[Jstower]

Hello I'm new to AC. Looking for some advice on building a pair Subwoofer Tower, similar to VMPs VLA Subwoofer
Lets start with the cabinet, it's approximately 7 cu ft inside with four 12" drivers, with 15" and or 12" passive radiators.
I would like to know how many passives to used, and the best placement of Passive radiator. I'm open for suggestions. Thanks Jim
 

[OldScott]

I happen to be the owner of  the second set of Brian Cheny's RM V-60's with two sub woofer towers (Dave Housteau owns the first). Yes, there are four 12 inch active speakers and two 15 inch passive radiators and the tower is slot loaded. A very interesting aspect of Brian's bass towers is that each of the active speakers has a different resonant frequency. He had the capability to change these from what was stock. As I recall, the frequencies are set at 20, 22, 24, and 26Hz. The four 12 inch speakers are front firing and the two passive radiators are at the bottom one firing to each side. Hope this helps.  Dave will probably see this and might want to chime in. 

[Jstower]

Hello OldScott, So yourself and Dave have the only VMPS VLA Subwoofers made. Yes, Brian was definitely good at what he did, make great speakers.
Is there a 12" passive in the bottom slot area?  I think the four 12" active were TC Drivers, and they are out of business. But there are several choices of good subwoofer drivers out there, so that's not a problem. Thanks for your input. Jim

[Housteau]

The VLA by VMPS is a very large tower.  The dimensions do not tell you the whole story.  They are two inches thick all around and come in right around 300 lbs. Each.

The original plan was for three passives, the two 15s Paul mentioned plus a down firing 12.  Since my pair were the first off the line Brian experimented and decided that the 12 was not needed.  My bottom port is sealed off, but the base still has the open slot for it.

Brian's objective was for pure musical base and not the ultimate in low extension.  So, instead of creating something for home theater going into the teens he kept it reasonable to the low 20's.

[Housteau]

One one of the passive cones has a small string of mortite putty.  Adding, or removing from it adjusts the moving mass of that driver for fine tuning to a specific room.

I really do not know how many bass towers, or complete V60 / VLA systems were made.  But, I believe them to be rare.

[WGH]

The Foundation subwoofers by Legacy are like mini-towers, 2 - 12" drivers with a 12" passive. Legacy has dealers and showrooms so you might be able to hear a pair while doing research for your new build. One thing I have noticed is that world class sub drivers have a 2" peak-to-peak travel.



Also consider stacked subs to keep the weight manageable. Another advantage of stacked subs is separate amps, each could be tuned to a different frequency and loudness for ultimate control.

[OldScott]

Jim, so you think Dave and I are the only ones with the bass towers? I really don't know but recall John Casler saying he only made two or three dozen RM V-60's and of course not everybody also bought one or two bass towers. Many simply used Brian's large subs.  Later Brian felt that perhaps a second mid bass unit would be desirable and decided to call those with this his V-60 Signature edition. I bought a second mid bass just before he died and therefor have the only, or one of the only  two or three such in the world. I was in error saying these bass towers were were slot loaded.They are not.They are not, just sealed units raised up two or three inches from the base. Dave is correct in that Brian was interested in musicality over bass extension. But that being said, my units  have a measured response that can be detected down to just above 14Hz. Yes he did build great speakers. May he rest in peace.

[Housteau]

I like the Legacy mini towers and just about everything Legacy does.  I always make it a point to visit their room several times at the shows I attend.

Paul is correct in that these towers will produce low, low bass.  My earlier statement may have been a bit misleading.  I meant that the design was more to maintain the ruler flat response into the low 20's.  In my room the gentle roll of starts at 21Hz.

[Jstower]

Hello Everyone I appreciate all the responses and information.

 QUOTE from OldScott:[Jim, so you think Dave and I are the only ones with the bass towers?] YES

As of now I own 2 Vmps Largers and are aware of the size of the VLA's, even if I stack the two on top each other they still fall short. Not really sure if anyone has ever built a pair, but there's a first time for everything. If I dislike the way they sound, I cut them up into single boxes and stack them up. 12" driver and 15" passive in each box like the old original VMP's subwoofers. Thanks Jim

[WGH]

You may want to hire a consultant/builder for these speakers. Making the two cabinets is not a 'Skil-saw-in-a-garage' project. I have made many 300 lb custom wood doors, by myself, and moving them can take a lot of forethought and experience so I don't get hurt or crushed.

Jim Salk of Salk Sound (driver and cabinet integration) and Dennis Murphy of Philharmonic Audio (crossover design if not using a plate amp) take on custom speaker designs, both individually and together. Jim's company has built many one-off custom speaker designs both painted and custom veneer. Jim is familiar with and has used Rhythmik Audio direct servo drivers and passive radiators in his designs. Using four 12" Rythmic drivers in a sealed box might blow the 15" passive radiator cones across the room (which actually sounds like fun until they fail).

[Jstower]

Thanks WGH, I own a skill saw and a saber saw, I should be good.    Sorry I could not resist , but I appreciate concern. Safety first,  I have owned a few large tower speakers that weigh 240lbs each (VMPS RM 40) (SuperTower ll a/r). Also I have a friend that has a large CNC router table, but he is very busy making plastic shields for everyone right now.
Its just eight 12" holes and four 15" holes. Once I route a sample hole for each size its goes pretty fast. I will glue it up in stages with the aid of wooden dowels and dados on internal bracing and Top and Bottom to help keep everything square. As far as the 12"drivers I'm  open to suggestions, but I have not finalized my choice. 15" Passives from Parts Express, there are not to many choices for those. Thanks Jim

[WGH]

Housteau wrote the VLA had 2" thick parts. I have done a lot of internal bracing on speakers I have owned, my current speakers have 1-1/8" thick sides, back and top with a 1-3/4" thick front baffle. Thick parts and lots of bracing really control the tightness of the bass. I think towers made with 3/4" MDF would resonate, muddy the bass and ultimately be a disappointment.

If I made the boxes I would first make all the pieces 2" thick using two layers of 1" thick MDF laminated together using a vacuum bag veneer press. I do this all the time for my custom veneered doors but now I'm on a 2 year sabbatical after woodworking nonstop for 40 years.

Did you notice that the Legacy subs 15" passive radiator has a 4" peak-to-peak travel? There is probably a good reason for that.

[Early B.]

You may want to hire a consultant/builder for these speakers.

Even if you plan to build these speakers yourself, you should use a proven design. You want to know how it measures and what it sounds like BEFORE building it. WGH gave you some good advice. Consider building four stackable dual subs - easier to build, tune, and move. Plus, you should eliminate the passive radiator which requires extensive design knowledge to implement properly. Servo subs from Rythmik Audio are a superior DIY option for achieving musical bass.   

[skifasterslc]

This is interesting to me, as I have been shopping for subs lately.  I am looking at Tekton's newer offering;

https://www.tektondesign.com/4-10-sub.html

Obviously not on the scale of the VLA tower

The price is very reasonable and there is a good thread at audiogon forums with user feedback.  Not designed to go below 20hz , sealed, tower style
I live in Utah so I need to visit Eric Alexander

[Jon L]

I wonder why there isn't more interest for Cardioid bass systems? 

Cardioid bass compared to other bass systems
https://kimmosaunisto.net/CardSub/CARDSUB.html

Some highly respected/reviewed speakers feature cardioid bass including:

Kii Three speakers
https://www.stereophile.com/content/kii-audio-three-loudspeaker

ME Geithain 901K speakers
https://sonicpurity.com.au/blog/2017/9/27/me-geithain-active-speakers

Dutch & Dutch 8C active speakers
https://www.stereophile.com/content/dutch-dutch-8c-active-loudspeaker-system

One can even just buy the cardioid bass modules these days:
QSC KS212C Cardioid 3,600W Dual 12" Powered Subwoofer
https://www.sweetwater.com/store/detail/KScardSub--qsc-ks212c-cardioid-3600w-dual-12-inch-powered-subwoofer

[Housteau]

The Tekton looks very interesting and they are practically free at $800.  Their site needs to have more description and technical info on the design of their products.

[Early B.]

The Tekton looks very interesting and they are practically free at $800.  Their site needs to have more description and technical info on the design of their products.

There's a reason it has a low price tag, and probably a very good reason why there's little technical info. For music, I'm skeptical of any sub that uses a cheap plate amp. I'll also bet that two 12" drivers of the same brand would sound equally as good (or bad) as four 10" drivers. Looks impressive with other Tekton speakers, though.

BTW -- this sub laid on its side and used to augment a center channel speaker in an HT system would be badass.

[WGH]

Some VMPS speakers used drivers made by MISCO, maybe Brian used their drivers for the VLA too. I did not see any passive radiators on their website. Contact them, I read they are nice people.
https://www.miscospeakers.com/

VMPS's passive radiators used a unique high-compliance suspension and a low moving mass diaphragm to achieve a low resonant frequency. The low mass of the passive radiator cone also meant it was very sensitive to small changes to the amount of putty (mass) on the cone.

[Jstower]

 

Even if you plan to build these speakers yourself, you should use a proven design. You want to know how it measures and what it sounds like BEFORE building it. WGH gave you some good advice. Consider building four stackable dual subs - easier to build, tune, and move.

  Look guys the design is proven. VLA subs exist. Another thing you need to realize is the amplifier, lets say ( 400 watts ) are feeding the four drivers ( 100 watts each )so the drivers are working at only 25%, compared say the same 400 watts to a single driver which now working three times harder.

I appreciate  everyone's comments, concerns and suggestions, but it just a couple hundred $$ in MDF, really not a big deal. If it sounds terrible, I can always add solid dividers between each sub or just cut the cabinet in half. Jim

[WGH]

BTW -- this sub laid on its side and used to augment a center channel speaker in an HT system would be badass.

Probably just bad without the ass. 
Home theater processors and receivers are designed to roll off the bass at 80 Hz, sending all the bass (center, sides, surround, etc.) to a dedicated subwoofer. Extreme clarity is a more desired characteristic in a center channel than bass response. I have found that a sealed center channel speaker works better than a ported one.

The same principal works for subwoofers, sealed subs are more musical than ported. A ported sub works best in a dedicated HT, where quantity is more important than quality.