaker. Most other speaker companies don't perform these measurements and optimizing their speaker sound using other means.


No, it works with any speakers from Harman group including Revel and of course JBL. As I noted though, it can be told that you have a third-party speaker and then it will do its best. There is then some variability there as it won't be as good as it knowing the speaker response precisely.


I didn't mention needing 8 subs. But the more you can have, the more degrees of freedom for the optimization analysis to find optimal placement so that your room has the best response without any EQ. You are often better off buying 4 cheaper subs this way, than one big expensive one.

You are right that very few people use multiple subs. My point is that we need to fix that, before we fix anything else such as applying EQ. Invest the money up front in more subs. And don't think subs need to be on the floor always. For example, in our reference theater we have subs in the ceiling and on the side walls. All hidden from view. Simulations can be done on variable number and you can choose the best set. For example, if you can do three subs comfortably but four painfully, the simulation can tell you that before you even purchase a sub! You can then make the call as to whether the improvement is worth it or not. In the case of the one simulation I showed, we deployed three. We are looking at 6 subs for our next system.

As an interesting aside, the optimization for the 3-sub configuration tried nearly 40,000 potential locations for the subs and recommended the best one which we used. No way can you do that manually.


I can't speak for the others but in case of JBL Synthesis, no, you don't need to be a pro. The only thing we typical adjust are the level of bass as sometimes it is too high causing the sub to clip, sometimes a bit low. It is usually a few minute adjustment. This is with an all JBL system. With other speakers, it may take more work.

The question in the context of these devices are moot in that they are only sold through the pro channel anyway. The Lexicon will be the exception when it comes out with this class performance.

Did I make you more concerned or less?

Fury wonders what percentage of the MP-20's price would be ascribed to the included "device" referenced above. There would be the percentage for the device itself and then the valuation for end user ease of use, in the setting of a post design/acoustic Rx of the room.

Also, Fury opines that there many on this forum, who have quite a significant bit'o jing in their rooms and can't or won't redesign/construct their rooms or tolerate more than two, or say three or whatever subs. Now, does the Mp-20 provide a likely benefit in such a scenario? the comment above, regarding a step backward after use of such devices is a bit disconcerting. It would seem that the Mp-20 should allow for some alteration of the fully automated, so to say, one button result. If so, have any of you who have done this sort of professional level work, expect that the Mp-20 is going to be a detriment to the end result of using that portion of it, referred to above, in any case?

Fury is a bit less concerned, although you would never know it by his post.

Thank you very much

Fury

Amir has trouble fully understanding what Furry just said . But answering the part that I got, the Lexicon MP-20 has comparable DSP resources to JBL Synthesis SDEC-4500. The architecture is a bit different so one may pull ahead a bit in one direction or the other but overall, lots of audio goodness has been stuffed into that processor .


Anything more than one is great. The simulations I showed were for 3 subs. You need minimum of two subs though. I didn't make the laws of physics . So please don't shoot the messenger . Sound waves cancel each other after the bounce from the walls and no amount of EQ with one sub gets rid of that.

I think people underestimate all the places a sub can be placed.


Sure. It provides a benefit regardless. But with 2 or more subs, you stand the chance of creating true state-of-the-art performance. One that is not "loud television" as Keith Yates would say. But something that sound so good that you wonder if you have ever heard a system that nice! Sadly I don't think people are exposed to such systems and don't know what they are missing. The definition of this is not bass that rattles the walls and stuff that flies over your head. The loud televsion does all of that. It is forgetting that you are in your theater. But in the picture. Flowery words to be sure . But I don't know how else to explain the sensation I get in our reference theater and what I see in the eyes of people in just a few minutes in the chair.


I can't speak to the user interface of MP-20 because that is not announced. Nor did I mean to say that the MP-20 will act that way. Rather, I was expressing my experience with room eq that could not fix speaker ills. In our Wisdom system, we were getting cancellation between its bass array and its planar modules. Audyssey Pro was powerless to fix that. As I said, you can't change the laws of physics.


No, based on track record of Harman, I expect them to put it through enough tests to make sure it does no harm. That is what they did as they developed the original system that is in JBL Synthesis. Here is the chart:



They are the two graphs on the left (one optimized for one seat and the other, multiple). Notice the performance above the reference line of doing nothing. And how some products did worse than nothing.


Fury is a good man. Don't say I said this about him though as it might go to his head.

I guess my message to outline more important things is shining a negative light on room EQ. I don't intend it to come across that much. I just want it to be clear on what it can do as we all want to hear that with a touch of a button, all the ills in our rooms and speakers go away. It is tempting to think that. I used to be that way . Then I experienced room eq not working in so many instances. Then I dug in. Spent time with experts in the field... Keith Yates, Dr. Tool. Alan Devantier. Took tours of Harman factory. Read the books. Played with the gear. And you are seeing the sum total of what sense I have made out it . It is a challenging road as it is a super complex field. Getting it down to simple statements of truth, can be exceedingly hard.

Excellent post Amir as usual

Can,

you can read up info on constant directivity HERE

That is why you will see that some speakers are 'preferred to' (IMHO) and work well in many rooms. Some of the speakers I am familiar with are Linkwitz (Orions), Gedlee, Don Keele's CBT Array, VMPS CDWG.

Regarding subs- you can check out Earl Geddes' method described here HERE

Hope this helps.

Regards,
Kishore

Can,

There's no such thing as a magic bullet, and there's no such thing as a fully-automated "room correction system" - that's part of the point of my ongoing experiment. What I'm trying to point out is that a consumer SHOULD have a professional involved in the EQ/correction process. Trinnov is an exceedingly powerful and complex tool to use, and you really need to know what you're doing to utilize it to the furthest extent....NOT CONSUMER FRIENDLY....not really, anyway- most people's head would spin looking at the data from a room with more than 11 or 12 channels.
Dirac is more user-friendly, once the software is running....but the hardware necessary can be cost-prohibitive for the consumer. There is less to adjust in Dirac, but there are still things that need to be paid attention to.

I have never said that I needed to remove chairs or even move chairs to complete this process, I have the rear-surround lower woofers and tweeters (MTM arrangement) shaded by 2 seats- that means partially blocked, not completely blocked- this caused a FR anomaly that I was questioned about and I answered.

I have not said that 8 subs are a necessity in a room, 4 is really what I would consider "right" for a room, but that is MY OPINION. In my career, I've worked on one theater that had 32 subwoofers, in addition to 11 22" subwoofers that provided LFE and full-range capabilities to the LCR speakers (8 LFE, 3 Full range bass) - so that room had a total of 43 subwoofers. Another theater I've worked-on had 20 subwoofers in it.

There is no real "right answer". The way I spec a room vs the way Amir specs a room or Yates or Harman might all differ- there's nothing to say that any of us is really more correct than any other. All systems will require EQ; that can either be done in a semi-automated process (Synthesis, Dirac, Trinnov, Audyssey, etc.) or it can be done manually, in a DSP by a calibrator. pick your poison.

Amir keeps mentioning power response; this is just ONE parameter that needs to be considered, Frequency response, phase response, and impedance response are all inter-related (the lovely science/art of loudspeaker design). Why is it important to consider these parameters? Because if you have a speaker that drops down to 1 ohm or less at a certain frequency- and maybe the drivers in that speaker don't have the best thermal handling- well you're going to want that speaker to get just enough current to make it move, and not much more than that, or you're cooking stuff. Input signal + gain/cut + local feedback = output signal

Now we need to be real about a couple things here: there isn't a box out there that's going to take a crap system in a crap room and make it work well with the push of a button. Not 'gonna happen. BUT that push of a button can IMPROVE that crap in a can, how much? who knows- but the claim was only to improve, not perfect. Dirac is the closest thing that I have seen to a system that the average consumer or enthusiast to perform the proverbial "push of a button" and get pretty darn good results. Not perfect, and not as simple as only pushing a button- you'll have to move the mic from spot to spot, but other than that, not bad.

Also, you need to know that if you're trying to add 20db gain at 30hz, chances are your amp is going to clip like crazy once you get to anywhere near reference level. So that's why I keep saying that a professional should be involved. Am I a Dr? no. So I'm not going to try to perform my own medical diagnosis, and the Dr should probably stay out of my field, too- because his experience is probably significantly less than mine at what I do.

Room EQ is not a panacea, room eq improves upon already good design, installation, and acoustical treatment implementation.

Is room eq a requirement for using the words "state of the art" ; no you can call your theater state of the art if you'd like- certainly lots of folks do. Bottom line, unless you've been to the mountain-top, how do you know where your system rates? Room eq should be something that any good installation/design firm is using, period- whether the customer "wants" it or not- this is science, people- you cannot change physics, nomatter how pretty your cables are, or how expensive your speakers were.

Why do you think Wilson Audio teaches dealers how to "voice a room" or "vowel a room" or whatever they call it...it's to be able to locate the loudspeakers in a relatively neutral location in the room so bass isn't bloated, etc., etc. PASSIVE EQ basically.

Pardon this, but just because KY uses CFD to make pretty pictures and "examines 40,000 locations" doesn't mean that's the best way- but it certainly justifies a certain billing level, doesn't it? I think Amir's company does it right- has Amir drank the Harman kool-aid? you betcha, but that's pretty good kool-aid to drink. The techniques he's espousing are solid, tested techniques to optimizing performance in a room.
BUT THEY ARE NOT THE ONLY WAY TO GO

This entire topic is so grossly misunderstood, and really at the fault of the companies that make these products, that this type of discussion was destined to happen. There will be those that say that it's impure, or that their particular system does not need it....fine, cool, knock yourself out. But answer one question for me....

Why does every recording studio, every mastering stage, every special venue include some form of digital signal processing or EQ??? These are the locations where the content is created, if they need it to properly hear their creations, what makes you think your room is better?

food for thought.

Dan

Ouch ouch... thanks for the chuckle. I am still reading and re-reading the responses but thanks (& Amir, Kishore) for answering.

As you already know, that there are many "audiophiles/purists" lurking on this forum. I'm one, but the key is I do have an open mind and I think that I should give this a try. I was somewhat discouraged though by the seemingly so many requirements, number of subwoofers being the main one. And also this idea about the process working well for only a few speakers with certain power responses that I will need to try to understand. Amir seems to also indicate that this is geared more towards the professional environment with $100k plus setups, not individual audiophiles with low/mid megabuck system?

1. Your note gave me some hope; are you saying even an imperfect room correction process could be better than no correction at all? As a Theta owner, your comment regarding the more automatic nature of Dirac gives me even more hope!

2. The subjective part of your evaluation bothers me a little bit. Being subjective, what if Dan Francis's setting is different from Curt's setting on same system? Which setting is right? Do I need to pick a pro whose golden ears have similar taste to mine?

3. The subjective nature also means, as I learned from modding my Porsche, you only use people with plenty and plenty and plenty of experience, no rookie. As a Theta owner, I honestly think I would wait until someone like you would make some sort of national tour for adjustment. And if you don't, then what? There doesn't seem to be an adequate support system in place, of pro's with enough knowledge and experience for me to trust.

4. In my system, audiophile recordings tend to have full, powerful bass - they sound perfect. Non audiophile recordings tend to sound very thin, and strident, with very little bass. Room correction does not alter this, right? If this is my main problem, a simple equalizer is all I need?

5. The number of subwoofers required still surprises and concerns me - so many. And if I can't satisfy this requirement, have I failed even before the start? It seems room correction doesn't correct the low frequency well, and that's why you have to correct with more subwoofers, instead of let Trinnov or Dirac do it?

6. AFAIK, Amir didn't merely say power response is one of many parameters to be considered, I believe he wrote that it's an area that is NOT fixable by EQ. That was what set off the alarm in my (admittedly amateur) mind. Why bother if my speakers don't "qualify."

Even as I remain somewhat leery of the process, I am in awe of the knowledge here. My apology if I continue to misunderstand something - pls be patient and thanks (Dan & Amir, et al) for your time.

Can- 'sorry if the tone of my post was biting, certainly not directed toward you. I guess I was just in a snarky mood, sorry. And if you're a Dr. - well sorry as well...kinda...just don't try to be an installer- or I swear I'll get that degree I saw online from that place in Honduras...I mean it!



Anyway,

to answer 2.) The subjectivity between Curt and my self (using Trinnov as an example) would be HOW we interpret the data that it provides. The target curve that is set is objective, not really subjective- because you're either going for flat (doubtful) or some variation on SMPTE (flat transitions but slight downward slope in magnitude as frequency increases). I chose a modified SMPTE for my room as a start because: 1.)I have a finite amount of time with the TEQ for this experiment, 2.) I need to give the Datasat an equal effort to optimize in order to compare the best against the best, 3.) even after going through the TEQ with Curt a couple times, it took 2 weeks to really start to become familiar with the tool and develop a proficiency at it. System tuning is mainly going to be objective, given your service provider has a certain skill level.You get subjective at the end; "OK here's as flat as possible, let's listen to some of your favorite music and you can tell me if I need to make changes..." is a phrase you should hear from any good calibrator/integrator.

Unless you're using Synthesis products (Arcos, etc) I'd say forget about power response as a factor for you, I've dealt with some of the most difficult loads to drive; as long as your power amplifiers have the cojones to deal with it- you should be fine (calibrator should be able to work around).

Thin recordings are thin recordings, not much you can do except use tone controls- at least if you had an EQ system, you could make up a preset or two to handle it for you. (believe it or not, they don't kick you out of Audiophile Academy if you use a tone control- but have half-and-half and you are OUT of Vegan Academy Bucko!) -random Scott Pilgrim reference.

There is no REQUIRED number of subwoofers. I have a customer with 4x 12" subs in his family room, another has 2x12" in HIS family room (which is big enough to hold the HOUSE of the first guy). Use what you have, and if you can distribute more throughout the room to even out the bass- great, if not, make the most of what you have. Not too tough really, do what you can where you can, Can.

Dan

I don't know about $100K but EQ systems being discussed here start at $15K and go up. Add amplification, speakers and projector and we are certainly in the expensive side of things. The JBL System is able to EQ *20* channels simultaneously! This allows multiple subwoofers plus bi-amping as many of the channels as you like. All of this flexibility prices it at the high end of the spectrum as with the rest of the solutions discussed.


I say this bluntly: if your room is not optimized, the bass you are hearing is nothing like what it is supposed to be! It is revelation when the resonances that are there are taken out. Bass becomes tight, as it should be. Overall tonal balance will also improve. Nothing subtle here.


I think I have tried to address this but keep failing . Let me put it this way. Two subs is infinitely better than one. I imagine anyone with a theater has at least one sub. Adding one more should not be an onerous thing. As I said, these subs can be smaller ones and put in any position.


I think in the interest of not getting deep into this topic, I have left out important details that should remove that concern. So let me get into it.

The key thing here is that the sound you are hearing from your speaker below 200 to 300 Hz is almost entirely defined by the room! Yes you heard that right. No matter how the speaker is designed, once you put it in the room, the low frequency response radically changes, by as much as 20 db or even more. Fixing this should be your #1 goal. Fortunately, since this problem is unrelated to the power response, optimized use of two+ subs and room EQ does wonders. Fix this and you will get an amazing boost in fidelity that is hard to describe.

BTW, the above is also what makes this an expensive thing as in bass frequencies, we need to be able to have very narrow band filters as the problem often is just a few hertz wide. So standard EQs do NOT work as they modify way too much of the frequency spectrum.

Above the transition frequency of 200 to 300 Hz, then the speaker dominates the sound you are hearing. In this situation, if you are happy by what you are hearing (with good or bad power response), then EQ is not needed . Overall tonal quality can be fixed still with EQ but not much else beyond that.


You are asking excellent questions. I think the way to look at this is that there is lots and lots of potential for fidelity improvement here. So overall message should be a very positive one.

Oh..., so you were addressing Fury, who is a Doctor, then. Well, your well on your way to Honduras, since Fury has been an AV/automation installer (albeit with limited expertise-this level clearly not included) as well. Fury has eschewed the "KY," noted above,however, except in well, certain situations... Fury can, but won't tell you how many self diagnosticians and lay treatment persons have presented to him over the years in both arbeits. Not Roninesque, mind you, but the point is that the analogy is not quite on point. The issue is the downside risk, which is clearly greater in one of these pursuits...Can you imagine an undersubed and badly Eq'd auditory room? Case..closed.

Now, many of the posters here actually enjoy the installation of their own kits (and the kits of others') tweaking it, increasing their kens, even while risking getting the whole thing knackered. Fury feels that he was essentially told to naff off.

The above discussions, at such a high level, of so many points, by all of the true experts, here is, at once, enjoyable and humbling for many of us to read. It makes Fury feel that ALGORES invention is just what the, you know, ........ ordered.

The Mp-20 is high in the short list of pieces that Fury is considering. Any word on CEDIA and a demo for that piece?

Fury will be quiet now, not treading or threading where he is not welcome.

Thank you very much

Fury

Hi Amir,

Notice you've used some of Keith's slides in your posts. Are you using him to do your rooms ? Having sat next to Keith for dinner on the last night of CEDIA, I remain in awe of the skill, effort and computational power he brings to the design of high end rooms. With Mark Seaton sitting opposite I just tried my best to stay afloat !!

Cheers,

Point taken, Dr Fury- however Dr Dan (Summa Cum Loud; Universitad de Concepcion) is trying to remind others to know the limitations of their expertise, especially when the subject of highly specialized tools is at hand, or is that in-hand, tool in hand....

Fury is certainly welcome in this discussion, which is really ENTIRELY opinion:
"can you have a SOTA home theater without some form of room-correction?"

Always enjoyable to read the musings of the Dr. Fury MP-20 may be shown at CES in prototype form, maybe even in production form. Hopefully it sounds better than the MC-12 did.

Dr. Dan OK, that's the last time I'm using that- I've been watching too much Craig Ferguson lately..

Hi Pete. Yes, we use Keith although until recently, that limited the job to very high end ones. With him now (through JBL) providing his sub optimization as a stand-alone service, and one where he wouldn't have to travel to the job site, I am hoping far more people can benefit from the groundbreaking work he has done to use science to solve the low frequency problem.

No question, sitting in front of him the first, or even third time discussing such things will no doubt be like taking a drink from fire hose . After a lot of trying though, I finally managed to distill the knowledge relevant to people understanding the need for what he does, and is accomplished by it in the presentation I post earlier. You have to get him to not try to teach you how to build a car engine, but what a car engine does for a driver .

If you have a measurement rig (Ok $250 investment in Dayton Omni mic on sale now or you can check out HomeTheaterShack) and three of $100 Polk subwoofers+LFE Sub and Behringer DEQ/DCX processor (<$300), I guarantee you can achieve 'most' of SFM in low frequency range without investing in high $$ SDEC/MP20/Theta processor. Of course SDEC is probably only box which can help in automating this and no wonder Amir references this (there is no other I know of).

For higher frequencies- getting a quality speaker will go a long way

Audiophiles who claim to be purists and do not measure their room/rig are total 'phools' IMHO

Regards,
Kishore

Hi Dan,

I think by power response Amir was referencing the power response of the speakers (i.e. off axis performance), and not speakers with difficult loads and having the amplifier with the cojones to drive them.

Great thread!

I have 4 JL F113 subs in my dedicated Rives theatre. "Back in the day" I thought I had a sota (or at least really good) quality sound without the need for dsp/eq. After all, I have 4 subs and should be able to get really smooth bass throughout. Fast forward a couple of years and when I got the ARC kit for the Anthem processor it was a HUGE step up in sound quality.

My 2 channel system is integrated with my ht (the ht goes to a bypass input on the stereo preamp). I dabbled with an Accuphase DG-28 digital eq between the cd player and dac. Sounded good but after all the $$ spent on Rives, the room and of course the gear (full active ATC setup) I expected more. I had Adam Pelz come up and he integrated the front pair of F113s with my main speakers and the improvement was phenomenal. Without some expensive changes to the acoustics of the room I think I've gotten it as good as it can be. I am hoping to audition a Trinnov ST-2pro or hifi version next month and believe it will help with that last little bit. I will try it in digital mode between my cdp and dac so that it doesn't "contaminate" my audiophile sensibilities. I'm just joking, b/c as much as I'm an "audiophile" I accept that improvements can and will be made by moving beyond accepted audiophile dogma.

Bottom line - I think that room correction is evolving into a real game-changer. The review of the Trinnov ST2 on the 6moons site makes me optimistic that I may finally "get there" although I am already very close.

If you do, I hope you'll post about your experience. You're not the only one intrigued by the 6moons review.

>>Can you have a State of the Art home theater without room correction?<< Yes. But it will sound better if it has some form of properly applied EQ.


You are correct that the assumption is that there's EQ. The mixing engineer is not constrained by this, but, liberated, knowing how it will sound in most theaters.


Since no expert replied, I will chime in. All movie theaters have EQ.


It is indeed the best way to know where to install subwoofers, and how many to use (assuming accurate construction details of the room are available), to achieve the desired level of bass performance. Moving in-wall subs after the walls are built is a major inconvenience and adds to both cost and time.


What does a speaker's power response have to do with amplifiers?

Dr. Dan could address himself as whatever he pleases, as long as he doesn't get confused and charges real doctor rate when he does his Theta Dirac national calibration tour.
Question for you (and Amir/others of course) please, regarding the "quality" of subwoofer to be added. So far I've heard mentioned $250 Polk Subwoofer, and I've heard $3000 fathom JL113 subwoofer (thanks Kishore/Bogg). In my system, different subwoofers sound different: some tight, some loose, some "deeper" subjectively than others.

1. Will the sound of each subwoofer be reflected in the final sound? Or will room EQ erases whatever difference that I've heard. More specifically, room EQ with a tight sounding subwoofer, will result in a different sound from room EQ with a loose sounding subwoofer?

2. Am I wrong to assume that a more well built/well designed/more expensive/etc., subwoofer, JL113, will sound much better than the $250 Polk Audio? In other words, you have mentioned bad in, bad out - this would be an example?

3. What do you advise your clients as far as which subwoofer to add? Do you advise to use the usual "audition at home and see which one sounds "better""? Or do you tell them to "get 12" driver subwoofer with such and such frequency response"?

An eq cannot transform a poorly designed subwoofer. But well designed subwoofers (from different brands) should integrate seamlessly if properly placed, crossed, and eq'd.


I don't know the Polk sub, but considering the price, I doubt it can hit 100db at 20 Hz, much less below that, so I'm not sure it could be considered as a "subwoofer"


I'm not Dan, but neither of those answers makes much sense. Unlike main speakers, subs can be very well evaluated by metrics; i.e. there really should not be a need to test them to see if the suit your home. Conversely, driver size and frequency response by themselves provide very little information.

Can, you know what I like in a great quality utility sub?

Alumapro Alchemy MX 12" , mass loaded cone, in a 2 ft^3 sealed- box. Works great, quits around 22hz. Does a great job of smoothing bass, stays tight and defined all the way and plays nice on 300W.

It's better in my opinion to use 4 good woofers than 1 great one.

Honestly, there are a ton of really great woofers available for not much dollars. The new Velodyne DD driveXLs look like they can perform. Those HSU 15s that you can buy a 4 pack of....etc.

Me, I personally don't really care for JL woofers- they have great output an all, but it has always sounded like one-note bass to me.

Better to start with better hardware, but you know that. Just don't go audiophile; these are tools and you need to view them as such- you'll be better-off like that.

The sound of the Bass and eq is cumulative. Having a flexible bass management system helps too. In reality, so far, from what I've seen with the Dirac and the Trinnov is that they do a great job with the top end, but can be equalled or even surpassed when it comes to bass. It depends on how you'd like to setup the woofers in the room.

There are several way to skin that cat, I won't get into it, but I'll say that I have experienced several methods and have formed my own opinions. If you're really curious, pop over to Chicago for a Leafs/Hawks game and I'll sit you down in my room and you can see what I'm talking about. Honestly, probably easier that way anyway.

More in a while.

Roger, I made a mistake, that's all. Thinking some compound of impedance response and power compression...'dunno why.

CFD; how do you know the algorithm is choosing RELEVANT or even effective locations to consider? Does it know the physical dimensions of the sub enclosure? does it place the woofer anywhere in the x,y,z planes?

Dan

Ahh, good. You said it with such conviction I was really wondering.


It is constrained only to the locations you will entertain. These may be discrete points so that it does not select an interference with wall studs or HVAC, for example, if that is a requirement.

In-room measurements match within *1 db* of Kieth's CFD simulations! It is that good. Reason is that everything can be taken into account from material type, true dimensions of the room, walls not being straight, chairs, etc. Everyone else just assumes idealized versions of a room which does not exist in real life.

So what's the name of that software package?

There is no software package. It is a *service* sold by JBL through its dealers called Flo. Keith does the work. The dealer works with the customer to make the drawings. Keith's team then does the simulation and provides the results.

The system Keith uses starts with a fluid dynamics package that has been augmented by custom code written by Keith's researchers. The engine is then driven by an iterative process which attempts to optimize and converge on a result. This is easier said than done as the permutations at the extreme are infinite. The software knows whether it is getting closer or further from a solution.

BTW, the 40K iteration was on the low side. For higher-end systems as many as a million iterations of sub locations & settings are tried! Imagine moving your subs around manually to try to achieve that!

Got it, another Harman-centric technology. Where would we be without their research programs?

Hate on them all you want, without question they innovate. (and I know you don't hate on them...quite opposite).

thanks for the enlightenment.

Dan

Software still bears crazy resemblance to CATT acoustic (used to be distributed by RPG, I think)