Which brings me back to point sources,Then try arrays. No sweet spot at all. Dispersed sound, like it goes from beyond the speakers. The next year I will bring on BAF 3-row arrays, open baffles: open baffles and dipoles are getting popular.
My arrays at home are currently in walls.
, they work for me! But, only because the electronics are sorted out well enough ... if they're off colour, even slightly, then the whole "mirage" collapses. The key is eliminating audible distortion, if this is too high then the ear/brain refuses to accept the "message" the system is trying to present, and you're back to YAH, yet another hifi ...As Tom Danley points out, what the ears pick up is pretty close to being a complete mess, it's only the brain decoding it competently that gives us a good mental representation of what's actually happening, even with live sound. Overload our poor old heads with yet another layer of mess added by the reproduction system misbehaving, and our brains give up, we get a headache, listening fatigue ...
Frank
Mr. Danley
What can not be modelled I guess (and thus corrected by pre distortion) in a horn is the mess that happens in the compression chamber (the volume between the driver diaphragm and the throat aperture of the horn), especially when there is no phase plug. “Near field” amplitude/phase variations, internal cross reflections, diffraction effects, volume resonances., high pressure chaos.
Jneutron, the process is adiabatic. Front of the wave, hot. Back of the wave, cool. As you say, heat travels with the wave. See left attachment for wave distortion that Mr. Danley is speaking of. On the right, Pick your curve and draw the distorted wave.
https://ccrma.stanford.edu/~dpberner/Thesis/thesis.pdf
http://www.diy-audio.narod.ru/litr/Modeling_Of_Horn_and_Enclosures.pdf
http://www.volvotreter.de/downloads/Dinsdale_Horns_1.pdf
http://www.volvotreter.de/downloads/Dinsdale_Horns_2.pdf
George
>Edit. Steven has already posted this and Jneutron responded.
I missed it. Sorry
Attachments
Last edited:
Huhh?? Speakers are speakers, amplifiers are amplifiers; actives are only so because the length of speaker cable is very short, and the output stage doesn't have to pump unused amps into the crossover. As I said in another post, electrically every system should be considered as a totally integrated mechanism; actives win over passives because the engineering between the amps and the speaker drivers is better sorted out ...
Frank
Ah, wait...the assumption is ideal gas law. With high spl and energy density, that isn't accurate. I pointed out that concern a coupla posts ago. The equation P1V1/T1 = P2V2/T2 no longer holds. All you can do is drop back to the relation P1/T1 = P2/T2 (Gay-Lussac's). Volume is not constant through the pressure wave, nor is temp. (The pv/t=pv/t equation is not deterministic by virtue of the model..as the wave passes, we are not talking about the same quantity of gas, the equation only holds for a specific quantity of molecules. Gay-Lussac's avoids that constraint.
As with all physical processes the temperature of the gas will lag the instantaneous pressure..heat capacity. That difference merely modifies the wave profile a bit over a zero heat capacity model, but the same basic effect as Tom mentions.
Very nice links. Grazed through the first one, very interesting. He was thanking the fusion guys at LBNL..
Will peruse the rest when I get a chance..
jn
ps. the second link appears to be cyrrilic.
ah, 3rd and 4th link, mention adiabatic. That is only true for an ideal gas with spl's not excessive.
As I recall, Abraham B Cohen (sp) discussed the adiabatic distortion of the throat, and I think he used the back compression chamber to balance that out. He never really formed many equations, but did seem to know what he was doing..Wasn't he a violin player?
Last edited:
Last edited:
You are right for large waves lengths, I believe not shorter ones (depend of the distance between the speakers and listener position) where it add only average 3dB.
That is to be taken in consideration too when we design filters, depending of the diameter and distance from the speakers (Pink noise measurements helps for that).
Last edited:
Frank, you can easily check this by recording your own upright with a good pianist at home and playing it back later. Something like a Behringer ECM8000 is sufficient. Beg or borrow a soundcard with P48V mike preamp. We are only checking for clipping which you can extrapolate to a 1000W amp.
It's not the average levels but the peak levels which are a problem. I used to sing with a choir that often sat in front of the brass section so I know how loud this gets.
Recording good small choirs is more difficult. There are various levels of 'in-tune'. If good enough, a choir of 12-20 can sometime show amazing peaks at very modest levels. What happens is that they sing so 'in tune', they add 6dB rather than 3dB for 2 voices for very short periods. When this happens, the short peaks are so high you can hear the intermod in your ears and your peak meters go through the roof. Only happens with the very best choirs.
I recommend anyone involved in audio to go out and make some recordings yourself. You don't need the very best mikes & supa equipment though it is far easier to get really good stuff this millenium. But your outlook on reproduced sound will change.
Last edited:
This is exactly what's done with a few extra bells & whistles in
AES E-Library Loudspeakers: An Approach to Objective Listening
We later highlighted the limitations of considering the speaker as a 1D transmission channel in AES E-Library Absolute Listening Tests-Further Progress
I coined the term Room Interface Profile as the most important characteristic of a domestic speaker. Pseudo prophet Floyd pretends to pontificate on all this.
Richard, I know where you're going with this, and this is the classic difference between the subjective impression of the loudness vs. what the meter says. And I've been down this road many, many times.
There are 2 factors at work here: if there are genuine short term high intensity peaks in the actual sound, well above 120dB say, then a choice has to be made with the recording mechanism: either the true peak levels have to be recorded correctly, which means that the average level is well down, the recording played back will sound incredibly soft, so you'll wind up the volume so it sounds "right", and then, yes, that peak will be clipped; or, as in nearly every case, this short term transient will be automatically compressed by some element of the recording chain - every CD you buy will be "victim" of this "manipulation".
And the other factor is that the subjective intensity of the sound, which is what you're talking about experiencing when standing in front of the real thing, is a characteristic of the level of distortion of the sound. The subjective "loudness" of my systems vary dramatically, depending on the state of tune; the volume control setting doesn't change, but the perceived intensity, the ability of the sound to seem to rip through my skull, in a nice way, will alter depending upon just about everything. I regularly do things like standing 6 feet away from a big band going full bore, bypassing the stupid PA nonsense, to calibrate the sensation of that intensity of sound ...
Frank
May i confirm ? Recording a piano is a nightmare and need *careful* limitation/compression for future realistic reproduction in a medium home system.
One of the best piano recordings i know is the Don Pullen "Sacred common ground ". There is one tune i can't afford without tears.
I was told that he was just back in the studio from the hospital where he was just tough he had an incurable lymphoma.
He sat at the piano and improvised. Engineers have been running the tape and it gave this piece, full of grief, anger, fear, and desperate love of life.
I don't know if the story is true.
I need to augment my Pullen collection a good deal. I do like Random Thoughts quite a bit.
Like many others I am intrigued by our perception of sound. This thread does cover a very diverse range of subjects so may be this post is not toooooooo far off topic. But while we are looking at this area has anyone got experience of the reaction of other species to reproduced sound?
I mention this because John Linsley Hood who was both a competent designer and someone who appreciated music, records some anecdotal accounts about his Siamese cat: Fingal. Apparently the cat noticed changes to equipment, reacted adversely to some modifications to circuitry and disapproved strongly of one particular amp'.
I recall he mentioned this in at least one of his published magazine articles but a more accessible reference that some members will own is his book "Valve and Transistor Amplifiers", page 195.
Any others had domestic pets express their views on equipment?
It crossed my mind that it is possible that they may be more "objective" their response. They would be free of preconceived ideas and commercial interests but how their opinions could be reliably documented would require some additional thought.........
Btw Scott we in Oz appreciate the new avatar.
Cheers, Jonathan
I mention this because John Linsley Hood who was both a competent designer and someone who appreciated music, records some anecdotal accounts about his Siamese cat: Fingal. Apparently the cat noticed changes to equipment, reacted adversely to some modifications to circuitry and disapproved strongly of one particular amp'.
I recall he mentioned this in at least one of his published magazine articles but a more accessible reference that some members will own is his book "Valve and Transistor Amplifiers", page 195.
Any others had domestic pets express their views on equipment?
It crossed my mind that it is possible that they may be more "objective" their response. They would be free of preconceived ideas and commercial interests but how their opinions could be reliably documented would require some additional thought.........
Btw Scott we in Oz appreciate the new avatar.
Cheers, Jonathan
Last edited:
Johnathan,
could it be that our animals are listening to what we would call out of band frequencies? I think perhaps they are hearing the high frequency hash that most upper frequencies will show any time you get over 20Khz if you are lucky. So if a titanium dome or a compression driver has increased output in this range and it isn't exactly musical in nature our dogs and cats are hearing that. Listener fatigue from the dog.......
could it be that our animals are listening to what we would call out of band frequencies? I think perhaps they are hearing the high frequency hash that most upper frequencies will show any time you get over 20Khz if you are lucky. So if a titanium dome or a compression driver has increased output in this range and it isn't exactly musical in nature our dogs and cats are hearing that. Listener fatigue from the dog.......
No. I mean that for active speakers they publish max SPL on 1M that the amp/speaker combination causes, without destruction and horrible distortions. For passive speakers they publish SPL on 1 M when input power is 1W. It is not about what wins, it is about how to interpret the numbers. They can't be compared, because active speaker can have for example a couple of 400W amps inside for 130 dB output, but each driver inside can have corresponding sensitivity that can be measured for 1W input.
Anatoliy
My dogs sometimes react on sounds of other animals in movies, sometimes don't. But they always react on a door bell sound.
Understood. Those max. SPL I would take as those corresponding to the onset of clipping of the amplifiers, because typically the monitors have decent protection from this sort of overloading. Interestingly, they also usually include the power of the built-in amps, so then it is relatively straightforward to determine the driver sensitivity.
Frank
It doesnt work for me. And, my speakers are not 94db or more effec. So back down on that number by several db and crank the power back up. I listen further away than 6 feet..... more like double that. I find that 250W is a minimum number. The point is that many have much less capability in speakers and power to drive them to reach a semblance of reality -- including low distortion and dynamic range. Thx-RNM
- Status
- Not open for further replies.