transparence dipole loudspeaker

Hi,

Tsa, tsa tsa....

:baby:

Poor you, bad boy using words you don't know?

FYI, "impulse coherent" is not ONE term, it is actually a combination of two terms, which I might add, have clearly defined and unambigous meanings that are not altered by using them one after the other.

The actual meaning of each term should be obvious to any person of a modicum of learning and intelligence, that failing the minimal expedient of looking it up in a dictonary will clarify. I trust this explains it, if not please avail yourself of the local WH Smith to purchase a dictionary and if required the services of your local colledge for some remedial english.

Excuse me, first, I do not have to explain anything to anyone, least of all you. You are in no position to deamnd anything, seeing you have not contributed anything here at ZG.

Secondly, I do not think I can let you off so easily on the subject of your claim that "digital room eq introduces phase distortion"....

Please either retract it formally or provide at the very least some theoretical concept and framework to support your assertation which can be subjected to scrutiny and inductive, deductive and logical analysis and suitable criticsm.

Failure to formally respond to my challenge to your assertation will be considered (not by me, by the general readership) as conceeding the point by default and that surely is something you wish to avoid?

L8er T

 

Johnny, you can gain a deeper understanding of the meaning and importance of time/impulse coherence by reading this article:

http://melhuish.org/audio/article3.html

Thorsten, if I might quote from the above article:

Taking this to its logical conclusion, this suggests to me that for the realistic reproduction of a musical instrument (or any other sound), we should use a single transducer, period, i.e. mono, not stereo.

By employing stereo transducers, we gain the creation of a soundstage but we inevitably blur the upper harmonics of each instrument and thereby lose the realism.

 

Why are multiple drivers not in time with each other at HF? Is it simply that at such a HF, and thus speed of movement, it is very hard for the drivers to be in EXACT time with each other? Or do you mean drivers that are crossed over?

I’m not quite sure I understand what you mean.

cheers

 

conceeding the point ?

I did look that word up in my dictionary, but such a word does not exist.

Even if you meant concede, your use of the word in such a way would be grammatically incorrect.

The word assertation is also non existent.

Proving the statement : "digital room eq introduces phase distortion" is trivial, since anything can cause distortion,and nothing is perfect (and I do mean in practise, not in theory.)

 

yes techno bear, obviously if you were recreating the sound of a single instrument, then it would be far more easily done using one channel to begin with rather than trying to do it with two.

 

Johnny how many languages do you speak fluently? I only ask because Thorsten (to my knowledge) can speak both English and German, so if he uses a single word in a slightly odd way it is only because he has twice as much info relating to languages in his head compared with most of us!

Interesting you couldn't pick on anything more worthwhile to counter him in this odd and directionless discussion.

 

There are many reasons. Here are 3

You are a different distance from each driver. Distance = delay = phase shift divided by freq

Even if you are equidistant from the centre of 2 drivers, the sound comes from the whole surface, so a 5" mid and a 1" teble have a distance variation of 6". Note that the various distances will not be moving in unison anyway. A cone driver is in 'breakup' or 'bell-mode' at HF - meaning different parts are doing whatever they want to..

Even if you had 2 perfect pistons and you were equidistant, the reflections of the wall, box diffractions, are not equidistant.

Even if you get this lot sorted, crossovers will mess it anyway due to phase shift versus freq

 

Okay so you are talking about different drivers in different places. Thats what I was unclear about. Simply having two drivers (implies identical drivers to me) and no reference to position I could not see why they wouldn’t not be in time.

 

Hi,

Alas, double key-stroke, it happens to me on occasion, just as it happens that I happen to get letters or even grammar back to front. There is a term for that, which escapes....

Alas, not so quick.

You claim a specific distortion and you imply that the the amount of distortion is material, material enough to exclude the use of digital room eq because of it.

So, go on.

In what way does using Digital Room EQ introduce phase distortion (excepting of inverse distortion of phase to that present in the speaker/room system which results in a NET undistorted [or realistically strongly reduced] phase distortion)?

L8er T

 

T, I do that, I call it Dyslexia!

...here come the jokes about Dyslexics no doubt

 

Hi,

Well, there was that dyslexic pimp, who bought a warehouse....

Ciao T

 

There was a girl at my secondary school who had a shirt that said 'Warehouse' on it. some kind of brand name I guess. I read it as ‘whorehouse’ for a few weeks before I looked properly!

 

Reading the Real Sonics page, it is easy to see why Johnny might question it. It reads very much like marketing BS dressed up with selected pseudo science designed to look like fact rather than personal theory.

No doubt this is the same as all other speaker manufacturers, but IMO should be taken with a pinch of salt. For instance, whilst there are references to some AES papers, there are no references to the work carried out by Floyd Toole, which shows that listeners consistently prefer neutral loudspeakers, +/-1db across the frequency range, with a smooth off axis roll off. These are specs that no single full range drive unit can hope to approach as far as I know, and therefore the dipole represents just another set of compromises, not a quantum leap as suggested by thorsten.

 

You'll be looking for spoonerism then

 

Hi,

Most of it is actually common sense, but I will add some references on the Subject of crossovers and single drivers soon (mainly work by Manger and the founder of Voicepoint), the rest can be easily confirmed by checking the references provided, did you do so?

Dr Tooles work is of interest, HOWEVER, the results are hardly of the nature you claim. I am very familiar with Dr. Tooles work and there are a number of conditions and limitations that apply to the findings. Among them are the conditions under which the tests where carried out, which have very little if any congruence with the conditions domestic speakers operate in. Also, his tests show significant areas of omissions in certain performance areas and hence the results are not universally applicable, not even close to being so.

Actually, I do not suggest a quantum leap at all, anywhere. I merely suggest an avoidance of the fundamental tecnological compromises found in multiway box speakers and a return to the sound principles (pun intended) the makers of many speaker systems from the "golden age" used, updated and modernised in terms of both looks and performance. Thus they are actually a return to sensible speaker design.

L8er T

 

I think this is what Thorsten meant though. Are we talking about identical drivers in theory or identical drivers in practice?

In practice, even carefully selected driver pairs will not be identical. They will differ in their Thiel-Small parameters by small amounts and this will lead to small differences in their responses. Not enough to make the speaker sound bad, but enough for the brain to know that it is hearing a loudspeaker and not real instruments.

There are other problems with multiple driver arrays at high frequencies. So-called comb filtering is one that has not been mentioned yet. When the reproduced wavelength becomes shorter than the distance between the driver centres, they cease to act as a single source. The wavefronts from the multiple drivers then interfere with each other leading to peaks and dips in the response. Moving your head a short distance can dramatically change the sound heard.

Most two-way speakers exhibit comb filtering around the crossover point and above. The wavelength at 3 kHz is about 11cm . Even on my baby Dyns, the distance from woofer to tweeter is around 13cm. The woofer still has significant output above that frequency.

 

Hi,

Yes, though this comb filtering is a direct result of the difference in distance to the ear (and to neighbouring sound reflecting surfaces).

Basically, with most speakers (even my dipoles) the diffuse field sound will be much higher in terms of SPL contribution than the direct sound from the speaker. If we have multiple sound sources we invariably introduce problems, if we correct them in the direct (on axis) sound they remain present in the diffuse field.

The best solution is to produce as wide a range as possible from a single point source. This way any transient is coherent no matter if it is a room reflection (which our ear brain system expects and tunes out) or direct sound.

I noticed Siegfired Linkwitz talk in a part of his website about his experience with the difference between live and recorded/replayed music. He commented that there seemed a general carpet of sounds upon which the music existed with reproduced music, compared the actual orchestra.

The reasons for this are manifold, I would however count the fact that any reflected transient sounds are no longer coherent as one of the main issues, together with resonant energy storage.

I noticed similar things with what used to be one of my favourite concert venues (Kenwood House open Air), when the switched from unamplified concerts in the old "Shell" bandstand to a larger venue with a temporary stage and amplification what was a really exhillarating and exceptional experience became extremely ordinary. It's still fund and we tend to go to at least one of the concerts each summer, but I used to miss a concert only if I really hated the music or could not make it at all....

There is some rather interesting work on the subject by Mr. Manger (sadly largely in german and obscure), who asserts that due to the way our nervous system and brain is "hardwired" by millenia of natural selection we respond very strongly to transient sounds (they usually spell "danger") and that failure to be able to clearly identify and discard as "safe" transient event leads to increased tension and blood pressure, something which would preejudice against enjoying music but would not really be easily noted in traditional AB and ABX tests....

Ciao T

 

If a transient is made up of a group of violins or three percussionists in an orchestra, surely that transient's reflected sounds are not coherent? Your theory only seems to apply for solo instruments.

 

Hi,

Sureley, if we have a plucked string or whatever they call it when bow and violin are used percussive, surely we have a group of distinct and spatially seperate transients, not one transient made up of a group?

Equally, if three Percussionists all strike their kettle drums, surely we have a group of distinct and spatially seperate transients, not one transient made up of a group?

And surely each distinct sound and it's location in space, as well as it's reflections are distinct, not just part of some amorphous sonic sauce?

Ciao T

 

Human hearing can easily tell the difference between one real plucked violin and three real plucked violins.

Telling the difference when reproduced through a loudspeaker will depend on the transient coherence of the loudspeaker.

The direct sound seems to be more important than reflections here. Human hearing is very good at distinguishing direct sound from reflections. It has to be in order to accurately locate threats.

However, if the direct sound is blurred then our hearing can't do much to sort it out as this blurring doesn't occur in nature. Instead it tells us that the sound is artificial.