[John Casler]

George,

I have moved these speakers all over the place and although placement did change bass response, I never got significant bass below 80 Hz.  I'm confident it isn't an amp issue, but I do have concerns about the speakers ability to do low bass.  I expect deeper, louder bass, especially using the megawoofers.

Joe M.

Hi Joe,

If I might ask a couple questions and maybe a couple suggestions:

I know, this is a simple question, but are the 6.5's and the 10" active?  That is are they moving when bass is in the recording?  

You know that the binding posts need a jumper and the "upper" pair go to the woofers.  Disconnect the jumpers and play the woofers only and see what happens.

If they are working, then play a bass heavy cut and go stand in each of the corners of the room and see how the bass is there.

If you have good bass in the corners it means the speaker is creating it, but as said earlier in the thread, your room is not "supporting it" at the listening area.

Adjusting the putty will not increase volume or amount of bass, it will simply cause the woofer to "react" at the most accurate speed and create the "cleanest" and "tightest" bass.

If there is "no" bass in the corners, then either the drive chain is not sending the speaker bass below 80Hz, or the speaker is not producing it, which is unlikely.

Now if your using a pre/pro, 80Hz is a popular x-over point if your speakers are set as small.  So if this is the case, make sure and check if you accidently have a x-over setting at 80 or 100Hz.

And if you have a "test tone" CD (I think I saw earlier you do), run 80Hz and below and physically "touch" (lightly of course) the bass drivers and PR's to see if they are actually moving enough to create bass.

Also, you may need to check and make sure all bass drivers are "in phase"

To do this, disconnect the jumper to the mid/highs, and get a 9 volt battery.

Plug the speaker cable into the "upper" binding posts and then touch the other ends to the battery's terminals.  Note which direction the woofers move.  They will either move "in" or "out".  Make note of whether it is in or out, and which terminal touched which speaker lead.  Then do the exact same thing on the other speaker.

All woofers (including the 10") should all move out, or in, at the same time with this test.  

If they do not then somehow they are out of phase, which is unlikely, but we can talk about how to fix it, if we find it.

Check out these things and let me know your result.

If you hear bass in the corners, it does show that the speakers are producing the notes, and your room is not allowing it to be realized in the listening position.

If you can imagine bass as a "wave" that travels from your speaker to you, then past you to the walls/corners behind you.  It then is collected at room intersections, compressed and comes bouncing back out.  It then "slams into the waves that are trying to come at you from the speakers.

The reflected bass's energy moving into the bass from your speakers, affects that bass, to the point of cancelling or adding to it.

It is hitting the recently launched waves head on and at angles.  It is energy against energy, and it has an effect.


If you want to see how this works (in a simple experiment) just run a kitchen sink full if water.

Wait till it is calm and plunk your finger into the water where your right speaker might be.  Watch what happens to the "ripples" that leave your finger.  They move in the sink in every direction, and you can see them "slam" into the sidewalls (of the sink) and follow the wall to the corners, where they meet other direct and indirect ripples.

They then sum their return energy (that is not absorbed) and it slams back out of the corners and into the sink.  This process happens "hundreds" of times a second (or whatever frequencies we consider bass, down 20 or 15 times a second for deep bass.

While this is a simple experiment, it shows that a chief goal is to absorb, dissipate and trap those big waves, to keep them from slamming back into the room and into the ones most recently launched at you from your woofers.

This is a big task, and every room dimension and surface will have an affect on the outcome.

Hope that helps.

[Danberg]

Boy do I find this topic interesting, as I had a similar experience with the RM-30's a short time ago!

Over the past 6 months I had been reading all that I could about VMPS speakers, joined Audio Circles.  My reading had lead me to want to purchase a pair of VMPS speakers.  Due to my needs, the RM-30's size appeared to be just what I was looking for.  Not having a dealer close to me I decided to take a couple of days off from work and drive almost 6 hours to the closest VMPS dealer.  I went with all intentions to to make a final decision and purchase a pair, upon audition.

Upon 1st listening, my initial and strongest impression was "where's the BASS?" The overall sound was missing all bass frequencies (RM-30 with 10" subwoofer, without the 6.5" Mega-Woofer option).  I found it difficult to believe, as VMPS bass energy was mentioned at times even being excessive.   Was my mind playing tricks on me?!  Was it the long drive?  Was it the electronics?  Maybe the speaker cables (Analysis Plus), Maybe the speakers placement?  Maybe the showroom size, acoustics?  Maybe my anticipation in wanting to be blown away by their sound?

After comment to another customer in the showroom about their lack of bass, he suggested that I listen to the RM-1's siting right next to the RM-30's.  He had auditioned all the VMPS products and felt the same about the RM-30's.  Using the same electronics, speaker cables, we connected the RM-1's.  The amount of bass they projected dramatically increased, more like I expected to hear.  Almost bass heavy.  My ears were'nt fooling me.

After further listening, it was quite obvious that the mid & upper frequencies were nowhere as clean on the RM-1's as with the RM-30's, which were simply superb, outstanding!

I moved the RM-30's closer to the wall ( the speaker backs about 2" from the wall).  The bass increased somewhat but still no where near the RM-1's, which ere about 2 feet from the wall behind them.  I listened to the RM-2's and their bass was less than the RM-1's but still substatnially more than the RM-30's.

I really identify with JERMMD's comment regarding the drop off of bass around 80hz.  I had the exact same experience myself.  80 hz to 32 hz difference, determined by placement and or putty adjustment?!!!  That profound of a variance?!!!

I'm interested to read more thoughts on this.  

To repeat what I said earlier, the mids and upper frequiences were stunningly fantastic!!:thumb:  Best I have ever heard in a loudspeaker.  But the lack of bass.

Big B could you explain?

[Brian Cheney]

Most likely explanation was that the lowbass woofer was not working, probably from not being jumpered together.  Bass on the RM 30 with the 6.5" MW is flat to 32Hz -3dB.

Where was this dealer?  Not many have the 6.5MW version.  One of our subs can fill in the lowbass with the standard drivers.

[jermmd]

John,

Thanks for your reply.  I haven't tested the phase of the woofers yet but I have considered your other suggestions.  There is sound coming out of the woofers, there is no subwoofer bypass in the equipment chain, and I can hear the loss of low bass volume even when I listen from an inch away from the drivers.  Doesn't this rule out room modes as the culprit?  The bass sounds better with the side firing woofer facing outward but the loss of low bass remains.

Danberg

Your post concerns me.  Is there anyone out there who can confirm that they are getting good bass below 80Hz from the RM30's?

Joe M.

[jermmd]

Brian,

I sent you a PM.  Is there some way to confirm wether the low bass woofer is wired correctly?  I'm not uncomfortable with a screwdriver and would be willing to open the speaker up and take a look.

Joe M.

[Brian Cheney]

A 9V battery can test woofer wiring.  Apply the + battery terminal to the red binding post on the upper inputs.  All three woofers should move forward.  If one moves in and the others out, the woofer moving in is wired out of phase.

[Brian Cheney]

The RM30 was originally designed for use with a dedicated Sub, the 215, which included a passive crossover trimmed precisely for use with the graphite 6.5" version of the system.

After much delay sourcing woven carbon fiber cone stock overseas, I had the Minneapolis Speaker people make a true lowbass 6.5" with a 4 layer VC and a 32Hz Fs, which is the current 6.5 Megawoofer.  This brings the system bass response down to 32 Hz.  However, because of its small enclosure the RM30 will never be a lowbass champ like the RM 2 or RM 40.  

While the StereoTimes reviewer liked the Megawoofered RM 30 just fine in the low bass many people will want a sub with it.  You can order any of our subs with the dedicated passive xover installed for use with the RM 30M or RM30M 6.5MW.  There should not be a problem obtaining the lowbass you want from the speakers.

Be sure to read the www.stereotimes.com review to get a good idea what the RM30 can do.

[jermmd]

I can't see the side firing woofer but the front woofers go forward as they're supposed to.  Neat trick by the way.  Does this mean the low bass woofers are wired correctly?

Joe M.

[zybar]

George,

I have moved these speakers all over the place and although placement did change bass response, I never got significant bass below 80 Hz.  I'm confident it isn't an amp issue, but I do have concerns about the speakers ability to do low bass.  I expect deeper, louder bass, especially using the megawoofers.

Joe M.

I promise you that the speakers will have no problem producing siginificant bass below 80 Hz (sounds like I am a dealer or something).

Have no fear...

George

[jermmd]

I just read the review and just about completely agree with the reviewers experience, even to the hump in bass at 150Hz.  But i'm getting bass roll-off at 80Hz, not 35Hz as mentioned.  

Brian, can you explain what is meant by a "dedicated passive crossover installed in one of our subs?"  How exactly would this be used?  

Joe M.

[jermmd]

George,

I can't wait to get you over here.

Joe M.

[jermmd]

1.  Is there some way to see the side firing woofer and determine if it is in phase?

2.  If the bass drop off occurs when listening from a few inches away, does that rule out room modes as the problem?  George,  

3.  I have a subwoofer with a variable crossover (Hsu VTF2?).  How would be best to set it up.  Set crossover to 80 and eliminate those frequencies in the RM30's or use the subs low bass IN ADDITION TO  the RM30's?

4.  I would prefer not to use a sub.  If I can get good response down to 35Hz, I really don't need a sub.

Joe M.

[Tyson]

Yeah, listening up close should remove the room as a consideration.  Sounds to me like the 10 inch side woofer is either out of phase, or disconnected.  

You can also just put your hand on the woofer (by pressing on the cloth covering) and just feel if it moves when you play some bass.

[bboplive]

I really identify with JERMMD's comment regarding the drop off of bass around 80hz. I had the exact same experience myself. 80 hz to 32 hz difference, determined by placement and or putty adjustment?!!! That profound of a variance?!!!  

I'm interested to read more thoughts on this.

Ditto the experience for me as well.  I experienced a sharp-drop off between 80-60 Hz.  This was well documented using the Radio Shack SPL meter and Rives CD, which is adjusted for variances.  No amount of repositioning or putty pulling will get the bass down near 32 Hz.  I had the added avantage of AB'ing them along with the Gallo Reference III's and Legacy Classics, both of which had lower bass response.  So it was not my room that was causing the loss of bass, nor my system, which is very good.  On the plus side, the midrange and treble findings were markedly better than the aforementioned competition.

If Zybar can get your bass down to even 40 Hz, I will be very surprised.

The answer coming from VMPS seems to lie in the purchase of an additional subwoofer, which brings the price significantly up from its advertised value. The presence of great reviews only support the fact that this speaker should be better than it really is in bass reproduction.

[rkapadia@ROOP]

jermmd,

What is your amplification currently?

Having experimented quite a bit with the RM30's here, I'd like to point out that the lack of bass experienced might really have to do with the amplifier.  If your amplifier isn't capable of instantaneous high-current delivery, the bass quality will really suffer on the RM30's.  

When putting the RM30 through the paces I tried a variety of amplifiers; surprisingly horizontal biamping with two less expensive NAD amplifiers provided a much improved bass response over a two more expensive Adcom monoblocks.

[Brian Cheney]

The passive filter is at 57Hz/6dB octave and is built into the Sub.  It can be used in conjunction with the standard HT 80Hz active characteristic for good results.

At CES I used the passive xover installed in a single 215 Subwoofer and controlled level with the Sub output of the Trinaural Processor.  Low bass was profound.  The TRIP has the 80Hz rolloff builtin which means the lowpass filter transits to 18dB/oct above 80Hz, a good combination.

Many people commented on the seamless transition to the sub.

To increase lowbass, do the following:
1. Place speaker closer to back and side walls;
2. Adjust toe-in with the woofers firing outward for maximum bass;
3. adjust putty mass slowly and carefully, fingernail full at a time.  It is easy to go past the optimum setting and be right back where you started.

Currently I use a pair of RM30 MW6.5 by themselves without sub in my 14x31' room with just a single Son of Ampzilla driving them.  The back of the cabinet is about 20" from the back wall and the side woofers are about 24" from the side wall.  Bass is excellent to the 32Hz cutoff and no one has expressed desire to use a sub in this setup.

[zybar]

jermmd,

What is your amplification currently?

Having experimented quite a bit with the RM30's here, I'd like to point out that the lack of bass experienced might really have to do with the amplifier.  If your amplifier isn't capable of instantaneous high-current delivery, the bass quality will really suffer on the RM30's.  

When putting the RM30 through the paces I tried a variety of amplifiers; surprisingly horizontal biamping with two less expensive NAD amplifiers provided a much improved bass response over a two more expensive Adcom monoblocks.

Roop,

I sold Joe the amp he is using so I know it pretty well.  The Sherbourn will have no problems handling the bass requirements of the RM 30's.

When I was last at Joe's he was using 4 out of the 5 channels to drive the 30's.  That config produced excellent bass with my RM 40's when I used the amp for my HT.

Again, I don't think this is an amp or speaker issue.  When I didn't have my 40's placed right, I wasn't getting bass below 40Hz and what bass I was getting didn't that good.  With proper placement (of both the speakers and the listener), I get pretty much flat down to 22Hz.

Hang in there Joe, help is on the way...

George

[jermmd]

So I removed one of the woofers to check that everything was connected properly inside and to get a look at the side firing woofer.  I did the battery test and all three woofers are working and in phase.  I was surprised to see the cabinet was completely stuffed with fiberglass so I called Brian and asked if that was as it should be.  He reassured me that everything was proper and basically said what George has been saying.  He feels its a speaker placement issue,  I need to move my speakers closer to the rear wall even if that puts my enormous RPTV in between them, and I need to play with the putty.

Now I have moved the speakers all the way into the corners.  They are about 6 inches from the side walls and maybe a foot from the wall behind them.  I angled the speakers so they cross about 1 to 2 feet in front of the listening position  Only the lateral half of the front drivers  are in front of the TV with this placement and angle.  I added all the putty that I had removed and started from scratch using CCR's Midnight special as my Bass reference.  I also readjusted the pots based on Brian's recomendations.

And the results:
1.  Despite the giant box (TV) between them, the imaging and soundstage are exquisite.
2.  The bass is tight and I find my CD's sound great.
3.  I'm not going to recheck test tones because I'm really enjoying the sound these speakers are making right now and why spoil it?
4.  I may have had too many beers while adjusting the speakers and my impressions may not be reliable at this point.

I think I'm going to leave things as they are right now and await George's input when he returns.  I listened to Henry Mancini's Pink Panther and Peter Gunn a little while ago (two bass heavy numbers) and I really don't think it could have sounded any better.

Thanks for all the help and advice,

Joe M.

[jermmd]

Oh, and I'll repost after George comes over. CTViggen also offered to come over and help with the setup.  I'll Post after I make changes or get any new opinions.

Joe M.

[lkosova]

Speaker placement with the 30's is critical and with any VMPS speaker. Just a couple inches off and the bass will go away. I use a very similar positioning that Brian uses in a 15 ft by 21 ft by 8.3 ft room and the bass is fine.

I recently was playing some cuts and I thought the bass was very full  and exact and then I noticed that the speaker wire pulled away and that the larger sub was not attached. I was very satisfied with the bass without the sub. Yes, I prefer the 40's and 30's with the sub but that is just me. I have the trt and megawoofer upgrades.

The woofers etc will pump when using a good amp and move aggressively when tested. I have seen this with a 200 watt amp and a 375 watt amp. You will "feel" each moving just by putting your fingers gently on them. If this is not what you are getting then something is wrong. Check to see that you are using the jumper wire(Analysis wire) correctly and recheck your putty as said before.....it is vey easy to go past the point of benefit!!!!


I would play around with the placement first and just move each speaker by cm's first. Once you hit the spot the imaging,midrange,high etc will be unreal......then I would play with the pots to "tune in " to your room and likeing. This is assuming that you removed a "bit" or putty first.

These speakers "need" 200-300 hours to open up. Yes they are great out of the box but really shine after "burning in"!!!! I left my on for three weeks(I needed to burn in my amps also).

I have several people coming this weekend and I will remeasure and report back. We will be using some Music Hall,CaryAudio, Sonic Philosophy,Rega Planet etc gear and will see how they feel the bass is  etc. We might even biamp(running full now) and play around a bit.

Hope this helps,

Larry
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