AudioCircle
Audio/Video Gear and Systems => Owner's Circles => VMPS Speakers => Topic started by: baco99 on 2 Jun 2016, 09:17 pm
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Hello! This is only my second post and I am happy to have found this site. I've been working on speakers for over 25 years as a hobbyist.
I'm working on a "light restoration" of a pair of VMPS SuperTower/R speakers that a friend of mine picked up. They need 6 new foams, which is no big deal. One of the bottom-mounted PRs also needs a new rope caulk mass added to it. The prior rope caulk install seems to have peeled off and been lost. All of the other drivers seem in tact and operational.
I have 3 questions, however.
1) When I looked in the box, the sides are coated with the optional VMPS white ceramic "Soundcoat" material. There's very little internal bracing which is shocking for a speaker this size, and there's no polyfill, fiberglass, or Roxul insulation in the cabinet at all.
a) Does the Soundcoat need to be reapplied at all, or is it a material that holds its value forever?
b) Has anyone added bracing to the inside of the cabinet to stiffen it? If so, where? If not, why not?
c) Is there any reason not to line the cabinet with polyfill or fiberglass as additional acoustic damping?
2) Has anyone experimented with using a different added-mass method than rope caulk and hot glue for the bottom PRs? This seems like a rather clumsy solution to me. I was thinking of doing what Snell did for the Type A and adding some kind of epoxy to the cone, or gluing a more solid mass made from wood or plastic. Any thoughts here?
3) The super tweeters on these were apparently upgraded by the owner of VMPS before his passing. They are ribbons but they look different from ones I have seen online. Does anyone have any info on the upgrade paths that were provided well after these speakers went out of production. The tweeters are Morel MDT28 with a rear chamber and ferrofluid. Are these the upgraded tweeters? Were the MDT29 the standard?
(Also, if anyone needs NOS voice coils for Morel tweeters, I have a bunch. )
THANKS!
Under the knife...
(https://c2.staticflickr.com/8/7336/27416019175_6fd06fee3c_b.jpg)
(https://c2.staticflickr.com/8/7033/27344925831_43c3421bd2_b.jpg)
(https://c2.staticflickr.com/8/7347/27416198005_b338e5078b_b.jpg)
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The soundcoat is a ceramic based coating and should last forever with no care.
My SuperTowers were built from a kit and the instructions said to fill the cabinets with insulation. I did and they are.
I have also upgraded the super tweeters in mine over 15 yrs ago and have no recall of what I used ot what the stock ones were.
The PR's have a tremendous amount of the putty added. There are upgraded PR's available that have a much better tuning system and increase the bass output. Contact John Casler. they are very similiar to these http://www.creativesound.ca/details.php?model=APR15
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Sorry, logged in under the wrong alias!
Carry on!
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Thanks RSorak for the reply
That's better... :green:
You know what's funny, I have had a 15" CSS PR with adjustable weights/washers in my workshop for 2 years without a purpose. Just set it aside for a rainy day. Maybe I'll restore one old one and try the new on and run some measurements for fun.
Interesting that your kit said to fill the cabinets. That's uncommon for a PR design. Usually you'd see *some* fill, like in a Polk SDA tower where it's used mostly to mitigate midrange leakage. But the PR is largely open.
Was the ceramic coating intended to replace the fill?
Also, confirmed that these use the MDT28, ferrofluid cooled 200w tweeters.
Can anyone tell if the wiring is also upgraded by looking?
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That PR has enough Mortite on it to choke a horse :duh:. All VMPS speakers were filled fiberglass with a vent pass to the PR.
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On my ST/R which I had re-foamed by Millersound, PA. the putty loading varied from Brian, according to James Romlyn who worked side by side building VMPS, Brian changed loading first with a 1 oz lead fishing sinker, then added 4-8" of putty to dial in the passives, worked great for me.
I bought the line thru type 1 oz sinker, hammered into a circle, then hot-glued it in three places, adding the rest of the putty loading directly onto the lead weights, clean and simple.
Your passives are a mess! Any weight or putty should be centered anyways, not on the cone itself. Once you get both passives re-foamed, vitrify them with yellow Elmers wood glue to stiffen the cones, then do your lead and putty loading ... good luck!!
PS: If James responds to this, listen to him ..... this was his VMPS era working with Brian and he has a wealth of info from back then.
DW
(http://www.audiocircle.com/image.php?id=144134)
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Just to add another detail on the fill. My speakers also have the soundcoat and more specifically the instructions said to fill most of the cabinets but leave space at the bottom empty of fill by the woofer/PR.
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with a vent pass to the PR.
What do you mean by this?
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Just to add another detail on the fill. My speakers also have the soundcoat and more specifically the instructions said to fill most of the cabinets but leave space at the bottom empty of fill by the woofer/PR.
Got it, I think this just answered my other question, above.
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also, any thoughts on adding bracing? That one piece of pine doesn't seem sufficient to me...
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This is how I braced my cabinets, right above the 15" woofer, also I raised the base by 3/4" so I could get my hand to the putty on the PR. Good Luck Zak
(http://www.audiocircle.com/image.php?id=144168)
(http://www.audiocircle.com/image.php?id=144169)
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Looks great Zak!
I see you recapped them. The pair I am working on seem to also have the wiring and crossover upgrade. The Monster "Powerlink Low Loss" wire is in the cabinet for the two woofers. I'm tempted to check the values and leave them if they are within spec.
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Baco99, Also I took out the toggle switch and will use an external jumper wire , or bi wire Zak
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I have read in several locations where Brian referred to these designs as aperiodic designs and not passive. But an aperiodic uses a tuned vent so i imagine this to be some sort of hybrid due to the amount of stuffing inside the cabinets being coupled to the passive radiator. This is only my guess from reading where he described many of these older models as aperiodic.
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FYI, the moretite on the PR measured 5.6 oz.
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baco99,
Yes way too much! Applied wrong also, but you will get there, killer loudspeakers.
DW
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Here is what my Supertower/R passive looks like
(http://www.audiocircle.com/image.php?id=144176)
Yes, Shear Bliss is correct there is a one ounce fishing weight hot glued in the bottom of cone.
(http://www.audiocircle.com/image.php?id=144178)
(http://www.audiocircle.com/image.php?id=108307)
I believe this is all original, factory built speakers. I measured the putty for my records.
(http://www.audiocircle.com/image.php?id=144179)
I added the VMPS logo to the center cap
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There is also a weight on the back.
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can anyone tell if these speakers also have the Wondercap upgrade? the caps look to be mylar or poly film (not electrolytic).
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They should be marked if they are Wonder caps. they look like this.
(http://www.audiocircle.com/image.php?id=144434)
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Thanks. I will double check, but doesn't look like he has those.
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OK, Some updates. I double checked and these speakers DO have the Wondercaps, however, there's only one. not two like the one pictured. I understand that there were several variations of this speaker over the years with driver changes, etc.
I got one speaker fully assembled and hooked it up just to see what the fuss was all about and I have to admit, I am completely disappointed. Bass is muddy and fat, midrange is uninspiring, and the high end completely weak. Considering these speakers have four tweeters in total, the high end was virtually non existent. I checked the crossovers and they are very simple.
There's no padding on the tweeters with the exception of the L-pad for "Brilliance" and the L-pad for the super tweeter mounted on the back. All the L-pads work and I cleaned them with DeOxit.
The tweeters make noise, they are just completely overpowered by the terribly bloated bass. So I looked at the low end connections. According to the marketing, the two woofers are supposed to be crossed over at different frequencies, which I find impossible because there's only one choke in the crossover. I haven't measured it yet, but both woofers are running in parallel off this choke. So they are crossed at the same frequency in mine, and by running in parallel. I cannot imagine this is right.
First, does anyone have a crossover schematic that they can post here or email?
Second, would these speakers benefit from a recap? The Wondercaps and other caps are all film type and should not degrade. But maybe they do?
Third, the wiring inside this speaker is a complete mess. The Low Loss Monster wire is so thick that the connection points are comprised of blobs of solder. Has anyone rewired and/or replaced this ridiculous Monster wire with something more reasonable that's easier to handle and solder?
Thanks again!
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As far as the rewiring . 14 gauge ANALYSIS PLUS CABLE (purple, black) is what is used in later VMPS speakers. Zak
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Thanks
Any help with a schematic?
The crossover points are supposed to be as follows:
15" = 22-200 HZ
12" = 200-600 HZ
5"x2 = 600-4500 HZ
1" x2 = 4500-15000 HZ
Ribbon = 15000-47000 HZ
I only see one choke for both the 15" woofer and the 12" midbass coupler. Other than that, there's no upper range cutoff for any of these drivers. I've measured Morel MDT28 tweeters to 22khz. A proper choke would need to be used for a second order cutoff at 15k as the manual claims.
Any help would be great.
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I suggest checking some basic things.
Are all drivers wired in phase? You can trace the wiring to check this, or I can send you the wiring check instructions where you use a 9V battery to see which way the drivers "thump" when the battery is applied to test points.
The bloated bass could be from the passive not being tuned, also did you listen with the cabinet empty or stuffed with fiberglass?
Dull midrange and treble could be from L-pads turned down or miswired. Start off at "default" settings of around 12 o'clock, then turn each L-pad fully counter-clockwise then fully clockwise. You should hear a significant volume difference from one extreme setting to the other. The "default" setting is a good starting point to dial things in. If things sound bad from there then there likely is an issue somewhere.
Ed
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Hi Ed
All of the L-pads function as they should with the resistance shift as indicated on the body of each L-pad. All the wiring looks to be in order. The woofers are wired in phase with one another. And I listened with the PR in place, weighted to 3.5oz, which is about half the original. And the cabinets stuffed with fiberglass. Trust me, this wasn't a "splitting hairs" kind of critical listen. This was a "within a half second" notice that these thinks sound "EW!" as my daughters would say.
To be honest, it just looks like a sloppy job all around. I've taken apart and refurbished hundreds of speakers, and for the price these things got, I'm simply in shock. Trying to suspend disbelief.
Also, thank you for the thread with your schematic. It confirms that the wiring is in fact, intentional. Just sloppy.
(https://c2.staticflickr.com/8/7097/27904155576_e1c2c86657_b.jpg)
(https://c2.staticflickr.com/8/7723/27904160146_ba81422178_b.jpg)
(https://c2.staticflickr.com/8/7434/27861266681_f62efbf4d4_b.jpg)
(https://c2.staticflickr.com/8/7684/27659700450_f753d426e8_b.jpg)
(https://c2.staticflickr.com/8/7100/27659719270_e2c5df2e7b_b.jpg)
Huge gobs of solder everywhere and some cold solder connections.
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The woofers in these pictures appear to have no surrounds. I don't know if that is part of the bad sound you are hearing but if you've rebuilt a lot of speakers you'd already know this.
Other than a setup or wiring error I can't think of much else to check at the moment. Bad crossover? Most everyone that owns/hears the Supertowers is pleased and even impressed with the sound. What you are describing is way off, I don't know what could be amiss.
Here's something else to check: How much and with what are the midrange chambers stuffed?
Ed
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I haven't opened up the mids yet, but I will check.
I noticed in your schematic that there a 15 ohm resistor in line with the 12" mid-bass coupler. I don't see that installed here. Maybe that's where all the muddiness is coming from.
And yes, I took the pictures before refoaming all six drivers. :green:
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Ed
Mid chambers are empty.
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The chambers should not be empty. The chambers should have either fiberglass or lambs wool. Brian recommended lambs wool for midrange damping.
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Please check the upper terminal cup wiring and compare it to my posted schematic. It appears to me the speaker cable polarity on the toggle switch is swapped from where it should be. The coil for the woofer should connect the negative speaker terminals and be on the same side of the toggle switch as the negative speaker cable from the other terminal cup. It looks like the *positive* speaker cable from the other terminal cup is connected there instead of the negative wire.
Ed
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Thanks Ed - I will check on that.
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Here's a summary of what is wrong with these speakers....
1) each cabinet missing all acoustic fill for the bass drivers
2) each cabinet missing all the specialized lambs wool fill for the midrange enclosures.
3) woofers and mid bass couplers in one cab are wired out of phase with the other drivers (all drivers are wired in phase according to the schematic)
4) woofers and mid bass couplers in the other cab not connected at all.
5) 12" mid bass couplers missing a 25 ohm resistor ahead of them which alters the crossover points for all drivers since the mids are connected in a series circuit. Ah!
6) The midrange cap measured at 5.4 uf, not the prescribed 49 to 54.5 uf in the schematic.
Once I fix these things, we might have something useful to listen to and evaluate further. Thanks Ed (ST86) for the assistance here!
Also, some of the absolute worst soldering I have ever witnessed.
(https://c2.staticflickr.com/8/7404/27984691525_7210d9e0f3_b.jpg)
(https://c2.staticflickr.com/8/7391/27950274946_8f4a4306f9_b.jpg)
What a mess!
(https://c2.staticflickr.com/8/7426/27370951733_c57dd6c349_b.jpg)
Also, I tested the caps and they are still well within rage, with the exception of the single Wondercap, which is supposed to be 2.5uF (I think) and reads 0.9uf. But I need to verify when I get a hard copy of the schematic.
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baco99, I don't think these were factory built speakers. Also is that a fuse holder in your second picture next to the L-pad. Zak
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baco99
"The midrange cap measured at 5.4 uf, not the prescribed 49 to 54.5 uf in the schematic."
My midrange caps measure 5.59uf and the tweeters caps measure 1.43uf .
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Weird. The schematic that Ed posted shows a 54.5 cap in front of the mids.
I think this was a factory build because the serial numbers are sequential and stamped on the paperwork attached to the back of the speaker. I think someone got clever and f-d everything up later on.
And yes that's a fuse holder.
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baco99 , Not to sure if the fuse is a factory thing, I've never seen it on another pair of VMPS. I think my speakers crossovers are somewhat similar to yours. All my drivers were updated sometime (2011-2012)
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I concur the fuse is not a factory thing, that looks like a mod added by someone. Never seen it on any VMPS speakers of that era and a fuse is not listed in the parts list or on the schematic for my Supertowers. With all the other problems found I would be surprised if these cabinets left the factory like that.
My schematic called out 54uF for the cap value for the original grey poly mids. When I bought the updated 12" Misco woofer and 5" mids (Brian called them "classic" mids) from Brian he specified changing the woofer inductor to 2.8mH and keeping the midrange cap value at 54uF. This is for the mids that I bought from him. I'd say different mid drivers require different cap value. The ones shown here are not the same as mine.
Ed
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Also the white damping material on the cabinet, I don't think is a factory job, because the drivers and crossovers would not have been there then the coating was applied.
Hello Ed, I think your right about the red and black wire on the switch, they need to be switched around, or better yet take the switch out. Zak
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Many VMPS speakers were also sold in kit form....This could explain many of the problems found in these speakers.
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Yes, I think what happened was someone bought them, and then later on tried to upgrade them according to the marketing pamphlet.
Serial numbers are 9049 and 9050.
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Also the white damping material on the cabinet, I don't think is a factory job, because the drivers and crossovers would not have been there then the coating was applied.
Hello Ed, I think your right about the red and black wire on the switch, they need to be switched around, or better yet take the switch out. Zak
ZAK - If I take the switch out, I would need to add leads outside the cabinet for bi-amp operation. The switch was part of the original circuit, as was the fuse according to the diagram on the back of the speaker.
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You don't need external leads. You can replace the switch with two pairs of terminals mounted to the terminal cup, connected by jumpers for single amp operation. For biamping remove the jumpers and connect each amp to each pair of terminals. Internal wiring would have woofers and mids connected to one pair of terminals, domes, and other two tweeters connected to other pair of terminals.
Ed
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You don't need external leads. You can replace the switch with two pairs of terminals mounted to the terminal cup, connected by jumpers for single amp operation. For biamping remove the jumpers and connect each amp to each pair of terminals. Internal wiring would have woofers and mids connected to one pair of terminals, domes, and other two tweeters connected to other pair of terminals.
Ed
See image of the rear label which shows the switch for biamp/normal operation (which does work, actually), and the 2A protection fuse. I'd prefer to keep this original.
(https://c2.staticflickr.com/8/7075/27385728353_633943564a_b.jpg)
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Well, this is a first. I've never seen a original Supertower with a fuse.
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baco99
"The midrange cap measured at 5.4 uf, not the prescribed 49 to 54.5 uf in the schematic."
My midrange caps measure 5.59uf and the tweeters caps measure 1.43uf .
My mid caps measure 5.53 and 5.54, respectively.
The tweeter caps measure 1.52 and 1.52.
The super tweeter Wondercaps are running .89 and .88
I plan to leave the original values that are here unless someone recommends otherwise
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Problem solved!
That 25 ohm resistor was the key to the whole puzzle. Wow! What a difference!
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One more note, I think I know why the previous owner wired one side the wrong way. The woofers have their poles on opposite sides. In other words, on one 15" woofer, the (+) terminal is on the right. One the other 15" woofer the (+) terminal is on the left. Same with the 12". I've seen this with EPI speakers before, but never in a sequence like this. The terminals are color coded, but the PO must have just assumed that the right and left terminals were the same, or never bothered to verify.
Waiting for some glue to dry and then we are off and running!