[meilankev]

This thread is in response to some recent posts from RM40 owners.  These posts have spoken of a thinness in the upper-bass from their speakers, and 3 or 4 owners have noticed the same problem.  When I read the first of these, I didn't pay much attention to it.  But I've got to admit that with this many owners experiencing the same limitation, well, it's becoming dangerously close to a trend.  Color me "amazed".

It's doubtful any VMPS owner shows off his/her system any more than I do.  As I've stated countless times, listening to music shouldn't be an individual sport.  And spending a few hours with another music lover is one of my favorite pastimes.  While my guests (who state an opinion) naturally mention different preferences (vocals, deep bass, piano, woodwinds, etc), the one thing that almost everyone mentions is the dynamics and impact of drums/percussion.  Without question, it is the "main drawing card" of my system.  And, of course, this is a product of upper-bass.

So, how can I reconcile this with these recent posts of other RM40 owners?  I'm not sure I can, but here's a few possibilities:

1)  Speakers are just one link in the chain.  Perhaps these differences in upper-bass capabilities are more a reflection of upstream components.  And the RM40s are merely presenting what they are being fed.  The strengths of the amps/sources of other owners may be elsewhere, and may outshine my system in those areas.  All systems are compromises.
2)  The listening room can have a big impact on "impact".  My room is 16 x 15, and probably a little on the lively side.  For comparison, a friend brought over some (home-made) room treatments for me to try.  There were advantages to be sure, but to my ears, these were gained at the expense of the dynamics/impact I love in my system.
3)  Our reference points are different.  Perhaps my previous speakers (Thiel CS-3.5) were extra deficient in upper-bass, and my RM40s sound wonderful merely by comparison.  Doubtful, but possible.
4)  Putty removal is an inexact science.  Certainly, this is the wild card, and can have a big effect on upper-bass satisfaction.

Don't get me wrong, I'm not saying that I'm right, and therefore, anyone who disagrees is wrong.  And I'm certainly not trying to get into a pissing contest with anyone - it's not in my personality.  I'm simply expressing my confusion, as well as I don't want any potential VMPS buyer to think wimpy upper-bass is a compromise all RM40 owners endure.  It's just not true.

Kevin

[JoshK]

I don't seem to have a problem with upper bass either.  While not overblown like some (not all) cone two ways I have heard it isn't thin either.  

Since you are running your 40s on tubes that could account for a lot of it since tube amps tend to have a lot of upper bass/ lower midrange bloom.

[audiochef]

Your're absolutely right Meilankev, the room modes have alot to do with the upper bass defficiencies mentioned here.

[Tyson]

My 40's have stronger deep bass than upper bass, while Gerry's (another 40 owner in denver) has stronger upper bass than deep bass.  That's the problem with full range speakers, they are very, very room dependent when it comes to their response, especially in the bass.  The tuning can help you get a much better match to a particular room than would otherwise be possible (without some form of active EQ, that is), but by itself it won't completely overcome room response.

Part of it is also amp dependent.  I find upper bass is actually more difficult to get right than low bass.  Low bass tends to just rumble, while upper bass has to have power, impact, and definition.  My old Odyssey amps were good, my AVA 550ex is better, and the all-digital panasonic and Spectron Musician were the best I've heard in my system.

[Redbone]

One of the things that I've noticed reading this forum is that people's tastes are wildly different when it comes bass, mid bass and impact.  Everyone seems to agree that the Ribbon Speakers produce wonderful to spectacular midrange sound, but there is some disagreement when it comes to bass and impact.  I suspect that a lot of this boils down to individual taste.

One other variable to throw in is the bi-amp option.  Although most owners, and I believe even Big B recommend against large adjustments to the pots and putty, I am only happy with the bass performance of the RM40 when I can independently adjust the gain on the ribbons and cones by means of two separate amps.  Theoretically the same results could be achieved with one amp by adjusting the pots, but it has not worked for me.

[SWG255]

Tyson's observations got me thinking about my RM-40s. I'm using a Carver ZR 1600 modified by Eighth nerve, and perhaps this is contributing to my sense that there is no problem with the upper-bass reproduction of my RM-40S. They certainly have plenty of impact without any trace of heaviness or chestyness which I alluded to as problematic for other audio reproducing systems in the RM-40 review thread. I also feel that my previous system had too much mid-bass and perhaps upper-bass energy in my room, most contributed by the Sunfire subwoofer and some by the Synthesis LM-300s. With my old setup, upper bass detail improved when i switched to the Carver switching amp, so perhaps this added detail is evident as good impact and no feeling of lost musicality when reproducing upper-bass on my new RM-40S.

Part of it is also amp dependent.   ...

[Q]

I can only reply that if there is no deficiency, why is VMPS offering the crossover upgrade?   See BC's previous post about the change in the 30s and then offering it to new and existing 40 owners.

It (upper bass thinness) was the first thing that hit me at two separate auditions/locations....and is the ONLY reason there is not a pair in my living room now.  I truly loved every other aspect of these transducers.
Q

[Marbles]

I won't be making the upgrade to my RM40's because in my room with my amps there is no need.

The only time I heard the 626R's (mated to a VMPS sub) I thought there was a mid bass deficiency, so the ones I bought from Ric Schultz will have the upgrade.

[Juan R]

I am running my rm-40 with ampzillas, I believe is plenty of power, I have good upper bass, my problem is with deep or low bass. But my room have something to do with it . marble floor with open space is not the best setting for deep bass.

[John Casler]

The old upper bass impact question

While Brian has offered to apply the change in the x-over to new speakers and through a kit for user installation, the creation of such was not so much a move to satisfy a "deficiency" as to satisfy a couple goals.

First off it is difficult to say just how accuratly "any" speaker creates this dynamically transient, impactful area.

While many cone drivers certainly do produce a very dynamic and impactful SPL in that area, "is it real"?

I have played drums, and electric bass years ago so I have a little experience in the real world transient.  Now if you are only feet away from the instrument, it certainly sounds (and feels) impactful.

In most recordings however, the soundstage is set up with the drummer several feet behind the perfromer and up on a raised platform and many feet from you the listener.

So the impact from most of these instruments is not the same as close up, and to make it so is not reality.

Now while it is impressive to be "kicked in the chest" with each beat of the kick drum and snare, this is not nessesarily a "real" sound except in recordings that offer it that way.

Recently at CES I was in the VonSchweikert room with I think the VR4's while they were playing a big drum solo (maybe Kodo) and the impact using the 300wpc Spectron amp was incredible!!!

But it was not even close to real.  It was a Kodachrome Cartoon Sonic Image with the emphasis on visceral impact.

So the point is that there is a thin line between reality and reproduction and personal preference.

Now then why would Brian change the x-over and frequency?

Well Big B is never one to "rest on his laurels" (if you've ever seen his laurels you'd know why ) and in designing new product, he may find that a tweak in crossover might lend itself to an improvement.

This adjustment while it certainly could lead to slightl more air being moved by the woofs in the upper bass also reduces the load on the neopanels and can offer a more robust performance through their then slightly reduced range.

So in making this change he might be giving those who like this additional impact more of what they want, as well as making a 3 neopanel speaker have nearly the sonic impact/perfromance of a 4 panel speaker.

B, generally considers the perfromance of the speaker "as a whole" rather than in sections.  You'll find him telling you that bass improved, because of him adding the FST.  This is an "organic" approach to speaker design.

Now with the RM40 in particular, as I have mentioned before, in nearfeild listening, the mid/upperbass woofer is at the top of the column.  This can cause the mid/upperbass to not reach the listener who sits rather close. (like me)

For this group, I offered the "sonic director" tweak which virtually resolves any reduced frequency range or SPL in the upper midbass.  It is a simple tweak and can be placed into postion in 5 seconds for "serious listening" and removed just quickly when finished (if desired).

So in any event, I found the RM30 to be one incredible performer (with plenty of visceral impact, but not beyond the scope of reality.

I'm sure the other speakers from the RM/x down to the 626R will offer the same with these changes.

[dubravko]

I'm sure the other speakers from the RM/x down to the 626R will offer the same with these changes...

I expect the arrival of an RM2 with upgraded crossover (w/FST, Auricaps and Dynamat), to be a center loudspeaker in Trinaural setup with a pair of the same RM2s (except older crossovers). With them as a pair, I don't feel the lack of upper bass, and when A/B I liked RM40s better in the same room, because their bass sounded cleaner and faster. Good amplifier, placement and "putty" adjusting are now making RM2s sound good enough I don't lust for RM40s when bass is an issue, on the contrary, bass is now very articulate and goes deeper and stronger. I say "putty", because in that particular room, a added a 2.55g of lead shot to the original mass to get what I wanted. Anywhere else, slow removing of putty works, but in this room adding was a key.

I only hope that new RM2 will be able to maintain the tonality and bass clarity I achieved with other two units - because they sound great now as is, and because center room position might be the worst place in the room for dealing with room modes.

Apart from that fear, in my case J. Bongiorno was right, after listening to Trinaural for a couple of days there's no going back. To be honest, in my case one nice morning was enough. Maybe the reason is I actually wanted someone to come up with something like that years ago.

[warnerwh]

"Now with the RM40 in particular, as I have mentioned before, in nearfeild listening, the mid/upperbass woofer is at the top of the column. This can cause the mid/upperbass to not reach the listener who sits rather close. (like me)

John: I think you hit the nail on the head right here and it's definitely room related to why some people have no problem with it and others do.  No doubt this is why some have felt the tweak of changing woofer positions sounded better.  I'm sure Brian took into account the lower bass driver being near the floor and would leave them that way. Been bugging me as I know Brian has never really designed any speakers that were weak anywhere in the bass in his quarter century of building speakers.  The weakness I felt, or should I say didn't feel, is that the mid/upperbass sounded like it was correct but the weight behind it isn't and this made a peculiar effect.  The ones I heard had a high angled ceiling and were well out away from any walls and this no doubt affects it as well.  

Another point is I think alot of people like to feel the upper bass or are used to it as most large speakers this is common.  I'm not sure but I think the reason Brian has to keep the the mid/upper woofer at the other end of the cabinet is so that the backwave sound from the lower woofer doesn't interfere with the upper woofer sound.  This is a weakness in the ST/R SE's I believe but I'd rather have this weakness than weak feeling upper bass and is the main reason the RM 40's have not been on my list for my next speakers even though I like VMPS great sound for the money (I'm on my second pair and have had VMPS in my room for 8 years). It may be that the new crossover design helps this area considerably and I'd bet alot of people are curious of the results, I sure am.

[ekovalsky]

At least in my room (14.5' L x 17' W x 10' H, speakers along long wall) the RM/X low and mid bass response is in a different league than the RM-40.  Probably a combination of 12" vs 10" drivers, the side firing woofers, low height of all woofers, and the new crossover circuit.   These are first speakers I've owned that are truly full range, in that I have no desire to add a subwoofer(s).

Adding absoption to the speaker end of the room helps too.  The mid & tweeters level pots can be adjusted higher, since there is more absorption by the room, but the extra bass output at the mid panels low end will not be absorbed.   I wonder if many of those who experienced mid-bass weakness in the RM-40's were using them in untreated, live rooms?  To keep from sounding too bright, the midrange and tweeter controls would be dialed down from the factory recommended settings which would also attenuate the mid bass...

[zybar]

Eric,

I realize it is a different speaker, but what do you have your pots at?

GW

[ekovalsky]

Kinda of trick question!

On the RM-40's best balance was around 11:00.  That is without any room treatment.

With the RM-X and a good amount of room treatment, I originally had the pots at about 12:00.  At CES Julian told me that I wouldn't be getting the best sound if the pots were set at the exact same clock positions.  Why?  Because they are not attached to the cabinet with the exact same rotation.

So I turned each pot all the way counterclockwise to its lowest setting.  Sure enough, they weren't the same.  One speaker was at about 7:00 and the other about 8:00.  I turned each pot from the full down position  180 degrees clockwise.  My left channel wound up at 1:00 and the right channel at 2:00.  

I definitely recommend this "tweak" to all VMPS owners, at least those with perfectly symmetrical rooms like mine.  If you've struggled to get each speaker's pot settings exactly the same, you probably have inadvertently set them differently!

The very fine adjustment on the VMPS pots is nice for maximum flexibility.  But a unit with fewer steps (maybe 0.3 or 0.5db over a 2-3db range) would make exact channel matching easier.

[SWG255]

Since I'm happy with the mid-bass performance of my RM40s in my room with my Carver ZR-1600 amp, I thought I'd also chime in and say the pots on my RM40s are still in their 12 o'clock positions as delivered by Big B. I haven't been able to decide where to set them, so I haven't. I know, I know I should be a little more adventurous, but I haven't really had the large block of time available for long-term listening in the last month.