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

Hi Guys,

I'm really sorry if this question has been asked before, but I couldn't find any exact information.

A friend of mine, has an SVS 16-46 PCi which he keeps bottoming out, because his room is too big. It's 20x20 and the ceilings are 16 feet high, I believe. Anyway, the SVS bottoms out, at -15dB from reference, and it's calibrated properly.

What he wants to know, is how much more output does a B4+ have than the 16-46 PCi? Will he finally be able to play his movies AT reference, without having his sub bottom out all the time?

It has quite a bit. I would email Tom or Ron at SVS for the exact answer. I have it in email from them somewhere, but I cannot seem to find it. :frowning: I think it just may fix his problem.

I am happy with my B4+, no bottoming out. My effective room size is ~6000 cu. ft., very close to your friends.

I have yet to come even close to bottoming mine out...as TV said, the amp will clip long before the sub gives out (I use a crown K1...1500 bridged. I have it in a 4500 CF room...one of the best purchses I've made...hands down

BTW, I power mine with a Peavey GPS 3500 (bridged).

David,

Your friend bought probably the poorest choice for a room that size if he's interested in approaching reference level bass I'm afraid.

It goes very very deep, but it's certainly not the output king for typical movie bass, and not in a room that large.

Adding a second PCi would be the first best way to improve things. Adding a PC-Plus (with close to twice the raw output of a PCi) would be even better. The PC-Plus could be run a bit "hotter" than the PCi and he'd have virtually the output of three of his current subs by simply adding the PC+.

Cost-wise that's the way to go, the fact we give returning customers a little discount or free shipping means it'll soften the blow even more.

The B4-Plus?? It won't be as flat to 15Hz probably but it'll hardly matter. Figure close to 4-5 of your buddie's PCi subs without too much trouble at all. We're talking totally different sort of league here (good as the PCi subs are).

Have hime drop us a line, even though it sounds like the PCi is working its heart out, he needs more grunt to get low and loud for sure.

Ron

I run three 25-31CS+'s which is about 80% of a B4+ in a 2880 cf room. Headroom is not a issue and I have plenty to spare. Dual would be more than sufficient in my situation. Your friend should not have a problem with bottoming out the B4+. More could be said about tuning and bottoming but the B4+ would provide the headroom needed to deviate from the original 25 hz stock tune if called upon also I would think? SVS would need to confirm this of course.

From the reading, TV once told me the best scenario is with the K1 powerwise (that they offer) jumping up 1000 watts would only yield a 2-3 DB gain on headroom... I think he used 5000 watts and gave it the true test..Ron can probably confirm this...so really you don't need to have gobs of raw power to hit 130 DB's...if that is what your into. Sell the PCI, and grab a PB2...another option

What's the difference between bridged, and un-bridged? What exactly is that, and what does it do? Which is better?

Bridged is combining two channels into one for the affect of more power/watts.

Going from 1800 watts (K1) to 2500 watts (K2) yielded a 1.5 dB increase in SPL. Above 2500 watts, odd order harmonic distortion jumped considerably and compression (probably thermal and suspension induced) started to set-in.

1800 watts is just about perfect for the B4+; anything more is a quickly diminishing return.

The other big advantage with the B4+ is the native tune point of 25 Hz. At the frequencies where all the huge bass hits are occurring, the B4+ is tightly coupled with the resonators (vents) and cone excursion is considerably reduced and well controlled. It would be damn near impossible to bottom a properly set-up B4+ (or a PB2+ for that matter) on the typical hot bassy DVDs.

Contrast that to the 16-46 enclosure with a 16 Hz tune point. The woofer has to shoulder almost the entire load in the >20 Hz region, with little help from the vents. Cone excursion is considerably higher in the 25 Hz region as compared to a 25 Hz tuned sub like a 25-31, a PB2, or a B4. It is comparatively easy to bottom a 16-46 enclosure in this region, and that's why SVS usually recommends two of them (or a even a different model size).

Regards,

Ed

As always, ED puts the finishing touches on it...but I KNEW the law of diminishing returns came into play somewhere in that neighborhood Ed, how goes the battle anyways? Good to hear from ya tom

Maybe he has already tried, or is stuck with a certain (un-best) placement location.

BUT, has he tried different locations in the room to maximise what he already has.????

It is a large room and Ref spl regardless of placement is most likely not possible period. Still I am curious as what he has done to get the most from the single 1646-pci 16Hz tune.

Geoff

Hi Tommy! The "battle" goes very well, thank you. I spent the better part of yesterday messing around with placement and fine tuning the PB2+.

I moved it to a corner and really started experimenting with the phase control and the low pass filter setting (yes you read that right). I must have run at least 3 dozen Quick Sweeps with True RTA. I learned that both controls have a huge impact on the in-room curve at the seat, and not just near the xo point.

There is absolutely no way I could have learned as much as I did about these controls and room interaction without my test rig. 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.

I can't wait for the single band parametric EQ SVS will be including on the PB2-Ultra. Talk about tweaking.....

Ed

Geoff I'm sure you know he would not be able to come close to reference levels of performance in a room that size with the 16-46. The tune as Ron and Ed state is just way to susceptible to bottoming in a room that size. When I first read the post I said (O my Gosh) that poor 16-46. Put a 25-31+ in there and it will do much better but it still would be asking it to carry quit a load.

Ed maybe we (other members) ought to put our heads together and come up with a new nickname for you? Something to do with Tweaker

Triple Threat

Already have one....it's "Dr. Spec". :b

Nickname was originally given to me by my long-range shooting buddies for my uncanny ability to dredge up all sorts of ballistic, wind drift, and trajectory data for different calibers. It's stuck ever since, and it's my handle over at Club Polk.

I didn't know that the B4+ was tuned to 25hz. Hmmm, I don't think he would like that at all, since he doesn't really want to HEAR the bass, he just wants to feel it.

Which other SVS subs give more output in the 16-20 hz region?

It comes with port plugs...so it can be tuned any way you like it...trust me, you feel it far more than hear it check my HP to see what the ports look like...its nice having this feature.

Yes, having a stock tune point of 25 Hz, doesn't mean it won't extend lower. In a typical room with all ports open and corner loaded, the B4+ should be strong down to 20 Hz before starting to trail off.

Like Tommy said, it can be tuned even lower with output to spare. Plug one port and you should see strong response to about 16 Hz - plenty deep for any DVD or music.

Remember, the 16-46 actually extends down to around 12 Hz in most rooms. It's tuned almost too low for most popular applications; you give up quite a bit of headroom (compared to a 25-31 for example) for that last bit of subsonic material that is extremely rare in any source material.

exactly...its kind of a "custom" deal...I run it fully open for the most part, but 1 port plugged doesn't seem to effect headroom any, and you get some good clean spl's from it...it is one of my best HT pieces purchased yet!

The B4+ has three tuning plugs, you don’t need to keep it at the stock 25Hz (In my room it goes down to 21Hz flat with no ports plugged). I play with my tuning all of the time. With one port plugged, I am getting ref SPL down to 17Hz in my room. I am also getting down to 10Hz only ~-1dB with three ports plugged. It goes down to 8Hz and below no problem with three ports plugged, and not a major drop in dB. I have my B4+ corner loaded ports firing into the wall.