Larger Subwoofer question

Deven · « **on:** 21 Jun 2006, 12:59 am »

I went by the VMPS website, and I am/was interested in the larger subwoofer, and on the site Brian goes on to mention the merits of separate sub from amplifier, avoiding class D amplifiers, etc. My friend just ordered one and told me that the sub now comes WITH an amplifier (class D)? Why the contradiction/change in design? Can the larger subwoofer come without the amplifier, or is the sub better with the amp supplied vs external monoblock? I was leaning towards the VMPS sub, but if it comes with the amp, I might as well just buy a SVS sub then? Thoughts, comments?

Brian Cheney · « **Reply #1 on:** 21 Jun 2006, 01:02 am »

Our subs are available with or without amps.

The amp we like is class AB, 1000W rms into 4 Ohms, and is encapsulated. It features an electronic crossover and a single band parametric EQ. It's $400.

For more info go to the sticky "After 21 years, powered subs!"

john1970 · « **Reply #2 on:** 21 Jun 2006, 01:10 am »

Deven,

I own a pair of VMPS RM40 speakers and feel that there is no need to add a sub for music. However, I did purchase a SVS PB10 sub for HT purposes. In my medium size room (14' W x 25' L x 8' H) with a near-field (9') listening position I am very satisfied with the VMPS RM40 bass for the music and the SVS sub bass for movies.

In my opinion if the sub is going to be used for music go with one of the VMPS subs with an external amp. My experience with sub plate amps (from well respected manufacturers) is that the amps do not last too long. If the sub is going to be used ONLY for moives I would go with a lower end SVS because you will save some money relative to the VMPS. PLEASE NOTE THAT FOR MUSIC OR DUAL USE THE VMPS IS THE BETTER CHOICE.

Cheers,

John

P.S. I went with the PB10 becuase for ~$450 it is an excellent sub for movies only. Good luck.

CornellAlum · « **Reply #3 on:** 21 Jun 2006, 01:37 am »

The VMPS larger is truly a giant killer, reccomended wholeheartidly. The best complement I have ever had on the sub was the question, "is the sub on?"

John Casler · « **Reply #4 on:** 21 Jun 2006, 07:31 am »

It is late, but I will chime in tomorrow about placement information about Mains and Subs, that is critical to getting the best "musical" response.

There are far too many set up and placement errors commited, when adding a sub into the system.

Let me get some "shut eye"

and I'll try to cover some of them. (that is if someone doesn't post them before I wake up

)

John Casler · « **Reply #5 on:** 1 Jul 2006, 04:39 pm »

Quote from: John Casler on 21 Jun 2006, 07:31 am

It is late, but I will chime in tomorrow about placement information about Mains and Subs, that is critical to getting the best "musical" response.

There are far too many set up and placement errors commited, when adding a sub into the system.

Let me get some "shut eye" and I'll try to cover some of them. (that is if someone doesn't post them before I wake up )

What a great nap that was. What was it about a week?

In any event, my advice to those who use a sub with their mains is this:

Integration - many sonic problems are realized because we try and "integrate" our subs with our mains with too much "overlap" of the frequency band. If we have small woofers (in the mains) and larger woofers (in the subs) producing the same frequency, then we can have problems.

Those problems are many:

a) the overlapping frequency will create a peak or rise in SPL
b) the two drivers will not be exactly 'in phase' and we have rubbery, or wooly bass
c) the two drivers are "in phase" but not in the same plane, which causes them to still arrive at the listener and not be "phase coherent".

The solution is to:

1) set the crossover to minimize the overlapping frequencies
2) Make sure the phasing is correct and if your crossover has a phase dial, spend some time adjusting this to achive the best result
3) Arrange your sub(s) in an ITU (a semi-circle where all speakers have their acoustic centers the exact same distance from the listener

Now these tips are not as important for HT as they are for music. In HT, much of the duties for the sub are simply to add "sonic impact" to various "foley" and effects, and the subtlties of detail and such are less important. This will aloow you to place the SUB in the corner or out of ITU config, simply to promote additional "room gain".

And I might add there are specific devices and programs (DEQX, TACT, and some other room and speaker equalization systems) that will allow the sub to be placed out of the ITU place, and correct for arrival time, and phase coherncy via signal manipulation and timing.

But, in general, if you want the most detail and clean bass, you will need to be aware of reducing the problems of "integrating" the drivers properly.