Beyond the Ariel

[Pano]

Originally posted by Lynn Olson
I'm still not 100% sold on the subjective qualities of CD horns, but that's a matter of personal taste.

Then how are you feeling about the non-CD AH425 horn? It should be a lot more neutral than a typical horn. And that 288 is a great driver. =)

...minimum stored energy (combined with generous headroom). In measurements, stored energy appears as the "clutter" that appears after the initial impulse...

It would be nice to see some CSD plots from various amps and preamps. As a sort of baseline. They must be around somewhere...

... Gary Pimm's quasi-cardioid cotton-filled boxes with the rear panel open.

Gary is doing great work with that cotton insulation. I saw some of the new configuration recently. Didn't hear, just saw. Interesting stuff- if you'll excuse the pun!

Glad to know you are actually running. Best of health to you.

[kevinh]

First Glad to hear you are feeling better. At our age it is a long road, hope things continue to go well.

Sounds like your found the compliment of drivers. Sounds like the Horn is meeting your expectations. If you go with the 2 414's is the plan still to run 1 all the way up the the xover for the 288 and roll the other off an octave lower?

[John Sheerin]

Originally posted by Lynn Olson
There are, but I'm not at liberty to share the data.

Then what is the point of this massive thread if there won't be any data presented to support any conclusions that are (maybe?) presented?

Since I've been planning on using a supertweeter all along, the absence of CD is not a major concern.

I don't see the correlation here... Not that CD is required to use a super tweeter per se, at least if that's not in your philosophy, and especially since most super tweeters are not CD, but it would still be a good idea to match the directivities so you don't have drastic changes in the timbre of the indirect sound.

[planet10]

Originally posted by IslandPink
It would be interesting to combine the 45-degree slant edges of the HF Olson RCA LC-1A speaker with the double-wall Onken vents. This would substantially lower diffraction and retain the double-wall lossy vents of the Onken. Another clever variation would be to have different thicknesses of cabinet wall for the inner and outer surface, which would stagger the wall resonances, and make acoustic coupling from one to another less efficient.

We've been doing that is the Fonken/miniOnken for years.

http://www.planet10-hifi.com/fonken.html



If just used at low frequencies it wouln't have as much impact on diffraction as it does when uses in a FR box.

dave

[planet10]

Originally posted by chrismercurio
Another great thing about Bonded Logic is the price

One downside of it, is that 3" is as thin as it comes -- it is a pain to use if you need a thinner piece (i'd like to see 1/2")

dave

[Pano]

Hey Dave, I think they have some new stuff out that is thinner. For cars - IIRC. Foil backed?

[chrismercurio]

Originally posted by planet10


One downside of it, is that 3" is as thin as it comes -- it is a pain to use if you need a thinner piece (i'd like to see 1/2")

dave

Dave,

It's insullation for 4" stud bays 1st, and cheap highly effective loudspeaker damping second. It also squishes down very well. I haven't tried to squash it to .5", but I bet you could get it down to a third of its normal thickness. I would try for you but the unit that I bought is completely populating a pair of 10.5 cubic foot MLTL's that GM and Jay Fisher designed. It really is too big for me visually, but the sound!

Best,

Chris

[g3dahl]

Originally posted by John Sheerin


Then what is the point of this massive thread if there won't be any data presented to support any conclusions that are (maybe?) presented?

The data that Lynn referred to isn't his, so we'll have to wait until he either makes his own measurements or receives permission from the other party. I am glad to hear encouraging news, even if things aren't moving quickly.

I now have my horns and drivers, and am hoping to have some measurements on the AH-425 and GPA 288-16H completed within the next week or so.

Gary Dahl

[Lynn Olson]

Originally posted by John Sheerin

Then what is the point of this massive thread if there won't be any data presented to support any conclusions that are (maybe?) presented?

The impulse and frequency-response data I've seen was from one of my collaborators, and he requested that it not be re-republished. As a courtesy to him, I am honoring his request. He expects to measure higher-quality data in the next few weeks. I expect to be doing my own MLSSA and ARTA measurements in the future, and these will be published here and on the Nutshell web-page.

I don't see the correlation here... Not that CD is required to use a super tweeter per se, at least if that's not in your philosophy, and especially since most super tweeters are not CD, but it would still be a good idea to match the directivities so you don't have drastic changes in the timbre of the indirect sound.

I've been thinking about the importance of directivity recently. Case in point: the Quad ESL57, by any standard, has a pretty wacko frequency vs directivity pattern, far less well-controlled than modern Floyd Toole-designed speakers from Revel and the Harmon International group.

The distinguishing feature of the ESL57 is very low stored energy - from the cabinet (there isn't any), and from the diaphragm (which is very light and non-resonant). As a result it has extremely quick and non-resonant energy-decay characteristics.

Do I hear "drastic changes in the timbre of the indirect sound" from the ESL57? No, I don't. I hear a speaker that is more natural and realistic-sounding than nearly any contemporary speaker. It has obvious headroom limitations - 95 dB max under any condition - but within that constraint it is a superb loudspeaker. To my ears, at least, it's one of the very few speakers that can occasionally fool you into thinking it's the real thing.

The Ariels were specifically designed to mimic the sound of stacked ESL57's - they were designed for Mike Spurlock in Portland, who owned a pair of stacked Quads at the time. People who own Quads are surprised by how close the Ariels sound - well, that's not an accident. It was designed in. But the Ariels and Quads have radically different directivity patterns. What they share are similar energy storage patterns, and a similar direct-arrival frequency response.

I'm aware the modern consensus is to design speakers that have a tightly-controlled frequency vs directivity characteristics - preferably, not too wide, not too narrow, and constant with frequency. THX standards combined with Floyd Toole's research have steadily driven the industry in this direction over the last 15 years.

This is where I part company with modern speaker design. I just don't agree. My first priority is minimum energy storage, followed by flat response at the listening position, and then (in this project) ample headroom. Fortunately, as a retired guy, I don't have to report to a boss at Harmon International or comply with THX standards, or make the reviewers at $tereophile or Absolute $ound happy, so I can design speakers and amplifiers as offbeat and idiosyncratic as I like.

P.S. Planet10, yes, a scaled-up Fonken seems like a good candidate for the 414, for those who want to avoid the hassle and complexity of a bi-amped dipole system.

[planet10]

Originally posted by panomaniac
Hey Dave, I think they have some new stuff out that is thinner. For cars - IIRC. Foil backed?

Originally posted by chrismercurio
It's insullation for 4" stud bays 1st, and cheap highly effective loudspeaker damping second.

I know exactly what it is... after getting a sample about a tear ago, we bought a bale of the 3.5". It is lovely stuff, but most of our speakers need about the same density but 1/2" thick.

I have a bat downstairs i'm going to be using in a midTL i'm doing.

When we got it, we were told there was nothing thinner, if they have brought out some that would be very helpful. Edit: just went and looked, they now have 3/8" which would be useable, but the Al foil is something that would have to be worked around.

dave