[opnly bafld]

In any event, I already answered that the pair for sale (now SOLD) was NOT the pair from the "initial" review, but from the "second" review.

http://www.audiocircle.com/index.php?topic=14949.0

[opnly bafld]

And I bought those RM-40s from Opnly a few years ago. If anyone can tell me what changes are needed to the crossover to move the mid panel cross over point up to 260 Hz I would appreciate it.

Also I am looking to replace the twin spiral tweeters with AC G3 ribbons I picked up a year or so ago, I'd love to have that help on this crossover change also.

Be sure the 280hz x-o info comes from a pair of speakers without the midwoofer upgrade (like the pair sold here).

Might want to start a new thread on x-o help for more exposure.

[Brax]

I completed the mid woofer upgrade, adding the new driver and changing the xo. I received the parts and instructions from Brian, so these 40's are up to date in that aspect.

[opnly bafld]

I completed the mid woofer upgrade, adding the new driver and changing the xo. I received the parts and instructions from Brian, so these 40's are up to date in that aspect.

Is it possible that you raised the x-o when you did the mw upgrade?
It seems odd that Brian would have you change only part of the crossover (two birds ~ one stone).

[PMAT]

I'll explain the apparent contradiction.  The old BG single ended alnico magnet planar midrange crossed @ 166 Hz.  The 5' long BG panel crossed about 115 Hz.  The push pull neo planar that replaced the BG crossed at 260 and this pole never changed.  I owned speakers with every one of these drivers.  Multiples in fact. 

The neo panel will quickly self immolate crossed lower than 260 Hz.  Brian stretched it as far as it could be stretched from the start.   

The difference in low end cutoff is one striking advantage the older panel had over the newer panel.  I know this from personal experience, testing them with brian with his test mic and computer readouts and ABd them several times.  None of this is 2nd hand passed along info as per the authors of every link posted here, which sum total value to me is nothing re. the spec in question.

None of these authors tested anything. 

Readers are welcome to believe any mythology you please. 

PS: I'm not saying this happened in this instance.  But it is highly possible Brian mis-quoted the spec too in writing and this myth became "fact" somehow, passed around amongst the authors.  A mid planar panel crossed @ 166 looks better than crossed at 260.  Brian once told me his sensitivity formula is to add 3 dB overall for the passive, which is a bit of a stretch.  Yes, the passive increases sensitivity, but not to overall bass output, only in the lowest half octave.  It's just a mass of air like that in a port.  Brian's sensitivity specs back in the days were 4-6 dB over stated.  Some other makers did the same, so I'm not singling him out. 

I remember the original SOTA speaker Brian was designing.  The cabinet arrived at .33 cubic feet while Brian specified almost 1 cf.  Stuff happens.  In that case it was someone else's fault I won't name now.     

Brian and I joked for decades about one demo he did when I was there with a mid range missing from one old Mini Tower (behind a grill)...Brian loved his sound room being super dark.  We laughed about that incident for many years.     

immolate........ a truly great word. Anyhoo, Yes I found many quotes on VMPS x-over poles that were probably wrong. There is also the probability that some kits were built wrong and that Brian threw some oddball builds out there over the years. I have a pair of RM-1s from the same production (serial #s) that had one of each x-over! I was having a bass driver repaired at the "factory" and Brian peered in the speaker cabinet and gave it the oddest look. A look you wouldn't forget. When I got home I popped off the driver and the guts were different. Later when I had the bass system modified by a local speaker builder he measured them and replaced some parts to make the poles the same. Brian never said a word. I bought them used so who the hell really knows.

[James Romeyn]

immolate........ a truly great word. Anyhoo, Yes I found many quotes on VMPS x-over poles that were probably wrong. There is also the probability that some kits were built wrong and that Brian threw some oddball builds out there over the years. I have a pair of RM-1s from the same production (serial #s) that had one of each x-over! I was having a bass driver repaired at the "factory" and Brian peered in the speaker cabinet and gave it the oddest look. A look you wouldn't forget. When I got home I popped off the driver and the guts were different. Later when I had the bass system modified by a local speaker builder he measured them and replaced some parts to make the poles the same. Brian never said a word. I bought them used so who the hell really knows.

I have personal experience seeing the above described look on Brian's face dozens of times.     

I guarantee readers: for every single VMPS speaker employing neo push pull planar mid panel, Brian's intended HP crossover pole was approximately 260 Hz.  Any statement contrary is incorrect.  But........... 

Several fine points muddy the water:
I have no idea and neither does anyone lacking test equipment whether the above pole is electrical or acoustic.  If Brian was here I further guarantee every single reader that minus water boarding this is the kind of detail Brian kept confidential.  Why I have no idea.  No one reading this had closer relationship to Brian in designing speakers than did I.  I could ask him three different ways.  His reply would range from nothing to something so tangential it would be silly.  Same as his reply when I asked his reason for choosing direction of nut/screw head in the planar terminal repair.  I asked him several times point blank.  Never got a straight reply.  Brian was enigmatic.   

Brian described this crossover point as either "dual pole first order" or "second order" depending on the weather.  Persons reading this might or might not understand that the difference between the two could be either a very fine point or not.  Related questions are: "How closely staggered are the two poles?  .2 octave?  1.0 octave?  The difference might allow Brian to be accurate in both descriptions.  A dual pole 1st order slope indeed is a 2nd order slope at the lower pole.  Again, the earlier point applies: Are we talking acoustic or electric?  An electrical 2nd order slope is almost certainly acoustic at least 3rd order if not 4th order at some particular frequency.  1st order electrical slopes almost always equal 2nd or 3rd order acoustic at some frequency. 

No neo push pull planar mid panel employed primary 166 Hz pole, which pole not coincidentally was employed in the prior alnico single ended planar mid panel, thus being one of the reasons possibly explaining the myth. 

Readers need to simply, IMO, stop referring to something that never existed, being a 166 Hz primary xo pole for the neo push pull planar mid panel.   

On a related item: persons employing Brian's recommended active digital crossover (John Casler, Dave Houseau, etc.) can indeed tell us exactly what did Brian recommend for the planar HP pole(s)?  Again, these electrical poles do not translate directly to acoustic.  The planar's own electro-acoustic roll off adds to the electrical slopes to equal X acoustic slope.

My guess is Brian described two 1st order slopes, the higher one at middle C (261 Hz) then another 1st order slope (2nd order sum total electric) around 150 Hz.     

[James Romeyn]

Another small example where VMPS intent and reality refuse to align.  Re. three per channel 6.5" mid bass employed in the generally stellar RM-V60 "Wing."  This is the first ever VMPS model designed specifically to require separate bass augmentation, buyer's choice (buyer could employ one of several VMPS choices or some other make). 

In the bass range the worst offending mode is usually the dreaded ceiling/floor bounce, the most common mode for rooms with flat ceiling.  The shortest legal ceiling is about 7.6' with modal frequency of about 74 Hz.  Brian's original intent was for the Wing mid bass to roll off above this frequency, allowing users to cross subs below the ceiling/floor mode, thus eliminating it. 

But Wing owners well know the 6.5" mid bass rolls out much lower, around 55 Hz, the modal point for 10.3' ceiling.  If I owned Wings (I suggested this several times to Brian) I would invert one mid bass in each channel: either the same diagonal firing (L or R does not matter) on both channels...OR forward firing on one channel (either channel) and diagonal firing (L or R does not matter) of opposite channel.  This would only smooth overall bass response and increase time accuracy in the mid bass range. 

It's critical to invert the same diagonal mid bass in both channels (both diagonal L or both diagonal R) or forward firing on one channel and either diagonal on remaining channel.  Do not invert both forward firing and do not invert mirror image mid bass on both channels.  I'd be shocked if this did not audibly increase performance.

Potential decreased output between 200 Hz-300 Hz is offset by smoother response and increased time accuracy from 45-200 Hz (Schroeder frequency).       

[opnly bafld]

     
1) I guarantee readers: for every single VMPS speaker employing neo push pull planar mid panel, Brian's intended HP crossover pole was approximately 260 Hz.  Any statement contrary is incorrect.  But........... 

2) Several fine points muddy the water:
   

Your second point makes your first point invalid.
I will not argue with you, but I believe you are wrong.

Brian giving incorrect information to reviewers (and on the webpage) would serve no purpose, but yet it is (was) documented in several places that the first version with the dual spiral tweeters crossed at 166 hz and 10k hz and the improved version with FST crossed in the high 200s and low 6k range.

Your "guarantee" is worthless IMO.

[mjosef]

 

I wonder if 'He' would stand behind that "guarantee" ...
 I have a pair of RM1's with carbon fiber woofers, that came with 166Hz crossover to the neo-panels. It been years now since I went active between the bass and midrange, first at 320Hz and now currently at 250Hz.
I also have a 626R pair with the same stated 166Hz crossover, but this one I have not measured.

[Stimpy]

I wouldn't be so quick to discount James' viewpoint, and experience.  James did after all work for Brian; at the factory.  I doubt that many here can claim that fact.  So, maybe, a little respect is in order, IMHO.

Personally, I would have loved being in James' position at VMPS!  While I'm sure that Brian could be enigmatic, and not always divulge his secrets in total, the experience, I feel, just the same, would have been priceless!

Also, it shouldn't be too difficult to measure a few different crossovers.  Get some actual inductance and capacitance readings.  One could then input the values into one of the many online sites, that have crossover calculators.  That should provide a rough idea of crossover frequency.  Plus, maybe show if Brian tweaked as he went, and crossover points shifted up or down, over the years...?

[PMAT]

It looks like this is going to go in circles. James, thanks for the info and insight. Many of us will need you in the future. Brian was a complex cat. He seemed to like being enigmatic. I got the feeling that he got a kick out of it. He could also dish out supreme bullshit. Too bad he is gone.

[duck851]

...

Also, it shouldn't be too difficult to measure a few different crossovers.  Get some actual inductance and capacitance readings.  One could then input the values into one of the many online sites, that have crossover calculators.  That should provide a rough idea of crossover frequency.  Plus, maybe show if Brian tweaked as he went, and crossover points shifted up or down, over the years...?

Can anyone explain how to measure capacitors and coils?

[gab]

Can anyone explain how to measure capacitors and coils?

LCR meter

MCM Electronics has some inexpensive ones: http://www.mcmelectronics.com/browse/Capacitance-LCR-Meters/0000001242

I have a Tenma and it works well

[James Romeyn]

Your second point makes your first point invalid.
I will not argue with you, but I believe you are wrong.

Brian giving incorrect information to reviewers (and on the webpage) would serve no purpose, but yet it is (was) documented in several places that the first version with the dual spiral tweeters crossed at 166 hz and 10k hz and the improved version with FST crossed in the high 200s and low 6k range.

Your "guarantee" is worthless IMO.

If by "documented" you mean by reviewers who never tested anything.  That's the sum total "documentation" so far. 

Let's see: the alnico mid did cross at 166 Hz.  If the neo mid crossed at the same frequency (it did not) then the low end response must be similar or Brian crossed the alnico mid much higher than he could have.  Proof that he crossed as low as possible is the fact that the 5' alnico mid crossed about 115 Hz.  I owned the FF2 SRE employing that mid too. 

Anyone positing similar low end response between those two mids never heard them outside a speaker.  That would be everyone disagreeing with me on this point.  I heard them, tested them with Brian, and installed them in his speakers, and owned the mids separately outside of speakers.  The alnico goes almost one octave lower.  Brian and I talked about this point.  In this area the BG alnico is better than the neo.   

Now explain why/how Brian employed the same crossover on two mids, one which extends almost one octave lower than the other?     

[James Romeyn]

Your second point makes your first point invalid.
I will not argue with you, but I believe you are wrong.

Brian giving incorrect information to reviewers (and on the webpage) would serve no purpose, but yet it is (was) documented in several places that the first version with the dual spiral tweeters crossed at 166 hz and 10k hz and the improved version with FST crossed in the high 200s and low 6k range.

Your "guarantee" is worthless IMO.

Guarantee was used euphemistically.  I'm not charging for this advice. 

You quote, but leave off the part of the quote clarifying the introduction.  You edit my post, then use this edited version to support your statement.  If that's not intentionally dishonest, I don't know what is.

Let me be more clear to help you avoid obfuscating this time:

For all VMPS employing 8" planar mid, the first/highest pole in the high pass network:
BG alnico magnet single ended: 166 Hz
Neo push pull: 260 Hz

The figures posted by the reviewers are incorrect.  They never tested anything. 

Brian had all kinds of strange statements stretching the truth: such as adding 3dB sensitivity for his passive radiator, pure silliness.  He called 4-way speakers "five way" for the passive radiator.  The other post selling Mini Towers has this in Brian's add copy.  Go there now and read it yourself.  So now, per Brian's text, reflex loading (a PR is just another reflex loaded woofer) makes a 4-way a 5-way.  I post this only to prove that Brian stretched the limits of credulity as is common practice. 

Switching from the alnico to the neo had one down side and that was moving the crossover up a half octave.  Brian certainly would have been happy to hide this fact on the first neo equipped speakers offered to reviewers.  It's funny reading posts from persons making statements about Brian contradicting me who knew him intimately for about 30+ years and worked for him and at CES.       

IMO, when the neo first appeared Brian barely had a web page and it certainly was often outdated.  Remember how it was poisoned with a virus for several months before it went dead?  Posting that the web page said so to support your position, compared to someone who worked there and assembled speakers with him?  You seem strangely deranged, to be frank.

Did Brian ever converse with you personally about crossover poles? 

Did you believe Sony's "Perfect Sound Forever?"

I'm getting pretty fed up with this stupidity in case reader's did not notice. 

My vmps contributions since the 80s:
Internal wiring change, silver plated teflon coating, different gauges per driver (mid treble only)
RM50 first (and unfortunately last) vmps side firing passive
RM50 first ever VMPS bipole
RM30 series II...I hammered Brian relentlessly the cabinet was too small
Scan Speak domes

Others I can't recall now.

Anyone contradicting me what Brian might do or not do that might improve his business position certainly had considerably less business and personal time with him than did I, including Casler.  Yes, I decreased my participation when Casler started his involvement.  Casler lived several hundred miles south of Brian.  I lived 30 miles from Brian and worked there.  Casler appeared after CES setup and disappeared prior to tear down every single year. 

My understanding is Casler's sum total direct first hand knowledge of vmps internal design was minimal to none.  Everything he "knew" is what Brian told him.   I worked with Brian directly with his test gear, especially when the neo panels appeared. 

Brian stretched the truth as is often the case in this business.  I'd rather not state specific examples that were glaring examples but will if pushed to make my case that it would not consistent with Brian's practice to "misquote" something like the fact that the outgoing BG alnico panel had one advantage over the new neo panel, being lower cutoff, which difference mandated higher neo pole.   
   

[James Romeyn]

Seems to be a bit of confusion here.  Maybe I can sort it out.

First the initial review written by Marty is for the "FIRST" pair of RM40's Brian sent him which had dual Spiral Tweeters and the 166hz XO.

The second pair which we just sold, had the FST tweeter, and was built "after" Brian had decided to raise the XO to between 220Hz and 280Hz (he was experimenting a bit with different models depending on the woofer).

The other two RM40 reviews referenced above that mention the 166hz XO point clearly also state that the pairs had the twin Spiral Tweeters and not the FST.

I am not sure about the RM30 review (Roger might remember), but it was the new RM30 that caused Brian to raise the XO point, so either Rogers pair was so early that B hadn't raised it yet, or he was given misinformation (or used "old" information) in the review.

So to recap:  Early VMPS panel speakers (after I came on board) had XO's as low as 155hz - 166hz and then raised in all models to 220-260hz.

The primary reason for the change upward, was to allow the dynamic cone woofers to increase the impact and air movement to sounds like snare strikes, rim-shots, and other percussive dynamics which needed "more air" to move.  It was also one of the reasons Brian designed the RM30 with the intention of having twin 6.5" megawoofers to create that impact.  And soon after he also started using improved MegaWooofers, finally ending up with the latest MegaWoofer with 40oz magnet.

In any event, I already answered that the pair for sale (now SOLD) was NOT the pair from the "initial" review, but from the "second" review.

Openly Baffled (on AC) purchased the first pair from Marty with the twin Spirals.

John,
Just for other reader's knowledge, not to hammer you at all.

You know not what you speak re. the neo panel crossover.  I have read you post things about VMPS maybe 100x that were half truths and complete fabrications.  I'm not blaming you at all, seriously.  I can only presume and am happy to presume in every case they were honest errors and never meant to trick or harm anyone.   

I'm simply posting this to let readers know your information above is false concerning several items, specifically one of them Brian changing the neo crossover from 166 to 260 Hz. 

Please state your exact source.  If it was Brian, say so.  If anyone here and now claims there ever was a 166 first/highest pole for the neo panel, this is false.  No such pole ever existed.  Quoting what a review believes in pretty stupid on this particular subject when they did not test the specs.   

That was the pole for the old alnico bg panel.   

[John Casler]

John,
Just for other reader's knowledge, not to hammer you at all.

You know not what you speak re. the neo panel crossover.  I have read you post things about VMPS maybe 100x that were half truths and complete fabrications.  I'm not blaming you at all, seriously.  I can only presume and am happy to presume in every case they were honest errors and never meant to trick or harm anyone.   

I'm simply posting this to let readers know your information above is false concerning several items, specifically one of them Brian changing the neo crossover from 166 to 260 Hz. 

Please state your exact source.  If it was Brian, say so.  If anyone here and now claims there ever was a 166 first/highest pole for the neo panel, this is false.  No such pole ever existed.  Quoting what a review believes in pretty stupid on this particular subject when they did not test the specs.   

That was the pole for the old alnico bg panel.   

Hi Jim,

You have no hammer that I know of, and I prefer to not waste time on this.

The facts I posted are accurate as I know them.  They are directly from the original VMPS Website (which is probably where some of the reviewers go their info) which CLEARLY stated the XO point at 166Hz, and from Brian himself.

He and I had weeks if not months of discussion on his plans to raise the crossover point from 166hz to 220-280hz depending on the model and why he felt this was needed.  I agreed with him that it was needed and it was raised.  I have already explained the reason he gave for doing so.

So maybe there is an alternate reality, but I am not interested in exploring it.

These points are probably discussed in the old posts, because I no doubt announced them as they happened.

The few who have also posted here with those same numbers have done so because that is what Brian and the Website stated.

But again, it is of little consequence and that is as much energy as I will waste on it.

[Brax]

Jim,

Now I am confused, you have several posts dated back in August of ’03 talking about the 166hz crossover. Here is a quote from one of those posts,
“The tube amp drives a passive high-pass crossover, which filters the bass frequencies, then that filtered signal feeds only the upper range drivers.  In the case of VMPS, that would be the ribbon mids & tweeters from 166Hz up.”
This is after the introduction of the RM40 and during the roll out of the RMX. I guess I assumed the RM40 always came with the Neo mids and not the BG drivers.
All I can say is that the bickering on this board is very disheartening and is really changing my opinion of what type of company VMPS was and how its products were presented.
As I mentioned before, I now own the RM40’s that are claimed to have the 166Hz crossover mentioned in Marty DeWulf’s review. I couldn’t tell you if they are or are not crossed at this frequency but I’m just trying to understand what I have.

[DFaulds]

Does it really matter what the high pass point and slope are on the panels if you like the sound of your speakers?  I would say for most to just ignore these exchanges and enjoy your VMPS speakers if you've got em.  Whatever Brian did seemed to have worked because his reviews always seemed favorable and he stayed in business for an eternity.

[fredgarvin]

Now I am confused, you have several posts dated back in August of ’03 talking about the 166hz crossover. Here is a quote from one of those posts,
“The tube amp drives a passive high-pass crossover, which filters the bass frequencies, then that filtered signal feeds only the upper range drivers.  In the case of VMPS, that would be the ribbon mids & tweeters from 166Hz up.”

  Maybe Hammer im Romeyn needs tested?