[pmcneil]

I recently purchased the 'New Larger Subwoofer' (with 'Mega' upgrades).

I was surprised to find that the 15" unit I received was not (the most obvious visual difference, the wooden phase plug absent in the unit I received) what is presently depicted (see...http://www.vmpsaudio.com/pics/sublarg.jpg). Instead, I got a 'made in China' unit very similar to the Dayton 'Classic 15" subwoofer" (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-470).

Brian informed me that the 15" driver I was expecting (VMPS exclusive?) is no longer available.

Does anyone know whether this change, from advertised VMPS 15" driver is something to regret not getting?

Certainly, I can't, in my room, get the 17 hz bass I expected based on the web site information: 25 hz, based on my Velodyne SM1 measurement/equalization unit data, is the lowest it will go.

Perhaps I am expecting too much! The bass I am getting is excellent....

[Brian Cheney]

The only manufacturer of 15" woofers left in the US is Eminence, where we source our VSS and VLA drivers. 

Our current "made in China" woofer is an improvement over the one that was once made for us by Gefco, however.  Twice the magnet, twice the voicecoil, lower Fs, diecast frame, twice the power handling.  We've had it for several years now and will update the site photo.

[DFaulds]

Acoustic Elegance, a small boutique manufacturer, still makes 15's in the states.  Of course, like almost all speaker mfrs these days, they source most of their parts from over seas, but the actual assembly/manufacture is done here.  I think TC Sounds is also still made in the US, again using foreign sourced frames and probably magnets.

I was wondering why the original poster was referencing the Dayton "Classic", since I thought your new sub drivers were much more robust, as you noted, with cast frames, larger magnets and longer VCs.

[pmcneil]

I didn't realize that the 'big boys', from Eminence, were reserved for the VSS and VLA units. But, price should have been the clue! The 15" I received is not a 'big boy'! (I'll weigh it if any of you want quantitation...).

As I said, the bass i'm getting is excellent, but not as extended as I expected: not 17 hz, in room, as the website blurb implies and NASA got, certainly. If I increase the amp gain (Dayton, 1000 watt external subwoofer), I begin to get measurable 25 - 15 hz frequency output at ~70 dB (measured from my Velodyne equalization unit), but, I also get an off-putting rattling noise (a driver exceeding xmax?).

I'll live with it, and probably won't notice the difference in real world conditions, even in bass-heavy movies.

[DFaulds]

Does the woofer have a cast frame?

[ctviggen]

I didn't realize that the 'big boys', from Eminence, were reserved for the VSS and VLA units. But, price should have been the clue! The 15" I received is not a 'big boy'! (I'll weigh it if any of you want quantitation...).

As I said, the bass i'm getting is excellent, but not as extended as I expected: not 17 hz, in room, as the website blurb implies and NASA got, certainly. If I increase the amp gain (Dayton, 1000 watt external subwoofer), I begin to get measurable 25 - 15 hz frequency output at ~70 dB (measured from my Velodyne equalization unit), but, I also get an off-putting rattling noise (a driver exceeding xmax?).

I'll live with it, and probably won't notice the difference in real world conditions, even in bass-heavy movies.

Sub placement and measurement location will also affect the measured frequency response.  If you're not getting the output you expect at a certain frequency, move yourself around the room and see if you can find areas of lower and higher outputs (that is, if you can "hear" 17 Hz anyway).  If so, then the sub is producing those frequencies, but you need to move the sub or the measurement location.

[pmcneil]

First, yes, DFaulds, it seems to be diecast basket (I'm no expert, but there are major right angles when I look at it).

But, still, frustrated by the lack of 15 -25 htz bass, I began to look around, and found online the 'infinite baffle' solution. Basically, the indisputable point is it that the bigger your enclosure, the better that bass.

So, I have a half-door to a attic storage room (huge, and anyway infinite, since it is open to outside) off of my home theater room. I replaced this door with an oak 3/4" plywood panel (heavily reinfored), cut-out circles, and pulled, out of the closet, several unused drivers... a Dayton 18" 'classical subwoofer' (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-475), and two 10" drivers, a NHT unit, no longer sold, and an HiVi Sp10 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=297-460).

I shut off my two Definitive Tech 18" subwoofers (in front), and the VMPS (in back corner).

And, now, for the first time, I've got extension below 20 htz (as measured by a Velodyne SM1 unit), and CLARITY, in dialogue, etc., that I did not know that I lacked before.

Is this the 'infinite baffle', or moving all the bass to the back of the room? (I remember reading somewhere on the VMPs site about the advantage of moving the bass 'back').

(I haven't switched in yet the VMPs subwoofer (have to find another amp), but this has been a revelation.)

More later, if you are interested...and any comments appreciated.

[DFaulds]

I think the best deal for IB subs is probably the acoustic elegance IB15's which you used to be able to buy for $400/4 but I think John raised the price to $500/4, which is still an excellent price.  PE also sells drivers specific for IB, but the ae 15's are cast frames with a higher xmax and a more sophistcated motor, using copper shorting rings for lower distortion.

I've never owned VMPS subs so I can't comment on their performance, but Brian has been around for a very long time and his speakers have been noted for their low end performance.

[pmcneil]

Seeking extended bass, as I've indicated in my previous posts, I've now gone totally to an infinite baffle, or  IB (http://ibsubwoofers.proboards.com/index.cgi). Thus, three boxes gone, and their noise.....

No box can compete with what I now have (But, of course, IB subs are not something that you can buy. They must be custom built).

Thanks, B, for refunding so smoothly and without hassle my purchase of the larger sub.

[speakerman19422]

Gefco made some nice oem units for Fried. They are in the same league as the most expensive units from Europe. I wonder why no U.S. company hasn't been able to make a dome tweeter that compares to the ones made in Denmark.

[Taterworks]

Stamped frames are generally acceptable for 15" drivers acting as subs when either the moving mass or the mass of the magnet is not ridiculously large, and when the subwoofer driver will not be expected to reproduce the upper midbass or lower midrange. The main virtue of a cast basket is suppressed resonance, but this only results in reduced midrange coloration when midrange material is present; if the midrange content is being effectively filtered out of the incoming signal to the subwoofer amp, then the resonance of a stamped frame is less likely to be excited, and the magnitude of the excitation will be much smaller. I don't see a problem with the use of a stamped frame on a subwoofer driver that doesn't have a ridiculous Xmax, ridiculous Mms parameter, or ridiculously-heavy motor structure. I think Brian has a Designer's Corner article on why he still uses stamped frame drivers for many applications, but this should summarize it.

That said, John J. of AE Speakers specializes in lower-volume products built to order, and his Lambda-series 15" woofers appear to be a huge hit, being used in the Lotus Granada, where the complete system costs more than most people's homes - though apparently not more than the homes of some high-end hifi customers. The TD series woofers' acceptance by uber-high-end clientele accentuates the credibility they've gained in the audiophile world. I think Brian might do well to contact John and discuss his needs.