VMPS Larger Subs - Upgrade or Replace?

Linkwitz Riley · « **on:** 18 Feb 2011, 06:07 pm »

I have an all VMPS HT system that employs 2 Larger Subs (about 10 yrs old). They are passive and running off of a Crown K2 amp & an Audiocontrol RichterScale to flatten the response (X/O=80Hz). The room is about 22' X 22' x17' high but the entire lower level of the house is wide open and well beyond 10K' cubic. Most of my listening is music. I have always experienced "bottoming" of either a driver or PR during movie explosions etc., so I upgraded the 12" & 15" to Megawoofers when they became available, about 5-7 years ago. This still did not fix the problem and I have now noticed that when I kill the power to my Adcom GFA-555/RM2s and play only the subs, they actually struggle through certain parts of music such as Steely Dan's "Two against Nature". I have also noticed that my subs have a unique "sound" that is unlike other subs. They go deeper than most, but lack the visceral impact of many. Perhaps one may say that this impact is unnatural, but I'm not talking about bloated midbass. As a 35 year long "semi-audiophile" I have heard many, many systems and know good sound when I hear it. I am now certain that I want to either upgrade again or just replace these two subs. There have been so many iterations of drivers for these I must admit I'm a little skittish at throwing another grand or so at this & and not solve the problem again. I am looking at 2 VMPS options, either the TC sounds drivers (12, 15 & PR) or the Ultramegawoofers, with metal cones & big bump PR. I was told by Big B that the recommended move is the UltraMegas, but there seems to be a lack of info about these drivers other than the metal cone and their 'made by Eminence' pedigree. Has anyone done this? Can you relate your experience? I am assuming that the TCs would be too big (depth?) and powerful for my (too thin, inadequately braced?) cabinets? The alternative would be to sell the largers and buy something else, either new VMPS or Elemental Designs A7S-450's (without plate amp) or something else that would deliver enough sound to fill the space, be musical & handle movie soundtrack better. Any suggestions would be welcome!

Brian Cheney · « **Reply #1 on:** 18 Feb 2011, 10:28 pm »

I don't recommend fitting the TC 15" into the Larger because the relief isn't wide enough and recutting the front baffle would be necessary with a jig and router.

The Ultramegs have not bottomed out in the field even when used with big amps such as the Crown, which is why I recommend them.

Linkwitz Riley · « **Reply #2 on:** 19 Feb 2011, 03:12 am »

How would you describe the new sound of the larger with the ultramegas vs. the megawoofers w/standard PR? Are any other changes required (adjust fill amount, add bracing, etc.)?

Brian Cheney · « **Reply #3 on:** 20 Feb 2011, 02:16 am »

The Ultramegas have a much lower Fs (18Hz vs 24Hz) and a cleaner sound thanks to their metal cones. The result is punchier, more extended bass, higher output levels, less distortion.

ctviggen · « **Reply #4 on:** 20 Feb 2011, 12:28 pm »

You bottomed yours out? Hmmm...I have never done so, but then I haven't been able to play anywhere near reference level sound for a while with two kids in the house.

Waltlaw · « **Reply #5 on:** 20 Feb 2011, 07:04 pm »

Brian, on your website you give metal cones a "D" grade for noise and lack of self-damping. Have the Ultramegas changed your opinion in this regard?

Brian Cheney · « **Reply #6 on:** 20 Feb 2011, 09:32 pm »

Metal cones still lack self damping and have pronounced resonances (primarily cone breakup modes). What has changed in the past few years is that the breakup mode has moved away from the passband far enough to be properly suppressed with crossover.

This leaves self damping as a problem to be addressed. Good solutions include much higher, heavier surrounds of thick rubber, tapering of the cones themselves, and not using the drivers above a fairly low frequency. In the RM50 that's 220Hz, with a 24dB characteristic. You are left with pistonic motion in the passband and better clarity due to excellent stiffness-to-mass ratios. Motors are also typically much bigger, with high Xmax and improved BL products.

Linkwitz Riley · « **Reply #7 on:** 21 Feb 2011, 01:45 pm »

Yeah ctviggen, mine will bottom out badly on movie soundtracks and come close on music played at a higher level. I think part of it may also have to do with the fact that these 2 are trying to fill a large room and when I use the RTA on my AudioControl Richter Scale III and the 1/2 octave EQ, I end up boosting some of the lower frequencies by as much as 6db in order to achieve a smooth response. It does sound very good at low to medium levels, but when I am doing my critical listening to music I like it a little louder. I can get through a movie without bottoming by engaging the subsonic filter & rumble reducer switches on the AudioControl, but it really kills a lot of bass. Disengaging the EQ on the unit makes the bottom end sound bloated and very unnatural. I need drivers that can handle this scenario.

John Casler · « **Reply #8 on:** 22 Feb 2011, 08:57 pm »

I was just going to post that when Brian beat me too it

Jack D. · « **Reply #9 on:** 24 Feb 2011, 07:37 am »

Hi Brian, (John, anyone)

What are BL products?

Thanks, Jack D.

Brian Cheney · « **Reply #10 on:** 26 Feb 2011, 08:43 pm »

BL product is one of the Thiele-Small parameters that quantify many aspects of loudspeaker performance. BL product is the product of magnetic field strength times the length of wire immersed in that field. Higher field strengths
follow from using stronger magnets (with full magnetization) and longer voicecoils (say four layer VC's as opposed to two layer). Power handling also increases with increased wire length, if all else (VC wire gauge and surface area, plus venting) remain the same.

There is a danger in increasing magnetic field strength in that travel can be restricted (this is called magnetic self-damping). So, too much magnet field strength results in higher sensitivity but lower excursion, or loss of LF extension. It's a delicate balancing act.

Brax · « **Reply #11 on:** 27 Feb 2011, 12:34 am »

Are the drivers bottoming out or the PR, I'll assume it's the PR. I was thinking of upgrading the the Big Bump PR to make sure this doesn't happen.

I've always read that you should only cut on the EQ, then just boost the whole sub level.

Linkwitz Riley · « **Reply #12 on:** 11 Mar 2011, 07:42 pm »

I noticed that the high end option on a new VMPS Larger Sub includes The TC sounds LMSr-15 & 12 drivers but not the TC sounds VMP. It uses the Big Bump PR instead (better?) So....the question is: If I can modify the openings on the front baffle of my existing Larger Subs to fit the TC drivers, would this be the best upgrade possible? Is the cabinet strong enough? Do I need to modify the internal bracing? I just want to go with the best variation of this sub and be done with it. I don't mind doing any required modifications.

John Casler · « **Reply #13 on:** 14 Mar 2011, 02:42 pm »

LR,

Brian can answer this best, but the short answer is yes, to achive the best result, you would certainly want to reinforce the bracing.

As we now know it does also entail modding the baffle.

At this point the subs that work best for the OMG mod are the VSS and the VLA.

While B can also answer this, I think he has stated that the Big Bump is sufficient for that use, and that the dimensions of the TC's don't allow easy use of the VMP PR in that case. (all the TC's are deeper)

Linkwitz Riley · « **Reply #14 on:** 14 Mar 2011, 05:51 pm »

OK, if it is possible to modify my VMPS largers to use the TC sounds drivers and BBPR I would like to do it. I don't mind working a little harder for the best sound! Can someone provide some instruction and the parts list & cost for drivers & any other parts which are required?

Vr3 · « **Reply #15 on:** 18 Mar 2011, 02:37 am »

In the stock enclosure the 15" will hit the PR -- trust me I tried putting it in there before I sold mine.

The only way you could mount the 15" is to put a space ring on the cut out to bring out the driver and regardless of this mod you wouldnt be able to use the grill anymore.

The TC Sounds drivers just dont work in the stock enclosure.

Linkwitz Riley · « **Reply #16 on:** 18 Mar 2011, 12:26 pm »

OK then...Ultramegawoofers (12" & 15") and BBPR sounds like the only practical way to go! Anyone out there done this? What do you think of the results?

Long Ear · « **Reply #17 on:** 29 May 2011, 02:22 am »

I just finished installing the new ultra-mega 12" & 15" woofers & BBPR in my 2 year old larger subs last night.These are run through a DSPeaker anti-mode 8033 for each channel & are powered by the Dayton 1000 watt amps x-over at 75 hz.
My main speakers are stock RM40's also 2 years old.
The difference is amazing & justifies the added expense.
The bass is now tighter & punchier along with much better
definition & can be turned up louder with no boominess, cone break-up or bottoming out of the BBPR even when the
clipping indicator on the sub amps flickers.
Heartily recommended upgrade...go for it.
Now if I can convince myself to install the new CDWG's

Brian Cheney · « **Reply #18 on:** 29 May 2011, 07:28 pm »

Terry from The Long Ear in Coeur d'Alene ID (formerly located in Big Bear Lake Ca) is the oldest VMPS dealer in continuous service, now over 33 years. He is an experienced audiophile and always great to deal with.

In the past year and a half, no one has been able to bottom out the Ultramegawoofers, even when using the largest high power pro amps. Nor has anyone burned one out or experienced a failure of any kind with these cast frame, metal cone, 160oz-motor behemoths.

DFaulds · « **Reply #19 on:** 3 Jun 2011, 01:43 pm »

I have a line on a larger sub with mega woofers and the 1,000 watt amp. What would it cost to get the ultra-megs and the better passive?