VMPS Rehab

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claymonkey

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VMPS Rehab
« on: 7 Jan 2010, 03:27 am »
I bought some old VMPS speakers recently in very nice shape, but in need of some work.

Here are a couple of pictures of the outside/inside:





The drivers are 2 x 12" woofers, 1 x 12" downward firing passive, 1 mid, 2 tweeters (I think they are both tweeters, one is morel), and 1 upward firing supertweeter.

Can anyone tell me what model these are (I've gotten conflicting information)?

Are these cabinets made by VMPS (in homage of Bozak Symphonies)?

I need to refoam all the 12" woofers, including the passives.  Can anyone tell me what is up with these passives?  Is all that crap supposed to be there or should I get new passives from VMPS?  I thought the wadding was placed on the other side?




I will also add damping material and bracing to the inside of the cabinets.   I have ideas, but would love suggestions.

I'll replace all the capacitors too and I plan on eliminating the biamp switch, using jumpers instead.

Any advice or ideas on this project are very welcome.

Thank you.

John Casler

Re: VMPS Rehab
« Reply #1 on: 7 Jan 2010, 03:57 am »
I bought some old VMPS speakers recently in very nice shape, but in need of some work.

Here are a couple of pictures of the outside/inside:





The drivers are 2 x 12" woofers, 1 x 12" downward firing passive, 1 mid, 2 tweeters (I think they are both tweeters, one is morel), and 1 upward firing supertweeter.

Can anyone tell me what model these are (I've gotten conflicting information)?

Are these cabinets made by VMPS (in homage of Bozak Symphonies)?

I need to refoam all the 12" woofers, including the passives.  Can anyone tell me what is up with these passives?  Is all that crap supposed to be there or should I get new passives from VMPS?  I thought the wadding was placed on the other side?




I will also add damping material and bracing to the inside of the cabinets.   I have ideas, but would love suggestions.

I'll replace all the capacitors too and I plan on eliminating the biamp switch, using jumpers instead.

Any advice or ideas on this project are very welcome.

Thank you.

Welcome to the VMPS Circle and WOW!!!! what a surprise those speakers are.

If they are VMPS (and they do have many of the earmarks of VMPS) they certainly pre-date me or any pictures or literature I have ever seen.

The only person who could answer your questions is Brian himself and he is in VEGAS at THE Show right now.

You might have the "Grandaddy" of all the VMPS speakers, while Brian gives birth to the newest (RM50 Dual Line Source Bipole) this weekend.

I'm sure if this is a real VMPS, Brian can offer comment.

Has all the signs (Passive Raditors, Slot loaded, Putty Damping, L-Pads, Ceiling firing tweeter, etc)


claymonkey

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Re: VMPS Rehab
« Reply #2 on: 7 Jan 2010, 04:20 am »
Thank you!

They are almost certainly some sort of VMPS kit, I just wonder about the cabinets....

The backs of one of the speakers has the VMPS setup guide and operating instructions for the VMPS Tower II / Super Tower (I can provide a pic of this later).  So, I guess this is one of those?

and there's this tag on around the mid/tre L pads


I have other pictures if they would help/anyone is curious.

I look forward to seeing what Brian has to say when he gets back.

S Clark

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Re: VMPS Rehab
« Reply #3 on: 7 Jan 2010, 05:39 am »
Very cool find!  :thumb: Those huge boxes are really going to need major reinforcement to keep from ringing.  I'd be tempted to line the complete interior with 5/8" mdf, put braced every 8-10", and line with No-Rez,  Black Hole 5, or an equivalent. They are going to take some work, but should be impressive when you finish.

Pez

Re: VMPS Rehab
« Reply #4 on: 7 Jan 2010, 05:52 am »
 :o Crazy!

claymonkey

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Re: VMPS Rehab
« Reply #5 on: 21 Jan 2010, 02:33 am »
Very cool find!  :thumb: Those huge boxes are really going to need major reinforcement to keep from ringing.  I'd be tempted to line the complete interior with 5/8" mdf, put braced every 8-10", and line with No-Rez,  Black Hole 5, or an equivalent. They are going to take some work, but should be impressive when you finish.

Thanks!  I'm still figuring out how I might want to brace the cabinets.  I'm reluctant to make it so that the front baffle cannot be removed again.

And, I do think that these are not VMPS cabinets, but actually Bozak Symphonies, look, the front baffle was cut out and replaced:



That's a VMPS mid (will be remounted on the front of the baffle) at the bottom, a Motorola 645 tweeter in the middle (same as the up-firing tweeter), and a Morel MDT-29 tweeter at the top. The morel tweeters will be getting new diaphrams. Is there anything I should think about doing to the mids or motorola tweeters?

I'm still trying to figure out what's up with these passives?



Is all of the glue and mortite really supposed to be there?
I know passives have to be loaded/tuned, but is it done on the front of a downward firing passive like this?
Also, should the chamber that the passive fires into get any sort of treatment?

And, the crossovers/speakers were wired differently! Yikes! Can anyone help me figure out what it should be? Here are sketches of the two layouts (and I have lots of pictures too):








Thanks!

James Romeyn

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Re: VMPS Rehab
« Reply #6 on: 21 Jan 2010, 03:58 am »
Those are Tower II kits w/o cabinet installed in a custom "enclosure".  The box looks about twice as large as prescribed.  Ask B if he has a couple empty unused enclosures (I guess no).  I might have packed and shipped the parts.  The only Tower II older than those had paper cone 12s.     
 
The boxes look quite incorrect for good sound.  The dome is either Audax or Morel MDT-101; mid is Brian's own design (pretty darn good actually), piezo supertweeters (one fires foward, the other top-firing).
 
Looks like you just need a couple of new 12" PRs, new boxes, pull the domes back to original shape, check all drivers for problems and double check the xo's are done right (not easily done; B had to carefully double/triple check QSO XOs even after making a thousand of them).       
 
I doubt B still has cabinet plans but he might.  If you make new boxes, surprisingly my experience (and that of several others very familiar with them) is that the Tower II boxes w/ mirror imaged arc mid-treble array beat the later Tower II SE, in which all drivers are in-line.  In other words, if you make boxes copy the older mirror-imaged arc array and NOT the later straight inline array.
 
TIIs done right move serious amounts of air, are extremely musical and smooth and are super dynamic; their bass cutoff is so low as to seriously excite bass modes in your room you didn't know existed.
 
For properly working OEM versions the weakest points, performance-wise, are the tweeters (tossup which is weaker: the dome or front firing piezo, I'd say the dome is weaker)...the top firing piezo is not a weak point and no upgrade was ever offered for it.
 
Just an afterthought...I have a pair of Scan Speak D2900 soft domes (offerred as an upgrade at my suggestion, still a world-class dome IMHO) and two NOS original long-gone JVC ribbons that were upgrades for the piezo.  The inline cap for the dome would have to be tweaked; ditto the ribbon needs a 12 dB slope IIRC (Brian may but may not remember the ribbon xo values).   
 
Getting back to the OEM boxes...I tend to believe they were a bit too small for the two active 12s, resutling in a slightly higher than ideal Q (manifesting as either sounding oh-so-slightly overipe or a bit too thin while adjusting PR mass; Tom Norton of Stereophile noticed the same in his glowing review).  I'd estimate best to go with a slightly larger than OEM box and/or more PR area (15" PR could go side-firing or two 12" PRs).  Because the mid bass 12 extends up super high, it would be best to put it in its own sealed subenclosure to keep the internal standing waves well below the xo pole. 
 
I think best performace would arrive from putting the midbass 12 on the front lowermost and the low bass 12 on the rear uppermost.   
   
Warning: I did not look at the schematic you posted.  The series nature of the OEM QSO XO splits the input between the midrange and tweeters, not as per expected practice between the bass and mid.  Another way to say it is that only the bass/mid is QSO; the tweeters are on separate standard XO circuits. 
 
My 2 kopacts.   

Brian Cheney

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Re: VMPS Rehab
« Reply #7 on: 21 Jan 2010, 05:51 am »
Jim is right, those are Tower II drivers with everything else changed.  I can't tell about the crossovers but I'll guess they are not stock.

The cabinet, while beautiful, is really not suited to the Tower II driver complement.

mosawdust

Re: VMPS Rehab
« Reply #8 on: 21 Jan 2010, 12:09 pm »
I would sure be interrested in those JVC ribbons if he's not. I just ordered some patrs for my ST/R's and this is one of the parts I needed which Brian told me was no longer available.

James Romeyn

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Re: VMPS Rehab
« Reply #9 on: 21 Jan 2010, 05:27 pm »
I would sure be interrested in those JVC ribbons if he's not. I just ordered some patrs for my ST/R's and this is one of the parts I needed which Brian told me was no longer available.

Email on the way.
 
Love your username.
 
PS: also have one pair 93 dB NOS Focal inverted fiberglass (vs. the more aggresive sounding kevlar) T120 (vs. the smal magnet T90) inverted domes, offered for a time as the dome upgrade from the Morel.  The early lower cost Morel was reliable, sounded OK and was used for a long time, but IMHO had less musical likability vs. the earlier Audax and later domes employed.  The later more costly Morel domes were a performance upgrade.  Again, the old Scan Speak D2900 is still a fantastic dome, its Achilles heel being the tacky dome coating that attracts and holds dust.
 
Still miss my old SuperTower Rs.  Do yours have top firing piezo or are they the later SE versions?  They both kick butt.  Lived in a condo at the time, had a friendly relationship w/ the mellow next-door drug dealer (nice clients, no noise, no disturbances, probably just mainly mj).  The refrigerator sized ST/R were located near the one wall we shared.  At some point his quasi-wife told my wife the pictures hanging on that wall in their condo fell off their anchors.  Sota TTs play incredibly deep bass, at that time far lower and greater bass than ANY CDP.  Concrete soundroom floors are tops (current 26 x 16 Utah mancave has concrete floor AND front wall).
 
Factory assembled MSRP for ST/R was $1998/pr, each enclosure having:
15PR
Active 15 low bass
Active 10 midbass
(2) mids
(2) domes
Ribbon supertweeter
Top firing piezo
 
Those things moved more pant-leg flapping bass at 20 Hz than anything below about $20k.  Almost frightening.  The first time you heard TII or ST/R (with appropriate source) you just look at them wondering what the heck you are hearing, because you never heard bass like that outside a concert hall.             

claymonkey

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  • Posts: 8
Re: VMPS Rehab
« Reply #10 on: 21 Jan 2010, 06:20 pm »
Those are Tower II kits w/o cabinet installed in a custom "enclosure".  The box looks about twice as large as prescribed.  Ask B if he has a couple empty unused enclosures (I guess no).  I might have packed and shipped the parts.  The only Tower II older than those had paper cone 12s.     
 
The boxes look quite incorrect for good sound.  The dome is either Audax or Morel MDT-101; mid is Brian's own design (pretty darn good actually), piezo supertweeters (one fires foward, the other top-firing).
 
Looks like you just need a couple of new 12" PRs, new boxes, pull the domes back to original shape, check all drivers for problems and double check the xo's are done right (not easily done; B had to carefully double/triple check QSO XOs even after making a thousand of them).       
 
I doubt B still has cabinet plans but he might.  If you make new boxes, surprisingly my experience (and that of several others very familiar with them) is that the Tower II boxes w/ mirror imaged arc mid-treble array beat the later Tower II SE, in which all drivers are in-line.  In other words, if you make boxes copy the older mirror-imaged arc array and NOT the later straight inline array.
 
TIIs done right move serious amounts of air, are extremely musical and smooth and are super dynamic; their bass cutoff is so low as to seriously excite bass modes in your room you didn't know existed.
 
For properly working OEM versions the weakest points, performance-wise, are the tweeters (tossup which is weaker: the dome or front firing piezo, I'd say the dome is weaker)...the top firing piezo is not a weak point and no upgrade was ever offered for it.
 
Just an afterthought...I have a pair of Scan Speak D2900 soft domes (offerred as an upgrade at my suggestion, still a world-class dome IMHO) and two NOS original long-gone JVC ribbons that were upgrades for the piezo.  The inline cap for the dome would have to be tweaked; ditto the ribbon needs a 12 dB slope IIRC (Brian may but may not remember the ribbon xo values).   
 
Getting back to the OEM boxes...I tend to believe they were a bit too small for the two active 12s, resutling in a slightly higher than ideal Q (manifesting as either sounding oh-so-slightly overipe or a bit too thin while adjusting PR mass; Tom Norton of Stereophile noticed the same in his glowing review).  I'd estimate best to go with a slightly larger than OEM box and/or more PR area (15" PR could go side-firing or two 12" PRs).  Because the mid bass 12 extends up super high, it would be best to put it in its own sealed subenclosure to keep the internal standing waves well below the xo pole. 
 
I think best performace would arrive from putting the midbass 12 on the front lowermost and the low bass 12 on the rear uppermost.   
   
Warning: I did not look at the schematic you posted.  The series nature of the OEM QSO XO splits the input between the midrange and tweeters, not as per expected practice between the bass and mid.  Another way to say it is that only the bass/mid is QSO; the tweeters are on separate standard XO circuits. 
 
My 2 kopacts.   

Wow!  James, thank you very much.   I appreciate all the information.  Any idea how old the kit is?

It sounds like I'd be crazy to try to modify this cabinet to work with these components.

So, I don't suppose anyone has extra cabinets (Brian?) or a design for them?
Does anyone have a set of these that wants to take some measurements/photos for me?
Even seeing how the next generation of cabinets after mine are constructed would help me.
Anyone have a schematic of the proper x-over for a Tower II of this age?

James, that dome is the Morel MDT-29, btw.  I don't know if that makes a difference in your evaluation of it?  I was going to replace the diaphrams.

I hadn't planned on upgrades yet, but, I hadn't planned on making new cabinets either!  So, I'd love to talk to you (email) offline about your kind offer.

Thanks again James!  It's cool that you might have handled these very pieces.

claymonkey

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Re: VMPS Rehab
« Reply #11 on: 21 Jan 2010, 08:39 pm »
Jim is right, those are Tower II drivers with everything else changed.  I can't tell about the crossovers but I'll guess they are not stock.

The cabinet, while beautiful, is really not suited to the Tower II driver complement.

Thanks Brian!

You don't have any old cabinets still kicking around do you?
Or the design for them?

Thanks for still supporting these OLD products of yours.

John Casler

Re: VMPS Rehab
« Reply #12 on: 21 Jan 2010, 08:51 pm »
Clay Monkey,

Here is the "stock" TOWER II cabinet look and Driver Array configuration.


claymonkey

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Re: VMPS Rehab
« Reply #13 on: 21 Jan 2010, 09:57 pm »
Clay Monkey,

Here is the "stock" TOWER II cabinet look and Driver Array configuration.



Thanks John!  That is a good start.

If the drawing is to scale, I should be able to get a basic idea of the dimensions from it.

James, is this the driver arrangement that you were talking about?

Brian Cheney

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Re: VMPS Rehab
« Reply #14 on: 21 Jan 2010, 10:00 pm »
Dimensions are 43"Hx14.5"Wx17"D, construction was 3/4" MDF throughout. 

claymonkey

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Re: VMPS Rehab
« Reply #15 on: 21 Jan 2010, 10:13 pm »
Dimensions are 43"Hx14.5"Wx17"D, construction was 3/4" MDF throughout.

Great!  Thanks Brian.

What about that bottom foot?  I'm guessing it is open in the front and is where the passive fires into?  Is that included or how do I size it properly?

James Romeyn

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Re: VMPS Rehab
« Reply #16 on: 21 Jan 2010, 10:34 pm »
WARNING!  DANGER WILL ROBINSON!  Pairs must be mirror imaged or you are in very deep quicksand.  Sound best w/ tweeters on the inside unless they are spaced very very closely (like 2-3').  Yes those are the arc array that myself and others prefered over the later SE versions, which incidentally were shorter lived.
 
I'd LIKE a pair of those, but the ST/R are about twice as big and that much better.  Whose got room for a spare pair of older speakers THAT huge? 
 
The 17" depth includes the kick panel below and the grill; minus those pieces yields 16-1/4, but these minor differences are uncritical.  I still recommend greater PR area than the OEM single 12 (1x 15, 2x 10 or 2x 12).  I found good audio results side-firing the PR sans slot loading.  Some like Theil and one popular current lower cost brand even front fire their PR.
 
Toss the toggle switch; if biwire/biamp option is desired just hard wire to separate binding posts and parallel them externally for single wire.     

mosawdust

Re: VMPS Rehab
« Reply #17 on: 21 Jan 2010, 11:17 pm »

Email on the way.
 
Love your username.
 
PS: also have one pair 93 dB NOS Focal inverted fiberglass (vs. the more aggresive sounding kevlar) T120 (vs. the smal magnet T90) inverted domes, offered for a time as the dome upgrade from the Morel.  The early lower cost Morel was reliable, sounded OK and was used for a long time, but IMHO had less musical likability vs. the earlier Audax and later domes employed.  The later more costly Morel domes were a performance upgrade.  Again, the old Scan Speak D2900 is still a fantastic dome, its Achilles heel being the tacky dome coating that attracts and holds dust.
 
Still miss my old SuperTower Rs.  Do yours have top firing piezo or are they the later SE versions?  They both kick butt.  Lived in a condo at the time, had a friendly relationship w/ the mellow next-door drug dealer (nice clients, no noise, no disturbances, probably just mainly mj).  The refrigerator sized ST/R were located near the one wall we shared.  At some point his quasi-wife told my wife the pictures hanging on that wall in their condo fell off their anchors.  Sota TTs play incredibly deep bass, at that time far lower and greater bass than ANY CDP.  Concrete soundroom floors are tops (current 26 x 16 Utah mancave has concrete floor AND front wall).
 
Factory assembled MSRP for ST/R was $1998/pr, each enclosure having:
15PR
Active 15 low bass
Active 10 midbass
(2) mids
(2) domes
Ribbon supertweeter
Top firing piezo
 
Those things moved more pant-leg flapping bass at 20 Hz than anything below about $20k.  Almost frightening.  The first time you heard TII or ST/R (with appropriate source) you just look at them wondering what the heck you are hearing, because you never heard bass like that outside a concert hall.             


I received your email James. Let's see what we can work out.

I purchased these from Brian as a kit in 1993. I went over to his house and listened to them in his living room and knew I found exactly what I wanted . Best purchase I ever made. You are correct, these things will rock. I'm in the process of going through them now so I can get another 20 years out of them. Mine do have the top firing piezo tweeter (not the SE version). I'm replacing the PR's, Woofers, adding bracing, lambs wool in the mid enclosure...

I still have, which may be of use to some others here, all original paperwork that came with these. Original brochure, Complete assembly instructions, test & set up instructions...

Thanks so much for the response and I will be getting back to you here quickly.

Many Thanks,
Brian

claymonkey

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Re: VMPS Rehab
« Reply #18 on: 22 Jan 2010, 06:20 pm »
WARNING!  DANGER WILL ROBINSON!  Pairs must be mirror imaged or you are in very deep quicksand.  Sound best w/ tweeters on the inside unless they are spaced very very closely (like 2-3').  Yes those are the arc array that myself and others prefered over the later SE versions, which incidentally were shorter lived.
 
I'd LIKE a pair of those, but the ST/R are about twice as big and that much better.  Whose got room for a spare pair of older speakers THAT huge? 
 
The 17" depth includes the kick panel below and the grill; minus those pieces yields 16-1/4, but these minor differences are uncritical.  I still recommend greater PR area than the OEM single 12 (1x 15, 2x 10 or 2x 12).  I found good audio results side-firing the PR sans slot loading.  Some like Theil and one popular current lower cost brand even front fire their PR.
 
Toss the toggle switch; if biwire/biamp option is desired just hard wire to separate binding posts and parallel them externally for single wire.     

I understand the mirrored image thing.  Good info on the side firing PR. 
I planned on tossing the toggle switch, but was going to preserve the ability to biamp if desired by using jumpers.

Thank you again for all your valuable time and information.