A while ago when I was very seriously considering the RM-40. I had some reservations about some bass issues I had read about here and so I had started a thread with a question to the community about basically doing what you have done.
http://www.audiocircle.com/index.php?topic=31633.0
The twist was that I was asking:
"if a separate subwoofer was part of the system from the beginning of design, would the tower sections be built the same, or would changes be made to optimize them for the frequencies they would be running? For example: Would there still be a mid bass and low bass driver, or would two mid bass drivers be used instead?"
Thanks for the link.
My concern is not with the bass issues of a speaker.
You can always buy bass, it is cheap.
My concerns are the lower midrange of my particular set of older RM 40's.
Design decisions sometime involve compromise.
Brian intentionally placed different woofers in the RM 40's to avoid one note bass.
Fine and good, for bass.
But, this means the two woofers now roll off in their upper range at different frequencies.
This means that only the top woofer is left to play the bottom part of the vital lower midrange of the speaker!
The VMPS woofers are already far less efficient then the ribbon array is.
This forces you to turn the panels down to match the lower efficiency of the woofers.
With two old midwoofers in the RM 40's, instead of one midwoofer and one Megawoofer, the woofers now BOTH play well up into the midrange, solving the lean tonal balance issue, solidifying images, and allowing more panel level, hence more efficiency.
There also seems to be a more Punchy mid bass, although some low bass is lost.
So, it is a trade off, as you can see.
For me, and Jay, we will gladly trade the loss of some low bass for what we feel is better everything else.
Perhaps the new Midwoofer option fixes these issues, and maybe I will eventually buy 4 NEW Midwoofers and slap em in ?
But, I gotta be real here, and say what I feel.
I want both of MY woofer/mids playing the same thing, and I will incur the one note bass Brian has tried to avoid to get it.
BTW, I am not getting any of the one note bass either, at least in my room.
I have emailed Brian suggesting he might consider making an
RM 40 - VHE ?
RM 40 - Very High Efficiency
It is my feeling that many people who use RM 40's will use the excellent subwoofers anyway.
So, why cripple the RM 40's with the burden of making deep bass.
TANFL is in order here !
TANFL means 'There ain't no free lunch"
IOW, if you want deep bass, either the cabinet must be larger, or efficiency must be sacrificed to get it.
If Brian would instead shoot for a higher frequency bass 3 db down point, say 40 hz instead of 20, efficiency could be gained, and perhaps a lighter, faster woofer could be used to further improve the already excellent midrange ?
This might allow the use of a smaller, less expensive amp, leaving the VMPS customer with more left over money to purchase one of the excellent VMPS subwoofers ?
Based on what I heard, and what Jay is hearing, Brian might also consider a TSA option for the RM 40's ?
TSA of course is "Totally Symmetrical Array".
This would allow the customer to choose his compromise between bass performance or full symmetry by simply adding midwoofers ONLY to the RM 40, instead of one midwoofer and one Megawoofer.
I have not heard a newer RM 40, or even one with a midwoofer update.
But I have heard mine, and two other older RM 40's here locally.
In the older RM 40's w/o midwoofer updates, I prefer the two midwoofers.
It is interesting you also questioned this a long time ago !
Again, thanks for the link!
