[randybessinger]

Jim, is there a benefit from having the midrange be an open backed "tunnel" rather than mounted on a straight open baffle?

I believe so based on comments from other vendors, but I would love to hear Jim's viewpoint.

George

Hi  I got Jim into this sort-of-open-back thing, so I'll give my reasoning.  We'll see if it all pans out on Saturday.  The main limitation of the various designs I've done for Jim has been soundstaging.  I think the HT-series and the ST series soundstage quite well for a conventional front-firing design, but they won't give you the full sense of air and depth that can be achieved by providing some kind of rear wave information.  A full open-back midrange design on a flat baffle (like the Archos) does fill in the missing information, but it poses placement issues.  There's a lot of rear-wave, front-wave, boundary interactions, and the speakers will sound best in locations that might not be best from a practical standpoint.  And in a lot of these designs, there's a trade-off between depth and presence and detail.  After a whole lotta of experimentation with various cabinet and driver combinations, I think I've come up with an implementation that is much more flexible.  For large rooms where the speakers can be placed well away from the rear walls, the Beast can be run with the midrange chamber wide open.  There's won't be as much rear wave contribution as with a thin open baffle arrangement, but there will be more than enough to open up the sound stage, and there will also be enough presence and detail to provide a very accurate recreation of what you would hear in a concert hall or other live venue.  If less rear wave is desired, the cavity can be filled to varying degrees with acoustic polyfill.  And if none is wanted or practical because of placement issues, the rear can be sealed.  Much to my surprise, the Beast still provided a deeper soundstage than the ST's or HT3's with the rear opening blocked.  I think that's due to the nude mounting of the RAAL and to the naturally open sound of the FAL midrange driver.  Anyhow, that's the theory and my experience, we'll see if anyone salutes tomorrow.

Dennis, has anyone else done this type of cavity for the mid-range?  I wonder if it is patentable (is that even a word)?

[DMurphy]

This is definitely not a new learning.  Although I didn't know it at the time, the Vandy 5A has something similar, although I can't quite figure out where the midrange rear wave opening is.  Jim Holtz, an amateur speaker builder, has a design with a similar rear opening, and I've been running this kind of configuration in my personal HT main speakers for 4 years, albeit in a cabinet that's so deep there's hardly any effect.  This is the first implementation that I was happy with, however (I haven't heard the Vandy).  It's very tricky to get the benefit of the rear wave without causing some midrange coloration.  In the case of The Beast, the solution turned out to be running the mid over a very narrow range.  Fortunately, the RAAL ribbon tweet can be crossed very low, and that proved to be a critical factor. 

[randybessinger]

This is definitely not a new learning.  Although I didn't know it at the time, the Vandy 5A has something similar, although I can't quite figure out where the midrange rear wave opening is.  Jim Holtz, an amateur speaker builder, has a design with a similar rear opening, and I've been running this kind of configuration in my personal HT main speakers for 4 years, albeit in a cabinet that's so deep there's hardly any effect.  This is the first implementation that I was happy with, however (I haven't heard the Vandy).  It's very tricky to get the benefit of the rear wave without causing some midrange coloration.  In the case of The Beast, the solution turned out to be running the mid over a very narrow range.  Fortunately, the RAAL ribbon tweet can be crossed very low, and that proved to be a critical factor. 

Interesting.  I really didn't know any of the Vandy's had something similiar.  Well, anyway, if they are as good as I expect, I may have to sell everything (probably not the wife but then again.....) and pony up.

[cliffy]

This is definitely not a new learning.  Although I didn't know it at the time, the Vandy 5A has something similar, although I can't quite figure out where the midrange rear wave opening is.  Jim Holtz, an amateur speaker builder, has a design with a similar rear opening, and I've been running this kind of configuration in my personal HT main speakers for 4 years, albeit in a cabinet that's so deep there's hardly any effect.  This is the first implementation that I was happy with, however (I haven't heard the Vandy).  It's very tricky to get the benefit of the rear wave without causing some midrange coloration.  In the case of The Beast, the solution turned out to be running the mid over a very narrow range.  Fortunately, the RAAL ribbon tweet can be crossed very low, and that proved to be a critical factor. 

Check out the VMPS RM V60 for another unique implementation.

[martyo]

A few folks have asked the size, this is from earlier in the thread:

Can anyone draw the dimensions, assuming that's a 12" woofer on the bass bin? 

VERY roughly, I get about 40"H x 15"W.  (The HT3 is 40"H x 12"W according to the Salk Sound Web site.)  Not including plinths and spikes, of course!

Close enough for government work.  My HT4 is 41" high with appropriate spacing between the two cabinets. 

[zybar]

This is definitely not a new learning.  Although I didn't know it at the time, the Vandy 5A has something similar, although I can't quite figure out where the midrange rear wave opening is.  Jim Holtz, an amateur speaker builder, has a design with a similar rear opening, and I've been running this kind of configuration in my personal HT main speakers for 4 years, albeit in a cabinet that's so deep there's hardly any effect.  This is the first implementation that I was happy with, however (I haven't heard the Vandy).  It's very tricky to get the benefit of the rear wave without causing some midrange coloration.  In the case of The Beast, the solution turned out to be running the mid over a very narrow range.  Fortunately, the RAAL ribbon tweet can be crossed very low, and that proved to be a critical factor. 

Dennis,

The implementation of the mid-woofer and mid-range on the 5As is completely different from the HT4 and I apologize for being confused and thinking they were of a similar design.  

The open back on the 5A is for the mid-woofer and not the mid-range.  The mid-woofer is loaded by a resistive transmission line, which vents at the rear of the upper module. The purpose of this line is to eliminate in-band resonances and to flatten the impedance curve while preventing reflection of the rear wave back through the diaphragm, not to augment bass or enhance the soundstage - there is no sound wave that comes out of the back of the Vandy 5A.

The mid-range unit has a similar, but slightly different design.  The back of the mid-range driver is loaded by a resistive transmission line designed to control driver resonance and impedance while absorbing rather than reflecting rear wave energy. This line is closed (instead of vented like the mid-woofer) and rear wave energy is completed dissipated.

One thing that the 5A's and the HT4's share in common is that the top module is built in a constrained layer fashion.  The 5A's top module is made from 22 layers of machined MDF. Each layer is .750" thick and the layers are laminated together using several adhesives to vary and disperse resonances.  The HT4's utilize "X" layers of trans-laminated bamboo to form what appears to be a very solid enclosure for the beautiful RAAL and FAL drivers.

Again, kudos to Jim and Dennis on what appears to be a finely designed, engineered and implemented speaker.

Now back to discussing the HT4's.

George  

[DMurphy]

Thanks for clearing that up, George.  I studied the diagrams of the 5a and couldn't see a mid opening, so I'm glad the explanation isn't my failing eye sight.   Well--better get to bed.  I've got a very early plane to the greater Linvonia area. 

[Nuance]

I wish you (or me) could hear the HT4's, George, as the Vandersteen 5A's are my favorite speaker of all time that I've heard, and I'd love to make or get a comparison of both.  I am pretty sure they are your favorite too, considering you own a pair.   

Well, I tried guys, but the wife said I needed a "playmate" to go with me (nope, not the Hugh Hephner kind).  My brother is busy and so are my audio friends.  Who can blame them, as it was short notice.  So unless I can find someone to keep me company as I drive (because my wife thinks I'll fall asleep), I will not be attending.  Just another thing piled on top of my heartbreaking, disappointing year.  Oh well, such is life. 

Good luck at AKFest, boys.  And to those who attend, PLEASE take pics and give us your listening impressions ASAP.  I REALLY want to be there...oh well.

Thanks.

[zybar]

I wish you (or me) could hear the HT4's, George, as the Vandersteen 5A's are my favorite speaker of all time that I've heard, and I'd love to make or get a comparison of both.  I am pretty sure they are your favorite too, considering you own a pair.   

Well, I tried guys, but the wife said I needed a "playmate" to go with me (nope, not the Hugh Hephner kind).  My brother is busy and so are my audio friends.  Who can blame them, as it was short notice.  So unless I can find someone to keep me company as I drive (because my wife thinks I'll fall asleep), I will not be attending.  Just another thing piled on top of my heartbreaking, disappointing year.  Oh well, such is life. 

Good luck at AKFest, boys.  And to those who attend, PLEASE take pics and give us your listening impressions ASAP.  I REALLY want to be there...oh well.

Thanks.

I wish I could attend too, but I couldn't leave until tomorrow morning and flights were just too pricey.

Maybe Jim will lug a pair out to Denver for RMAF 2009 (hint, hint).

George

[Kokishin]

Since Vandersteen 5A's seem to be a favorite, here is a pic from their website.  Looks-wise, I prefer the HT4's.  Sound-wise, I expect the HT-4's will be spectacular.

OK.  I probably won't have time to post any information in the next few days, but we did take some photos today.  Here is a full shot...



Unfortunately, we are going to have to cut down a lot of those trees in the background just to get these out of here.

- Jim

[oneinthepipe]

I've got a very early plane to the greater Linvonia area. 

AKA Detroit.   

[DMurphy]

Not really--pretty much half way between Detroit and Ann Arbor.   In my experience, the closer you get to Ann Arbor, the better. 

[rydenfan]

Not really--pretty much half way between Detroit and Ann Arbor.   In my experience, the closer you get to Ann Arbor, the better. 

Drink a Bells for me 

[funkmonkey]

Not really--pretty much half way between Detroit and Ann Arbor.   In my experience, the closer you get to Ann Arbor, the better. 

Drink a Bells for me 

have two   

Have a great time this weekend...  and definitely drink some Bells beer (man, I miss Bell's out here on the left coast)

[Nuance]

There is Bells a plentiful around these parts, and it's delicious.  If we all do make it to the Oregon GTG, I'll bring some. 

[lonewolfny42]

Nice....Thanks Bill....

Jim....They look great...good luck to you at the show !!

[cujobob]

I got to hear these speakers today at AKfest and really liked them...they look great (though fairly short), too.  The bass didn't do it for me on some tracks so I'm not sure if that was the room, the material, or what exactly...overall very impressed.  My rooms at home are probably too small for this speaker unless Jim and Dennis make one with a smaller bass driver so I could incorporate subs with more tuning options.

The Songtowers looked and sounded great, of course...brought my gf along and she commented that she liked them (rarely says that about anything audio)

[JoshK]

The bass didn't do it for me on some tracks so I'm not sure if that was the room, the material, or what exactly...overall very impressed. 

I'd bet it was the room. 

[zybar]

The bass didn't do it for me on some tracks so I'm not sure if that was the room, the material, or what exactly...overall very impressed. 

I'd bet it was the room. 

+1

The bass from the HT3 was very, very, good, so I can't imagine the HT4 being anything less than excellent.

George

[Nuance]

I got to hear these speakers today at AKfest and really liked them...they look great (though fairly short), too.  The bass didn't do it for me on some tracks so I'm not sure if that was the room, the material, or what exactly...overall very impressed.  My rooms at home are probably too small for this speaker unless Jim and Dennis make one with a smaller bass driver so I could incorporate subs with more tuning options.

The Songtowers looked and sounded great, of course...brought my gf along and she commented that she liked them (rarely says that about anything audio)

What about the bass didn't you like?