Xt1086+bms 4540nd

[Ludvig]

After Branwell's good experience with the BMS/DDS combo, I was inspired to test the pro consept myself. But this time I mated the BMS 4540ND with the well regarded CD horn XT1086 from Eighteen Sound. I tried them as HF units above 1.5kHz in my XLS12/RS180 dipoles. The XT1086 is unique that it is designed much like the OS waveguide that Geddes recommends to eliminate the nasty "horn sound" common in pro gear.

The sound is a real chock compared to the 1" dome sound that I'm used to. Subjectively it is completely distortion free, no matter how hard I try to push them. The dynamics seem to be almost unlimited. The sound is also very smooth and pleasing to listen to. Within the beamwidth of the horn, the sound character is stable, and drops smoothly outside.

I love this sound, but.......

it doesn't sound natural :cry: You get a really, really good speaker sound instead of a natural presentation of the source material.

It sounds like the speakers are placed in a completely dead room. There seem to be no high frequency reflections at all. This is impressive, but not natural.

I suppose that the "dead room" sound comes from the directivity control that simply eliminates much of the off axis high frequency radiation. I also suppose that the "speaker sound" comes from that the power response is greatly reduced in the XT1086 operating range compared to the woofer and midrange operating range that in dipole mode holds up the power response all the way from low bass up to 1.5 kHz.

I think that the large difference in power response between dipole radiation and a CD horn is somewhat a showstopper. With a boxspeaker however I think this combination can result in a very good sounding system.

I have ordered a more shallow waveguide to see if I could tame down these drawbacks and still get the low distortion/compression sound.

The story will continue...

[ThomasW]

Interesting observations....

Do you have any measurement gear so you could post both nearfield and 2m response plots? Those would be fun to see.

[noah katz]

Yes, most interesting.

Are you listening in just stereo? Perhaps multichannel would supply the missing ambience.

I hope so; I'm committed to building some for HT use.

[Mark Seaton]

Two quick points.

First, frequency response is key with compression drivers on horns. What means are you using to smooth/flatten the frequency response?

Second, with CD horns I usually find that you don't need, nor often want to be listening directly on axis. Since the response is pretty smooth over a reasonable window, you can aim/toe the speakers to balance the off-axis response. If you are used to a more classic "hi-fi" presentation, try toeing the speakers out a bit to increase the lateral reflections a little. With so much less energy going to the front wall, you will also likely find different placement will be preferred to get the effect you desire.

Even with these compensations you typically see much smoother response at the listening position with a good implementation, even though the 1m anechoic won't be quite as smooth. I also don't think you are wrong about the attention needed to the power response. My personal experience with CD devices is that you need to focus as much if not more on the power response and then get the on axis as "reasonably correct" as possible without messing up the power response.

[Ludvig]

Do you have any measurement gear so you could post both nearfield and 2m response plots? Those would be fun to see.

Wife and kids are out tomorrow, so I plan to run some measurements then. They are for some strange reason not that fond of high SPL sine sweeps 8O

Are you listening in just stereo? Perhaps multichannel would supply the missing ambience.

Yes, I have only listened in sterero.

Frequency response is key with compression drivers on horns. What means are you using to smooth/flatten the frequency response?

I'm using a DCX to flatten the response based on ungated, in room measurements. This was chosen since on-axis response and power response differs so much between CD horns and domes. I suspect that equalization based on gated, on-axis responses would give a wrong equalization curve. What do you think? Maybe I'm wrong on this point.

My personal experience with CD devices is that you need to focus as much if not more on the power response and then get the on axis as "reasonably correct" as possible without messing up the power response.

Yes, the power response seem to be the key here. More experimentation will be neede before I give up this idea.

[Paul W]

it doesn't sound natural You get a really, really good speaker sound instead of a natural presentation of the source material.

It sounds like the speakers are placed in a completely dead room. There seem to be no high frequency reflections at all. This is impressive, but not natural.

Ludvig,
So far, my limited experiments have the same result. A very precise sound, but not convincing because I am always aware of the speakers.

Attaining reasonable frequency response with a simple crossover is not a problem, and the difference in power response is not as audible as I thought it would be. So far, I believe what I don't like is the lack of room reflections (too much directivity).

Just to be sure, I plan to follow through with a complete system before moving on to a couple of other ideas.
Paul

[noah katz]

"So far, my limited experiments have the same result. A very precise sound, but not convincing because I am always aware of the speakers."

Paul,

What horn/driver & woofer have you used?

I'd have thought the directivity would make it sound like a big pair of headphones, with a more diret window into the recording venue acoustics.

[Mark Seaton]

In the limited designs I have played with, the magnitude, phase and polar response resulting from the chosen means of integration of the tweeter and midrange can have a very significant effect on the subjective sound.

As Noah suggests, if the system is well integrated and doesn't make very abrupt changes in directivity, the sound should reduce your own room's effect and let you hear more of what's on the recording. The simple test is to have a few tracks you know to present very different senses of space. The added directivity should help distinguish between the different recordings, where many systems make them all sound similar. Of course not all horns are created equal, and how you integrate them with the lower sections is always a bit of a trick. I've heard more bad examples than good, but when good, they do things I have not heard from other systems.

Once you step into mult-channel use the benefits increase dramatically, as you now have 5 or more speakers creating the sound field, and you don't have to rely on reflections to add to the sound field.

[Paul W]

Image not available

So far, I've only tried a Vifa 27TG35 and a Seas 27TDFC on a crude conical/pyramid flare crossed to a W22 mid (the second W22 is a .5). The mid was open, but stuffed to attenuate the backwave. XO was 1k with a trap on the W22s.

The drivers aren't the source of my dissatisfaction. My sense is that there is too little HF radiation to the sides. (I listen to music in 2-channel, multi-channel for movies.) I think my dissatisfaction is caused by a horn/guide too deep relative to width. Depth was set to give the tweeters a good chance of making it down to a goal of 1k...my personal max XO for the W22. The tweeters make it to 1k, but I miss those subtle sidewall reflections!

If hi-fi tweeters can't get to 1k with adequate side radiation, pro sound drivers certainly will. A lot of variability here, so modular speakers are in the works as a sort of "journey".

[Mark Seaton]

Hi Paul,

One thing to keep in mind with the horn you built there is that you really should add at least another step to the horn with a wider angle. The abrupt transition at the mouth of the horn causes a few problems, one of which being a very significant narrowing of the pattern where it colapses near the point where the horn looses directivity before quickly widening. Adding the extra step makes for a smoother and more gradual transition to omni radiation.

[Paul W]

Hi Mark,
Thanks for the tip...I could pack my knowledge of horns in a thimble! Making this one 2X oversized for the 1k XO seems to have been worthwhile and I also considered a 1.25" roundover, but wasn't up for a full-body workout that morning.

I've since spent some time with Hornresp so the next one will be significantly different and, hopefully, closer to goal.
Paul

[Ludvig]

Measurement results

After more listening, I spent some time measuring the performance of the BMS4540ND and the XT1086. I also compared it against an Eighteen Sound HD1040 compression driver. HD1040 is what you get from Eighteen Sound for about the same money. This is a 44mm polyethylen diaphragm driver with 1" exit throat.

Frequency responses @1m. The horn is standalone with no baffle, so I suppose that much of the wiggles are edge diffractions. Unfortunately the plot of the HD1040 only reach 10kHz. I discovered this when all measurement gear was put away.
4540ND in red, HD1040 in Blue.


I must say that I am pleased with the responses. They should be no match to EQ flat pretty easy.

First round, distortion sweeps with the fundamental fixed at 90 dB average @ 1m.

4540ND


Pretty solid little performer! While the 2nd harmonic is higher than I had expected the rest of the harmonics are simply gone. I can assure that this little baby sounds clean!

HD1040


This one is as impressive as the BMS driver. High order harmonics seem to be no problems at all with compression drivers.

OK, lets crank it up a bit. 100dB @ 1m:

4540ND


Now we can see that the driver starts to work. The curves indicates that the driver is most confortable above 1.3 kHz. The upper harmonics don't seem to care much about the SPL level at all...

HD1040



At this level the HD1040 starts to be stressed down low. Don't want to use this one below 2 kHz.

Since the application is for home use, I did not put time on testing at even higher levels.

If I was responsible for the Eighteen Sound product development I would really start so scratch my head by now. An 80W, 1.8 kg, 44mm membrane driver is both less efficient, and beaten heavily in low frequency distortion performance by a 60W, 0.5kg, 37 mm membrane driver. Do I have to tell you that the BMS driver is 25% cheaper?

The ringradiator technique that BMS uses seem to be very successful.

It would be interesting to fire up a more respectable driver from Eighteen Sound such as ND1090 to see what we get. But that's in another price league of course.

[noah katz]

Ludviq,

Thanks for the interesting measurements.

Is the BMS 10 dB really more efficient, or did you displace the graphs?

I'd have expected more of a top end rolloff from the constant directivity effect spreading the high freq power out.

[Ludvig]

Is the BMS 10 dB really more efficient, or did you displace the graphs?

Thanks for your careful reading. No, I messed it up when I compensated for the efficiency loss of the BMS driver that I have (16ohm) compared to how efficient the 8 ohm driver would be (I'm talking voltage sensivity now, not power). It is more like 5 dB in favor of the BMS driver. The graph is now updated.

I'd have expected more of a top end rolloff from the constant directivity effect spreading the high freq power out.

The high end roll of matches the 4540ND datasheet pretty well. They are measuring on a CD device as well.

[dwk]

Interesting stuff Ludvig. The distortion measurements are encouraging - at least on par with top dome tweeters.

As far as the subjective impressions of the system, I think this illustrates a couple things.
a) continuity in the power response is probably important. CD crossing to dipole may be tricky to get right.
b) room design and room placement will generally be different for different types of speakers. We are probably used to a particular balance between direct and diffuse sound, and the waveguide alters that balance. Changing positioning and/or acoustic treatments to restore that balance may make up for some of it. In this case, the advantage of the waveguide is (hopefully) that it reduces early reflections and pushes the diffuse soundfield out farther in time.

I'm only listening in mono to my quasi-Unity prototype right now, but am excited by what I'm hearing. The most noticable characteristic though is how clear it is in the next room - far more articulate than my conventional mini-monitors from what I remember. Mono vs stereo might be part of this, but I'm guessing the relatively lower degree of reflections is also contributing. I'm eager to get to a stereo setup, but that may be a while as my garage/shop is full of 'stuff' right now

[Ludvig]

a) continuity in the power response is probably important. CD crossing to dipole may be tricky to get right.

You're right, and that's what I'm trying to find a satisfactory solution for.

b) room design and room placement will generally be different for different types of speakers.

Absolutely. As suggested by Mark Seaton earlier in this tread, I tried to toe in the speakers rather much to listen at off-axis only. That made quite a lot of difference. The ultra directivity and "attention please, your loudspeaker is placed right here" character was reduced and a more natural soundfield came up.

I'm only listening in mono to my quasi-Unity prototype right now

What kind of animal is this?

[ThomasW]

What kind of animal is this?

Unity Horn.

[dwk]

As suggested by Mark Seaton earlier in this tread, I tried to toe in the speakers rather much to listen at off-axis only. That made quite a lot of difference. The ultra directivity and "attention please, your loudspeaker is placed right here" character was reduced and a more natural soundfield came up.

Yes - I find this with my 60x60 conical horns as well. I think Geddes says the same thing, so there seems to be some concensus. In my case I have a very narrow room and I'm looking to 'aim' the speakers so that the main axis hits the sidewall even with the listening position. This puts me 10-15 degrees off axis, and virtually eliminates early sidewall reflections. Seems to work well, although I have very limited time playing in stereo

What kind of animal is this?

The Unity in general, or my quasi-version? The google search Thomas posted will get you started in general, and look at danleysoundlabs.com, or yorkville.com (look at the Yorkville U15)
For my version, look at the 'RS52 tweaks' thread here that is still on the front page.

[noah katz]

"I think Geddes says the same thing,"

Yes; in fact, he recommends that the toe-in be enough so that you get the right speaker's reflection from the *left* wall and vice-versa.

The delay from the direct sound will be enough to add spaciousness instead of confusing imaging, and the effect is increased by the "oppositeness" of the reflection.

[JonMarsh]

Relevant to current discussions, I'm doing a moderator "no-no" :nonod: and bumping this up... I only vaguely remembered this thread, but it pops up on Google on the first page if you type in BMS 4540ND. This was around the time my work life started taking over everything.... didn't spend much time on the guide until Xmas.

Looking around I spotted a few other "wavguides" similar to the XT 1086...




including the XT120 - but this is a bolt on.




Too deep and too narrow in dispersion, possibly, but still interesting... It's the right frequency range for what I want, I've got my fingers crossed on how the MCM waveguide and the BMS 4540ND will work together.

~Jon

[timber_mg]

The XT1086 is a diffraction horn I am afraid but for a CD horn in PA use it is excellent with very little pattern flip.

The XT120 is indeed very deep (look at the polar plots showing rising directivity) and is much more horn sounding than an OS but in PA use works well mated up to 8" drivers. I have heard a nice-sounding 8MB400-XT120 (with their small 1" comp) combo.

[EspenE]

The XT1086 is a diffraction horn I am afraid......

In what way is this bad? (Pardon my lack of understanding, but my knowledge of horns is sketchy, to say the least....)

What excactly is a "diffraction horn" compared to a "waveguide"?

Example: Both the DDS ENG-90 waveguide and the Eighteensound XT1086 have gotten a lot of attention in various threads here. Both seem to be very usable as "waveguides" for 1" compression drivers. As I understand it, both of them are CD devices.

But are they differect according to principle? Is the DDS waveguide a diffraction horn also?

[Ludvig]

I've got my fingers crossed on how the MCM waveguide and the BMS 4540ND will work together.

I have tried that combo, but was not that impressed. The frequency response is rather wiggly and the highest octave is rather "wild west". More troublesome is that the power response peaks at 3.5 kHz.



0, 20, 40, 60, 90 deg.

Compare the above response to the wonderful dispersion control of the 4540ND+XT1086 below.
Horisontal:



0,15,30,45,60,75,90 deg

Vertical:



0,15,30,45,60,75,90 deg
The peak at 18 kHz is in the driver and is not a horn resonance.

The smooth curvature of this horn seem to work well because the sound doesn't have any trace of "horn sound". It is just extremely dynamic and relaxed at all power levels.

I'm very interested to compare this to the DDS waveguide if I could only get my hands on any. DDS has no distributors in Europe so I have to import from US.

[timber_mg]

A diffraction slot basically allows designers to have very clean polar response at the cost of reflecting part of the wavefront back into the horn and these reflections are responsible for the sound horns have, especially at higher volume levels which explains why some horns even though they might measure very clean don't sound natural at high levels.

The XT1086 is smooth after an elliptical diffraction slot that isn't evident in pictures I have seen of it thus far. Modern waveguides according to Geddes have very good polar performance without the slot assuming the velocity profile of the driver exit matches that required by the waveguide and the lower levels of reflections result in a much more bearable sound, sometimes reminding me of headphones.

[Dennis H]

Timber, just to be clear, are you saying the 18sound waveguides have an audible "horn sound?" Have you tried the DDS waveguide?

[marc g]

Glad this thread came back ! I was also interested in the BMS horn and/or the 18 sound combo for use with my Foster line arrays. I had bit the bullet on an array of 32 Dayton neo dome tweets and have yet to mount them in the baffle. I had an idea to mount the tweeter array AND a central hf horn to compare / contrast but I never got much input on the horn use other that I may get to a nice target slope with a simple one cap hp filter.

Do the radiation patterns complement each other for a line array ?

Marc

[Tommythecat]

Has anyone tried distortion testing with BMS or anything else at closer to 115-120db? I'd really like see what kind of driver it takes to keep 2nd order harmonics close to -40db at maximum dynamic levels.

[Branwell]

Hi,

Here are some factory graphs of a BMS 4552. The bottom one in the set is running at 10W and above 115db.

http://www.assistanceaudio.com/graphics/4552ND_freq.jpg

B

[timber_mg]

I got quite excited when the local 18Sound distributor got them and when I got to see the slot I decided not to even touch it, even though it is a very nice horn by many accounts by those who have used them on the speakerplans.com forum and others. The XT120 definitely has a honk to it at higher levels compared to an OS waveguide like these.

Image not available

None of the 18Sound guides will be nearly as bad as say an old large-format 2" diffraction horn (something like an Altec Manta-Ray) from a HOM pov and they're definitely not a mistake. Seeing that I was very happy with an RCF H100 horn for ages and the 18Sound horns aren't that expensive and likely beter sounding by a fair margin I'd not want to deter anyone from using them. The slot is likely much less harmfull as it is a small elliptical slot close to the throat (which is why one doesn't see it on the pics)

From what I saw from Zaph's WG trace when I CADed it up the MCM is definitely not OS and I'd rather try my hand at the DDS because it seems more conical.

[Tommythecat]

Branwell, do you know what scaling they're using? I cant tell if it would be -20db as opposed to -15db. Or am I reading it wrong? Either way, it doesn't look too good.

Also, I'm not so sure which attribute gives a horn its sound more - the flare or the mouth termination. From this thread: http://audioheritage.org/vbulletin/s...ad.php?t=12967 - of which I cant remember its origin (where I found it), he discusses why mouth termination is a very important aspect of horn design. So Im not quite sure where to put my eggs right now. But I also dont have enough experience to start considering HOM in my analysis of horns.

[timber_mg]

The important parameters in a CD design are the transition from a theoretically planar or spherical velocity profile to a spherical one and the diffraction at the mouth. This means that for a horn body with a mostly conical midsection the first few cm and the terminus are important. If you fire a conical waveguide with a spherical wavefront of the same angle you have a simplification of an OS which is effectively conical. This also has the consequence that with smaller enclosed design angle dome tweeters become much less likely to perform as well as compression drivers (disregarding sensitivity and the like)

[Branwell]

Hi Tommy,

Unfortunately I don’t know enough to answer your question…however I would be very interested to learn a little so I can better understand why I think the small BMS sounds so much better than the 1” domes I’ve tried.

Branwell

[Dennis H]

After Branwell's good experience with the BMS/DDS combo, I was inspired to test the pro consept myself. But this time I mated the BMS 4540ND with the well regarded CD horn XT1086 from Eighteen Sound. I tried them as HF units above 1.5kHz in my XLS12/RS180 dipoles. The XT1086 is unique that it is designed much like the OS waveguide that Geddes recommends to eliminate the nasty "horn sound" common in pro gear.

The sound is a real chock compared to the 1" dome sound that I'm used to. Subjectively it is completely distortion free, no matter how hard I try to push them. The dynamics seem to be almost unlimited. The sound is also very smooth and pleasing to listen to. Within the beamwidth of the horn, the sound character is stable, and drops smoothly outside.

I love this sound, but.......

it doesn't sound natural :cry: You get a really, really good speaker sound instead of a natural presentation of the source material.

It sounds like the speakers are placed in a completely dead room. There seem to be no high frequency reflections at all. This is impressive, but not natural.

I suppose that the "dead room" sound comes from the directivity control that simply eliminates much of the off axis high frequency radiation. I also suppose that the "speaker sound" comes from that the power response is greatly reduced in the XT1086 operating range compared to the woofer and midrange operating range that in dipole mode holds up the power response all the way from low bass up to 1.5 kHz.

I think that the large difference in power response between dipole radiation and a CD horn is somewhat a showstopper. With a boxspeaker however I think this combination can result in a very good sounding system.

I have ordered a more shallow waveguide to see if I could tame down these drawbacks and still get the low distortion/compression sound.

The story will continue...

Ludvig, I don't know if you've seen the thread about Siegfried Linkwitz's latest. He put a rear, out of phase tweeter on the Orion and loves it. It would be interesting to take the tweeter, horn and XO from one of your speakers and duct tape it to the back of the other to boost the power response of the treble. SL says, with the tweeters out of phase, he only needed to cut the tweeter level about 1 dB to get it to sound right.

http://www.linkwitzlab.com/orion++.htm

[JonMarsh]

If one is counting on the reproduction room to add a sense of reflection and acoustic space, well, I think the "problem" is more with the recording than the reproduction.

Did you try some naturally mic'd classical or jazz with the XT1086's? Even SL admonishes that has the speakers get a lot better, the problems with the recordings become more evident, and he has done some of his own in order to have more natural sounding test program material.

[Ludvig]

Ludvig, I don't know if you've seen the thread about Siegfried Linkwitz's latest. He put a rear, out of phase tweeter on the Orion and loves it.

Yes I saw that yesterday evening. And you are completely right about what I'm gonna test tomorrow night when kids are in bed and my wife is at work. 8)

Did you try some naturally mic'd classical or jazz with the XT1086's?

I have a few of that kind of recordings, but not many. You are right that such recordings tells another story about the speaker performance. The main drawback of the XT1086 compared to domes is even more evident with that kind of recordings. The sound is beautiful, but lacks a bit of space. I think headphone sound is the best way to describe it. I'll see what a rear mounted XT1086 can give in terms of space.

I also have have the "Sound pictures" of SL:s own recorded sounds. That record is very funny! I love the truck welding shop. The truck that is started up and drives through the soundstage is almost scaring!

[Ludvig]

I spent the evening experimenting with an additional, out of phase horn on the back of my dipoles. I must admit that it works! The "loudspeaker sound" that I experienced with the XT1086 is very much reduced. For understandable reasons, I don't have four XT1086 for my two speakers, so I have just tested this in mono. As you all know, mono sounds really boring mono, but with the rear tweeter you get a kind of depth in the sound.

At the same time as I am pleased with the results, I must admit that I don't know if this rear tweeter makes the loudspeaker pain up a more correct soundstage or if it is just an added, artificial soundeffect that happen to be very good sounding.

I also tested this configuration with the MCM waveguide. Even though they measure rather poor, they sounded surprisingly pleasing. Only at very high SPL:s the MCM starts to cry. The curvature is smooth in the waveguide, but there is a very poor match between the throat flare rate and the compression driver exit flare. Maybe this is one reason for it's problems.

[Dennis H]

Glad to know it works Ludvig. As SL says, creating a sound space with only two speakers is an exercise in tricking our brains so it's sort of a matter of whatever works.

I'd be interested in seeing off-axis plots of SL's setup. With one tweeter, the dispersion widens between 2K and 6K. I'm wondering if the rear tweeter would give any dipole null in that frequency range, giving a more even polar, or if dual horns like you're using are required to really get an ideal figure-8 at all frequencies.

[crackyflipside]

I spent the evening experimenting with an additional, out of phase horn on the back of my dipoles. I must admit that it works! The "loudspeaker sound" that I experienced with the XT1086 is very much reduced. For understandable reasons, I don't have four XT1086 for my two speakers, so I have just tested this in mono. As you all know, mono sounds really boring mono, but with the rear tweeter you get a kind of depth in the sound.

At the same time as I am pleased with the results, I must admit that I don't know if this rear tweeter makes the loudspeaker pain up a more correct soundstage or if it is just an added, artificial soundeffect that happen to be very good sounding.

I also tested this configuration with the MCM waveguide. Even though they measure rather poor, they sounded surprisingly pleasing. Only at very high SPL:s the MCM starts to cry. The curvature is smooth in the waveguide, but there is a very poor match between the throat flare rate and the compression driver exit flare. Maybe this is one reason for it's problems.

After reading this post I decided to mess around with my computer speaker set-up.

For reference, I use 2 pairs of satellite sized speakers which measure reasonably flat from 16k down to about 100hz. The sub covers the lower end of the spectrum and is directly in front of me so there isnt any major localization problems. The speakers face me from a corner.

I literally just got one pair of speakers and spun them around and aimed them into the corner backwards. I was able to mute one pair and the other without changing my listening position at all. What I noticed was that when the speakers that were backwards were played by themself, the sound would appear to flow over me and behind me; a very strange sound. When the regular front facing speakers would play by themselves it would sound like a regular speaker set-up with the soundstage centered directly in-between the speakers.

But when the two were played together it made a pretty neat effect. The soundstage would seem to lift and the imaged center of sound would appear much larger. Stereo effects seem to not really be affected, I listened to plenty of albums including Amused to Death which has some really wild stereo effects and it seems to add a wider sounding effect especially during quieter parts of songs. I'd advise anyone to try this out.

;x( For my computer office listening set-up, it sounds excellent.

[robertwb70]

Hate to drag this old thread back out but I'm looking at horn/waveguide stuff and found some real measurements here that look pretty good but I noticed a problem (maybe) when I started looking at the parts

the BMS 4540ND is a threaded driver and the XT1086 appears to require a bolt on driver- are you guys using an adapter or modifying something?

and for the "ambiance" of a rear facing driver couldn't that be done with something like a Visaton B200 or do you think the different FR/ dispersion issues would cause too much of a problem?

[Ludvig]

I used a home made adapter between the XT1086 and the BMS4540.

[Ludvig]

I love this sound, but.......

it doesn't sound natural :cry: You get a really, really good speaker sound instead of a natural presentation of the source material.

It sounds like the speakers are placed in a completely dead room. There seem to be no high frequency reflections at all. This is impressive, but not natural.

It is always fun to quote oneself!

After a year of struggeling I have FINALLY got three pieces of th DDS ENG 1-90 Pro horns to compare to the XT1086. I have not made any measurements yet, but after a few hours of listening evaluation I can conclude that they are playing in a higher league than the XT1086. Less HOM at high drive levels, and the best thing of all, they do give a spacious sound despite their directivity! The somewhat dead, unatural soundfield that the XT1086 gave is not present with the ENG's. Probably because of their wider dispersion. Subjectively they keep the same low distortion and high dynamics as the XT1086 combined with a more natural soundfield, so for me the 1086 is put to rest from now on.

[JoshK]

Glad to see this avenue has not died. I finally got around to purchasing some BMS 4540's and picked up a pair of B&C DE250s too based on feedback on other forums. This is so I can compare. I also have the DDS ENG 1-90s and the PE 12" WG's (dirt cheap). So hopefully I will make some test baffles and play around with them soon.

I bought the cheap selenium adaptors for the 4540's but I don't like them at all. The front of the CD is not flush with the throat of the WG using the adaptor because the adaptor has roughly 1/8-1/4" straight pipe section in front of the CD when it is screwed in. This is far less than ideal considering the throat is the most crucial part. I think I will have to make my own adaptors as well. I really don't know what they were thinking when they made those adaptors. :scratch:

Ludvig, are you doing any CD eq? I've read it is important.

[ThomasW]

I finally got around to purchasing some BMS 4540's and picked up a pair of B&C DE250s too based on feedback on other forums.

I'm interested to hear your impressions of each

I bought the cheap selenium adaptors for the 4540's but I don't like them at all. The front of the CD is not flush with the throat of the WG using the adaptor because the adaptor has roughly 1/8-1/4" straight pipe section in front of the CD when it is screwed in. This is far less than ideal considering the throat is the most crucial part. I really don't know what they were thinking when they made those adaptors. :scratch:

Yep ran into that same situation..... :roll:

[Ludvig]

Ludvig, are you doing any CD eq? I've read it is important.

Yes, but since I've not made any measurements yet, I just used the same CD EQ as for my XT1086. While this is not optimal, it's accurate enough for a "first impression evaluation" i think. The CD falling curve will probably be rather similar between the horns, but the crossover region need to be totally revised of course.

[noah katz]

Re the HOM, don't forget they can be significantly reduced by filling the WG with 30 ppi foam.