[Dionisio]

I have about 8 year old RM2s, mega woofers, upgraded to Neo panels.  I use them for both music listening and home theater.  No sub.  Recent Onkyo 886 processor.  Had been powering them with 1 NAD 218.  Went to biamping recently for the woofers with a Yamaha xp5000, with a type of downconverter power supply amp (IEEE engine or something like that).  Kept the 218 for the mids and tweets.  Still have the popping on moderately loud movie passages, explosions, that type of thing.  Sounds more like the pop you would get if you touched the input of the amp.  Did it with the 218 and still with the Yamaha.  I read some of the entries about driver or PR bottoming, doesn't sound like that to me, but maybe it is.  Any ideas would be appreciated.

[John Casler]

I have about 8 year old RM2s, mega woofers, upgraded to Neo panels.  I use them for both music listening and home theater.  No sub.  Recent Onkyo 886 processor.  Had been powering them with 1 NAD 218.  Went to biamping recently for the woofers with a Yamaha xp5000, with a type of downconverter power supply amp (IEEE engine or something like that).  Kept the 218 for the mids and tweets.  Still have the popping on moderately loud movie passages, explosions, that type of thing.  Sounds more like the pop you would get if you touched the input of the amp.  Did it with the 218 and still with the Yamaha.  I read some of the entries about driver or PR bottoming, doesn't sound like that to me, but maybe it is.  Any ideas would be appreciated.

FIRST; Welcome to Audio Circle and the VMPS circle

From your description it is hard to tell if you are getting the sub to bottom out or not.

While the RM2 has exceptional deep and musical bass, it can be driven too hard if you play it too loud. This will seldom occur with music (except some RAP at high levels)

The transients present in some of the newer action films are exceptionally low, with steep rise times.  The RM2 woofer and PR do not have a large excursion and play deep due to large surface areas, not long throws. (xmax)

This is the reason the VMPS bass is so resolving.  It doesn't fight the physics of accleration and momentum as much as the high XMAX drivers.  But that quality does reduce slightly the SPLs.  LFE (Low Frequency Effects) are pretty much created for SUB reproduction at higher SPLs.

However it might also be that the amp is not tracking the transient and momentarily clipping.

It could also be that the Passive Radiator is too light (add putty) and is over responding, has deteriorated, or is leaking (not sealed)

Solutions:

Simplest and best is to get a sub for HT use, and run it from 40 or 60 on down for HT.

Or install a new PR which has been vitrified.

[Dionisio]

I think it is likely that the sound is the driver bottoming.  It appears I do have leaks in the units, the PRs are deteriorated with some small splits in the surrounds.  So I definitely need two new PRs regardless of what I do ultimately.  I would like to not add a sub if possible.  Are there also 12" Ultra Mega Woofers available for the RM2s?  If yes, are they longer throw than what I have?  Or other advantages to handle movie soundtracks?

[Brian Cheney]

You can order the VLA 12" for $240ea for the RM2.  New PR's are $48ea.  The VLA 12" have 18mm of Xmax and have dustcaps.  Should solve the problem.

[John Casler]

I think it is likely that the sound is the driver bottoming.  It appears I do have leaks in the units, the PRs are deteriorated with some small splits in the surrounds.  So I definitely need two new PRs regardless of what I do ultimately.  I would like to not add a sub if possible.  Are there also 12" Ultra Mega Woofers available for the RM2s?  If yes, are they longer throw than what I have?  Or other advantages to handle movie soundtracks?

Then B's suggestion is the ticket.

The ULTRAmegaWoofer is a beast.  And as B says it has a higher Xmax which creates HUGE bass impact and dynamics.

It has a lighter, stiffer cone, a larger stronger magnet and basket, and you add that with the new "vitrified" PR's and you should be in business. (as long as your amps are not clipping)


How do you like your 886?

I have recently been placing 5507's and am awaiting feedback.

Are you using it as a 2 channel Preamp too?

[Dionisio]

I would like to purchase the new PRs and woofers.  Are you available to place the order today?

I don't think the Yamaha amp is clipping.  It is rated at 500 watts/channel into 8 ohms and about 700 watts into 4 ohms.  I did quite a bit of research before I purchased this amp to drive the woofers.  It is Yamaha's version of a tracking power supply, combining class AB and D. 

I am pleased with the 886.  I use it for 2 channel also.  I have the Denon 2900 for SACD and DVD Audio.  For analog stereo and multichannel inputs the 886 offers no further processing of the signal through its Direct and Pure Audio selections.

People also like the 886 to do the decoding for DVD Audio and SACD through HDMI with a player like the OPPO.

[Dionisio]

Just a few other comments.  Hopefully the new woofers and PRs will fix the problem with movie sound effects, but I noticed that the 886 allows "Large" fronts plus still choosing a subwoofer.  In this way the only audio which goes to the sub is the LFE, so it would not affect my music playback.  I could then get a small sub, which I could find space for, suitable for sound effects.

 

Some more info on the Yamaha XP5000.  This is a "White Paper" on the technology of the amp:

 

http://www.yamahaproaudio.com/downloads/documents/data/white_papers/yamahapoweramp_whitepaper_en.pdf

 

It has selectable maximum gain.  I am using 32 dB and then cutting it back to 29 dB to match the NAD 218.  The cooling fans have not come on in my use, and they are temperature controlled, continuously variable speed.