[SWG255]

Greetings:

I've begun removing putty from the passive radiators of my RM40s and the results are surprising and somewhat different than I expected. With no putty removed the sound was focused, but the bass seemed restrained and overly tight. After removing the first fingernail's worth, the sound became a little warmer, and the bass was fuller, but the upper bass and lower midrange seemed to loose focus. I was about ready to put the putty back, but I decided to try removing some more first. This seems to be the correct approach. With two fingernail's worth removed the system has become much more focused. The upper bass lower midrange "fuzziness" (I really can't think of a good way to describe it) is gone. The bass has more impact overall, and seems more detailed. There has been no loss of warmth, although I don't think the system is warmer than after the first bit was removed, it is warmer than when no putty was removed.

I was expecting the process of removing/adding putty to the passive radiators to be a linear progression toward the "sweet spot", with steady deterioration of the sound when too much mortite was removed. This isn't the case in my listening room and with my electronics.

I must say that being able to tune one's loudspeakers in this manner seems daunting at first, but when one can hear the differences and zero in on better sound, the effort is justified.

Have other VMPS owners noticed this non-linearity of sonic improvement as mortite is removed from their passive radiators? By this I mean that on the way to the right amount and right sound, have you found the sound can change in unexpected and not always desireable ways?

[Redbone]

What's up ?  Hope you have worked out your polarity issues.  First off,  as Julian has been gently trying to drill into me, I hope that your amp has at least 200 wpc @ 8 ohms to drive the bass.  Next, make sure that the cabling is really solid. I would consider running two sets of cables from the amp rather than using jumpers.  This can have an effect on the speaker tone.

I have not started in earnest to tune the passive woofer because I want to resolve the above two issues first.  But I have noticed that the tone/timbre of my system is MUCH better since I cleaned up the cables.  The speakers and/or CD player also seem to be breaking in and I am getting a much fuller and richer sound with better imaging.  The midrange is excellent bordering on fantastic.  I have issues with the bass and high frequency.  

First I am addressing the bass by getting a good, inexpensive, POWERFUL amp.  When that arrives I will also replace the speaker wires, but not all at the same time.  I have learned to make on and only one change at a time and assesing the result before changing something else.  Otherwise you end up running around in circles.

One thing to consider is that you are placing these speakers on a carpeted floor (as I recall) and this will dramatically affect the sound.  As the carpet crushes down and compresses, the sound will change.  Also, try reclining (tilting back) the speakers.  This dramatically affects the overall sound in my room, and with carpet you will certainly notice a difference, but I can't predict exactly what.  You may very well get better bass, even though I got some bass loss doing this with a concrete floor.

Pete

[zybar]

Pete,

I have talked to numerous people and haven't heard anybody say you need 200WPC min for the bass....

Well, I am going to find out this weekend how 100WPC of Class A Triode tube power will do.

Although I am not expecting SOTA bass, I am expecting it to be very, very nice  

GW

[SWG255]

Redbone,

My Carver ZR 1600 is one of these "new-fangled" digital amps and is rated at 300 watts into 8 ohms. I can't remember what the 4 ohm rating is, but that would be more germane since the RM40s seem to be a 4 ohm speaker.  As for my speaker cabling, it's Audience Conductor, and it's brand-new. I'll consider your bi-wire recommendation, but I know Brian Cheney has not recommended bi-wiring in many instances. Others say the opposite. I suspect it depends, as usual on the associated equipment and the speaker cabling used.

As for tilting the speakers back, I usually sit when I'm listening seriously, so the fall off of high frequencies when I stand doesn't bother me.

As for the putty changes, the sonic issues I'm describing here are not large, but they are noticeable. Part of my dissatisfaction with the sound came from a round of listening to some recent classical releases a good friend brought over. While he thought the speakers were excellent, he felt there was something "funny" in the lower midrange. He's a Quad ESL owner, so when he talks of instrumental tambre, I listen.

What's up ?  Hope you have worked out your polarity issues.  First off,  as Julian has been gently trying to drill into me, I hope that your amp has at least 200 wpc @ 8 ohms to drive the bass.  Next, make sure that the cabling is really solid. I would consider running two sets of cables from the amp rather than using jumpers.  This can have an effect on the speaker tone.

I have not started in earnest to tune the passive woofer because I want to resolve the above two issues first.  But I have noticed tha ...

[Redbone]

Sounds like you have everything under control.  I would still try adjusting the tilt just for the heck of it.  Hmm, digital amp.  Let me know how it works out.  I am planning on going with tubes up top, eventually.

[Redbone]

Pete,

I have talked to numerous people and haven't heard anybody say you need 200WPC min for the bass....

Well, I am going to find out this weekend how 100WPC of Class A Triode tube power will do.

Although I am not expecting SOTA bass, I am expecting it to be very, very nice  

GW

Hey, let me know how the tube amp works, I am planning on powering the ribbons with tubes.  That should be a great sound.  

Julian is the one who keeps telling me about powering the bass, if he doesn't mind my saying so.  Right now I have an old SS HK 6250, 35 wpc @ 8 ohms, and I can tell you for sure that that isn't near enough to drive the bass.  If I turn it up much past "kinda loud", it clips like crazy.  I've been running the 40s at a moderate volume and they still sound real good.  But I'm shooting for fantastic.

[John Casler]

A couple words about the bass adjustments of the RM40.

It will produce very adequate bass with even modest tube amps, but as with anything else, there are other factors that will affect its LF ability such as the ability to harvest "room gain".  

I recently placed my pair of RM40s with a great fellow who brought along his amp for the audition.  It was a Jolida 502 which is 60wpc.  While we didn't "blast" (probably 80-83 db average listening level), we did have reasonably good musical bass when it was in the recording.

Now obviously if you wish "authoratative and thunderous" LF, you need plenty of watts/amps to move and control that cone.

Also, as far as putty adjustment:  Keep in mind that it is best to make adjustment when listening to "familiar" bass passages.

Even better yet, I would suggest selecting specific "bass reference" recordings to use, anytime you feel you want or need to make an adjustment.  This is because different recordings have differently engineered bass and if you try to adjust for eac one, it will be a never ending process.

That doesn't mean you can't add excellent cuts that help you make the adjustments, but you should probably not make major adjutment without you "references" to rely on.

[SWG255]

John,

Interesting that you suggest making the adjustment to the putty with a few well-known recordings. This sounds like a good procedure to me, but I got somewhat contradictory advice from Lucius Morris at Dynamic Sound Audio (from whom I bought the RM40s). He suggested on settling on a particular putty adjustment only after listening to a wide variety of recordings. When i think about it, I believe you are both right. It is important to listen to a wide variety of recordings with which one is familiar when deciding on the right adjustment for the damping putty on the passive radiators.

Lucius also suggested that the "sweet spot" isn't really approachable incrementally, but that it is at a narrow range of mass values for the putty. This begs a question, how did you RM40 owners out there know when you'd found the sweet spot for putty adjustment?
 

A couple words about the bass adjustments of the RM40.

It will produce very adequate bass with even modest tube amps, but as with anything else, there are other factors that will affect its LF ability such as the ability to harvest "room gain".  

I recently placed my pair of RM40s with a great fellow who brought along his amp for the audition.  It was a Jolida 502 which is 60wpc.  While we didn't "blast" (probably 80-83 db average listening level), we did have reasonably good musical bass when it was  ...

[warnerwh]

You'll know when you found the sweet spot for putty adjustment after listening to alot of different recordings. Obviously it can't be optimized for everything.  This due to the fact recordings vary so much.  Don't forget the L pads on the back often need adjustment when removing or adding putty.  VERY slight adjustments is the smartest thing to do! It's easy to be out of the park doing any more.  Trust me on this.  Also position of the speaker can be critical in getting a good balance so the position you think is best when doing the adjustments may not be and you'll have to replace some putty or remove even more.  
You guys just learning to do this adjustment need to pay attention to the midrange also as it can become fuzzy or more clear.  The entire balance of the speaker will change. Much experimentation is needed to know that your speakers are optimized and I personally suspect most people get their speakers to where they sound pretty damn good and think it's as good as it gets when they can be even better.  These speakers adjustments are truly a double edged sword.
Cheers