Has anyone tried using one of these risers with their Axiom sub?
I'm thinking of ordering one for my EP500 v3.
The dimensions are perfect for the EP500.

Zak


GRAMMA
Dimensions:
23" long x 15" wide x 2.75" high
Weight Limit: 300lbs.

GRAMMA Isolation Riser

I don't have the Gramma, but I have the Aurolex MoPads that I use for my center and it works wonderfully.

How did you position them under the VP180? Aren't the MoPads only 12" deep?

I would imagine he just has parts of the speaker which aren't directly supported by the foam. If you use all 4 of the MoPads under the center it would still give more than enough support/isolation.

(Last post before 1000.. Took several years).

I use the Mopads on the outer sides. They come in "slivers" which allow you to adjust the angle as needed. In the end, I only needed to support the speakers on the outer edges, so only 2 Mopads are being used for the VP180 (currently).

Oh right, he's probably using them level. I wonder how / if they can still be used to angle a VP180 or M80.

oops, we must've been typing at the same time

thx for the info

I made two of them for my friend and I for about $10 dollars each using mdf , carpet for car stereo speakers and foam from the packaging from my SVS .

[img]http://forum.blu-ray.com/album.php?albumid=571&pictureid=4282[/img]

Sorry for asking this but what does a riser do? And what does mopads do for the VP180?

Hello Griffith

No apology necessary for asking a perfectly legitimate question. Looking at the physics of the riser/mopad, it would reduce or suppress mechanical vibration of the subwoofer cabinet or the VP180 enclosure from being transmitted to the surface below.

However it would do nothing to prevent the acoustical vibration generated by the subwoofer's sound waves or the VP180's acoustical output from resonating the floor or surface beneath the center channel, respectively. To claim otherwise would contradict fundamental rules of science and the propogation of sound waves.

You could accomplish the same end by using four tennis balls under the subwoofer or those squishy rubber balls under the VP180. However, they would look peculiar---if you could see them.

Regards,
Alan

So, the rubber feet under my EP800's don't do that?

I have a glass shelf that my VP180 sits on and I used 8 large IsoNode Anti-vibration feet from Bright Star Audio. They are reasonably priced and work well.

Thanks Alan I think I get it now. So basically if the sub or speaker is playing loudly. The riser and/or pad would eat the vibes so the surface its setting on would not feel the force. Am I on the right track or still off? Thanks

Hi,

Yes, you're on the right track. And to address Micah's comment about the rubber feet, sure, the rubber feet help. The photo shows the subwoofer with the rubber feet resting on the riser. It's the combination of dissimilar materials that reduces transmitted mechanical vibration to the floor or shelf beneath the speaker, but not acoustically generated vibration elsewhere in the room or even in the same surfaces (the floor and shelf) resulting from the subwoofer or speaker's direct acoustical output.

Some suppression is desirable because you don't want spurious resonances in vibrating shelves, floors, and walls mixing in with the music or dialogue. It can be annoying and distracting; e.g. metal or wooden venetian blinds vibrating at certain frequencies at high playback levels.

The argument for allowing some vibration/resonances is that they contribute to the realism of a musical experience. The best example is a big pipe organ in a church. If you've experienced that, the wooden pew and floor (if it's wood) in the church will vibrate with very deep pipe organ pedal notes and you can feel those in the wooden pew and floor. The same thing occurs in concert halls with deep bass from a symphony orchestra, or even in a club/concert with powerful electric bass. So it's part of the experience, and if that's what you're trying to simulate or recreate at home, then some bass vibration in the floor/furniture is desirable.

By the way, the place where you do NOT want any resonances is in a shelf holding a turntable for vinyl playback or in tube amplifiers. Vibrations in a turntable or tube amp may be transmitted back to the platter/disc and cause feedback. Tubes may become microphonic and pick up mechanical or acoustically borne vibration.

Regards,
Alan

Regards,
Alan

So because my center sits on the top of my shelf, and the Blu-Ray under it. I should think about mopads or something similar, once I upgrade to the VP180. Because the added movement (or resonances) might effect the disks playback. Thank you Alan

Normally moderate vibration has no effect on any Blu-ray, CD, or DVD optical disc playback, or on solid-state (transistor) electronics.

If the vibration was excessive, then it could perhaps disrupt the laser pickup in an optical player.

Optical players do vary from brand to brand and within different models in terms of sensitivity to vibration or jarring. If a player was unusually sensitive, it could result in audio drop-outs or image freeze-ups or other glitches in playback.

Alan