Just got my RM30m order in the queue....

OTL · « **on:** 1 Apr 2006, 11:11 pm »

After driving Scott Mayo crazy and raking in all my shekels, a new pair of "full boat" RM30's in MLS piano black are on their way to my home.

These are replacements for a pair of 13 y/o Apogee Centaurus that recently had a ribbon go south. I'll certainly be looking for that "presence" and "immediacy" that only a good ribbon can provide. Sarah Vaughan, Miles and Jimmy Witherspoon are missed and need to make a reappearance in my living room.

Hey Brian! Take your time, burn 'em in well and pack with love. I'm counting on you to put Sarah and the gang back into my living room.

Waiting for the delivery that reinstates my world...

Mike B.

Brian Cheney · « **Reply #1 on:** 1 Apr 2006, 11:24 pm »

Container arrives Monday, expect it out of customs and delivered to us by Friday. After that, 10 days delivery.

john1970 · « **Reply #2 on:** 1 Apr 2006, 11:36 pm »

Mike,

I hope that you enjoy your new speakers. I enjoy the RM40s very much. Please keep me posted if you have any questions.

Cheers,

John

John Casler · « **Reply #3 on:** 2 Apr 2006, 05:46 am »

Quote from: Brian Cheney

Container arrives Monday, expect it out of customs and delivered to us by Friday. After that, 10 days delivery.

Hope we have another container on the way since we have quite a few of these spoken for.

The Award for the Best Sounding cabinet goes to the Diamond Finish Piano Black. In addition to the new cabinets being more sturdy, that extra "hard coat" layer of the Piano Black makes this (potentially) the slightly more inert, and best sounding cabinet.

The Best Looking cabinet is gonna be a toss up. The Ebony, the Rosewood, the Piano Black...All are stunning to look at.

John Casler · « **Reply #4 on:** 2 Apr 2006, 05:49 am »

Quote from: john1970

Mike,

I hope that you enjoy your new speakers. I enjoy the RM40s very much. Please keep me posted if you have any questions.

Cheers,

John

Yes, Mike..Welcome to the VMPS Circle.

I think you'll find them a very special speaker, and with an even more special, Signature Sound.

timr · « **Reply #5 on:** 13 May 2006, 06:31 pm »

I too have been (patiently) bothering Scott and Big B. with RM30 worries conjured up with ample time (no spikes?) and ETA's. I was glad to find the cabinet pics from China so I could show something tangible to my growingly skeptical wife.

The moment of truth is upon us. It would be interesting and hopefully helpful to compare notes as we set these up.

I'm replacing Snell CVs in a music only system. Powered by a Classe' Audio Fifteen (175W @ 8, 350W @ 4). I'll hazard a guess, from your handle, that's quite different than your rig. However, I'm fantasizing that my next upgrade may well be to Transcendent. That's down the road. VMPS, as fairly high efficiency speakers, also have the reputation for responding well to power so I'm planning on good results. I can plan on anything I want can't I? I also plan to let these run in for a while before fine tuning anything and will contact Scott then.

If I do change anything in the near future it's likely to be speaker cable. Currently bi-wired with Tara-labs space+time and Kimber 8TC.

I first heard VMPS by chance while not shopping for speakers ten+ years ago. Thanks to Clarke Johnsen, (sorry if I spelled that wrong) still the best music system I've ever heard. FF1's powered by big VTL monoblocks of some model. OH, so that's what a sound stage and imaging are.

Fun, Fun, finally on the horizon.

Brian Cheney · « **Reply #6 on:** 13 May 2006, 06:46 pm »

Yes, the first of the passively EQ'ed RM 30 CDWG are now landing softly at locations around the country. Excellent customer response so far.

I have to admit that the passive EQ xover is touchy as hell and requires me to spend about an hour with each pair, dewinding coils one turn at a time and adding cap values in 0.01uF increments (about 1/100% of total value) until right. It absolutely amazes me how sensitive to small crossover changes a constant directivity speaker can be.

So, each pair is custom matched to each other, and compensated for every driver variable. PR tuning is done during the tweak session so it is unlikely the owner will have to adjust either control settings or PR putty mass. Of course, if you want to experiment with such you're welcome to do so.

Tim's SO should be very pleased with the look of the mls rosewood RM30's. They are stunning.

OTL · « **Reply #7 on:** 13 May 2006, 10:30 pm »

Quote from: Brian Cheney

Yes, the first of the passively EQ'ed RM 30 CDWG are now landing softly at locations around the country.

As I type, my SO is digging out the lawn chairs, the cooler and the citronella candles. We're setting up a constant vigil in the backyard, looking skyward until we see our long awaited RM30's descending from the sky beneath a golden parachute and "landing softly" close to our house.

Our home has been without tunes for so long this is no longer about want, it's about NEED! We've been listening to cable music channels for two months and REALLY need a vinyl fix.

Thanks for all the extra work B. Can't wait to listen to your work.

Cheers!

Mike B.

jermmd · « **Reply #8 on:** 14 May 2006, 02:58 am »

Please post pictures all you new RM30 owners. I look forward to seeing the MLS cabinets set up in real listening rooms.

meilankev · « **Reply #9 on:** 14 May 2006, 12:21 pm »

Mike,

Congratulations on your purchase. I hope these VMPS speakers bring you as much enjoyment as mine have brought to me.

And welcome to AudioCircle!!!

Kevin

ka7niq · « **Reply #10 on:** 14 May 2006, 05:01 pm »

Welcome Mike!

In my opinion, you are in for a real treat!
you will find your RM 30's to be even more revealing then the old Apogees Centaurus, and much more reliable too!
I just finally got RM 40's, though my friends Kevin and Mike here in Tampa have owned them for years.
I can feel your excitement!

In my opinion, one of the beat parts of being a VMPS owner is all the support and comaradire you will find on this forum.
You ask a question, and you will get answered quick.

Welcome Aboard!
Chris

diy_freak · « **Reply #11 on:** 15 May 2006, 01:11 am »

Quote from: Brian Cheney

I have to admit that the passive EQ xover is touchy as hell and requires me to spend about an hour with each pair, dewinding coils one turn at a time and adding cap values in 0.01uF increments (about 1/100% of total value) until right.

Some crossovers react more violently to components tolerances than others, but 0.01uF being audible in a speaker filter is strechting it beyond belief. Why would a design being CD influence this behaviour?

Brian Cheney · « **Reply #12 on:** 15 May 2006, 01:58 am »

Why not build a Constant Directivity speaker with first order networks and find out for yourself?

diy_freak · « **Reply #13 on:** 15 May 2006, 12:57 pm »

Quote from: Brian Cheney

Why not build a Constant Directivity speaker with first order networks and find out for yourself?

I assume there is an explenation for my direct question. I'm quite happy with learning from theoretical principles as I'm not going to be around long enough to learn everything by experience... as are we all.

Brian Cheney · « **Reply #14 on:** 15 May 2006, 03:19 pm »

There certainly is an explanation, but my patent attorney hates it when I reveal secrets.

As another naysayer so memorably put it, I practice "needless precision"!

diy_freak · « **Reply #15 on:** 16 May 2006, 01:58 am »

Quote from: Brian Cheney

As another naysayer so memorably put it, I practice "needless precision"!

I'm not a naysayer. In fact, I'd have to agree with this person on the subject of your crossover tweaking 'precision'.

Quote from: Brian Cheney

There certainly is an explanation, but my patent attorney hates it when I reveal secrets.

"CD" isn't patented by you and neither is "first order" for that matter. My questions was: "Why would a design being CD influence this behaviour?", with the behaviour being extreme reactions to components tolerances.

Quote from: Brian Cheney

Why not build a Constant Directivity speaker with first order networks and find out for yourself?

As far as I know, CD has no influence on the deviations due to component tolerance. And higher order filters react more in general to components tolerances than low order filters.

If you can't provide an explenation for the behaviour you describe, that's cool to. But then it would be your opinion or 'gut feeling' and not a fact of loudspeaker design principles as you seem to present it.

Let's take a look at the influence of a 2% tolerance (which is considered a tight tolerance) on a 10uF first order highpass on a tweeter, in steps of 0.5%:

Not much to see here. Zooming in at around 1K, at about 15dB below the tweeter's passband spl, where the minute differences start to show:

So it seems that 0.5% difference in the component value leads to a deviation of about 0.04dB. You mention component value differences of 1/100%, which is 50 times less than the steps in the graphs above. As I said, beyond belief. Apart from that, there are many parts in a loudspeaker that influence the SPL much more than a filter component with such a tight tolerance.

I would advise you to do some measurements of the results you get after tweaking the crossover for hours. Or buy a piece of software that can do tolerance analysis. Lspcad 6 Pro is such a program, which I highly recommend. I assume the Standard version has it as well in case you want to spend less money.

Brian Cheney · « **Reply #16 on:** 16 May 2006, 03:02 am »

Yes, you're absolutely right, component tolerances of, say, 1% or better have no measurable influence on frequency response.

That's textbook design, and you're welcome to it. I don't think anything I would say would sway your opinions, and I don't care to spend the time to refute them by technical argument. If you're interested in my patent, it will be laid open for public inspection in about a year, at which time you are welcome to email me.

Please do not waste any more time posting here.

Dr. Krull · « **Reply #17 on:** 16 May 2006, 03:22 am »

Quote from: Brian Cheney

Yes, you're absolutely right, component tolerances of, say, 1% or better have no measurable influence on frequency response.

(Unless one builds speakers in a different solar system it also holds true for phase.)

-Krull

Brian Cheney · « **Reply #18 on:** 16 May 2006, 04:13 am »

I would have to disagree with you there.

Dr. Krull · « **Reply #19 on:** 16 May 2006, 04:30 am »

Quote from: Brian Cheney

I would have to disagree with you there.

John Murphy sums it up nicely.

The topic of "delay distortion" or "phase distortion" in audio systems is certainly not trivial and has been a source of considerable mystery in the audio enthusiasts (and engineers) over the years. I think we can achieve a good understanding of the topic only by starting with traditional electrical engineering circuit analysis and then studying of the best technical papers on the subject...such as the Leach paper cited above.

Mystery is the key word.

Here's the Leach paper that he referenced if you're not familiar with it:

W. M. Leach, Jr., "The Differential Time-Delay Distortion and Differential Phase-Shift Distortion as Measures of Phase Linearity', Journal of the Audio Engineering Society, vol. 37, no. 9, pp. 709-715, Sept. 1989

Some day I'd like to read your published works which contradict those of Leach, Linkwitz, Toole and the likes. Guess I'll have to wait a year.

-Krull