Wave-guides and.....don't hit me....compression tweeters

[Branwell]

Hello,

In the quest for lower crossover frequencies (midrange to tweeter), wave-guides used in conjunction with standard tweeters seem to be presenting themselves as possible solutions.

The problem is; Implementation.

Mostly, the info I've come across revolves around wave-guides designed for screw in compression drivers modified to use standard domes. Seems logical on the one hand, but it assumes that there are no compression tweeters that can compete with good 1” domes from a sound quality point of view.

If we where to address the sensitivity issue and the FR that needs optimizing in a compression setup, would a good compression tweeter still sound inferior ?.

Seems drivers like the BMS 4540ND have a very strong following in some circles. Many say it sounds fantastic. If this is true relative to a high-end dome, used at the SPL levels more in line with home usage, it might just be worth looking at.

http://www.woodhorn.com/BMS/bms_4540nd.htm

Has anyone any experience with this compression tweeter ?.

Branwell

[JonMarsh]

Not here. It would be interseting to compare distortion performance- fs, maximum travel, etc. In a real horn, the radiation resisitance is higher, and the design parameters don't require any Xmax to speak of- then, with a short VC, efficiency can be optimized. For a shallow waveguide, the parameters and performance may not be as we desire.

~Jon

[Paul W]

FWIW...PE has a very interesting assortment of horns and waveguides. The shallow round plastic types up to 12" diameter. There is a B&C 1.4" throat constant directivity horn with what looks like a flat flange (maybe no significant machine work for a non-pro 1" tweeter).

PE waveguides

[JonMarsh]

Geez, checking out the behavior with all of those could be time consuming! I wonder what their crossover frequency recommendations are based on? Probably more convnentional crossovers than I usually do. Hmmmm. Probably ought to check out the 8" and 10". They look (from the pictures) a bit deeper than the MCM or SPtechnology speakers.

[Dennis H]

They say they're a 70 degree conical. Maybe a bit narrow for home use?

[JonMarsh]

I think probably so, in most cases. I noticed the 70 degree rating also.

[Branwell]

Hi,

Here is the URL to a 10" Wave Guide that is getting good press tied to the BMS 4540ND. http://www.ddshorns.com/catalog.php?page=ENG190Pro

And I think its a 90 degree coverage device.

Only one way to find out…. :-)

Branwell

[noah katz]

Does the directivity apply to the full spec'd freq range?

Thanks

[Mark Seaton]

Listed directivities are generally "nominal" or average over some frequency range. Lower frequency control requires large enough dimensions for the specified angle. Look at the link to the DDS horn to see how it performs. Occasionally there are some differences in how a driver interacts with a specific horn so far as directivity, typically at relatively higher frequencies.

[noah katz]

Thanks Mark.

What I'm really wondering if the dispersion at the top end is wider than with a direct radiator.

[JoshK]

Slightly off topic, I spend an afternoon at Dr. Geddes place and got to hear his Summa speakers in both a 2 channel audio system upstairs and a HT system downstairs. This speaker uses a compression driver in a 15" WG.

I am still in MI at the moment and this connection is too slow to upload some of the pictures I took, but will do later. Basically I heard quite a number of things that I really liked about their sound and a couple of things I was a bit confused about. Absolutely the best sound HT system I have heard and I heard a couple of >$100,000 HT systems with all Wilson audio speakers. This was more dynamic, impactful and engaging. Dr. Geddes played a cream dvd that was off the hook. We were playing at 110db (c-weighted) and there was zero compression what-so-ever and it sounded like you were really there at the concert.

Large scale orchestral (Exotic Dances, Eijie Ouie, Ref Rec.) was played with major authority. Details were all there but not overemphasized, plenty of seperation but not dissected. Definitely a mid to rear hall perspective.

Absolutely no honking, no bite in the treble and yet I heard all the detail I am used to hearing. Did I mention he was able to play really really loud with zero compression?

[noah katz]

"Basically I heard quite a number of things that I really liked about their sound and a couple of things I was a bit confused about."

What were you confused about?

[JoshK]

well I just got back to NYC after a fiasco with my car breaking down in detroit.

I wanted to put together a bit more of a detailed review, since I think very few have heard this speaker, but I am probably going to take too long to get to that, so I'll try to answer that question now.

I loved the dynamics of the Summas, never have I heard dynamics like these before. When we were listening at extremely high levels, it didn't sound that loud (Geddes ideas on distortion at work here?). I could think of no better HT/Rock/large-scale-orchestral speaker. These are pretty far from a typically audiophile 2-way.

My own RM40s have a lot more dynamics and low end and "able to play loud without compression"-ness than virtually any other speaker among my audiophile buddies, but the summas were on a complete other level. Maybe this is why some still are entrounched in the hi-eff camp. There was also no honking or aggressiveness like a typical Klipsch speaker would have. I think Dr. Geddes said the Summa was ~97db/w.

Dr. Geddes is a non-believer in electronics. Upstairs in his 2 channel system in an untreated room (about as bad as mine) he had ~$200 in total electronics (sony changer into pioneer receiver iirc). Some cuts played on this system sounded quite good and surprising for such a bad room and mid-fi gear, while others had me scratching my head. I heard on a couple tracks played, some overblown midbass, which I am not sure was due to room, electronics or speaker tuning. Dr. Geddes commented that the tracks were poorly recorded, which is probably true, but I still haven't heard that problem on any other speaker I have listened to these tracks on.

Downstairs is another story altogether. Dr. Geddes has an excellent HT room, sound proofed, full treated to his specs and overall an excellent listening environment. I am seriously jealous of such a room. We listened to both 2 channel and multichannel material. I played a couple of the same tracks I had played upstairs, but not the really problematic track. I never noticed the midbass problem down in this room. Electronics down here are a HTPC into a Pioneer receiver.

I played a hole bunch of great tracks I use for testing systems and our audio group uses at each GTG to make comparisons easier. Things sounded excellent overall. Plenty of depth of field perspective. Sound stage was reasonably wide for such a typical narrow room. Imaging was centered but not razor sharp IMO. Imaging was a bit better higher up than lower down in the vocal range, again IMO. The overall voicing of Dr. Geddes speakers was little behind mid hall (something like 3/4 back).

The midrange was there, plenty of details but not quite as pronounced as more audiophile speakers protray, particularly in the upper midrange. To me this made them sound a bit more natural, but definitely a bit different than a lot of what I am use to in friend's systems. This could also be a pyschoacoustic affect of having more bass power at higher volumes than I am use to, it could also be that the 15" woofer is not as resolving in its upper range as a typical 6.5" two way monitor. This was one of those things that had me puzzled. I definitely didn't dislike it, but it was different. Not your typical jazz lover speaker.

Overall, I came away really wanting to experiment with the WG's more and also to try a hi-eff project at some point. I seriously loved the dynamics and lack of compression, it was a breath of fresh air.