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Old 24th December 2010, 03:49 AM   #121
Previously: Kuei Yang Wang
 
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Joachim,

Quote:
Originally Posted by Joachim Gerhard View Post
ZDL stands for Zero Difraction Loudspeaker.
In my book that would be a soffit-mounted Speaker, in other words one in an infinite baffle or alternatively a speaker fitted with a suitable waveguide or alternative means of directivity control to avoid any sound "bending around" (diffracting around) the baffle/driver mounting plane.

What is shown at the beginning of the thread is more like a 100% diffraction loudspeaker, as the sound is allowed to diffract (bend) around the bare drivers maximally, although this is not enough for a true omni radiation.

It seems to parallel the B&W Nautilus principles.

The merits of such a solution will depend heavily on the room conditions and personal preferences. I tend to be on the other side of that particular fence in the "minimum diffraction" camp, instead of in the "maximum diffraction" camp, but "horses for courses" and "different strokes for different blokes" and all that...

Ciao T
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Old 24th December 2010, 04:00 AM   #122
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Thorsten, i have heard your speaker. You have not heard the one i am designing here.
When my speaker is ready, please visit me and bring yours. What i claim is, that a speaker designed like a ZDL i defined " disappears" when listened to in the nearfileld.
We can then discuss at length if yours " disappears " better. I whould call it "maximun dispersion" and not " maximum diffraction" anyway because, as i have already shown, a small enough tweater in "free air" does not suffer much from defraction.
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Old 24th December 2010, 04:09 AM   #123
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Hello Gents,
Here is a question for the driver thinkers, I hope that it is On Topic. The Peerless SLS woofer has a higher Qtc than other woofers. With the higher Qtc less air compression in the enclosure is needed to dial the total Q of the speaker (dirver and enclosure). This is the question, all other things being equal is there any difference in the stored energy performance between combination A, high Qtc driver + big box ,Q = 0.71 and combination B, low Qtc driver + small enclosure, Q = 0.71?
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Old 24th December 2010, 04:24 AM   #124
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by Joachim Gerhard View Post
...When my speaker is ready, please visit me and bring yours. What i claim is, that a speaker designed like a ZDL i defined " disappears" when listened to in the nearfileld.
We can then discuss at length if yours " disappears " better. ...
Ooh, I like this approach. Too bad we live so far apart.
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Old 24th December 2010, 04:25 AM   #125
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First the Peerlees needs a big enclosure and yes it will store more energy in the lower reaches simply because there IS energy. Think about it. Its quite a shock to listen to speakers with full bass extention. Many novices will call the sound "slow" at first but when they switch back to their minimonitors they get another shock.
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Old 24th December 2010, 04:35 AM   #126
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DT, reading your post again, in theory the two systems you proposed should perform the same given that the effiiency is the same. Problem is that the low Q woofer whould need more cone mass and a substantial magnet. I know from experience that you can not substitude a big box against a small one and expect the same subjective performance.
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Old 24th December 2010, 04:49 AM   #127
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Hello Joachim,
I am liking the Peerless woofers not picking on them. For my moderate size listening space i am thinking that the larger (40 cm) SLS woofers in 137L sealed enclosures will be solid down to 27Hz (-9db plus room effect). My question about stored energy is looking for better understanding the differences between using high and low Qtc speakers.
<edit> i missed your post #126, thank you for you insights.
DT
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Last edited by DualTriode; 24th December 2010 at 04:55 AM.
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Old 24th December 2010, 04:59 AM   #128
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A speaker that is shallow in extention provokes less room resonances so it may sound more clean in the particular application. I think you can not go wrong with the 30cm version in a closed enclosure. If it booms simply put more damping material into it. Many people think that low Q woofer are "faster" but that is not the case given that you optimise the volume of the box.
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Old 24th December 2010, 05:43 AM   #129
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by Joachim Gerhard View Post
When my speaker is ready, please visit me and bring yours. What i claim is, that a speaker designed like a ZDL i defined " disappears" when listened to in the nearfileld.
Simply logically this would be true. Except I never volountarily listen in the nearfield. And I may add that I am not much into "soundscape" and "3D", which are limited illusions (if nice to have) and value other factors.

Quote:
Originally Posted by Joachim Gerhard View Post
I whould call it "maximun dispersion" and not " maximum diffraction" anyway because, as i have already shown, a small enough tweater in "free air" does not suffer much from defraction.
Hmmm.

In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. (wikipedia)

The process of sound appearing across a greater angle than 180 degrees with a minimal size tweeter would certainly fit this definition as diffraction (waves bending around obstacles - in this case the tweeter housing and magnet).

I have personally found the various approaches to minimum baffle speakers and indeed "maximum dispersion" types (e.g. Omni's) interesting, but in far-field conditions very unsatisfactory.

In conditions where listening is in the nearfield of the speaker, with all room surfaces much further from the listener than the speaker this may very well change, I just do not so far enjoy near field listening at all (and I hate 'can's).

That was the "different strokes for different blokes" part.

I do hope it works out the way you desire.

Ciao T
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Old 24th December 2010, 06:38 AM   #130
ScottG is offline ScottG  United States
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Quote:
Originally Posted by ThorstenL View Post
I just do not so far enjoy near field listening at all (and I hate 'can's).

That was the "different strokes for different blokes" part.

I do hope it works out the way you desire.

Ciao T

Ah, but *WHY* don't you enjoy listening in the "relative" near field?


"cans" are a whole 'nuther thing, and are actually more similar to a *reduced* dispersion field that you claim to prefer.
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