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« Reply #20 on: 23 Apr 2015, 05:12 am »
Thanks, both of you for your suggestions. 

Both of your notes are the main reason I've not tried really tried anything until now.  It's a frickin' lotta' work and as John said, it is the most difficult thing to achieve.  And like John said, it just may not be possible in this room config. that I've had for 7 years now.

The frustrating part is having heard at some point in time past a bass that is so tight, well-defined, and musical that if/when that "perfect" location can be found, it's worth whatever time it took to get to that level.  But again, so frustrating in that the infinite amount of variable / possible locations and it may never be found and/or may not exist.

The bass has been so "satisfactory" in their original positions that I've not spent any real time pinching putty.  I lost the original compound strip the seller provided but a few weeks ago, I purchased some Mortite.  I cut about a 1" square piece x 0.25" thick and stuck that to the passive drivers.  It seemed to thicken the bass just a tad and maybe gain 1Hz.  Considering the small pinch recommendations, it did not have nearly the effect I thought it would so I removed the newly installed Mortite.

Last week was my first attempt at moving the speakers.  Originally, the woofer fronts were nearly 7.5ft out from the back, er, front wall but are now 6.5 ft out.  No real difference in bass, just a slightly more uniform soundstage presentation.

I've deliberately left the speakers toed in to only about 5 degrees because the RM40's can easily become overly bright if one is not careful.  I've got the treble and mid-range adjusting screws set at about 11:30 right now.  If I toe them in more direct to the chair, which I've tried, they become borderline overly bright.

I've tried opening both pocket doors behind the chair but I was unable to notice any difference.  Thank goodness, because I have family members and 2 cats.

So many options and variable and so much weight at 240 lbs. per side.   8)

I do have a Radio Shack SPL meter but lack knowledge and experience how to use it in this regard.  And I'm unfamiliar with any software.  But I'm open to your suggestions.

In time past, (different room and speakers) I found that roughly 5.5ft out from the front wall and 2.5 ft from side walls worked quite well as a starting point.  So maybe that's the next step.  But the soundstage depth has already collapsed a bit going from 7.5ft to 6.5ft.

Tell me this.  Do either of you believe that most room / speaker combos have a near perfect or most optimal speaker position somewhere/anywhere and it's just a matter of finding it 1-inch at a time? 

Or do you believe that for some slightly unreasonable rooms (like mine perhaps) certain room measurements simply prohibit any opportunity to locate that magical synergistic spot?

I'm not trying to be lazy about this.  Rather, I'm simply trying to be realistic that in my pursuit to find a pot of gold at the end of the rainbow, I may instead discover I've been chasing windmills.  As John implied.

Anyway, thank you both for your input.

John Casler

« Reply #21 on: 23 Apr 2015, 07:08 am »
You can also turn the L-Pads down so that the woofers will play proportionally louder.

So rather than 1:00 try 9:00

That will also reduce the brightness, if they are converged "on-axis".


« Reply #22 on: 24 Apr 2015, 07:50 am »
Yes, I could try that.  However, that will not improve the bass depth which is what I'm after.  Remember that at present the RM40's in my room are generally going down only to perhaps 28Hz with serious rolloff beyond that.  For a speaker with two 10" woofers plus a 10" passive radiator, I would hope them to go down to 24Hz.

But again, I'm not faulting the RM40's in any way as they really are quite musical, even in the bass.  I'm only questioning the speaker positioning within the shoebox dimensioned room.

BTW, I probably should have mentioned that since just before receiving the RM40's, I've been using a passive volume attenuator via the OPPO 105.  Needless to say I still have one of the most dynamic systems I've heard because I'm also using 575 wpc mono amps.  With an active preamp and these new 575 wpc amps, the dynamics were so over the top and in-my-face, that combo actually took me further from the live performance.  The OPPO's passive pre section was exactly what the doctor ordered to put all the music back up on the soundstage while my ears remain entirely in the audience.  In other words, the dynamics are there and still among the most dynamic I've heard but now in a more natural sense with a distance between my ears and the music on the soundstage.



« Reply #23 on: 27 Apr 2015, 02:05 am »
I tried toe'ing in the speakers so they are more direct, to maybe about 12 - 15 degrees so I can barely see the sides of the cabinets, which produced a nice improvement on focus (just as you suspected John) and even more uniform soundstage.

At the same time I moved the RM40's about 5 inches further back toward the back, er front wall and a few inches closer to the side walls.  This seemed to help gain another Hertz or 2.  I'm probably down to about 27 or 26Hz before serious roll off.  That's not bad considering my shoebox of a room. 

Also, don't get me wrong, the bass that I'm getting some might say is already perhaps above reproach.  Being an idealist in this regard, I'm simply hoping I can dial the RM40's down to maybe 24 or even 23Hz which would be ideal.

If I can do that, then I can avoid the subwoofer route, which will bring a whole 'nuther can of worms but hopefully greater potential for the subterranean which exists on a surprising number of recordings, including classical.

Anyway, thanks for the suggestions.

John Casler

« Reply #24 on: 27 Apr 2015, 06:41 am »
You could also try "ADDING" putty.

The putty adds mass.  The mass "slows" the Passive Radiator response.  A slower response will of course be a lower frequency.

The trick however is to then "sync" that with the active woofer system, which is where the very small adding or pinching comes in.

You may even find that a good preamp (beyond the volume controls in the OPPO) will, due to a larger power supply, give you more noticeable bass.


« Reply #25 on: 27 Apr 2015, 07:52 am »
I already did.  Last night I re-installed the small glob of Mortite I purchased a few weeks ago.  The difference fairly insignificant both times.  I'll have to re-read the putty pinching thread.  It seems that there wasn't much putty up there to begin with (I never messed with it since getting the RM40's last summer because it sounded so musical to begin with).  So perhaps I need to start that process from the very beginning.

Yes, no doubt an active pre would do some positive things for the bass but because of the rather unique dynamics I'm able to achieve already, the initial attack of most any instruments' note would once again be so in my face that there's no way the trade off would be worth it as it would be taking a step away from the absolute sound, not closer to it.  The OPPO's passive pre was exactly what the doctor ordered for putting all the music back up on the soundstage where it belonged.  Before the OPPO's passive pre, it was as though my ears were 1 foot from an instrument's initial attack and then back in the first row for the remainder of the note.  Not very realistic.  Imagine a .45 caliber gun shot 5 ft from your head and then imagine that same gunshot 30 ft. away.  The dynamics are all still there but at a realistic distance, I'm no longer jumping out of my chair by an electronics induced jump factor (caused by an active preamp's gain stage). 

Moreover, the OPPO's fabulous volume attenuator is really quite musical. There's a white paper on the OPPO employing the 32-bit SABRE DAC's that at least theoretically induces zero signal loss.  The levels of improved detail with pristine and now delicate highs seem to indicate a significantly lowered noise floor or absence of distortion that perhaps most active preamps induce by the amplified gain stage.

So as one who takes great pride in dynamics and swore many times I'd never go passive, today with the dynamics my technology is able to attain along with the 575 wpc amps, I wouldn't have it any other way.  And I still have the most dynamic system I've yet encountered, only now it's far more natural and slightly rounded and with a distance between the music on the soundstage and my ears planted well-into the audience.

On the other hand, I'm rather pleased with the improved level of musicality just from the speaker moves (including toe-in and chair moves) in the past few days.  The front half of the room has filled with an ever more palatable and uniform soundstage and indeed the focus has improved as has the bass.  Not real significant but after listening for several hours tonight, rather pleasing. 

Hopefully, with further speaker positioning, in the next few weeks I'll find a few more Hertz.  Definitely a long row to hoe here but already it's paid off.

Thanks again for your suggestions.


« Reply #26 on: 13 May 2015, 12:52 am »
John Casler, I'd like to ask you a few questions about the RM40's bass plate if I may?

I have some universal speaker stands that I designed and had machined a few years ago and I have my own special cones/points.  See pic below.

I know Brian did not recommend stands or points for the RM40's.  Nevertheless, I''d like to see what sonic improvement (or differences) I might attain.

Can you confirm whether or not the bass of the RM40 is made of 1" thick MDF?   

If I attached my low-profile speaker stands to the RM40's base plate by drilling four 1/2" through-bores in each bass plate and then using 1/2" socket head bolts, nuts, large washers, etc. do you think the base plate at the fastener locations can easily handle the stress of 240 lbs.?  Each bar would have 2 bolts fastened to the base plate.  The real question is, let's say I mount these stands to the base plate, one toward the front and the other toward the rear, 2 bolts per bar with washers and tightly fastened.  If I walk these behemoth's of a speaker into position, would you guess the stress at the washers during this time might possibly tear away or crack the MDF?

My last question is, the black vertical slats (1 in back and 2 sides with open transmission line front) that the base plats mount to.  Do those 3 slats go all the way up to the speaker tops as a type of structural beam.  Or are these slats just a few inches tall?

Much appreciated,
« Last Edit: 13 May 2015, 04:30 am by stehno »


« Reply #27 on: 13 May 2015, 01:40 am »
Those bases have 4 long screws in them, so you can remove  base to get the passive radiator.  Here is picture with base off. Good luck. ZAK



« Reply #28 on: 13 May 2015, 02:12 am »
Thanks, Zak.  Not quite on topic but you shed some light on quality of materials and construction in this region.

Based on your picture, I think my universal stands are out of the question as they would most likely induce severe stress points either at the base where the stands would connect or at the base where they mount via the 4 long screws to the MDF sides. 

I think if I really really want to get this hefty speaker on my points, I would need to machine some custom aluminum base plates and screw them at the MDF panel ends about 1" apart just to ensure any stress is distributed as much as possible through the MDF.

Appreciate the info.

Man I hate MDF.  It truly is good for nothing, especially when it comes to vibration control.