How much more output does a B4+ have? (1 Viewer)

[steve nn]

I tried MATRIX RELOADED in the 16 hz tune at -6 with my three 25-31CS+s and it was a hoot! Not a common practice but still a experience to be experienced.

Thats a good idea Mike. I should put the bass disk in and see just what I'm looking at in regards to response. It only goes down to 15 hz though.:frowning:

 

[TommyL]

Spike, you've hit 8 Hz? what kind of spl's you hitting at that level? Just curious because I may have to get my port plugs out and try it on the darla scene to see just how deep that goes

 

[Mike_Skeway]

In my room I am hitting about 104dB @ 8Hz with the volume set at reference. I can get more out of it with different settings (but then the bass doesn’t blend very well.) and by going beyond reference. There is quite a drop in SPL from 10Hz to 8Hz. With some test that I would not recommend, I was able to get it down to 5Hz., not much SPL in the listening position though. 1 Hz produced no SPL but the woofers moved in and out slowly. I never bottomed out this sub. (I ran through some tests that can be bad for subs, these are what I used when I was building automotive competition systems, BTW I blew many a system in my day).

I rarely listen at reference, even below reference, my B4+ will shake the house, I have been leaving three ports plugged lately. It is not having a problem with SPL and I get nice and low to boot. When I want max SPL, I do unplug them all though or maybe just leave in one.

YMMV

 

[Zack_R]

The Darla scene is fun but not as low as others in the movie. Give the whale scene a whirl with your port blockers. It offers much more potent subsonic activity.

 

[John Doran]

i agree; the opening scene when trinity and the agent are falling from the building, the part when the bomb goes off, and hammer at the end, are all ridiculous exercises in bass.

 

[dave alan]

"...Frankly, I was floored at what I was seeing on the PC screen as I tried various combinations and re-ran FR sweeps.

I have a new found appreciation and respect for the continuously variable phase control SVS wisely chose to include in the Plus series of powered subs.

And while I can't recommend it for basic set-up, engaging the low pass filter on the SVS and cascading it with the low pass filter in the pre/pro can also provide a great deal of tuning ability in the 60-100 Hz region. Normally, the filter should be disabled, but if you know what you are doing and have the ability to check the effect of enabling this control at various frequencies, it can really be an eye opener."
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Edward,

I've been experimenting with placement (in relation to the distance to the mains), phase adjustment and filter slopes (including cascading an outboard filter with the Preamp's LP filter) for several months now. I've been able to arrive at a time aligned, flat FR curve (+/-2dB) using no EQ.

It, of course, makes an easily audible difference, regardless of the sub used.

If a sub is placed in a corner (say, 3 feet farther away than the mains) and DSP based EQ is employed to flatten peaks and the phase is not properly adjusted, then you'll experience anywhere from 6 to 30MS of smear, along with cancellations and peaks, every time.

When you add the mismatch of filter slopes, in-room, you generally have a fairly poor utilization of your sub.

You're correct to point out that proper equipment is required to monitor the changes, but it can be done on-the-cheap if you have some patience and the right procedure.

It's great to see that someone else is experimenting with other facets to sub tweaking besides parametric EQ and hit-and-miss sub placement.

 

[Edward J M]

Hi Dave:

I was running Quick Sweeps from 10-20,000 Hz and it was very interesting to watch the combined FR of the sub and mains go from just awful to really quite flat just by tweaking the continuously variable (0-180) phase control and the low pass filter.

I had no idea the phase control affected the FR to that extent. It seemed everything just fell into a "sweet spot" with the phase set at about 110 degress and the 2nd order SVS low pass filter engaged at 60 Hz and the 4th order pre/pro low pass filter engaged at 80 Hz. Suddenly the curve was +/- 4 dB (with no ugly peaks or valleys), from 35 to 110 Hz - and that's at 1/24 octave resolution.

Below 35 Hz, room gain comes into play and the response steadily and smoothly rises to a plateau from 23-16 Hz where it is about 7-8 dB higher than baseline. This room gain can't really be heard on most music sources, but it definitely makes its presence known on deep HT stuff.

Anyway, I put my test rig together on a shoe string budget. Mic, preamp/mixer, software, and professional calibration of mic and preamp/mixer set me back around $400 (sans PC of course). It needs a pretty powerful PC to work, as the real time analysis takes a chunk or processing power. I'm running a Pentium 4 2.0 gHz and 512 RAM and it seems to require about 40-50% of the PC resources while it's running.

Whenever you are done with your project, I'd sure like to see you go public with the results - some really cool stuff you are working on.
Ed

 

[TommyL]

Hey Doran, good to hear from ya man!