ttan98 said:
PE has the DE250 on sale for $105 right now. Assuming a 1.5K Hz LR4 crossover, how do you guys think it compares to the BMS 4540ND or 4550, Beyma CP380/M, or the cheaper 18Sound driver? I'd most likely use the DDS Eng 1-90 waveguide with them.
BTW Lynn, what made you decide to use teh LeCleach profile over a Geddes waveguide?
augerpro said:
The Geddes waveguide is patented, and requires a special grade of foam - Dr. Geddes indicated over in his thread that not just any open-cell foam would do, and I take him at his word. The existence of the patent, and the requirement for specialized foam, means the only (legal) source of the waveguide is Dr. Geddes himself, and I expect he has better things to do than deal with a bunch of high-maintenance DIY'ers. I sincerely hope his commercial ventures are a success, so more people can hear his designs.
I remember reading the Summa has a complex crossover - 22 parts, or something like that. That's more complex than I'd like to do, and I don't want to go down the digital-EQ route for the main part of the audio spectrum.
There's also a big element of personal taste here - I've heard Le Cleac'h horns sound very good with minimalist systems, and that's encouraging in terms of keeping overall complexity down. I've designed complex-crossover systems before (my first commercial speaker designed in 1976 used 46 parts in the crossover), and am not enthusiastic about going back down that route.
The Ariel has a much simpler crossover, and I found chasing out cap-coloration a nuisance with that speaker. With more revealing high-efficiency drivers, I expect the parts-coloration problems to be worse, not better, so that's a strong incentive to avoid crossover complexity. I usually draw the line at one notch filter per driver, and try to avoid them if at all possible. As mentioned earlier, this is a personal-taste matter, and there are plenty of others who have no problem at all with complex crossovers (multiple notch filters etc).
P.S. Nice little find today - Al Klappenberger makes a nifty little transformer tweeter attenuator. These gizmos are way better sounding than L-Pads, since the tweeter sees a low source impedance instead of the series resistance of the L-Pad. By putting a TTA between the compression driver and the crossover, and putting an 8-ohm resistor across the primary of the TTA, it is possible to buffer out almost all of the wild impedance variations of the compression driver from the crossover network. Highly recommended for all horn speakers with passive crossovers - I certainly plan to use a transformer or autoformer for just this purpose.
P.P.S. Al's discussion on elliptical filters, or extreme-slope crossover networks, is well worth reading. Horn/waveguide drivers are in a special position to benefit from these types of networks, since the increase in excursion below horn cutoff is so extreme for compression drivers.
You really want the electrical power to be very greatly reduced at frequencies at driver resonance or below, since the horn is outside its passband and no longer providing any diaphragm loading. That's why professionals use 24 dB/octave crossovers, for example - not just to protect the drivers, but keep distortion within reasonable bounds. Yes, there is a price to be paid in terms of impulse response, but the reduction of IM distortion is a worthwhile tradeoff.
Lynn Olson said:
Duke LeJune has done a really good job of combining audiophile finesse with engineering sensibility. Every speaker he's made has been an improvement on the last. I wonder what he'll be creating five years from now?
It would be excellent to see his gear sold in more markets.
Could you imagine how much he'd sell if his products were available in a boutique in Santa Monica, New York or Bellevue?
Lynn Olson said:
Just in response to the above and not to argue staunchly for the Geddes' profile, but I think there is a bit of misconception, at least the way I see it.
The Geddes' profile, from what I know isn't patented. The overall design might be but the profile is prior art according to what I've read what Geddes himself says. A few of us DIY'ers have built excel tools for graphing the Oblate Spheroid for different parameters and Geddes himself had a look at a tool I helped write.
In his book I beleive he argues that he OS profile has the minimum HOMs and so that is what he uses. The foam insert is to further reduce HOMs and could be used on the Le'Cleach just as easily as the OS. Or the corollary, the foam insert could be excluded from the OS just as it would with your Le'Cleach and theoretically still obtain better results.
The complexity of the crossover is, I think, a biproduct of Geddes optimizing the whole power response and not just the axial response. Conceivably you could approach the crossover with the OS profile just as you would the LC profile.
Basically, all I am saying is that I don't think your arguements rule out using the OS based on complexity, patents or foam plugs. I think the real issue is trying to find a manufacturer who can make a large enough OS waveguide to use as you would like to use the LC.
Josh
If we could narrow down the parameters of the desired LC or OS, maybe some intrepid soul would knock one off.
To my knowledge, Geddes' only reservation about the routine Josh refers to was that the throat entry shown was perpendicular to the axis. The driver Geddes used has an angle of 6 degrees. So, Geddes' point was that the entry angle of the throat needs to match the driver.
To my knowledge, Geddes' only reservation about the routine Josh refers to was that the throat entry shown was perpendicular to the axis. The driver Geddes used has an angle of 6 degrees. So, Geddes' point was that the entry angle of the throat needs to match the driver.
Lynn Olson said:
Maybe just a technicality, but as far as I can determine, the patent on the foam has not issued, but he does have an issued patent on at least one profile: http://patft.uspto.gov/netacgi/nph-...INNM.&OS=IN/"geddes+earl"&RS=IN/"geddes+earl"
I say a technicality, as I don't suggest that people take advantage of Dr. Geddes ideas without compensation or permission. He sold me some foam. He might be willing to license individuals for a modest fee.
JoshK said:
I agree with Josh, no technical reason not to try the OS profile. I disagree in that it shouldn't be much harder than a Le'Cleach horn. The mouth size controls the lower frequency limit in either case, and that's the big part of the horn, therefore the hardest part to make. As far dealing with it being deeper, making it in two pieces, entry and mouth sections, wouldn't be difficult. The one issue with being deeper is the larger offset from throat to mouth.
Sheldon
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 Cléac'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 Cléac'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 Cléac'h
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 Cléac'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 Cléac'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 Cléac'h
JoshK said:
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.
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.
Soundstage
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
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
Re: Soundstage
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
dobias said:
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
Re: Soundstage
.
.
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 said:
.
.
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.
.
.
soundstage
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
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, 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
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
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
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
Jmmlc said:
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.