Waveguide benefits/drawbacks - ongoing studies

[Mark Seaton]

That KEF coaxial waveguide looks pretty sweet from the response curves, but I withhold judgment until I see one particular kind of measurement - I want to see a multi tone IMD spectrum, with one high frequency tone driven through the tweeter, and one through the midrange. Then I'd like to do the same test on a normal two way system for comparison. I'm not sure what I'd see, but I wouldn't be surprised if things look a little funky and unexpected in the waveguide coaxial.

This is an interesting point to bring up, and something I'd be curious if anyone has tested on any coax.

Personally I expect the question is more one of how much cone excursion is too much for the frequency range that is using said cone as a horn. I've done a few designs now where the coax cone isn't asked to deliver lower frequencies. I don't discount the change in transition at the neck and edge of the cone, but so far as absolute motion, if maximum excursion is less than 2-3mm p-p, that's a pretty small fraction of a wavelength until we get above ~15kHz. As usual, how you want/need to use a component has a big impact on its suitability.

[AJINFLA]

Seas has the technology and the Uni-Q license to manufacture something like the 207/2 driver (unless there are stipulations in the license that limits what they can do?). We now (finally) have what appears to be movement towards standard WG faceplate tweeters. Could the writing be on the wall for a full blown Hexadym, flat surround, Excel coaxial?

Dave, do you plan on using the KEF's in a design eventually? Perhaps your own Gradient Revolution? :W
Which I was reminded recently, a statistical dead heat with Geddes Summa in listening tests during development.
Kind of reminds me about what SL has remarked about the importance of very even radiation at varying angles, whatever the speaker type.

cheers,

AJ

[dlr]

Seas has the technology and the Uni-Q license to manufacture something like the 207/2 driver (unless there are stipulations in the license that limits what they can do?). We now (finally) have what appears to be movement towards standard WG faceplate tweeters. Could the writing be on the wall for a full blown Hexadym, flat surround, Excel coaxial?

Now that's something I'd like to see! But NOT a 6.5", it's gotta be in a midrange, maybe 5".

Dave, do you plan on using the KEF's in a design eventually?

Yes, but nothing of any consequence. They drop into the Insignia box easily, so there still has to be a woofer under it of some kind. No plans yet. I have started on the crossover and have been surprised at how difficult it is to do it passively given the exceedingly high peaking of the tweeter down low,.

Perhaps your own Gradient Revolution? :W

Never had the opportunity to hear them.

Which I was reminded recently, a statistical dead heat with Geddes Summa in listening tests during development. Kind of reminds me about what SL has remarked about the importance of very even radiation at varying angles, whatever the speaker type.

I don't have a position on that yet. I can't say for any system I've heard or designed that I know exactly what the directivity really was for them. I do know that I prefer small diameter midrange drivers that may, even for a standard system, have a smoother power response. But that's still a bit of speculation on my part as I've not tried to verify precisely what it is for these. Small mids have just always sounded better to my ears.

[EdL]

Mark posted: "but so far as absolute motion, if maximum excursion is less than 2-3mm p-p, that's a pretty small fraction of a wavelength until we get above ~15kHz."

Isn't 15kHz above the area of influence of a waveguide? / or: Aren't frequencies above this beaming?

[dlr]

I like the idea of midrange only

This is an interesting point to bring up, and something I'd be curious if anyone has tested on any coax.

Personally I expect the question is more one of how much cone excursion is too much for the frequency range that is using said cone as a horn. I've done a few designs now where the coax cone isn't asked to deliver lower frequencies. I don't discount the change in transition at the neck and edge of the cone, but so far as absolute motion, if maximum excursion is less than 2-3mm p-p, that's a pretty small fraction of a wavelength until we get above ~15kHz. As usual, how you want/need to use a component has a big impact on its suitability.

The driver I have (SP1447 P/N, 207 or whatever the official designation) is a true midrange. I can't even see it move when I press on the midrange cone. It probably won't go below 200Hz I suspect. This should effectively limit the IMD.

AJ:

The point about a poly cone is also be a bit misplaced (IMO) due to the limitation as a midrange. If you read the KEF literature, they point out that the cone profile was designed for two issues, both valid.

First, as a proper waveguide for the tweeter, they improved the response significantly there. This would be regardless of the other cone properties. The depth and profile were optimized for tweeter loading.

Second, and too often ignored or dismissed as a negative, is that they also purposely developed the cone with a non-constant thickness. This is critical for any driver with a relatively deep cone if good extension is desired while avoiding significant breakup issues and, maybe more importantly, phase issues. The woofer is fairly smooth and flat up to about 4K. The transition has no peaky breakup and the rolloff is smooth. I think that KEF crosses somewhere around 3.5K, probably due to tweeter limitations, so this behavior is a benefit.

If the woofer on this mid, as deep as it is for waveguide duties at this diameter, were absolutely pistonic (as in hard-coned), then the depth alone would drastically limit the extension due to severe non-linearities when the distance from former to center of the front plane was a half-wavelength. A curvilinear cone that progressively flexes at higher frequencies is the only way to get that kind of smooth extension in a cone of this depth.

I'd also bet that it also improves the directivity , making it more constant to higher frequencies since the overlap with the tweeter is still important in this area. I still would prefer a shallower one that is a pure midrange unit. In that case, a stiffer cone would be less of an issue on extension.

To re-address the Gradient question, their site says that the revolution is a cardioid midrange and crossed at 200Hz. I doubt that this driver can handle the power required for compensation in the low end unless the crossover were to be moved up a lot higher.

[AJINFLA]

TB finally figure out where the tweeter belongs?
W6-1530S
The horn, err...waveguide looks rather ugly (perhaps not to infringe on the KEF patent? Although the Insignia....).
Strangely, I could not find it on the TB site, but rather here
Not exactly a mid/tweeter with smooth horn/cone transition or flat surround, but at least it's a baby step in the right direction. If the price is right, could make a decent HT LCR. Could .

Cheers,

AJ

BTW, has anyone else had trouble reaching Assistance Audio via phone/e-mail?

[JoshK]

Just an FYI. I posted an updated OS profile spreadsheet on diyaudio... I made the correction for the CD exit angle.

Here is the link...
link

[Kevin Haskins]

I personally am not sold on the waveguide idea. If you need the gain to maintain lower distortion I'd rather pick a higher crossover point and adjust the midrange accordingly. You don't gain that much directivity control and its only over a limited bandwidth. What I'm looking for in a midrange is something that can crossover relatively low so the limited excursion capability of the KEF wouldn't be attractive either.

If I where designing a coax, I'd use a 5" midrange that could be used 200-3K without problems. Design a 1" tweeter to go in the center and its not difficult to get a 1" dome to perform well to a 3K crossover. A 5" diameter driver properly designed should match accpetably with a 1" dome @ 3K or there abouts.

[augerpro]

Kevin I think Josh's spreadsheet is just for compression drivers.

[Kevin Haskins]

Kevin I think Josh's spreadsheet is just for compression drivers.

I know... I was talking about waveguides as used in coax designs with dome tweeters and specifically commenting on the KEF design.

The DXT tweeter would give Earl fits.... :lol:

I like the directivity control and I like the fact that you don't get diffraction effects from the cabinet edges. I'm just not sure I like to be shoehorned into the constraints that waveguides force upon size and shape. Earl is always pursuing the absolute, based upon his research, but I'm more interested in building something that average people will actually want in their room. Something that will fit under a TV, on a back wall, of moderate size and shape that people can actually live with.

The reason I like the idea of a coax is because of the point source nature of the device. It can allow for a design without the off-axis response issues of systems with drivers separated either vertically or horizontally in space. I'll live with the directivity issues of the drivers because the only way to fix them requires devices that are too large for my design goals.

[A9X]

Hi Paul,

Re: Wave guide sound….

I’ve been playing with BMS 4540ND compression tweeters in DDS I-90 waveguides crossed to 10” PHL mids crossed to 15” bass drivers. The crossover I use is the DEQX.

For reference, with the same crossover, I’ve had systems with Seas W22, W18ex SS18W/8545, PHL1340, 1120, Seas Millennium, SS9900, Morel 110, G2, 45” Newform and a bunch of other stuff in sealed, ported, and dipole configs.

Realism: To me, regardless of music played, the pro sound setup mentioned sounds more real.

Enjoyment factor: Prosound setup hands down.

Sound stage: Not sure the pro sound drivers have an advantage, but they are not at a disadvantage.

Sense of ease: The prosound drivers mentioned make standard drivers mentioned sound like toys. The prosound drivers are in a different league when it comes to headroom, dynamics and lack of congestion on complex recordings.

Range of recordings: I’ve noticed a funny trend among audiophiles. Seems the better the speaker, the fewer recordings it can play without sounding nasty. Apparently the truly great speakers have such good resolution that any recording flaw shows up. This was pretty much my experience with standard drivers. Interesting thing with the pro sound drivers mentioned, the flaws show up, but not in a nasty way. i.e. the sound never gets hard and brittle. I can still enjoy 95% of my music collection.

Well that sounds all up. What’s the down.

Very efficient drivers require very quiet electronics. Any hums or buzzes will easily be heard.

The dispersion pattern is narrower. Might be more even to a point, but the wave guide tweeter definitely rolls off on the top end more than a 1” dome off axes.

The FR of the raw drivers is not as smooth as the standard drivers mentioned. A genius with passives, of which I am not, might be able to deal with it, but I needed to resort to digital active to solve that issue.

Box size. Big drivers need big boxes. Not a problem if you have the room, but….

Overall, while I still listen to my setups that use standard drivers, I find myself less and less satisfied with them. They just don’t sound as real.

Branwell

Got to say Branwell, I agree 100% and your descriptions of the ease of big systems, huge dynamics and lack of compression, as well as an amazing tolerance (if that's the correct word) to mediocre recordings is spot on.
My forthcoming system will be JBL 2225, 2123 and BMS 4592 in a WMTMW config. Inspirations were intially the Daniels system and Jack Bouska's, though I have some different design goals and preferences.

I realise the post is over a year old, but I'm new here, and thought it deserved comment.

[A9X]

I'm just beginning to get serious on a path very similar to yours. BMS4552ND, same DDS waveguide, 18Sound 10NDA520 mid, BMS 18N850 woofer in a damped U-baffle.

Just wondering if you ever did anything with the 18Sound 10 and what your imoressions of it are? Contemplating obtaining these or the 10NDA610 for a project, and opinions of them are very thin on the ground.

[AJINFLA]

I personally am not sold on the waveguide idea. If you need the gain to maintain lower distortion I'd rather pick a higher crossover point and adjust the midrange accordingly. You don't gain that much directivity control and its only over a limited bandwidth. What I'm looking for in a midrange is something that can crossover relatively low so the limited excursion capability of the KEF wouldn't be attractive either.

Hi Kevin, I not quite clear on what you mean here. Could you explain how one adjusts a midrange accordingly at 3k? Limited directivity control? Here is Earls Summa and one of the latest KEFs:

Image not available


Here is a typical 5" mid, the Seas H1262

Image not available

If I where designing a coax, I'd use a 5" midrange that could be used 200-3K without problems. Design a 1" tweeter to go in the center and its not difficult to get a 1" dome to perform well to a 3K crossover. A 5" diameter driver properly designed should match accpetably with a 1" dome @ 3K or there abouts.

Could you define "without problems"? It appears as if Jim Thiel may have blueprinted something like what you desire, but I have seen no measurements of it (yet). I also strongly doubt the XO's will be anwhere near 3k and 200hz.




I'm guessing strong off axis radiation towards the nearest room boundaries is desired in your design? Could you elaborate?

cheers,

AJ

[Paul W]

Just wondering if you ever did anything with the 18Sound 10 and what your imoressions of it are? Contemplating obtaining these or the 10NDA610 for a project, and opinions of them are very thin on the ground.

When I bought the 520's it was between them and the 610...I felt the 520 was a better choice for the slightly lower operating range I wanted. Excellent build quality & measurements were extremely close to the 18Sound factory curves. AIC works as claimed. Smooth frequency response and impedance...easy to work with. Good sounding drivers...very precise.

If I had to complain, it would be that the basket shrouded the back of the cone more than I liked...and the mounting flange is a PITA.

I changed the objective, so the 520 (or no 10") had the directivity I wanted so they are back in the box waiting for a suitable project. No fault of the drivers...I changed the requirement.

Very impressed with 18Sound overall and will probably use more of their drivers later this summer.

[thadman]

I changed the objective, so the 520 (or no 10") had the directivity I wanted so they are back in the box waiting for a suitable project. No fault of the drivers...I changed the requirement.

Were you unable to match the directivity of the DDS ENG 1-90 and the 10NdA520 or did the combination simply not comply with your desired directivity performance?

[Paul W]

The DDS and 10NDA520 worked well together from about 1200-1400. The DDS loses directivity control below that point.

In the end, I decided to shoot for directivity control even lower, with larger waveguides, so began working with arrays like this:

[rc white]

In the AES Journal No. 9 1976 Klipsh published an engineering note about the measured and audible differences between spaced and coaxial tweeter frequency modulation distortion.
He illustrates this with charts that show there is a considerably larger amount of it in the coaxial case and states that it is "clearly audible" whereas in the separated case it is "hardly audible".

[Kevin Haskins]

Hi Kevin, I not quite clear on what you mean here. Could you explain how one adjusts a midrange accordingly at 3k? Limited directivity control? Here is Earls Summa and one of the latest KEFs:

A crossover for a 5" driver @ 3K is not rare. Its probably more the norm.

Earl's response is excellent but it is an apples and oranges comparison because its a 15" device. The KEF is a valid comparison because its roughly the same size and format of the other devices we are talking about. With the size waveguide used on these tweeters you only gain directivity control down to about 2K at best.

While that response curve you show is nice, there are any number of products without waveguides that get results that are very close.

Could you define "without problems"? It appears as if Jim Thiel may have blueprinted something like what you desire, but I have seen no measurements of it (yet). I also strongly doubt the XO's will be anwhere near 3k and 200hz.

I defining "without problems" to be where you can crossover at that point without large on/off-axis response dips. Large isn't tightly defined but I'd certainly call a 5dB dip @ 30deg. off-axis a design problem. If I where doing a design I'd play with it and not hold myself to an arbitrary point though. If it needs to go to 2.5K to achieve that goal you do it.

I'm guessing strong off axis radiation towards the nearest room boundaries is desired in your design? Could you elaborate?
AJ

Strong off-axis response towards room boundaries is the norm in small listening spaces. I don't see how a standard 5" midwoofer is outside of the norm in that regard. Its how 99% of all home audio systems are designed. The point we are arguing though is bringing in a directivity controlling device to the tweeter over a bandwidth of 2.5K-6K. In the KEF, or any other standard format driver using a small waveguide the vast majority of the bandwidth has limited directivity control (or at least its controlled like any other direct radiator).

I don't have a design in mind other than a coax that has the advantage of having the tweeter in the same physical space, horizontal and vertical as the midrange. The impulse response/time alignment isn't that important to me.

The midwoofer would have to be flat, or close to it so as to not have response problems with the tweeter in the middle. The issues caused by a large moving membrane in close proximity to the tweeter dome may be an issue. Its just speculation on my part though.

[AJINFLA]

A crossover for a 5" driver @ 3K is not rare. Its probably more the norm.

Would you mind posting some on/off axis data, as I have provided, for a 5" driver XO'd @ 3k.

Earl's response is excellent but it is an apples and oranges comparison because its a 15" device.

Not at all. It is an example of using an appropriately sized waveguide (or horn :B ) matching the directivity of the woofer. The off axis will be similar for smaller sized woofers/horns. Here is a 6" 2-way





Or check out Earls new site AI

The KEF is a valid comparison because its roughly the same size and format of the other devices we are talking about. With the size waveguide used on these tweeters you only gain directivity control down to about 2K at best.

Yes, one crosses based on directivity matching, which of course is related to the size of the horn. The size of the horn can be varied, even with a coax. Would you like examples?

While that response curve you show is nice, there are any number of products without waveguides that get results that are very close.

Results? Please provide some data. Thnx.

At work, so i'll have to leave the rest for later :W

cheers,

AJ

[Kevin Haskins]

Would you mind posting some on/off axis data, as I have provided, for a 5" driver XO'd @ 3k.

Results? Please provide some data. Thnx.


cheers,

AJ

I don't have the data nor the time to gather it to the degree you are asking.

Lets stick with data all from one source though, taken in a chamber in the same way. There are plenty of examples of non-waveguide designs on Soundstage measurements, as well as the KEF and a Paradigm with a small waveguide on the tweeter.

Look at the PSB B1s. It is using a 5.25" midwoofer and looks to have a 3K crossover.

http://www.soundstagenetwork.com/measurements/speakers/psb_alpha_b1/

Look at the 45, 60 & 75 deg off-axis data. It looks very good with a noted drop-off in the high-end.

Lets compare that with the KEF. It looks to me like the KEF maintains better directivity control far off-axis 45, 60 & 70deg but only over the range of 2K-10K. The far off-axis of the PSB is still pretty good, although narrowing with frequency.

I'm not sure one these characteristics is obviously better than the other when it comes to subjective preference. The KEF acts like any other direct radiator though up to 2K, had a controlled directivity from 2K-10K. The question is does that characteristic translate to subjective preference?

Earl's design is obviously better over a much wider range, well into the midrange, but it takes a large device to maintain the directivity over a wide enough range to be meaningful, in the Summa's case down to below 1K.

Back to the original question though. Advantages/Disadvantages of Horns.

In the good column:

#1. Directivity control, although only over limited bandwidth without a large device.
#2. Fewer baffle related diffraction issues.
#2. Some acoustic gain although narrow in bandwidth.

In the bad column:

#1. Early reflections in the horn. HOMs in Earl's terminology which are traded-off for the diffraction issues of the cabinet edges.
#2. Additional size/format restrictions.
#3. Cost disadvantage.
#4. Extra design complexity (might be wrapped in with cost)
#5. Possible response issues with larger/deeper horns.
#6. Possible consistency issue unit-unit. Horns have critical dimensions in the throat where small changes unit-unit can have large consequences.

It is the same fight people have been having for years although now horns are being called waveguides and the directivity is the focus rather than the acoustic gain.

[PaulTM]

Hi guys!
I've been watching you for quite some time now, I always enjoy reading the posts here.
Could you please tell me your opinions about the Ciare PT383 ( http://www.ciare.com/consumer_en/pro...ofessional.htm -->click Tweeters on the left side and then click PT383 -->the data sheet is below the codes & stuff) tweeter with the little 13 cm waveguide?

[ThomasW]

Don't you think the massive dip at 5kHz is a little extreme...

[69Stingray]

removed.

[AJINFLA]

Lets stick with data all from one source though, taken in a chamber in the same way.

Ok. Let's also stick with non-coincident drivers with WGs, since you stated

I personally am not sold on the waveguide idea.

and treat coincident (coaxial) driver arrangement such as the KEF separately, since we are looking mainly at horizontal data.

Look at the 45, 60 & 75 deg off-axis data. It (PSB) looks very good with a noted drop-off in the high-end.

PSB B1 vs Amphion argon2. Please note the 10db scale. I guess our definition of very good is quite different. To me the off axis of the PSB is terrible ("norm"?), with +/- 5db variation in the 800-2k range.
The on axis (not shown) is also much worse, most like due to increased diffraction effects from the strongly illuminated baffle edge.
Of course, we do not have the raw driver FRs. The distortion profiles will also be driver dependent, but I doubt you are going to argue against the reduced distortion provided by the corrected horn loading?
You can do a easy compare of the same driver on a flat baffle vs horn loading here
Horn conversion

I'm not sure one these characteristics is obviously better than the other when it comes to subjective preference.

Start here

http://www.harman.com/wp/pdf/AudioScience.pdf

http://www.harman.com/about_harman/technology_leadership.aspx

then keep going.

Advantages/Disadvantages of Horns.
In the good column:
Home Directivity control, although only over limited bandwidth without a large device.
Forum Fewer baffle related diffraction issues.
Forum Some acoustic gain although narrow in bandwidth.

#1: Hmm. Who forces you to use them only in monopoles? Even so, the Amphion is large?
Two #2's? :W Jeez, showing a bit of bias here?
Groups Reduced distortion in ears most sensitive region.
Uncategorized Groups Reverberant field/power response (related to #1)
Special Effective ACs closer aligned (z axis).

In the bad column:
Home Early reflections in the horn. HOMs in Earl's terminology which are traded-off for the diffraction issues of the cabinet edges.
Forum Additional size/format restrictions.
Blogs Cost disadvantage.
Groups Extra design complexity (might be wrapped in with cost)
Uncategorized Groups Possible response issues with larger/deeper horns.
Special Possible consistency issue unit-unit. Horns have critical dimensions in the throat where small changes unit-unit can have large consequences.

Home No, not for short, low gain horns.
Forum Blogs ??
Groups No. Zaphs example shows this to be over generalized, with a simpler network. So what if a bit more complexity is required for superior performance?
Uncategorized Groups Special Anything is possible if poorly designed/executed.
Now how about listing some negatives of a tweeter + woofer flat on the face of a box?

It is the same fight people have been having for years although now horns are being called waveguides and the directivity is the focus rather than the acoustic gain.

Fight? Wanting to raise performance above the mediocrity of the "norm" is confrontational? Hmmm. Not sure about that.
Please do keep us posted if you develop a flat coax. I'd love to see some measurements when complete. Might buy four myself to place back to back wired out of phase. Something like the Thiel might be nice :W .

cheers,

AJ

[AJINFLA]

Some more examples, the Magico Ultimate.

No. That is not an example of topic of the thread. Unless you mean an example of what not to do.

cheers,

AJ

[Kevin Haskins]

Hey... you win! I'm don't have the stamina to respond to all that.

[CraigJ]

About now, I really miss Jon. :cry: On the other hand, where is Thomas with his big stick :g> Children.....

[Kevin Haskins]

AJ..... no hard feelings on my side. I just don't want to get drawn into a long debate on something where I can see it's not going to be productive.

This is how I make my living and it's not in my best interest to argue with potential customers. But hey... like everyone here I'm passionate about the topic and my instinct is to act like a enthusiast. I like talking about audio and in particular, loudspeakers. But I don't have any desire to make this conversation into anything other than a friendly discussion of the topic.

If I crossed the line forgive me, I didn't mean to get crossways with you.

[Dennis H]

AJ loves coax drivers so take his bias into account. Too bad there aren't any real (easily available to DIYers) drivers that match the theoretical advantanges coax provides.

[AJINFLA]

Gracious, you have absolutely nothing to apologize for. You have said nothing offensive. We disagree on a few points. Agree on others. This is an audio discussion board.
Not sure what CraigJ is reading.
I would still be interested in discussing your flat coaxial idea, as it would involve quite a bit of technical difficulty to overcome. The Thiel perhaps illustrates this. Especially given your desired goals. I was sincere in stating that I would be interested in such a design...and yes I would be a potential customer. If well designed .

cheers,

AJ

[AJINFLA]

AJ loves coax drivers so take his bias into account. Too bad there aren't any real (easily available to DIYers) drivers that match the theoretical advantanges coax provides.

Hey, I love triaxials too :W.
May get my hands on a nice one soon. We'll see.

cheers,

AJ

[---k---]

AJ, I just think it is your avatar that is causing confusion. It looks like your throwing your hands up and screaming at us???

:P

[Kevin Haskins]

Gracious, you have absolutely nothing to apologize for. You have said nothing offensive. We disagree on a few points. Agree on others. This is an audio discussion board.
Not sure what CraigJ is reading.
I would still be interested in discussing your flat coaxial idea, as it would involve quite a bit of technical difficulty to overcome. The Thiel perhaps illustrates this. Especially given your desired goals. I was sincere in stating that I would be interested in such a design...and yes I would be a potential customer. If well designed .

cheers,

AJ

Very cool... the Internet is such that it is easy for a conversation to be taken wrong.

I don't have a coax design in the planning stages. I've been thinking about it for a couple months, mainly drawn to the aspects I've already mentioned but it is likely to stay a thought process rather than a product.

It would be an expensive project because I'd have to tool everything. The main problem is that I don't have the freedom of testing anything until it is tooled and built. At that point you have already spent a load of money so its a high risk proposition. :cry: I'm sure Seas or one of the Chinese companies will respond to the market demand if there is one.

[A9X]

When I bought the 520's it was between them and the 610...I felt the 520 was a better choice for the slightly lower operating range I wanted. Excellent build quality & measurements were extremely close to the 18Sound factory curves. AIC works as claimed. Smooth frequency response and impedance...easy to work with. Good sounding drivers...very precise.

Very impressed with 18Sound overall and will probably use more of their drivers later this summer.

Wonderful. Thank you. If these have the same cutout as the JBL 2123, they'll make an interesting substitute/upgrade.

The DDS and 10NDA520 worked well together from about 1200-1400. The DDS loses directivity control below that point.

In the end, I decided to shoot for directivity control even lower, with larger waveguides, so began working with arrays like this:

Ding. Just realised I asked you about these on diyaudio a while back. that's a BMS 18N850 isn't it? How high do you cross it? Probably higher than the 250-300 I'm looking at to cross to a 10 (but I want to use the 18N840v2).

Opinions on the BMS?

Cheers

[Paul W]

Yup, BMS 18N850. It is another well built driver with excellent performance. Incredibly powerful motor. I believe mine are V1 because they are not marked either way and I bought them before seeing the V2 announced.

Haven't tried them above 200Hz which is where they were crossed to the 10NDA520. In the configuration with the four mids, about 175Hz.

[Paul W]

Thadman,
Based on some documentation I found from a year ago when I was actually working with the 520 and DDS, some of the info I previously gave you was incorrect...

Though the original XO target was 1.1k, because of the lack of pattern control for the DDS, I eventually raised XO into the 1.5-2k range to get a decent match with the 520. So, in the sense that XO had to deviate quite a bit from target, I was not satisfied with the combination. However, no change in my recommendation for the 520 itself.

Sorry for the bad memory :Z
Paul

[ThomasW]

About now, I really miss Jon. :cry: On the other hand, where is Thomas with his big stick :g> Children.....

Posting on the forum has increased dramatically, as a result it's impossible for me to track what's posted in every thread in real time.

That said, the hammer will be used after the fact whenever needed.... 8)

AJ, I just think it is your avatar that is causing confusion. It looks like your throwing your hands up and screaming at us???

I thought it was just him having a seizure.... :B