[inRMsway]

In the ever obsessive search for the limits of audio playback, I didn't find a post on this entire site dealing with properly sealing the neoplaners to the cabinet. Maybe it doesn't matter, but unless I'm in my own delusion, I think it sounds warmer with more body to do this.
I peeled off the stock thin weatherstripping and replaced it with thicker weatherstripping, took some of the old and tucked it under the gaps at the sides of the wiring area and some on the bulges at each side and then put a piece of the thicker type across the notch. This makes them pretty well sealed and I think loads them better at the bottom of their range. Beyond that I pulled out the fiberglass, lined the walls with mattress topper and then stuffed with Acousta-Stuf from Madisound (I liked it better than the lambswool tweek). I think it kills more box resonance because I have no more honk or shout at any frequency. This speaker is tweekelicous!

[ka7niq]

People should read this whole PDF file http://www.eminent-tech.com/Manuals/LFT10Manual.PDF

It is from the guy who invented the midrange driver used in our speakers.

According to him, the speaker MUST be protected, IF sealed, from the back wave of the woofer, or the woofer will see the light diaphragm of the ribbon as an air leak! 

Now, if the woofer really See's the ribbon diaphragm as an air leak, what does the lightweight ribbon diaphragm SEE the back wave of the woofer as ?
A Thunderstorm 

I do not blame you, after reading this, for making SURE there are zero air leaks in any of the ribbons boxes. 

I haven't had the chance to get into the mid range boxes yet, but you surprised me when you said these was just fiberglass in there ?

I kinda expected a variable density damping scheme of some kind I guess ?

Hey, I got an idea ?

Lets bore a hole in the top of the 40's.
No one will see it, and we can use it to rig a port tube into the ribbon boxes ?
This will allow the ribbons to go deeper down in frequency, and with greater efficiency too,  perhaps solving the Lean tonal balance issues ? 

Seriously, I think playing with damping is important, and some have liked the Lambs Wool.

I might try this http://www.freepatentsonline.com/6338395.html

Or, do a graduated density damping scheme on mine ?

I wish I had measuring equipment so I could see what is REALLY going on in the RM 40, and why it is so lean sounding in the lower mid range ?

Is it the ribbons reluctance to play low with any real output, or are the woofers crossed in too low, creating a hole the ribbons can't fill ?

Whatever it is, it ruins what could be a truly great speaker IMHO.

My understanding is the newer RM 40's have a higher crossover point, ON THE RIBBONS.

Unless the woofers crossovers are raised as well, this would seem to create MORE of the hole I hear, not less.

It is becoming more and more obvious to me that the woofers need to play higher in frequency, IF the ribbons are unable to play low.

That is why I question WHY the top woofer and the bottom roll off at different points at all ?

The bottom Mega woofer is unable to come up and help it's top mounted "mid woofer" brother "fill in" the hole I hear. 

So, as I understand it, here is what is happening .

We basically have just the upper range of ONE 10 inch driver providing almost the entire lower mid range of our speakers.

Unlike some here, the RM 40 is not the only speaker I own, just one of many.

And, unlike Brian, I am not "married" to minimum phase, first order crossovers, etc.

My ears tell me these speakers need to have the woofers reproduce more of the music, since the ribbons can't play low.
To do that, the woofers need to come up farther in frequency, and BOTH need to play the same so the sound stage remains centered.

Perhaps a 24 db electronic crossover will allow this, and I am talking about using it on BOTH slopes, ribbons and woofers if I have to.

I do plan on replacing the Mega woofers with mid woofers first, so BOTH drivers play well up into the mid range, and play the same.

Maybe this will cure the lean tonal balance that I find so unacceptable ?

To a long time VMPS customer like myself, the RM 40 is a radical departure from the VMPS sound I once knew.

My old Super towers were warm and rich, with kick butt bass.
Everything sounded good.

Sure, the RM 40's image better, and are way more faster and transparent, and a better speaker in every way, EXCEPT ONE.

They are too lean in the lower mids for my tastes, a place where the foundation of the music lies.

One can not simply "reduce the pots" to "warm them up" because then the sound stage jumps UP to the top woofer.

I have played with the putty till blue in the face, and in fact  did it so much I now have a  hole in one of my passive radiators!

The hole in the passive was caused by my vain attempts to tune what I did not know were leaking woofers.

Brian offered to fix em free, but I had them done locally and saved freight.

One of the guys here is planning to send me his old passives, otherwise I would ask Brian to replace my done in passive, since the leaking woofers caused the in vain application and removal of countless globs of putty.

I may try your damping suggestions, but I want to try the mid woofers out in place of the mega woofers first, one thing at a time.

I will probably lose some deep bass, but that ain't no big deal.

I have two TC Sounds LMS 4000 15 inch woofers in corner mounted 9.5 cu ft sealed cabinets.

Ain't hurting for bass, I assure you.

I remember Jim Romeyn stating he swapped the two woofers, and placed the mid woofer on the bottom.

He liked it, and I would be inclined to agree with him, based on my experience with the RM 40 so far.

Now, lets take Jim's observations to the next step, and go ALL mid woofers, and see what happens ?

Maybe, the increased mid range output of another mid woofer will fill in the Lean sound I do not personally care for ?

Hey, IF it works, maybe I will but four new mid woofers from Brian with the bigger magnets ?

Brian did say he MIGHT come out with more efficient woofers for the RM 40's for his customers with sub woofers.

IMHO, this would be a GREAT thing, more efficiency, at the loss of some low bass.

This will allow smaller tube amps to be used, as the many ribbons in RM 40 are quite efficient.
They are being "held back", efficiency wise, by the power demands of the woofers.

IF Brian were freed of having to have the RM 40 woofers make deep bass, perhaps he could concentrate on efficiency and a faster woofer to better blend with the marvelous ribbons ?

I will name it for Brian, it will be called the RM 40 SHE
Or Super High Efficiency 

Anyway, thanks for your post!
 

[Brian Cheney]

Yes, the lean tonal balance was addressed about two years ago with the new .3 10" midwoofer ($95ea) and by our lowering the panel xover slightly. Power handling improves due to the new 4 layer VC.

The lambswool also provides greater clarity and less coloration than the old fiberglass damping.

It is indeed very important that the large midrange subenclosure be air tight.  Speakers as old as Chris' (first run) should be checked for same and caulked if necessary with hotmelt or silicon sealant.

[inRMsway]

Thanks Brian for your reply on this topic. I did have both leaking mid boxes and woofers and got everything sealed up as well as possible. I did do what Chris mentioned, which was to replace the Megawoofer with a Midwoofer which centered the soundstage at tweeter height and may have even overfilled the lean balance. I love the sheer speed and clarity of your woofer alignment and doing this symmetry trial has pleased me so far. I'm curious if sealing the Neos as I did is in your opinion a beneficial thing as the Neos will obviously leak through the wiring area notch with the standard weatherstripping as supplied. Maybe it just makes me feel better to have them sealed, but I swear I hear a nice difference.

[ka7niq]

Yes, the lean tonal balance was addressed about two years ago with the new .3 10" midwoofer ($95ea) and by our lowering the panel xover slightly. Power handling improves due to the new 4 layer VC.

The lambswool also provides greater clarity and less coloration than the old fiberglass damping.

It is indeed very important that the large midrange subenclosure be air tight.  Speakers as old as Chris' (first run) should be checked for same and caulked if necessary with hotmelt or silicon sealant.

Yes Brian, everyone should know my RM 40's are VERY old, and  the lean tonal balance problem  has been addressed in the newer models.

Just YOUR opinion Brian, what do you think will happen when I replace the megawoofers with all midwoofers ?

IF it works, maybe the  Hot Setup is to buy 4 New Midwoofers with the 4 layer voice coils and bigger magnets ?

What IS the theory, pro and con, of such a change ?

[ka7niq]

Hey Brian, what do you think about trying Kapok Damping ?
Or, a variable density damping scheme for the neo panels ?

[Brian Cheney]

Frequency response of the lowbass (.4 Qt) and midbass (.3 Qt) is similar, the difference is magnetization. I don't see why you couldn't experiment and find what sounds best to you.

As for Kapok and mixed damping materials, that would also be a matter for experimentation.  Feel free to try various configurations and report back.

There is no doubt that different methods of sealing and gasketing the panels affect sound quality.  Jim of ribbonspeakers.net has some experience here he might want to share.

[ka7niq]

Thanks Brian!
I am gonna give the dual midwoofers a try, and see what happens.
Not sure on the Kapok damping though, at least in the midrange ?

It would cost me a small fortune to damp the huge 9.5 cu ft subwoofers with the stuff.

Well, not really, if you figure 1 lb per cu ft, and you get 5 lbs for 30 bucks thats only 120.00 for both subwoofers.

The Kapok does not show it's big advantages in the midrange, and maybe Jim Romeyn or John Casler have some midrange damping ideas.

Jay {inRMsway} who posted above has had good luck with his mattress foam damping scheme.

It should not be construed that any of us here do not love our speakers, because we do.

But it has been my observations that many VMPS owners are obsessed audiophiles like myself, hell bent on getting the last little bit of what we can out of our systems.

Most who come over to hear my system are blown away as it is.

A speakers balance is a subjective thing, and many prefer transparency over a fat lower midrange.

And, on the best recordings, the RM 40's of mine as they now sit, are unchallenged by any speaker I currently own.

However, I do not listen to much well recorded stuff, and am willing to trade some transparency for a more "forgiving" sound.

Maybe Jim Romeyn will jump in ?
I know he has played with swapping woofers, etc.

[BrunoB]

Hey, I got an idea ?

Lets bore a hole in the top of the 40's.
No one will see it, and we can use it to rig a port tube into the ribbon boxes ?

That's an interesting idea. I measured that without a box, the midrange panel frequency response goes much lower (< 200Hz, there is also a resonance around 150 Hz, from memory). This was measured in open air with the measurement mic placed against the panel. The enclosure and too much stuffing reduce the low frequency extension of the panel. Adding a tube that would allow airflow might give you back the low frequency extension of the open air panel. The low freq response of the mid range panel in the V60 (and also my own modded open baffle 626R) might be better than for the "enclosed" models.

On a side note, two weeks ago, I opened a broken mid panel and replace the internal film and conductor with a home made one. This is just a first rough try: there is a loss of sensitivity and it  cannot play loud without distorsions. But what really surprised me, is that the low frequency response goes down to 50 Hz! . As above, this was measured in open air with the measurement mic placed against the panel.

Bruno

[ka7niq]

I WAS serious about the port tube for the panels!

You know, a LONG time ago, I played with the Strathern Ribbons.
So did Brian!

Anyway, before I was a VMPS customer, I was trying to build a ribbon speaker around the old Strathern Ribbon.

There was a guy, Julius from Audire, who would actually modify the Stratherns.


He increased the magnets spacing, and added a higher mass diapraghm.

You ran 6 of them full range in a 3 2 1 fashion from the bottom up.

So, you still had a vertical line

Julius made an eq box for them, and I built a system in a huge curved baffle, open backed.

The bass transients were fast, and they actually sounded good with subwoofers.

I should have kept them, but got on an anti EQ, first order square wave kick, and sold em


If you read the Eminent Technology information I posted, you can see he uses cloth to load them to the air.

The more mass to the diapraghm, the lower the resonance, and the lower the efficiency too.

One will note that the ribbon midranges are way more efficient then the RM 40 woofers.

Perhaps in the NEXT generation of RM 40's, Brian might ask Drago for lower resonance and efficiency ribbons just for the RM 40 ?

There is some extra un needed efficciency in the RM 40 application he might be able to trade off for a lower resonance ribbon ?

BTW, the ports for the ribbon section could just as easily go out the back of the RM 40 as the top.

A little foam in there could allow tuning of the ribbon arrays damping, to suit any amp .....

[inRMsway]

Before you guys go drilling holes through your cabinets, at least try sealing up the Neos properly and see if that does the trick! Remember if you do port the mids on your RM-40's you will be making a partial dipole and will have only certain frequencies exiting the port with who knows what effect on room influence and imaging. But like Chris said you could use foam and make more of a vari-vent (leaky box) effect, but that is really only for large air movement from woofers usually. The main thing is to make sure any box modes are quieted and your mids should sound pristine. Take baby steps before getting out the holesaw and PVC! :>)

[John Casler]

Before you guys go drilling holes through your cabinets, at least try sealing up the Neos properly and see if that does the trick! Remember if you do port the mids on your RM-40's you will be making a partial dipole and will have only certain frequencies exiting the port with who knows what effect on room influence and imaging. But like Chris said you could use foam and make more of a vari-vent (leaky box) effect, but that is really only for large air movement from woofers usually. The main thing is to make sure any box modes are quieted and your mids should sound pristine. Take baby steps before getting out the holesaw and PVC! :>)

The best way to check your Neopanel box for openings or leaks is to reduce your room lighting and push a light inside the RM40 behind the box.

You should be able to see if any light comes in.  If it does, then your sure that is an opening.

Follow B's instructions of hot glue or silicone.

I have also had some clients who did all the box corners with a large bead of caulk or mortite.

They then used the thinnest dmaping sheets from PtsExpss, to line the box walls, and then the Lamb's Wool.

[inRMsway]

Thanks John for your reply on this topic. My leaks were on the front where the 2 layers of faceboard are joined. When the cutouts for the woofers were made, it exposed that seam and after caulking it up I was all good as far as leaks from the woofer portion escaping through the mid box. I discovered it not with light as you suggest, but by pushing in a woofer and literally feeling air escape at the bottom (and top) edge of the mid box. In fact after after removing a Neo and the fiberglass, I used a lighter and could nearly blow it out by pushing in a woofer.
So, before anyone does re-weatherstrip their Neos for a good seal, they should make sure they have no leaks into that box from the woofers or the leaking air could damage them! Yikes!   

[ka7niq]

Hey, I got a "blilliant idea". LOL
When someone has new RM 40's, they COULD simply bore small holes in the Neo Panel boxes ?
This will allow the air from the powerful VMPS Woofers to "push around" the ribbons, breaking them in faster ?

THEN, when they are fully mellowed out, simply insert rubber plugs in the holes and be "good to go" ?

Actually, one could indeed bore holes in the NEO boxes, and Tune them with different density rubber plugs that would effect the vibration modes of the ribbon boxes!

Michael Green would LOVE it, LOL

Hey guys, JUST KIDDING of course, do NOT try this, it is a joke!

[ka7niq]

Thanks John for your reply on this topic. My leaks were on the front where the 2 layers of faceboard are joined. When the cutouts for the woofers were made, it exposed that seam and after caulking it up I was all good as far as leaks from the woofer portion escaping through the mid box. I discovered it not with light as you suggest, but by pushing in a woofer and literally feeling air escape at the bottom (and top) edge of the mid box. In fact after after removing a Neo and the fiberglass, I used a lighter and could nearly blow it out by pushing in a woofer.
So, before anyone does re-weatherstrip their Neos for a good seal, they should make sure they have no leaks into that box from the woofers or the leaking air could damage them! Yikes!   

Hey, see what YOU did Jay ?
Now, I am re hooking up the RM 40's as we speak.
You sent me into "audio relapse" again, and I was doing SOO Good too.

[John Casler]

Thanks John for your reply on this topic. My leaks were on the front where the 2 layers of faceboard are joined. When the cutouts for the woofers were made, it exposed that seam and after caulking it up I was all good as far as leaks from the woofer portion escaping through the mid box. I discovered it not with light as you suggest, but by pushing in a woofer and literally feeling air escape at the bottom (and top) edge of the mid box. In fact after after removing a Neo and the fiberglass, I used a lighter and could nearly blow it out by pushing in a woofer.
So, before anyone does re-weatherstrip their Neos for a good seal, they should make sure they have no leaks into that box from the woofers or the leaking air could damage them! Yikes!   

Hey, see what YOU did Jay ?
Now, I am re hooking up the RM 40's as we speak.
You sent me into "audio relapse" again, and I was doing SOO Good too.

Chris,

We need to get you to retire that pair to "Side Surround" duties.

I'm enticing another Floridian RM40 owner with "moving up to the RMv60" so if he does we need to get you his current RM40's (have most of the upgrades)

Then you could sell that older pair, or as I mentioned put them Horizontal and use them for side surrounds.

Crazy Idea, but so would be the Sonic Result.

[John Casler]

Or I guess you could take a Chainsaw, and a Drill Press, and whatever else and make a:

FrankenVMPS Monster.

Had a guy the other day, telling me that he was going to try taking his current VMPS RM40's and turn them upside down, and sit them on a pedestal to get the right height.

Then his PR would be facing the ceiling!!! (he has 10-12 foot ceilings)

[ka7niq]

It would make em easier to tune John ?
No more crawling on the floor fixing the putty ?

You can ALWAYS tell a VMPS owner at a CES show!
As soon as something don't sound right, they instinctively hit the floor, and crawl towards a speaker to adjust the putty.

[inRMsway]

"You can ALWAYS tell a VMPS owner at a CES show! As soon as something don't sound right, they instinctively hit the floor, and crawl towards a speaker to adjust the putty."

I always thought they were bowing down to worship them! You've shattered my illusions. :>)

[ka7niq]

You know, I am a long time VMPS customer, going way back to 1981.
I bought some Widerange Ribbons, great speakers too.
But I was not patient nor experienced enough to get em working, so Brian swapped me out some great big Supertowers.
So, playing with putty isn't exactly new to me, LOL

Once, at a CES show, I listened to the big Wilson WAMMS.
Had to wait almost an hour for a demo too.

When they played them, I heard boom in the bass, and started squirming.
My friend looked at me, and asked me if I was OK ?

Honestlly, I had to fight myself from attacking the WAMMS woofers with putty.
They were badly underdamped.

I was chewing gum, a big wad of it too.
It had long since lost it's flavor.

I swear, had it not been for the crowded room, the Wamm would have been blowing bubbles!