I don't have a monetary investment in "waveguides" other than buying the SEOS so I don't have to care about whether or not I'm taken seriously. IOW I am not investing in the idea of selling them or promoting them and never planned to. The fact that you are asking for "data" because I claim they sound like poop is kinda funny though.
If you follow the link above where the fellow used his 1" driver in his SEOS crossed at 700 cycles to an 18" woofer you may find some data to analyze. Me, i'll just blow a little more wind.
Unless there's some unspoken rule prohibiting the use of the BA-750 with anything other than a waveguide, I can't fathom what any of this has to do with mounting the BA-750 to a Le Cleac'h horn.
..pretty sure, at least it's something I've experienced AND seen others mention before in various situations (and I think) POOH/Magnetar/Mike, though perhaps not in relation to the SEOS before.
"Soft" dome's are almost always in a wide dispersion design, and often have plenty of diffraction and/or a bounding characteristic (..like with wide-baffle or in-wall designs).
Some describe the sound as "phasey" and not being "articulate" enough, also lacking quite the lateral placement of more directive designs.
Also, unless the speakers are within 1 meter of a wall - I don't think it has anything to do with wall reflections. Rather, I think it's a matter of cross-correlation (and the above issues as they relate to it).
The post is directed towards the Gedlee Co. and the poster that posted a link where they used that driver down to 700 cycles in a SEOS waveguide. I often see people and manufactures using compression drivers out of their range in the midrange along with waveguides. Using that particular driver in a horn that low I have yet to see. Maybe you have?
My comments were specific to the SEOS 12 and 15 inch waveguides. They are the ones I have. The sound was so far from what I'm used to I don't want anything to do with them or other waveguides.
OK. Waveguides and LeCleach horns are quite opposite with regards to mouth termination. The LeCleach termination begins at the throat and continues on as far as you like. A waveguide has virtually none (but deals well with the throat), and relies on its size and added termination to make it work in practice.
The consequence of this manifests in the changing directivity of LeCleach, which may be acceptable but may not be a plus at high frequencies.
The consequence of this manifests in the changing directivity of LeCleach, which may be acceptable but may not be a plus at high frequencies.
It is interesting and no doubt valid that Gedlee does not use them in Summa etc.
Also unless drivers are not designed to work with them or at least match well with them, they cannot give their best. I wonder about the term 'soft'
But clearly they have a place as a nearfield, certainly the round ones do. But I do not like the none symmetrical wave guides like the SEOS. So I can see where POOH is coming from, and he knows first hand what they are like
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The problem I see with the waveguide vs horn argument is that there is not sufficient data to directly link what we hear with the perceived sonic flaws in either of the design. There seems also no technical method to determine whether the flaw is in the horn/waveguide, the driver, or the matching between both. Personally at this point I would consider using horns at the low extreme and at the high extreme of the audio band simply because it cannot cover a wide enough continuous bandwidth of the critical region.
I have tried my hand at mixture concept of the Lecleach expansion, and OS waveguides, not really sure I did not like it because it was revealing amplifier flaws or whether it was one of what I mentioned above.
I have tried my hand at mixture concept of the Lecleach expansion, and OS waveguides, not really sure I did not like it because it was revealing amplifier flaws or whether it was one of what I mentioned above.
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In my experience using SEOS waveguide I found they require a different EQ than a horn (that loads the low end where the SEOS does not)
The SEOS, with all the 1" drivers I have used, has a midband rise from around 1.8 to around 3K - this requires a midband filter to EQ of around 8-10 db to get a linear response. Once the SEOS is EQ's the system barely has 100 db sensitivity and sounds soft. Soft sound to me is lacking dynamics, detail and precision of reproduction I get with multi-way horns. It also sounds diffused with soft imaging and in the room type presence "they are here" -I suppose in nearfield in some situations it will work for people. Probably the same people that like the sound of dome tweeters.
The SEOS, with all the 1" drivers I have used, has a midband rise from around 1.8 to around 3K - this requires a midband filter to EQ of around 8-10 db to get a linear response. Once the SEOS is EQ's the system barely has 100 db sensitivity and sounds soft. Soft sound to me is lacking dynamics, detail and precision of reproduction I get with multi-way horns. It also sounds diffused with soft imaging and in the room type presence "they are here" -I suppose in nearfield in some situations it will work for people. Probably the same people that like the sound of dome tweeters.
Super tweeter integration and active filtering
I used a 600 Hz Guigue Iwata horn for quite some years with a compression driver with low compression ratio (membrane surface / phase plug slot surface at the membrane side). Why low compression ratio: the volume of air between the membrane and phase plug V the phase plug open area creates a lowpass filter that is an important parameter for the high frequency extension next to the other parameters that have been mentioned such as membrane resonances, phase plug design and the short conical section inside the compression driver that controls the directivity for frequencies with wavelength/4 < length of conical section.
The advantage was that with a simple passive equalizing circuit no super tweeter was needed. The disadvantage was that all compression drivers I tested that were very good above 8 kHz, lacked 'body' and 'tone density' in the upper midrange (I am not an audio writer so this might be the wrong terminology) and therefore the optimum x-over frequency was > 1.8 kHz. An Altec 802 or 808 had the 'body' and 'tone density' and could be crossed over at a lower frequency but lacked the highest frequency extension.
In the end the in-room balance with a larger 300 Hz Guigue Iwata horn proved to more neutral (to my surprise), so I started experimenting with integrating the super tweeters. After many positions, different filters, level balancing, measurements, listening sessions (and Monte-Carlo simulations), I achieved very satisfactory results with a configuration as in the attached picture. There is a small patch of absorbing material in front of the super tweeter. The effectiveness is the same as covering the whole top surface of the mid-range horn with sound absorbing material (verified by comparative measurements and listening sessions). Integrating the super-tweeter was time consuming and not many good example were available when I started, but the end result is beyond what could be achieved by equalizing a compression driver.
To Oltos:
I you want to do active filtering you do not need extra active electronics. A Sallen-Key topology has a buffer as active element and a power amplifier with a gain of +A followed by an resistive attenuator of 1/A can take the place of the buffer in this topology. There are a few other requirements for the amplifier (non-inverting, same ground for output and input, no bipolar input for the low-pass configuration), but in many cases you can build a Sallen-Key filter of any order around an existing power amplifier without extra active circuits or interconnects.
Some to go to great lengths for time alignment:
http://blog.silvercore.de/wp-content/uploads/2011/11/IMG_25973.jpg
I used a 600 Hz Guigue Iwata horn for quite some years with a compression driver with low compression ratio (membrane surface / phase plug slot surface at the membrane side). Why low compression ratio: the volume of air between the membrane and phase plug V the phase plug open area creates a lowpass filter that is an important parameter for the high frequency extension next to the other parameters that have been mentioned such as membrane resonances, phase plug design and the short conical section inside the compression driver that controls the directivity for frequencies with wavelength/4 < length of conical section.
The advantage was that with a simple passive equalizing circuit no super tweeter was needed. The disadvantage was that all compression drivers I tested that were very good above 8 kHz, lacked 'body' and 'tone density' in the upper midrange (I am not an audio writer so this might be the wrong terminology) and therefore the optimum x-over frequency was > 1.8 kHz. An Altec 802 or 808 had the 'body' and 'tone density' and could be crossed over at a lower frequency but lacked the highest frequency extension.
In the end the in-room balance with a larger 300 Hz Guigue Iwata horn proved to more neutral (to my surprise), so I started experimenting with integrating the super tweeters. After many positions, different filters, level balancing, measurements, listening sessions (and Monte-Carlo simulations), I achieved very satisfactory results with a configuration as in the attached picture. There is a small patch of absorbing material in front of the super tweeter. The effectiveness is the same as covering the whole top surface of the mid-range horn with sound absorbing material (verified by comparative measurements and listening sessions). Integrating the super-tweeter was time consuming and not many good example were available when I started, but the end result is beyond what could be achieved by equalizing a compression driver.
To Oltos:
I you want to do active filtering you do not need extra active electronics. A Sallen-Key topology has a buffer as active element and a power amplifier with a gain of +A followed by an resistive attenuator of 1/A can take the place of the buffer in this topology. There are a few other requirements for the amplifier (non-inverting, same ground for output and input, no bipolar input for the low-pass configuration), but in many cases you can build a Sallen-Key filter of any order around an existing power amplifier without extra active circuits or interconnects.
Some to go to great lengths for time alignment:
http://blog.silvercore.de/wp-content/uploads/2011/11/IMG_25973.jpg
Attachments
For those that have more fully experimented with this - this is an exceedingly common response and result.
The "data" in this case is the number of subjective responses and ultimate conclusion/design. It's audible design evolution.
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ScottG,
I think this is why some of us have gone to a mid-range cone driven horn rather than any compression driver horn combination. I know the compression drivers have higher efficiency and may even have very low distortion but there is just something wrong with the sound, it never quite sounds natural there always seems to be something lacking in the sound, at least that is the case to me. It is most clear in vocal reproduction. I don't think a compression driver will ever fool me into thinking I am listening to a live production.
I think this is why some of us have gone to a mid-range cone driven horn rather than any compression driver horn combination. I know the compression drivers have higher efficiency and may even have very low distortion but there is just something wrong with the sound, it never quite sounds natural there always seems to be something lacking in the sound, at least that is the case to me. It is most clear in vocal reproduction. I don't think a compression driver will ever fool me into thinking I am listening to a live production.
The problem there is getting the waveguide for the driver correct - up to a point where a smaller driver can crossover (and still sound good). (..and of course the usual problems with crossover integration and vertical nulling.)
I've heard many designs like this (both smaller waveguides and larger horns), and not one sounded "right" in the 900 - 2+ kHz range.
It could be that I've not heard one with a small enough driver for it's higher-freq. cut-off.
If you look back at some of the "pro/consumer" designs from JBL - most have larger format compression drivers only crossed as low as about 1 kHz. Ordinarily I'd think that it was simply down to size/form-factor.. but if that's the case then why use a large format driver? You can after-all use a small driver down that low. You can even get very wide dispersion higher in freq. with a small diffraction slot.
JBL ex.:
https://www.youtube.com/watch?v=Zl6I3ACI1_o&feature=related
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It sounds to me like you guys are all talking about sonic areas around the crossover. Getting the crossover right between a direct radiator and a waveguide is not trivial. I'd like to see some polarmap plots of these "systems" to see how well this frequency area is handled in the design. My experience - the crossover is usually screwed up or the directivities of the upper and lower don't match (in which case the crossover can never work right).
Conversely, this is what first attracted me to (big) horns and compression drivers. Because they DID fool me into thinking it was live.
I took the easy way out with a short horn on the front of a 15" woofer that was basically the same size as the midrange horn, about 30"Wx19"H. Altec stuff.
The directivity at the crossover point was fairly similar between the two sections. The horn on the woofer is not without its problems, tho.
Earl,
You may be right about that. At the same time then I must say all the designers and all the different companies attempting to make this sound right, I just haven't heard a one that sounds right when it comes to vocals, especially that. I have always been able to identify that I was listening to a horn in some way or another. I've never heard your system so have no comment on that, but I have heard so many combinations over 45 plus years and still say the same thing, there is always some fatal flaw in the presentation.
You may be right about that. At the same time then I must say all the designers and all the different companies attempting to make this sound right, I just haven't heard a one that sounds right when it comes to vocals, especially that. I have always been able to identify that I was listening to a horn in some way or another. I've never heard your system so have no comment on that, but I have heard so many combinations over 45 plus years and still say the same thing, there is always some fatal flaw in the presentation.