Hi mwmkravchenko
I received your e-mail on the Unity thread which until then I had somehow overlooked.
So far as its operation, I would suggest you look in the archives at the High Efficiency forum at the Audio Asylum. Some years back I wrote a number of detailed posts trying to explain how it worked to a fellow named Wayne who was first convinced it couldn’t possibly work and then eventually what it accomplished was unimportant.
From these, the details can be gathered as well as the conceptual operation.
While I can’t tell you how to build a “product”, the DIY’r is free to experiment on his own if you catch my meaning.
The key to making these work is the relationship between the different frequency ranges at Crossover. Unlike a normal speaker where the different range drivers are physically far apart and only very loosely coupled, these are acoustically close which is the condition needed for them to add as a single source. That “closeness” also means that where one has cancellation’s, they produce very deep notches or interference artifacts.
While I have not used the DXEQ style crossover, conceptually it does offer some real advantages especially at the DIY stage. A passive crossover for horns like this IS a real challenge, possible but it takes some doing and is based on the acoustic and electrical magnitude and phase of each range.
One last caution, how the drivers combine is governed by their acoustic phase and amplitude. Many popular measurement systems do not measure acoustic phase but instead imply it based on the amplitude response. While many drivers are mostly “minimum phase” which makes the measurement simplification valid, this falls apart when there is more than one driver, changes in a radiators directivity or efficient horn and a number of other things which make speakers systems partly non minimum phase.
Fwiw, the Hilbert transform assumption for the direct radiating, acoustically small speaker is also a condition which can never reproduce a complex signal as that response spreads a signal out in time.
Bottom line, you need to measure these things while developing, the odds of correctly tuning by ear are about as great as making an Indy car without measurements.
While I do not wish to enter / participate in a debate about which systems don’t actually measure acoustic phase, I can tell you that the TDS (time delay spectrometry) process I have used for the last 20 years or so DOES and is based on the work of the late Dr. Richard Heyser (you might want to also get the Audio Engineering Society loudspeaker and measurement anthology’s).
While it may still be a bit much for the DIY’r, there is a new cheaper version in production now, as well as a user’s forum with many acoustic notables.
That would be a product made by a Goldline, called the TEF machine.
The new one runs off a USB port, that with a measurement microphone and your off and running.
Hope that helps.
Tom Danley
.
I received your e-mail on the Unity thread which until then I had somehow overlooked.
So far as its operation, I would suggest you look in the archives at the High Efficiency forum at the Audio Asylum. Some years back I wrote a number of detailed posts trying to explain how it worked to a fellow named Wayne who was first convinced it couldn’t possibly work and then eventually what it accomplished was unimportant.
From these, the details can be gathered as well as the conceptual operation.
While I can’t tell you how to build a “product”, the DIY’r is free to experiment on his own if you catch my meaning.
The key to making these work is the relationship between the different frequency ranges at Crossover. Unlike a normal speaker where the different range drivers are physically far apart and only very loosely coupled, these are acoustically close which is the condition needed for them to add as a single source. That “closeness” also means that where one has cancellation’s, they produce very deep notches or interference artifacts.
While I have not used the DXEQ style crossover, conceptually it does offer some real advantages especially at the DIY stage. A passive crossover for horns like this IS a real challenge, possible but it takes some doing and is based on the acoustic and electrical magnitude and phase of each range.
One last caution, how the drivers combine is governed by their acoustic phase and amplitude. Many popular measurement systems do not measure acoustic phase but instead imply it based on the amplitude response. While many drivers are mostly “minimum phase” which makes the measurement simplification valid, this falls apart when there is more than one driver, changes in a radiators directivity or efficient horn and a number of other things which make speakers systems partly non minimum phase.
Fwiw, the Hilbert transform assumption for the direct radiating, acoustically small speaker is also a condition which can never reproduce a complex signal as that response spreads a signal out in time.
Bottom line, you need to measure these things while developing, the odds of correctly tuning by ear are about as great as making an Indy car without measurements.
While I do not wish to enter / participate in a debate about which systems don’t actually measure acoustic phase, I can tell you that the TDS (time delay spectrometry) process I have used for the last 20 years or so DOES and is based on the work of the late Dr. Richard Heyser (you might want to also get the Audio Engineering Society loudspeaker and measurement anthology’s).
While it may still be a bit much for the DIY’r, there is a new cheaper version in production now, as well as a user’s forum with many acoustic notables.
That would be a product made by a Goldline, called the TEF machine.
The new one runs off a USB port, that with a measurement microphone and your off and running.
Hope that helps.
Tom Danley
.
Wow - nice to have the man himself chiming in.
Tom, I have a Unity-ish question that came on another forum. Mark S tried to answer it, but reading between the lines, he basically said 'try it, or ask Tom'.
So, the question is how does the Unity avoid intermodulation problems from the pressure from the mids loading back to the throat and driving the tweeter into high excursions?
With compression drivers, I can guess that the actual cross-section exposed by the time you get past the throat and phase plug is so small, it's not a problem.
However, if you read the thread Iinked to here (http://www.htguide.com/forum/showthread.php4?t=13074&page=2&pp=35 go to post 50), I got decent results with small planar-magnetic midrange panels in a 'conical'-ish flare. If I load some midbass drivers along the flare Unity style, it seems to me that there is a real danger of intermodulation. Does the impedance match ever come into it? Is so much of the energy reflected back before it reaches the throat that it becomes a non-issue?
I guess the answer is to try it, but my midbass dirvers are otherwise occiupied at the moment, so it's not a quick experiment.
BTW - thanks for all that you have contributed to various forums over time. The AA archives in particular are a gold mine of stuff.
Tom, I have a Unity-ish question that came on another forum. Mark S tried to answer it, but reading between the lines, he basically said 'try it, or ask Tom'.
So, the question is how does the Unity avoid intermodulation problems from the pressure from the mids loading back to the throat and driving the tweeter into high excursions?
With compression drivers, I can guess that the actual cross-section exposed by the time you get past the throat and phase plug is so small, it's not a problem.
However, if you read the thread Iinked to here (http://www.htguide.com/forum/showthread.php4?t=13074&page=2&pp=35 go to post 50), I got decent results with small planar-magnetic midrange panels in a 'conical'-ish flare. If I load some midbass drivers along the flare Unity style, it seems to me that there is a real danger of intermodulation. Does the impedance match ever come into it? Is so much of the energy reflected back before it reaches the throat that it becomes a non-issue?
I guess the answer is to try it, but my midbass dirvers are otherwise occiupied at the moment, so it's not a quick experiment.
BTW - thanks for all that you have contributed to various forums over time. The AA archives in particular are a gold mine of stuff.
Welcome
Hi Tom,
Nice to have you here. I should get the stuff from Nick today. Let the fun begin.
If you've read the entire thread, you know my level is novice at best. But hey, I'm an ambitious novice. To wit; what I'd like to do is bi-amp the horn itself. I was planning to first set it up with the supplied crossover, then back engineer it to make the crossovers and compensation networks at line level. Since I'm building the amps*, I can optimise them for exactly this application, even to the point of using internal coupling caps, etc., as part of the network. As I understand it the crossover is first or second order, so might not be too hard to translate. I haven't seen the crossover that Nick supplies yet, so I don't know. I do know that all the elements are interactive, so reverse engineering it in a straightforward way is probably wishfull thinking. And, as DWK pointed out earlier, probably implies that I'm nuts (he ain't the first). But I'm not starting from scratch, at least.
I could do this with something like the DEQX, but would prefer analog, if possible. I don't mind getting some measuring gear, but it looks like the TEF stuff would run several thousand - hard to justify for a one-off. Maybe someone in the area does acoustics that would rent me time. I'll check out what's available on e-bay too. Am I nuts as DWK says (a negative response here would allow me to maintain my happy illusions) ? Any guidance on how I might do this would be gratefully accepted.
By the way, John Hancock, in post 11 here, alluded to a mod that traded some output for improved linearity. He showed his horns in this thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=17642. I'm assuming that he was referring to the design at the mouth of the horn, and what looks like a defraction grating? Is this the same issue you addressed in your AA post regarding placing acoustic foam at the mouth of the horn?
Sheldon
*This is Nicks fault for taking so long to ship the speakers. I had to kill the time on an audio project. I'd always wanted to learn more about electronics design and ended up building several amps and my first tube amp. I have some cool old tubes that I want to use for low powered SE's on the horn. The whole thing is your fault, you know, for coming up with an elegant horn concept. Well, ok, my fault too, since I'm a sucker for clever ideas.
Hi Tom,
Nice to have you here. I should get the stuff from Nick today. Let the fun begin.
If you've read the entire thread, you know my level is novice at best. But hey, I'm an ambitious novice. To wit; what I'd like to do is bi-amp the horn itself. I was planning to first set it up with the supplied crossover, then back engineer it to make the crossovers and compensation networks at line level. Since I'm building the amps*, I can optimise them for exactly this application, even to the point of using internal coupling caps, etc., as part of the network. As I understand it the crossover is first or second order, so might not be too hard to translate. I haven't seen the crossover that Nick supplies yet, so I don't know. I do know that all the elements are interactive, so reverse engineering it in a straightforward way is probably wishfull thinking. And, as DWK pointed out earlier, probably implies that I'm nuts (he ain't the first). But I'm not starting from scratch, at least.
I could do this with something like the DEQX, but would prefer analog, if possible. I don't mind getting some measuring gear, but it looks like the TEF stuff would run several thousand - hard to justify for a one-off. Maybe someone in the area does acoustics that would rent me time. I'll check out what's available on e-bay too. Am I nuts as DWK says (a negative response here would allow me to maintain my happy illusions) ? Any guidance on how I might do this would be gratefully accepted.
By the way, John Hancock, in post 11 here, alluded to a mod that traded some output for improved linearity. He showed his horns in this thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=17642. I'm assuming that he was referring to the design at the mouth of the horn, and what looks like a defraction grating? Is this the same issue you addressed in your AA post regarding placing acoustic foam at the mouth of the horn?
Sheldon
*This is Nicks fault for taking so long to ship the speakers. I had to kill the time on an audio project. I'd always wanted to learn more about electronics design and ended up building several amps and my first tube amp. I have some cool old tubes that I want to use for low powered SE's on the horn. The whole thing is your fault, you know, for coming up with an elegant horn concept. Well, ok, my fault too, since I'm a sucker for clever ideas.
Measurement software has come a long way in the last few years. I believe most of the popular ones will measure "real" phase if you tell them to or, optionally, some of them will calculate the phase with a Hilbert transform. You can tell the phase is "real" because the curve changes from something really ugly to something that makes sense when you tell it to subtract the time of flight. JustMLS is included with LspCAD Standard and it should do the job. Keep the mic in the same position for measuring the tweeter and the mids in the horn. Use the same time of flight setting for both. Then tell LspCAD that all the drivers are located at 0,0,0 on the baffle and the XO simulations should work fine.
Hi Sheldon
Hey a lot of people tell me its “my fault” so it wouldn’t be the first time.
Building tube amps to power them too, I applaud your DIY itude, I would play with them more if I had time. I used to build tube amps in the old days, here is one (ignore the fat guy with the long hair).
http://www.livesoundint.com/archives/2003/april/water.php
Boy I have not talked to Nick in ages, I hope he is doing well, tell him I said Hi..
If you are getting Nick’s horn and the drivers that went with it, I have the data for those in my TEF machine.
If that is the case, I can run up a crossover for you that also has a minimum of impedance variation which your tube amps will like.
There were two issues with Nick’s horns initially, first, he did more of a job filling in the corners at the throat of the horn. His horns while made form the same blanks, looked nicer than the Sound Physics Labs production horns but that extra fill changed (slightly narrowed) the horns directivity up high which when combined with the normal crossover we used, made the top end sound / measure “hot”.
Second, with a fully symmetric thing like the horn and the small discontinuity at the throat aperture, there is a small internal reflection at about 4 KHz , which lands on the center of the last flare angle near the mouth. If not absorbed, it reflects again and results in the equivalent of a “black dot” (dip in the response) exactly on axis at 4KHz.
The foam triangles at the mouth absorb this pretty well while having no negative impact anywhere else.
On later designs I changed the shape of the holes which also solved the problem without the foam.
Some where I have a photo of the foam I had sent to Nick back then.
John H. was one of Nick’s customers back then and I was impressed how fast he figured out how they work. He probably gets paid way more doing what ever he does but he ought to be in audio someday, when he can afford the big pay cut ha ha..
Hi Catapult
Your dead on with your description on “how to”.
One would think “real acoustic phase” would be a snap, but as Ingemar says in the manual “In other systems such as LMS the acoustic phase response is extracted from the magnitude data by means of a minimum phase (Hilbert) transformation”.
That is to say LMS doesn’t actually measure phase.
LSPcad is an OUTSTANDING program however and would also recommend it highly.
He has added the phase target reference I had been bugging him about in the latest version too.
His use of LMS reflects the fact that it is fast and easy and much of the time the Hilbert assumption is “safe enough”.
I guess I am more sensitive to the issue because a “perfect and efficient” horn would measure approximately a zero degree acoustic phase with the TEF and about a –90 degree phase with a Hilbert based assumption. When you are trying to make a bunch of drivers play together as one, in one horn, or try to re-produce an input waveshape you HAVE to know what’s really going on with phase.
Best Regards
Tom Danley
Hey a lot of people tell me its “my fault” so it wouldn’t be the first time.
Building tube amps to power them too, I applaud your DIY itude, I would play with them more if I had time. I used to build tube amps in the old days, here is one (ignore the fat guy with the long hair).
http://www.livesoundint.com/archives/2003/april/water.php
Boy I have not talked to Nick in ages, I hope he is doing well, tell him I said Hi..
If you are getting Nick’s horn and the drivers that went with it, I have the data for those in my TEF machine.
If that is the case, I can run up a crossover for you that also has a minimum of impedance variation which your tube amps will like.
There were two issues with Nick’s horns initially, first, he did more of a job filling in the corners at the throat of the horn. His horns while made form the same blanks, looked nicer than the Sound Physics Labs production horns but that extra fill changed (slightly narrowed) the horns directivity up high which when combined with the normal crossover we used, made the top end sound / measure “hot”.
Second, with a fully symmetric thing like the horn and the small discontinuity at the throat aperture, there is a small internal reflection at about 4 KHz , which lands on the center of the last flare angle near the mouth. If not absorbed, it reflects again and results in the equivalent of a “black dot” (dip in the response) exactly on axis at 4KHz.
The foam triangles at the mouth absorb this pretty well while having no negative impact anywhere else.
On later designs I changed the shape of the holes which also solved the problem without the foam.
Some where I have a photo of the foam I had sent to Nick back then.
John H. was one of Nick’s customers back then and I was impressed how fast he figured out how they work. He probably gets paid way more doing what ever he does but he ought to be in audio someday, when he can afford the big pay cut ha ha..
Hi Catapult
Your dead on with your description on “how to”.
One would think “real acoustic phase” would be a snap, but as Ingemar says in the manual “In other systems such as LMS the acoustic phase response is extracted from the magnitude data by means of a minimum phase (Hilbert) transformation”.
That is to say LMS doesn’t actually measure phase.
LSPcad is an OUTSTANDING program however and would also recommend it highly.
He has added the phase target reference I had been bugging him about in the latest version too.
His use of LMS reflects the fact that it is fast and easy and much of the time the Hilbert assumption is “safe enough”.
I guess I am more sensitive to the issue because a “perfect and efficient” horn would measure approximately a zero degree acoustic phase with the TEF and about a –90 degree phase with a Hilbert based assumption. When you are trying to make a bunch of drivers play together as one, in one horn, or try to re-produce an input waveshape you HAVE to know what’s really going on with phase.
Best Regards
Tom Danley
Thanks Catapult. I'll probably get a copy of LspCAD. I've been trying to use Speaker Workshop. It seems pretty powerful for shareware, but the file structure confuses me, and I have to spend a bunch of time relearning where everything is and how to use it each time I try something after a few weeks. Maybe it's just me (halfheimers by now), but sometimes free is a lotta work. How is the documentation for Lsp. Is it fairly intuitive? The price seems quite reasonable for the standard version, which I assume would do what you describe.
Sheldon
Sheldon
Hi Tom,
Yeah, LMS is getting a little long in the tooth and hasn't really kept up. JustMLS works fine for basic measurements as do Soundeasy (cheap) and Speaker Workshop (free). Praxis (about $1K with the mic and preamp) is a full-on professional-level measuring setup with about every stimulus type, acquisition type and post-processing calc you can imagine. The days of having to spend several $K for good measuring gear are behind us.
Yeah, LMS is getting a little long in the tooth and hasn't really kept up. JustMLS works fine for basic measurements as do Soundeasy (cheap) and Speaker Workshop (free). Praxis (about $1K with the mic and preamp) is a full-on professional-level measuring setup with about every stimulus type, acquisition type and post-processing calc you can imagine. The days of having to spend several $K for good measuring gear are behind us.
Hi Sheldon,
I've been hearing rave reviews about the latest version of LspCAD with the new interface but I haven't tried it myself. I downloaded the demo and couldn't get it to run. Seems like I'm the only one with that problem. There's a learning curve with all of them but LspCAD, even the old version, seems easier than most.
I've been hearing rave reviews about the latest version of LspCAD with the new interface but I haven't tried it myself. I downloaded the demo and couldn't get it to run. Seems like I'm the only one with that problem. There's a learning curve with all of them but LspCAD, even the old version, seems easier than most.
Tom Danley said:
Thanks Tom,
Those old pics bring back some memories of the era. I had a full beard and shoulder length hair then.
I have talked to Nick only sporadically. He's not the easiest guy to track down. I leave a message, he eventually calls back. He has always been pleasant to talk to but he must have all he can handle on his plate. I pretty much had to beg to get him to finally ship the horns. I hope that whatever has him over taxed subsides some. By all accounts he's a nice enough guy.
I have some TAD 2001's that I'm using for the horns. Nick is supplying the mids and crossovers (not for the bass, though). If you have a passive crossover set-up you think would be better I would, of course love to have it. I also got his last couple of Apollo 15"ers, which I was going to use in a box with PR's like he had on his website, though I'm open to other possibilities. At one point, I was thinking of open baffle like John H. (the directivity of the OB would seem a good fit), but I would like to have the speakers back near the wall, if possible (they're big suckers).
What I really want though, is a crossover that I can do at line level, so I can bi-amp the horn (tri-amp the whole set-up - which probably means building a sand amp for the woofer). Actually I assume I just need the crossover frequencies, order, etc.. I can probably model the actual component specs. in TJC Filter Designer, a program I got from John Broskie's site: http://www.tubecad.com/. With that, and suggestions for tweeter non-linearity compensation, I should be able to get the horn to work fairly well. I can then tweak with LspCAD.
Once I do that then I assume that crossing over to the woofer is similar to what it would be for more ordinary drivers. I can imagine that the directivity of the horn makes the problem a bit different though. So, of course, any suggestions you have on crossing over to the woofer would be greatly appreciated too. I already figured that I may have to go with some eq on the woofer to account for in-room response, but there is lots more information available on that subject than there is on something like the Unity's.
Oh, and if you can find the picture of the foam application that would be great. Even just a brief description and I get a start. I can again tweak from there by using measurements. I'm assuming that when speaking of the newer models wherein the holes were modified, you are not referring to horns that Nick made? By the way, is modifying that end of my horns a possible option?
I'll take it a step at a time. It'll take me a while to get it all put together, but I'm looking forward to the project. It'll be unique for sure.
Sorry for the mass of questions.
Thanks again,
Sheldon
Ping RCA-Fan
Would be most interesting if Bill Woods (RCA-Fan) would chip in to tell us what he did differently on his version (and why) and or changes he would consider for use as a home brew non PA version. Also since I have a set of the lambda unity horns but not the drivers yet I would be interested in knowing if the Yorkville drivers would work on the lambdas's and if they are available through Yorkville.
To Tom and or John H. I would be interested in knowing if there are any mods that can be made to Nick's horn to bring it up to a more current version as I assume that much has been learned about the unity in the last few years? I guess it would be easy to try the foam idea (or John's ribs) without much if any trouble but I also wonder if cutting a chamfer or 1/4 round on the mid driver throat holes would make matters better or worse. I suppose that too could be tried and repaired with the aid of some bondo if push came to shove but I would rather have the "Nod" first before hacking away. Are thier current passive crossover designs available on line anywhere? I will read with interest this thread and see what transpires as it will be some time yet before I can afford the drivers for my lambda's. Thanks for the interesting input. Best regards Moray James.
Would be most interesting if Bill Woods (RCA-Fan) would chip in to tell us what he did differently on his version (and why) and or changes he would consider for use as a home brew non PA version. Also since I have a set of the lambda unity horns but not the drivers yet I would be interested in knowing if the Yorkville drivers would work on the lambdas's and if they are available through Yorkville.
To Tom and or John H. I would be interested in knowing if there are any mods that can be made to Nick's horn to bring it up to a more current version as I assume that much has been learned about the unity in the last few years? I guess it would be easy to try the foam idea (or John's ribs) without much if any trouble but I also wonder if cutting a chamfer or 1/4 round on the mid driver throat holes would make matters better or worse. I suppose that too could be tried and repaired with the aid of some bondo if push came to shove but I would rather have the "Nod" first before hacking away. Are thier current passive crossover designs available on line anywhere? I will read with interest this thread and see what transpires as it will be some time yet before I can afford the drivers for my lambda's. Thanks for the interesting input. Best regards Moray James.
I have a simple to ask question. But not so simple to answer.
Is the conical expansion of the horn the best way or could I go with a tractrix or something else? Conical always seems to add wierd colourations.
It may be a matter of practicality for the mounting of the drivers. On the other hand the pics of the comercial offerings are not always fully conical either.
About the driver mounting positions. I think I have come up with a decently good idea. To of course use a compression tweeter at the horn. Which one I don't really know ( the TAD looks awlully expensive ) Then the mids ( again don't know which one to go with ) could be placed at approximately the 1/4 wavelength as per the patent. If I were to mount the drivers on a round disk I could both play with the size of throat and by making it an offset hole ( not centered )it may be advantageous. I could rotate the disc/driver assembly and measure the phase relationship as it is rotated through an arc. The wheel or circle could be rebated into the horn so that there would no to very little discontinuity in the horn 's internal surface.
I remember an article in speaker builder a way back when that showed how the measure a relative phase with a microphone a set spacer block and a scope if I remember right. Time to do some more digging. And did I understand correctly that just MLS will allow true phase measurements? Because that I have.
Any good driver recomendations?
Thoughts ??
Observations??
Mark
Is the conical expansion of the horn the best way or could I go with a tractrix or something else? Conical always seems to add wierd colourations.
It may be a matter of practicality for the mounting of the drivers. On the other hand the pics of the comercial offerings are not always fully conical either.
About the driver mounting positions. I think I have come up with a decently good idea. To of course use a compression tweeter at the horn. Which one I don't really know ( the TAD looks awlully expensive ) Then the mids ( again don't know which one to go with ) could be placed at approximately the 1/4 wavelength as per the patent. If I were to mount the drivers on a round disk I could both play with the size of throat and by making it an offset hole ( not centered )it may be advantageous. I could rotate the disc/driver assembly and measure the phase relationship as it is rotated through an arc. The wheel or circle could be rebated into the horn so that there would no to very little discontinuity in the horn 's internal surface.
I remember an article in speaker builder a way back when that showed how the measure a relative phase with a microphone a set spacer block and a scope if I remember right. Time to do some more digging. And did I understand correctly that just MLS will allow true phase measurements? Because that I have.
Any good driver recomendations?
Thoughts ??
Observations??
Mark
Hi Moray, Bill is wonderfully interesting, but it was actually Todd Michael who developed Yorkville's version of the unity horn. Todd has great talent and a couple of advantages over us diy'ers - access to Tom Danley, his own lab with a TEF measurement system, and support from that terrific company (which I also work for).
Replacement drivers for Yorkville products should be available through Yorkville, L&M, or a dealer, but since the U15s are still under warrantee, you might raise a few eyebrows by ordering six midranges and wanting to pay for them. Call them and ask...
Hi Tom Danley - I suspect that the special thing about the mid drivers used in the U15 is that they are adequate for the task and reasonably priced. DIYers enjoy more $$ latitude for purchasing of drivers than working designers do, so would a good sealed-back midrange from a web retailer be usable ?
Cheers,
Dave Lalonde
Replacement drivers for Yorkville products should be available through Yorkville, L&M, or a dealer, but since the U15s are still under warrantee, you might raise a few eyebrows by ordering six midranges and wanting to pay for them. Call them and ask...
Hi Tom Danley - I suspect that the special thing about the mid drivers used in the U15 is that they are adequate for the task and reasonably priced. DIYers enjoy more $$ latitude for purchasing of drivers than working designers do, so would a good sealed-back midrange from a web retailer be usable ?
Cheers,
Dave Lalonde
Hey Dave: thanks for the reply and the informatiom. Do you think you could talk Todd into talking about the Yorkville Unity experience? Business never seems to stop TD from explaining ideas with the patience of Job (remember the Asylum)? I will look into the Yorkville parts dept. thanks for the idea.
Do you have any ideas as to what kind of changes to a unity would or would not be practical for use in a home enviornment as opposed to PA applications? I would be particularly interested in ways to match dispersion characteristics between the bass driver and the unity at the crossover. Would seem that a 15 inch driver would be the natural choice but are there options which would allow for matching dispersion if a smaller driver were to be used? Perhaps John Sherin could comment as he has a great deal of practical experience.
About John H's mod to the unity, hard for me to see but it did not look as if the half round ribs were on all four surfaces of the mouth flair. Jonh can you confirm this? Any comments on the mid driver throat holes, is an edge radius a good idea or no? Hey it would not be difficult to build small electrostatic drivers to do the job and the free air resonance could be tailored to work, would not be the first stat loaded horn as was done by Josef Merhaut (sp?) and published in JAES.
Re driver recommendations Bruce Edgar recommended to me a small 4.5 inch (in a cup) Pioneer as a good bet and said it was one of the best he had tried, they cost about $20.00 each and that adds up times eight. I have the T/S measurements of one of the mid drivers that Nick used on the Lambda, they were taken by a friend with a Sound Easy system. If there is any interest I can dig them up and post them. I wonder about small car or TV speakers on a cup to raise the Fs up to the 350Hz point. For home use you would not need as much Xmax or power handeling ability. There may also be a number of dome mid or tweeter units which also might work for cheap and an exacto knife and a lot of slits in a tweeter domes suspension can drop the free air quite a bit. Again for home use the limited travel might not be so bad. I ran a Phillips mylar 1 inch dome so modified full range on my Lambda's for quite a while before melting them and they sounded pretty good all things considered. Hope that more ideas come forward. I will probably mount my unity horns (when I buy the drivers) on top of a couple of modified Karlson cabinets.
Mark's idea for the disk to allow rotation of the mid throat hole is a good one and while I too had considered that I did not follow up as I have no way to measure the results and so a good close approximation would be as good as a pig in a poke, then I just decided to buy a set of Nick's Lambda's and save myself the grief. Best regards for now Moray James.
Do you have any ideas as to what kind of changes to a unity would or would not be practical for use in a home enviornment as opposed to PA applications? I would be particularly interested in ways to match dispersion characteristics between the bass driver and the unity at the crossover. Would seem that a 15 inch driver would be the natural choice but are there options which would allow for matching dispersion if a smaller driver were to be used? Perhaps John Sherin could comment as he has a great deal of practical experience.
About John H's mod to the unity, hard for me to see but it did not look as if the half round ribs were on all four surfaces of the mouth flair. Jonh can you confirm this? Any comments on the mid driver throat holes, is an edge radius a good idea or no? Hey it would not be difficult to build small electrostatic drivers to do the job and the free air resonance could be tailored to work, would not be the first stat loaded horn as was done by Josef Merhaut (sp?) and published in JAES.
Re driver recommendations Bruce Edgar recommended to me a small 4.5 inch (in a cup) Pioneer as a good bet and said it was one of the best he had tried, they cost about $20.00 each and that adds up times eight. I have the T/S measurements of one of the mid drivers that Nick used on the Lambda, they were taken by a friend with a Sound Easy system. If there is any interest I can dig them up and post them. I wonder about small car or TV speakers on a cup to raise the Fs up to the 350Hz point. For home use you would not need as much Xmax or power handeling ability. There may also be a number of dome mid or tweeter units which also might work for cheap and an exacto knife and a lot of slits in a tweeter domes suspension can drop the free air quite a bit. Again for home use the limited travel might not be so bad. I ran a Phillips mylar 1 inch dome so modified full range on my Lambda's for quite a while before melting them and they sounded pretty good all things considered. Hope that more ideas come forward. I will probably mount my unity horns (when I buy the drivers) on top of a couple of modified Karlson cabinets.
Mark's idea for the disk to allow rotation of the mid throat hole is a good one and while I too had considered that I did not follow up as I have no way to measure the results and so a good close approximation would be as good as a pig in a poke, then I just decided to buy a set of Nick's Lambda's and save myself the grief. Best regards for now Moray James.
The unity horn is of course a high efficiency system. I'm far from being an expert but I read that integration of horn and direct radiating loudspeakers can be challenging. Tom did mention an analogy to building an Indy car, if you succeed then you will have one (two!) inside of your house, so you might as well put the best tires on them, in the form of horn bass. In for a penny, in for a pound 
- you'll be in so much trouble with wife anyway once you start testing them. I don't know how big the Lambda horns are and if they will reach low enough to integrate successfully with a bass horn, so someone else will have to comment on that.
Again speaking as a rank amateur - unless your house is Huge, you won't be able to sit far enough away from an unoptimized horn system to ignore time alignment faults. JMLC has helped educate about integration of horn systems with appropriate use of time delays, and Tom mentioned the utility of dsp crossovers for diy unity development. So I too suggest that a dsp crossover with time delays will give you the ability to optimize your system for close in-the-home listening.
Warning - another kxproject plug - I have used the kxproject for dsp crossovers [search my posts] which is the cheapo way to do it, sort of a poor-man's omnidrive, and if I ever finish a project I will build a stand-alone dsp crossover to unchain it from my computer.
- you'll be in so much trouble with wife anyway once you start testing them. I don't know how big the Lambda horns are and if they will reach low enough to integrate successfully with a bass horn, so someone else will have to comment on that. Again speaking as a rank amateur - unless your house is Huge, you won't be able to sit far enough away from an unoptimized horn system to ignore time alignment faults. JMLC has helped educate about integration of horn systems with appropriate use of time delays, and Tom mentioned the utility of dsp crossovers for diy unity development. So I too suggest that a dsp crossover with time delays will give you the ability to optimize your system for close in-the-home listening.
Warning - another kxproject plug - I have used the kxproject for dsp crossovers [search my posts] which is the cheapo way to do it, sort of a poor-man's omnidrive, and if I ever finish a project I will build a stand-alone dsp crossover to unchain it from my computer.
Horn subs are on the way
Check this out
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54847
Now that I have seen Tom's new site I'm thinking that there may be a smaller method.
Mark
Check this out
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54847
Now that I have seen Tom's new site I'm thinking that there may be a smaller method.
Mark
moray james said:
Please. If nothing else, it would give me a data point to check my measurements (yet to be made).
bzdang said:
The Lambda Unity's are about 16" (41 cm) square at the mouth. I think the typical crossover frequency is around 300hz. John H crossed his over at 350, but he was using high order digital crossovers.
I'd like to eventually biamp the horn. I'm hoping Tom can offer up a recipe, but if not, comments on the following strategy would be welcomed:
My operating assumption is that the passive crossovers provided with the Lambda horns represent a good starting point. With that, I was thinking that I could measure the response of each driver individually, with and without the crossover. In order to have the proper control, I would crossover the tweeter on one horn to the mids on the other horn, to preserve the influence of each electronic section with the other but allow independent acoustic measurement. Measure the tweeter on one horn, with the mids on that horn unpowered, and visa versa. Then disconnect the crossovers and measure the tweeter, then mids separately. Normalize for volume and generate a transfer function for each driver. Then design line level filters to match the transfer function. Completely crazy?
Sheldon
Hi Sheldon,
Just a quick comment on your post about wanting your bass system close to rear wall.
You will find a ported or sealed design much harder to get a smooth response than a dipole if you do this.
Take a look at some of Linkwitz theory and measurements on his site about this. A dipole excites room modes "minimally" close to a rear wall whereas a monpole (BR, Sealed etc.) will excite them maximally.
I've had good succes combining a front horn with dipole bass, which is very close to my back wall.
Which vesrion of the Lambda's do you have? Mine (two per side) are the S version, which are well suited to dipole operation.
Regards,
Jonathan
Just a quick comment on your post about wanting your bass system close to rear wall.
You will find a ported or sealed design much harder to get a smooth response than a dipole if you do this.
Take a look at some of Linkwitz theory and measurements on his site about this. A dipole excites room modes "minimally" close to a rear wall whereas a monpole (BR, Sealed etc.) will excite them maximally.
I've had good succes combining a front horn with dipole bass, which is very close to my back wall.
Which vesrion of the Lambda's do you have? Mine (two per side) are the S version, which are well suited to dipole operation.
Regards,
Jonathan
jdunham said:
When you say close, how close? I'd like them pretty much smack against the wall, or maybe one foot out. The drivers are 15" Apollo's. I don't know the details on the TS parameters, as the site has long since disappeared, but I think the Qt was about 0.3. I don't have to use those drivers for a dipole. Could use a different one right under the horn in dipole and a sealed sub under that? Or I could use the Apollo's for the dipole driver and cross over a sub a little higher (getting pretty complex now).
Sheldon
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