Beyond the Ariel

[Lynn Olson]

Two rather simple reasons I favor the Le Cleac'h profile over others.

1) I can buy them right now, from Azurahorn in Australia, Music Concrete in France, and Experience Music in Memphis, Tennessee. These aren't the only people building them, but they're the ones I've been in communication with. All of the products look well-built, measure exceptionally well, and have a good track record from buyers and listeners.

2) I've head them at length, in high-quality systems (triode amplification, good turntables with Dynavector XV-1s cartridges, etc.) and liked what I heard. A lot. Although purely subjective, I always have a bias towards things I enjoy - partly because I know from experience there will be less to fix, alter, modify, and work-around than things that sound less enjoyable.

This bias towards things I like steers my preferences, although I usually find subtle measurable parameters that also correlate (although not always). This is the reason I'll be buying a pair of either Altec 288 or Great Plains Audio 399 compression drivers with aluminum diaphragms, as well either a quartet of Altec/GPA 414-16's or a pair of Altec/GPA 515's for midbass duties. A quartet of 15" medium-Q Seleniums are probably plenty good enough for bass-fill in the below-200 Hz region.

I like the sound, and I like that they operate well in the intended frequency range - 800 Hz to 7 kHz for the 288/399, and 200 Hz to 1 kHz for the 414/515. One reason I may prefer the Altec woofers is they are all underhung - and the linearity of the field geometry in the gap has a major effect on mid/HF sonics. One of the things that sets the RAAL ribbons apart from other ribbons is the field geometry in the gap - this is an area where a lot of driver manufacturers neglect, since it doesn't show in the specifications.

Back in my Audionics days, I designed speakers around drivers that I had mixed feelings about. Although I was reasonably successful removing the colorations I didn't like, it greatly extended the design cycle, and I usually didn't really like the finished product all that much. That's why I avoid carbon-fiber, Kevlar, or metal-cone midbass drivers, or JBL compression drivers, for example - it's just not a sound that I like, and going to enormous lengths to remove that sonic "character" results in a wishy-washy end result that is neither fish nor fowl, something nobody likes.

Rather than trying to remove coloration entirely, which I don't think is possible at the present state of the art, I'd rather get coloration down to low-to-moderate levels, and aim for a musically consonant and pleasing character for what's left. This is a different goal than other designers, and I'm OK with that.

[dobias]

Gentlemen,
Lately, we have been enthralled with the sound of our evolving OB. However, I feel the soundstage is small. Is there a site or a thread that addresses the requirements for a wide(r) soundstage? I've given up on adding center speakers, we prefer the phantom image instead.
dobias

[riff.ca]

Originally posted by dobias
Gentlemen,
... I feel the soundstage is small. ...

I haven't seen a thread, perhaps you should start one.

The sound stage from my OB's can be huge, routinely well beyond the speakers and up to what I percived as a couple of hundred feet wide on one track. Also experienced about a 240 degree wrap around and visited a large doomed cave.

Wonder how Lynn is making out with the 18 Sound drivers?

Regards

[Caferacer]

I'm still rooting for the Tone Tubby. :-)

[hasselbaink]

Originally posted by dobias
Gentlemen,
Lately, we have been enthralled with the sound of our evolving OB. However, I feel the soundstage is small. Is there a site or a thread that addresses the requirements for a wide(r) soundstage? I've given up on adding center speakers, we prefer the phantom image instead.
dobias

.
.
Narrow or small soundstage is not an artifact of open baffle. It would help if you could provide an overview of your playback system as well as what your aim is soundstage-wise.

Distortion, dispersion mismatch and other factors degrade soundstage and imaging, not open baffle.
.
.

[dobias]

Hasselbaink,
Thank you for taking an interest in my problem.
I hope I can describe adequately my speaker layout:
The arrangement is out of the ordinary, due mainly to arranging the TV in a corner. The living & dining areas are in a high vaulted ceilinged area called a great room. It is 24 ft. deep by 36 ft. wide.
The peak of the ceiling above is 24 ft. high. It is also open to a 24 ft. by 36 ft. loft above & behind the great room. The wall to the left side of the TV corner is almost all glass. The wall to the right of the TV corner has a glass French door & a window.
The OBs are 7 ft. apart & 8 ft. to a point in front of the listener's knees. The distance from the horizontal line connecting the OBs to the rear corner (behind the TV) is 10 Ft.
My OBs each consist of :
a 12" FR mounted above a 12" W in a 20" wide X 30" high front baffle. Reenforcing the FR is a 12" W mounted below the FR & a
second 12" W facing
the rear on a 16" X 16" baffle. There are two 3" cone tweeters
mounted
behind the front baffle, one faces up, the other faces 45 deg. up & to the rear. A super T is mounted to the top of the front baffle facing the front.
The FR is wired directly to an Audire Crescendo amp. The reenforcing woofers & tweeters are connected to an Ashly amp.
The #1 W is series connected through an air core 4 mH coil. The #2 W is fed by a second 4 mH coil that is wired in series with the first coil. I've found that the rear facing woofer must be wired out of phase to obtain the best sounding bass.
I also have a passive sub woofer connected to each side connected to the Ashly amp.
If further clairification is necessary, please ask & I'll answer to the best of my ablity.
dobias

[dobias]

Hasselbaink,

PS: the musicians now sound as if they're playing behind & between the speakers. Any enlargement of the soundfield would be appreciated.

dobias

[Retsel]

Dobias, there are a few changes I would suggest. Try widening the space between the speakers. This should widen the soundstage dramatically (up until a hole develops in the center). You can also try toeing the speakers in or out to test out their affects on the soundstage. Also, open baffle speakers need a lot of room behind them - at least 5 feet to the back wall, and even more would be better. This will reduce the chance that early reflections will muck up the direct sound and provide for a deeper soundstage.

The next point is that the preamp and amps have a very large impact on the soundstage. If you have a tube amp, try different tubes. Also whether the tubes are fixed or self-biased can have a large impact on the soundstage. The presence of capacitors, and other passive devices, in the signal path can have a very important impact on the soundstage.

Finally, if your open baffles have fairly deep wings on each side which are parallel to each other, I imagine that this negatively impact sound stage. Parallel wings are bad anyways because they cause resonances which contaminates the midrange. The wings should not be too deep and they should be angled to the outside of the speaker.

Retsel

[Retsel]

Dobias, there are a few changes I would suggest. Try widening the space between the speakers. This should widen the soundstage dramatically (up until a hole develops in the center). You can also try toeing the speakers in or out to test out their affects on the soundstage. Also, open baffle speakers need a lot of room behind them - at least 5 feet to the back wall, and even more would be better. This will reduce the chance that early reflections will muck up the direct sound and provide for a deeper soundstage.

The next point is that the preamp and amps have a very large impact on the soundstage. If you have a tube amp, try different tubes. Also whether the tubes are fixed or self-biased can have a large impact on the soundstage. The presence of capacitors, and other passive devices, in the signal path can have a very important impact on the soundstage.

Finally, if your open baffles have fairly deep wings on each side which are parallel to each other, I imagine that this negatively impact sound stage. Parallel wings are bad anyways because they cause resonances which contaminates the midrange. The wings should not be too deep and they should be angled to the outside of the speaker.

Retsel

[Patrick Bateman]

Originally posted by Jmmlc
Hello,

I think that inside Earl Geddes's OS waveguide the foam ensures 2 functions:

1) reducing the residual HOMs
2) absorbing reflected waves resulting from a poorly terminated mouth.

For a Le Cl�ac'h horn (the name was first given by David Mc Bean when introducing that profile in Hornresp), with a mouth opening at more than 180 degrees there is very few reflected waves from the mouth to the throat and the second function seems irrelevant. About the first function, Lynn as others reported no horn colouration from both the OS waveguide and the Le Cl�ac'h horn so to use a foam infilling of the later horn seems seems not very useful, even it can be detrimental if the foam possess some variation of absorption coefficient with frequency (something that can be useful to linearize passively the OS waveguide frequency response which one is far from being constant without equalization).

Best regards from Paris, France

Jean-Michel Le Cl�ac'h

Considering all the positive press Dr Geddes has garnered with his OS waveguides, I am dumbfounded that the foam plug hasn't garnered more attention. Honest to God, it's the single biggest improvement I've ever made to my horns and waveguides. The difference is NOT subtle, it's a revelation.

If I am not mistaken, Sheldon, Geddes and myself are the only three people on this board who have heard before & after. You really HAVE to hear the difference it makes, it's unbelievable. Lynn and a few others have heard systems with the foam in place, but hearing the before & after is the icing on the cake.