My problem with a lot of those speakers you linked to is that there is no way they have enough output to play back music at a realistic level. My standard target is a peak of 110 dB at 3m (~117 dB rms at 1m) with negligible power compression and nonlinear distortion, although I suppose that could be lowered 5-6 dB if I could be convinced the speaker would sound significantly better tonally.
Rybaudio said:
this is also a problem for me although my target is set much lower
how much dB one needs is probably very subjective and dependent on many factors
I have measured peak SPL around 95 dB in my room (28 square meters) at my listening position using various methods with potentiometer set as usually is when I am listening to "big symphonic music"
my conclusion is that carefully positioned 8 inches woofer is a minimum requirement and also sufficient for me
that draws my attention to omnidirectional loudspeakers with 8 inches fullrangers like Lowther's "The Ace"
Rybaudio said:
You may have missed some earlier posts where I said that as far as localization and coloration goes our perception is dominated by the region from 1 kHz - 8 kHz. I also said that one must get this region correct or everything else is kind of irrelavent. That is my goal. At some point the polar response has to widen and that has to be accounted for. But under no circumstances should the system be allowed to narrow then widen and narrow again as virtually all piston source systems have to do at the crossover. The Summa has a small amount of this, but I would suggest that your proposed "dome" system would be really bad. You may be able to get a smooth flat response with what you suggest, but it is a very wide response, which in my opinion is not good.
Achieving a system with very narrow coverage, smooth directivity (albeit accepting that it has to widen at some point below 1 kHz.), flat constant coverage from 1 KHz - 10 kHz. and very high efficiency and output is not trivial. What you propose will fail in the high output and narrow coverage aspects. The Summa achieves all of these.
Did you know that I used to live in State College? I lived in Lemont, just above where the new freeway cuts through. I really loved my time there, its a great place to live. Much like Ann Arbor where I live now.
There is an interesting article reviewing seminars given at major conventions (CEDIA, AES, etc) here:
http://www.multimediamanufacturer.com/articles/weinberg-conventioneering.pdf
Included is a summary of Toole's on-going class on "Loudspeakers in a small room" from 2006. (P8 in the article).
Nearly all the topics covered are relevant to the discussions we've been having here. There is also enough info to allow gathering a lot more information if we follow up with searches on the presenter's names.
I'm extremely busy right now but in spare moments I've been doing a systematic review of Google entries on psychoacoustics and small rooms. Even when the search field is considerably narrowed as in this example, there is a lot of stuff not relevant to our topic
acoustics "small rooms" psychoacoustics
http://www.google.com/search?q=+aco...oacoustics&hl=en&lr=&as_qdr=all&start=70&sa=N
Might be useful if folk could perhaps think of some other search parameters.
Some useful articles here not germane to our topic:
http://www.multimediamanufacturer.com/articles/
Gotta go
http://www.multimediamanufacturer.com/articles/weinberg-conventioneering.pdf
Included is a summary of Toole's on-going class on "Loudspeakers in a small room" from 2006. (P8 in the article).
Nearly all the topics covered are relevant to the discussions we've been having here. There is also enough info to allow gathering a lot more information if we follow up with searches on the presenter's names.
I'm extremely busy right now but in spare moments I've been doing a systematic review of Google entries on psychoacoustics and small rooms. Even when the search field is considerably narrowed as in this example, there is a lot of stuff not relevant to our topic
acoustics "small rooms" psychoacoustics
http://www.google.com/search?q=+aco...oacoustics&hl=en&lr=&as_qdr=all&start=70&sa=N
Might be useful if folk could perhaps think of some other search parameters.
Some useful articles here not germane to our topic:
http://www.multimediamanufacturer.com/articles/
Gotta go
Arcticals that I have read fall into three varieties:
1) good discussions that don't apply to small rooms - the preminate work here is the book by Kuttruff which anyone who wants to talk about this subject should read. Even Kuttruff himself, who I have discussed this topic with personally, accepts that his book does not apply to a small room.
2) discussions based on personal data which have not been verified by actual scientific research.
3)discussions which rely on nother previous discussions which are innacurate (namely points one and two). This seeems to be very predominate in the small room topic.
Floyd Tooles discussions are the best that I know of, but I am not in complete agreement with Floyd either. I think Floyd and I might be trying to achieve different things, and each has a commercial legasy to protect. But on the whole, Floyd and I are pretty close.
keep this in mind as you read the vast collection of stuff on the web.
1) good discussions that don't apply to small rooms - the preminate work here is the book by Kuttruff which anyone who wants to talk about this subject should read. Even Kuttruff himself, who I have discussed this topic with personally, accepts that his book does not apply to a small room.
2) discussions based on personal data which have not been verified by actual scientific research.
3)discussions which rely on nother previous discussions which are innacurate (namely points one and two). This seeems to be very predominate in the small room topic.
Floyd Tooles discussions are the best that I know of, but I am not in complete agreement with Floyd either. I think Floyd and I might be trying to achieve different things, and each has a commercial legasy to protect. But on the whole, Floyd and I are pretty close.
keep this in mind as you read the vast collection of stuff on the web.
In Audio Critic issue 16 it is written:
1) Dr Toole has never said he tested CD speakers
2) Positive correlation: increased beamwidth/constancy, no subjective brightness that microphone may suggest
3) CD speaker and spaced mic stereophony plus interaural cross correlation gives poor imaging so that beamy speakers are better here.
1) Dr Toole has never said he tested CD speakers
2) Positive correlation: increased beamwidth/constancy, no subjective brightness that microphone may suggest
3) CD speaker and spaced mic stereophony plus interaural cross correlation gives poor imaging so that beamy speakers are better here.
Is this the publication you're talking about?
http://www.theaudiocritic.com/back_issues/The_Audio_Critic_16_r.pdf
Spring/Fall issue, 1991, 54 pages?
If so, what pages are you referring to?
http://www.theaudiocritic.com/back_issues/The_Audio_Critic_16_r.pdf
Spring/Fall issue, 1991, 54 pages?
If so, what pages are you referring to?
Page 10. Ken Kantor in issue 20 on page 47 is telling that interaural cross correlation is the one parameter that really correlate with more/less pleasant sound also in concert halls. But how one can simulate this? Is head eliminating cross correlation better in one defined angle and speaker beam width? Of course we can use DSP for that or a kind of reflectors like Manger Holoprofile that for me works because the sound hologram is then stable everywhere in room when using bipolar arrangement.
Now I'm able to measure cross correlation in deep ear canal using Sonion 8002 2mm capsule (but need a suitable preamp).
Now I'm able to measure cross correlation in deep ear canal using Sonion 8002 2mm capsule (but need a suitable preamp).
gedlee said:
I just moved here and am still getting settled in; so far it seems like an interesting place. I'm living a little ways west of campus (Corl St). I'm a grad student in the math department but if I get bored with that I might have to see if I can get in the acoustics program. Any reccomended things to see/do here?
I also found the articles I was referring to earlier. The big summary of Toole's is "Loudspeaker and Rooms for Sound Reproduction- A Scientific Review" which was in the June 2006 AES Journal. The two articles that deal with the model used for prediction are:
“A Multiple Regression Model for Predicting
Loudspeaker Preference Using Objective Measurements:
Part I—Listening Test Results,” by Sean Olive (116th AES Convention)
“A Multiple Regression Model for Predicting Loudspeaker Preference Using Objective Measurements: Part II—Development of the Model” by Sean Olive (117th AES Convention)
For a loudspeaker played at a relatively low SPL level Sean's model and my design guidelines are completely in synch. But Sean's model does not consider effects that vary with SPL. His stuff is all done at a constant listening level and a relatively low one at that. His model would be far worse if different - higher - SPL's were involved as there are things that enter into the situation that were not in his model.
I haven't lived in State College for twenty years so I am sure that it has changed alot.
I haven't lived in State College for twenty years so I am sure that it has changed alot.
Rybaudio said:
Thats about my recollection also. Our diffraction study found that the audibility of diffraction effects really started to take effect just above this level. For legal reason we were not able to test above 90 dB, but at the rate that these effects were becoming audible, I suspect that at about 100 dB they would be a dominate effect. This level dependent perception is completely ignored in all of the Harman work. But otherwise, its quite good.
graaf said:
In the UK, you'd be in trouble after 85dB:
http://www.lhc.org.uk/members/pubs/factsht/79fact.htm
pinkmouse said:
I know that but are those regulations really applicable?
After all what has testing loudspeakers with microphones to do with "safety at work"?
And it is that "after exposure to 85dBA for 8 hours a day for 15 years, 5 per cent of workers will show hearing loss. The same length exposure to 90dBA will damage 14 per cent of workers; and to 95 dBA, 24 per cent of workers"
I mean, what are we talking about?
Those regulations are precautionary measures concerning "safety and health at work"
But testing loudspeakers with microphones or even listening to music at home is not something about "8 hours a day for 15 years" exposure to continuous noise, isn't it?
best,
graaf
As an employer, you have a duty of care towards those that work for you, (that includes listening panels), so the regulations are relevant and enforceable. In the freedom of your own home you are allowed to do whatever you want as long as it doesn't annoy the neighbours, but not in a work situation, and especially not in the litigious US. 
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