VMPS RM40 Custom Cabinets

Audio Architect · « **on:** 1 Mar 2003, 09:56 pm »

VMPS RM40 Custom Cabinets

For about 4 months I have been browsing the VMPS forums. What initially attracted my to these speakers were the following:
1. The extended range of the ribbon midrange used in some of the models in the product line, which eliminates crossovers in the critical range.
2. Ribbon drivers being used in some of the products.
3. Carbon fiber woofers are used in many of the products. I have often wondered why more speaker manufacturers do not use these.
4. The price to performance ratio of the products.
5. The fact that the products are offered as kits both with and without cabinets.

The last item above is what makes this post possible. After reading many of the posts on the forums I have noticed that some people have provided suggestions for revisions to selected VMPS speakers. Since every product represents a compromise between price, performance and perceived market preference there will always be room for improvement. Also because everyone has unique priorities and preferences a given product will never please everyone. With most audio products customization is not possible without buying the completed product first, which would probably make the customization uneconomical.

About two months ago I auditioned the RM40s at Cinema & Sound in Naperville, Illinois. At the time I was actually interested in the RM2 and since Scott the owner did not have the RM2s, I auditioned the RM40s with the assumption that they would be similar in sound quality.

Needless to say I was impressed with the RM40s. Scott has them in his home theater, which is probably not the ideal venue for 2 channel audio due to the abundance of sound absorbing material, which is appropriate for home theater or surround sound applications. The reason I mention this is that I am sure the RM40s would have sounded even better in a room optimized for stereo or in Scott’s room with a surround sound setup.

Since my audition of the RM40s I have decided that they rather than the RM2s may better serve me since whatever speaker I purchase may be my last. I would however prefer a more stable cabinet because I have multiple cats and I would also prefer that the mid range panels and the tweeter be mounted on narrower baffles.

All of the above has encouraged me to design a custom cabinet for the RM40 components, with the new tweeter from the RM/X. The design uses the same driver layout as the RMX including the adjustable tweeter. Brian has seen the design and seemed to liked it. I have attached JPEG files showing rendered views of the 3D model both with and without the grills. I plan on using a black finish but have rendered the models with lighter finishes because black does not render well.

I am an architect who has been interested in audio as a hobby and passion for many years. I actually designed and built a pair of speakers while I was in college. My reason for designing the custom enclosures for the RM40 components was initially only for my personal use, but since others have indicated an interest in revisions to the standard RM40 cabinet I decided to post my custom design to discover whether others may also be interested in it.

I plan on selling extremely detailed plans for the custom cabinet for about $150. If there is sufficient interest I may also sell the cabinets both completed both with and without finish and precut panels that will need assembly and finish. The standard RM40 can be purchased as a kit with cabinet for $4200 (including the new tweeter) and without cabinet for $3200, which makes the cost of the cabinet about $1000. Since the custom cabinet will be more difficult to construct, the cost of completed cabinets without finish is currently estimated to be about $1600. The cost of a completely finished cabinet has not yet been determined. I also believe that the same design with some modifications could be used for the RM2. If there is sufficient interest I may also pursue this.

Please e-mail me if you are interested. At this time I am not looking for commitments but only need to know if there is enough interest in the design to justify completion of the plans.

http://my.core.com/~cbugbee/Images/VMPS-RM40-Custom.JPG http://my.core.com/~cbugbee/Images/VMPS-RM40-3D-2a.JPG

Woodsea · « **Reply #1 on:** 1 Mar 2003, 10:16 pm »

Those look sweet, what is the estimated height. Nice job

Marbles · « **Reply #2 on:** 1 Mar 2003, 10:20 pm »

Those look incredible

I'm shocked at how great those look

Way to go!

nature boy · « **Reply #3 on:** 1 Mar 2003, 10:26 pm »

Truly an outstanding design. Congratulations.

NB

JohnR · « **Reply #4 on:** 1 Mar 2003, 10:33 pm »

Whoa, those are really cool!

Would the crossover need to be redesigned/tweaked?

Audio Architect · « **Reply #5 on:** 1 Mar 2003, 10:36 pm »

Quote from: Woodsea

Those look sweet, what is the estimated height. Nice job

The dimensions are as follows: 1'-8" wide x 2'-2" deep x 5'-0" high

Mathew_M · « **Reply #6 on:** 1 Mar 2003, 10:47 pm »

Agreed with all. Build it and they shall buy. I like the looks of it better than the current RM/X model. It looks like a piece of danish furniture or an exotic musical instrument. I think you and Brian need to work something out here! Hurry up before November 2003 so I can upgrade my 626's.

Audio Architect · « **Reply #7 on:** 2 Mar 2003, 12:33 am »

Quote from: JohnR

Whoa, those are really cool!

Would the crossover need to be redesigned/tweaked?

The lower woofer from the original speaker is the side speaker in the custom design and the upper woofer is the front firing woofer, which is mounted on a sloping baffle. The lower woofer should be substatially the same since its position has not changed significantly and because low base is not directional. The upper woofer which is now located lower on the cabinet will react with a room differently than before but this should be resolved be placement in the room and tweaking of the
PR mass.

JoshK · « **Reply #8 on:** 2 Mar 2003, 01:58 am »

I think those look fantastic! My wife said she didn't really like the design

but I do. I think they should add to the sonics by creating a narrower baffle and top mounted tweeter. I think this is a fantastic offering. I had thought about creating another enclosure for mine and testing one against the other but that will be many moons from now. My thoughts were basically leaving most else alone but have angled away baffles around the mids.

JoshK · « **Reply #9 on:** 2 Mar 2003, 02:11 am »

Seems like some crossover tweaking would be neccessary because of the baffle's reaction but I could be wrong. You could always send Brian an unfinished cabinet so he could mod the xo accordingly and save the results for use for anyone who wants to order a cabinet from you.

shokunin · « **Reply #10 on:** 4 Mar 2003, 02:44 am »

Looks nice!! However, from a DIY perspective, it looks like a gluing / clamping challenge. All those compound angles that need to glued and clamped and perfectly aligned or else you'll have a panel that's 1/8" off somewhere due to an incorrect angle or too much pressure on one clamp. I'm no architect, and I'm sure you have a better knowledge of structural advantage/disadvantages between a square box and an multi-angled box and potential decreases in resonance.

Any kind of veneering will be really tough, once again due to the angles involved in that kind of joinery. Definitely document your work and let us know how the project comes out. I'm sure there are number of people who want a mini-RM/x.

This would be a VERY complex DIY vs. a relatively simple box like the RM40's.

Audio Architect · « **Reply #11 on:** 4 Mar 2003, 03:38 am »

Quote from: shokunin

Looks nice!! However, from a DIY perspective, it looks like a gluing / clamping challenge. All those compound angles that need to glued and clamped and perfectly aligned or else you'll have a panel that's 1/8" off somewhere due to an incorrect angle or too much pressure on one clamp. I'm no architect, and I'm sure you have a better knowledge of structural advantage/disadvantages between a square box and an multi-angled box and potential decreases in resonance.

Any kind of veneering will be really tough, once again due to the angles involved in that kind of joinery. Definitely document your work and let us know how the project comes out. I'm sure there are number of people who want a mini-RM/x.

This would be a VERY complex DIY vs. a relatively simple box like the RM40's.

You are absolutely correct it would be a difficult project, but I know I can do it and I am not a professional woodworker, so someone who, like me does woodworking as a hobby could accomplish it also. I am also contemplating selling a version with precut panels which would simplify it somewhat. You would be surprised how talented some do it your selfers are.

I originally conceived of the design as either satin or piano black, even though the rendering shows a wood grain. I do not plan on offering a wood veneered cabinet, but I may offer the same cabinet, unfinished, without radiused edges to make venering possible. The clamping alignment issue will not be a problem due to the type of joint used.

Marbles · « **Reply #12 on:** 4 Mar 2003, 03:40 am »

Audio Architect, where are you located? I suspect it's not far from Chicago.

drphoto · « **Reply #13 on:** 5 Mar 2003, 10:38 pm »

Seems like you might be closer in concept to the RMX than the 40, which would make this an amazing bargain. Go for it.

James Romeyn · « **Reply #14 on:** 6 Mar 2003, 03:44 am »

To say the shape is beautiful & stunning, & a heavenly match with the Ampzillas is an understatement.

Problems: a reliable source with about 25 years experience producing specialty speaker cabinets predicts it won't happen. Packing materials will cost about $300pr in small quantities. Finishing the $1600pr cabinets (estimated unfinished) with paint or veneer to a professional level will bring the cost over the RMX. Takes up a lot of floor space. Other than that, it's a great dream. If the XO needs tweeking you're on your own (do you think Brian is twidling his thumbs with no work to do, come on, wake up...) Resale value about...0. Manufacturing problems about...endless. Shipping them at retail prices will be about...a lot more than RM40s. I have seen the Xs being constructed. There would be far fewer construction problems building up the baffle & making the X swooshes, as long as you can get the CNC router work performed.

If you do it replace the 10MW with the 12MW. Just make sure there is enough cabinet volume.

Jim Romeyn, 707 765 1992, VMPS sales/service

Mathew_M · « **Reply #15 on:** 6 Mar 2003, 05:21 am »

Don't be so testy Jim (you haven't lost any sales YET). Norh builds some nice, exotically shaped cabinets very in-expensively that are similar to the above VMPS concept.
Some examples:
http://www.norh.com/products/prism/gal.html

I know you'll point out that the speakers are built over in Thailand on the cheap. No offense to VMPS but it's cabinet design at least on the lower end of the spectrum leaves a helluva lot to be desired compared to what Norh offers. If Mr. Audio Architect can build a pair of these regardless of being able to sell to the public at a reasonable price I will be extremely impressed and envious as I would imagine you and Big B will be too.

Audio Architect · « **Reply #16 on:** 6 Mar 2003, 12:07 pm »

Quote from: RibbonSpeakers.net

To say the shape is beautiful & stunning, & a heavenly match with the Ampzillas is an understatement.

Problems: a reliable source with about 25 years experience producing specialty speaker cabinets predicts it won't happen. Packing materials will cost about $300pr in small quantities. Finishing the $1600pr cabinets (estimated unfinished) with paint or veneer to a professional level will bring the cost over the RMX. Takes up a lot of floor space. Other than that, it's a great dream. If the XO needs tweeking you're on your own (do you think Brian is twidling his thumbs with no work to do, come on, wake up...) Resale value about...0. Manufacturing problems about...endless. Shipping them at retail prices will be about...a lot more than RM40s. I have seen the Xs being constructed. There would be far fewer construction problems building up the baffle & making the X swooshes, as long as you can get the CNC router work performed.

If you do it replace the 10MW with the 12MW. Just make sure there is enough cabinet volume.

Jim Romeyn, 707 765 1992, VMPS sales/service

When I posted my design I realized that it would not be for everyone, which is good because I am not in a position to make a lot of these. Originally I only wanted to offer plans for ambitious woodworkers and do it your selfers like myself. As I have stated before the intent was only to offer a sustitute cabinet for the RM40 components with no changes to the components themselves. Your comments about shipping are probably correct, but may be worth the expense for the people who are interested.
Also I may offer a panelized version which would be easer to construct than using plans, and would be easier to ship.

I fully realize that if Brian used a more complex cabinet for the RM40 the added cost would probably decrease his sales volume of that product and would also decrease its price/performance ratio and since that is one of the major things that differentiates VMPS from some of the other high end companies I can certainly understand it. The fact that many high end manufacturers look at wealthy people, as suckers who will pay almost anything if they want something is what has hurt this industry, but that is another issue.

Your suggestion about replacement of the lower woofer and I aasume the PR would probably produce lower base than the RM40 but may cause the cabinet to get too large in the lower portion and would also require a revised crossover, which I am not qualified for.

Marbles · « **Reply #17 on:** 6 Mar 2003, 04:28 pm »

Audio Architect,

I think the renderings of the cabinets look great, and would love to see and listen to a pair when finished. I think lots of people who are within a reasonable drive from your location would too.

If I decided to buy them it would be with the intention of buying a completed speaker. I would be able to pick them up so shipping would not be a problem.

I'm in no hurry, and don't know if the speakers could be finished in time to show them at the Midwest audiofest April 11th and 12th, but that would be a great forum to show them off.

doug s. · « **Reply #18 on:** 6 Mar 2003, 07:33 pm »

personally, i have wanted to see an rm-40 w/a cabinet much the same as the present cabinet, w/exception of the front baffle radiusing back from the planers, on a ~4" radius, into the side panels. then, yust taper the cabinets in towards the radius'd portion at the upper & lower woofers. perhaps the total cabinet would have to be an inch or so deeper, to compensate for the reduced internal wolume due to the radius. i don't see this being much more expensive to make than the standard rm40 cabinet, especially for a diy-er... and, if brian would sell a pair of add'l tweets, ya could stick 'em in a box, control 'em w/a hi-pass wolume pot, set 'em on top of the rm40's, & have no hi-frequency drop-off, when ya stand up!

i would actually *prefer* this to a pair of rm/x. some day...

doug s.

nathanm · « **Reply #19 on:** 6 Mar 2003, 08:01 pm »

A thought I had for a DIY kludge when I saw the RMXs' was to mount the ribbon drivers on a very narrow box just wide enough to get by and then use two pieces of PVC cut length wise as the curve for the baffles on each side and the top and bottom. Maybe covering them with some absorbent fabric would be additionally helpful? The gloss black does look wicked though. Anyway, something like this broken image which I've since deleted from my web server:

Perhaps the gap between the pipe and the cabinet could be filled with sand for extra damping goodness?

It wouldn't be easy to make obviously, but perhaps an alternative to the ultracore CNC approach which is out of most folks' reach. Hmmm. Not sure how easy it would be to rip a length of PVC pipe into quarters.