Jazzman's ESL/TL speakers

[steve s]

[quote="rowuk

Speed is a convenient term that has no correlation to sound. We know how much speed is necessary for 20 khz, 1k or 20 hz. Audiophiles still talk about "fast bass" which does not exist.

[/quote]


Thats the common view
Must say its not one that i agree with ,i will comment later on my thoughts

[chris661]

There is little or no correlation between specs and sound.

Are you sure?



About the Adire paper about woofer speed: what they should've done is equalised the frequency response flat. Sure, adding an inductor will "slow down" the impulse response, but that's because the high-frequency response has gone.
In more conventional setups (ie, having the woofer crossed over somewhere sensible), I'd expect the impulse response of the LF section to be very similar.

Chris

[Jazzman53]

For guys like me with not much tech savvy, "speed" might be a better descriptor than "transient response" or "impulse response".

[IslandPink]

Very good point by Chris there !

One of the main issues with getting bass to sound 'fast' or timing to be quick and crisp, is phase shift ie. group delay from the loading method. The age-old conundrum is that enclosures that give best bass extension from moderate-sized drivers also tend to be the worst for group delay . This is hence the reason some of us have gone to big bass drivers on OB . TL in this respect should be a bit better than bass reflex, also the low-end can be pretty damned low on TL's which pushes the bad G.D. region down into the 20-30Hz area and not up at eg. 60-70Hz where it's more noticeable .

[rowuk]

100% sure. Every waveform known to music can be reduced to its fundemental and overtones, the frequency and output determine the speed necessary to accurately follow the waveform. The math is quite easy. Still, it doesn't explain anything. There is an awful lot of spec assumptions based on air.

I believe that ESLs like these sound the way they do, not because of distortion or speed, rather because they produce a large coherent wave, have a well defined power response, and no crossover where our ears are most sensitive. A normal woofer is so much smaller and essentially has to move a lot more to get a comparable quantity of air moving. That pumping is audible (compared to an ESL) regardless of the box. Still, it says nothing about the sound. ESLs are no guarantee for sonic superiority. They can sound wonderful or like garbage. The specs themselves simply tell us nothing. I have heard big horn systems that measure far worse than other types of speakers, but they sound far better. Valve amps with very high levels of distortion and limited bandwidth due to the OPTs are deemed by many to sound far superior to SS amps. phono cartridges with low channel separation, non-flat frequency response and resonant behaviour are deemed by many to sound better than digital sources with hundreds of times better specs. The examples for lack of correlation are many.

It is not the gun, it is he/she who pulls the trigger.

There is little or no correlation between specs and sound.

Are you sure?



About the Adire paper about woofer speed: what they should've done is equalised the frequency response flat. Sure, adding an inductor will "slow down" the impulse response, but that's because the high-frequency response has gone.
In more conventional setups (ie, having the woofer crossed over somewhere sensible), I'd expect the impulse response of the LF section to be very similar.

Chris

[Jazzman53]

I want to pursue the woofer/panel blending issue further but I hope no one minds if we take a temporary detour to talk about dispersion and imaging. Roger Sanders gives his views in this Youtube:
https://www.youtube.com/watch?v=Vdf3VA06iSA&sns=em
I mostly agree and I too prefer flat panels but, as any businessman might do, I think Mr. Sanders glosses over the [off-axis] downside to sell his speakers. I will say the downside isn't horrible but it is significant.

The knock on flat panels is their tightly focused "head-in-a-vise" sweet spot, which leaves anyone not in the sweet spot out in the cold. Whereas; curved panels project a wider sweet spot at the expense of less slam and less-precise imaging.

As much as I love my flat panels' magnificent, addictive imaging, I find myself wishing for wider dispersion whenever guests drop in, as they can't all sit in my lap at the sweet spot.

The ingenious Quad 63 and later Quad flat-panels use stators with concentric rings of discrete conductors receiving sequentially time-delayed signals to make the diaphragm project a quasi-spherical wave-front. Again here; trading off slam and imaging for wider dispersion.

Some other flat panel ESL's use two or three discrete, different-width vertical panels, receiving discrete frequency bands (narrowest panel receiving HF). And some DIY flat panels use electrically segmented vertical wire stators with discrete wire groups fed with time-delayed signals to project a quasi-cylindrical wave-front. These configurations too trade some slam and imaging for wider dispersion.

I toyed with the idea of building a removable sound dispersing lens for my existing flat panels, like the ones shown in the links below, but decided against it, as they would make my pretty speakers butt ugly.
Beveridge lens:
http://www.freepatentsonline.com/3980829.pdf
JBL slant plate lens:
http://images.search.yahoo.com/search/i ... ustic+lens

It would be great if the dispersion pattern were switch-selectable. I don't know if anyone has tried this but it's actually quite feasible with a vertical-wire-stator ESL using electrically segmented wire groups fed through selectable time-delay filters to curve the wave-front.

Thus configured, the delay filters could be bypassed for narrow dispersion/superior imaging or switched in for wider dispersion when guests drop in. Of course, each dispersion pattern would need its own EQ curve but that too could be selectable using a digital EQ with memory settings. If I ever decide to build myself some new speakers, this would be my direction.

The link below shows an ultra-efficient DIY wire-stator ESL, which uses discrete wire groups and time-delay filters for a wider sweet spot. It doesn't have selectable dispersion modes but it theoretically could.
http://kenseibert.com/www/kenseibert/esl/

Another ESL builder on the DIY Audio Forum (user name "Bolserst") has created an Excel spreadsheet for segmented wire stator ESL's that calculates component values for the delay filters, and the resulting dispersion pattern.
All kinds of possibilities here!

[rowuk]

The best ESL (or dipole) setups for my ears have been so called LEDE rooms (live end/dead end) If the room is decently sized, the panels are placed at the live end and the back wave "fills in the holes".

Pinpoint imaging is in my opinion one of the BIGGEST distortions in playback/recording. I am a trumpeter in a symphony orchestra and don't even have pinpoint imaging on stage next to the instruments!

If we want the stereo to crush gallstones or laser holes in eardrums, then pinpoint is an obvious choice, but for creating a plausible acoustic soundstage in rooms smaller than the original concert hall, I find the audiophile sweetspot to be unlistenable. Of course with popular music, the goals are different.

Most of the ESLs and fine horn systems that I have heard do have the natural/artificial switch built in however. It is called "toe in". Pointing the panels/horns directly at the ears heightens the pinpoint and accentuates the top octave somewhat. Setting the speakers parallel or to cross in front of us, reduces the unnatural stage to more "realistic proportions". It means that we need two optimum setups.

Delay is a touchy issue as everything is affected and we have an automatic comb filter - not a spherical wave. Again, perhaps an enjoyable distortion but hardly high fidelity.

[Romy The Cat]

Pinpoint imaging is in my opinion one of the BIGGEST distortions in playback/recording. I am a trumpeter in a symphony orchestra and don't even have pinpoint imaging on stage next to the instruments!

Actually it is a bit more controversial then you think and your credentials as musicians are not applicable to this subject in my view as the subject is pure playback/listener interface not music/consciousness interface. Imaging might be a biggest artificial byproduct of playback but at the same time it might not be. I wrote a lot about it in past. To make it short: a best playback shall be able to throw a very serious imaging if recording is called upon it but it would seldom do it. I wrote in past that there are 4 stages of imaging, like cancer…. Generally a better imaging from playback is a very good sign, as one gets it then s/he begin to learn how to kill it but not by the venture of playback efforts but by venture of proper listening techniques. Also, do not forget that imaging is a phenomenal debugging tool that very first shows any problem that playback might have.