B4+ Where are the other two drivers? (1 Viewer)

[David Ruiz]

Ok...this might seem like a REALLY stupid question to all of you people who know much more than I do about subwoofers, but where the hell are the other two drivers inside of the B4+?

If I'm not mistaken, there are supposed to be a total of 4 drivers inside of it, am I correct? And two of the drivers can easily be seen at opposite sides of B4+. You can also see how big their magnets are, if you take off that black peice.

Just two drivers nearly go from side to side already. Couple that with the four ports which are EXTREMELY deep (practically reaches the other side) and you're left with almost no space what-so-ever to fit another two drivers (same size) as the ones that can be seen at the opposite sides. I'm guessing that we're left with about 8 inches of space (after the ports end) in order to fit more stuff, but the drivers are 12" right?

Maybe I'm just mistaken. Perhaps there are only two drivers in this thing. I can hardly believe that there is any room for all 4 drivers in there.

 

[frank manrique]

quote:
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Ok...this might seem like a REALLY stupid question to all of you people who know much more than I do about subwoofers, but where the hell are the other two drivers inside of the B4+?
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If you look at one of the longer sides of the enclosure or "box" you'll find what appear to be is a speaker grill. Pull it out and you'll see where the other two drivers are located (inside and opposite to their mate's location, which is on the outside)!

Please note that the B4-Plus subwoofer uses a bass loading configuration called "push-pull." Such loading requires the use of two, four, or even more bass drivers, the actual number being dependent on what design engineers wish to achieve, hence the deployment or arrangement of said bass drivers.

Hope this helps...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[Edward J M]

This should help clear things up. Here's the two inner drivers. Photo courtesy of John E. Johnson Secrets Of Home Theater and Hi Fi

 

[Dan Halchak]

Puuuuuurrrrrrrrttttyyyyyy.

I want one, I want one!

 

[SandellV]

i want to see ultra's in there instead of the plus...

 

[Kenneth Harden]

You can bet we will see that at some point.

 

[Scott Goldsmith]

Yeah, but the box would be as big as some small houses Those Ultra's need some room to breath!

 

[David Ruiz]

It is at all possible just to take out the current B4+ drivers, and install the Ultra ones in their place? Or perhaps just the back ones (the ones that can not be seen)? That would be cool...especially if you have tons of power to give them.

 

[ChrisWiggles]

This is something you should ask SVS if you own this sub.

But because of the way isobarik loaded drivers work together, different drivers probably is a bad idea.

 

[David Ruiz]

You're probably right. But it would be fun to switch out all 4 drivers then, and replace them with the Ultras. That way there wouldn't be different drivers in there. I wonder if someone could actually do it. I do have the B4+ but I'm still paying for it (on my credit card) so I can't afford to buy these Ultra drivers to replace the current drivers with.

As much as I absolutely *LOVE* the B4+...it's the very best subwoofer I've ever owned, and I've owned lot of them over the years, I still manage to bottom it out a few times. I'm sure that wouldn't happen with the Ultra drivers in there.

Don't get me wrong though....it's the best subwoofer in the world, but when you've got an extremely large room like mine, and it's all made out concrete, you tend to want the concrete floors to shake (like wooden floors) and the only way to do that, is the run the sub about 15dB too hot, and that of course, causes the drivers to bottom out.

 

[frank manrique]

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You're probably right. But it would be fun to switch out all 4 drivers then, and replace them with the Ultras. That way there wouldn't be different drivers in there. I wonder if someone could actually do it. I do have the B4+ but I'm still paying for it (on my credit card) so I can't afford to buy these Ultra drivers to replace the current drivers with.

As much as I absolutely *LOVE* the B4+...it's the very best subwoofer I've ever owned, and I've owned lot of them over the years, I still manage to bottom it out a few times. I'm sure that wouldn't happen with the Ultra drivers in there.

Don't get me wrong though....it's the best subwoofer in the world, but when you've got an extremely large room like mine, and it's all made out concrete, you tend to want the concrete floors to shake (like wooden floors) and the only way to do that, is the run the sub about 15dB too hot, and that of course, causes the drivers to bottom out.
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David, he's quite right, you know...

Look, even if it was possible--which it isn't because a whole new sub utilizing the "Ultra" drivers would have to be designed from the ground up--to switch to the TV-12 bass drivers (and am not saying it wouldn't be fun doing it!)...they're so costly (nearly $600 each) in addition to what shipping charges would have to exact from your pocket-book...that cost-wise would be totally counterproductive!

In my opinion, in your case the best AND cheaper solution would be either to get another B4-Plus sub, or sell it and then purchase two PB2-Ultras. Choosing either route will greatly reduce or lessen any chances of driver bottoming down from happening in your HT environs ever again!

Now I have to ask: are you absolutely sure that what you heard was actually driver (s) bottoming down rather than the driving amplifier running out of gas instead?

You know, I own two B4-Plus (bought them recently) and for a while was auditioning them in what I call "small" HT system.
I availed the use of an old Soundcraftsman 250 watts (RMS) @ 8-ohms per channel amplifier to temporarily power the B4+s and although some of the listening sessions (I was "testing" a pair of new speakers in this system as well) were rather spirited (reference levels), I never heard any bottoming down, not even with one sub alone (it occurred when the right channel of the power amp blew a speaker line protective fuse during one of those sessions), so that's why am asking if what you heard was actually severe amplifier "clipping" instead.

By the way...because the main, "big" HT system is located in a rather large acoustical environment (not quite as large as yours, but still larger than most HT rooms) and because I want as clean sonic playback performance as it's possible to obtain from what I've assembled as the sound system thus far...I finally decided to spend the bucks and utilize several subwoofers in order to increase dynamic range (headroom) capability to a level not possible otherwise, greatly lessening dynamic compression under heavy playback loads (at "reference" sound pressure levels and then some!), while diminishing distortion components to as inaudible levels as the system would allow.
Of course, suitable amplification power availability had to enter the equation and be considered too, so had to take care of that end as well (and am not done yet!).
It was to this end that I wound up purchasing eight SVS 16-46 cylinders (from the very first batch ever manufactured by SVS, I believe) with which to achieve my initial intended target.
However, I began to think that it would also be terrific to experimenting and see if I could integrate SVS' new subs with this tubed subbass array, so I purchased the above referred to pair of what I call "Black Beauty" twins.
I reckon that no driver bottoming down will ever happen with this ensemble!

Overkill you say? Well, some will say it is. On the other hand, some will say is A-OK. I say it's my wont so am sticking to it!...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[David Ruiz]

You know...I never really gave dual B4+ a thought, but now that you mention it, it would probably solve any problem I might be having right now.

I don't think it has anything to do with the Crown K2 Amp that I'm using to power the B4+ though. You mention that I might be clipping the amp, but it comes with these little dots that will light up should you be pushing the amp too hard, and one of the them, should let you know when it's clipping, and I've never seen it turn on. The K2 provides 2,500 watts of power, and I've heard many say that even a K1 is more than enough for a B4+ because most of the power from a K2 amp will never even be used anyway.

I have two of the 4 ports plugged, which greatly reduces my overall output, but I love the deeper bass that it provides that way. I've heard a ton of people talk about port noise (when multiple ports are cover) so that could be what I'm hearing, but I have a feeling that the drivers do bottom out on occasion. Sometimes I push the thing incredibly hard, more than any normal person in the world would do, so I'm sure it's bottoming. I even play it louder (on occasion) than those people that have extremely bassy car systems that go around disturbing the entire neighborhood with their extremely obnoxious bass.

 

[Edward J M]

It's been done by SVS. The B4+ was the only subwoofer that didn't obviously benefit from the dB-12 to TV-12 upgrade. And the weight went up considerably.

If you bottomed the B4+, I would recommend the use of a very steep high pass filter set to around 15 Hz.

Frank, your approach to low distortion, dynamic bass is laudable and right-on.

 

[frank manrique]

quote:
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You know...I never really gave dual B4+ a thought, but now that you mention it, it would probably solve any problem I might be having right now.

I don't think it has anything to do with the Crown K2 Amp that I'm using to power the B4+ though. You mention that I might be clipping the amp, but it comes with these little dots that will light up should you be pushing the amp too hard, and one of the them, should let you know when it's clipping, and I've never seen it turn on. The K2 provides 2,500 watts of power, and I've heard many say that even a K1 is more than enough for a B4+ because most of the power from a K2 amp will never even be used anyway.

I have two of the 4 ports plugged, which greatly reduces my overall output, but I love the deeper bass that it provides that way. I've heard a ton of people talk about port noise (when multiple ports are cover) so that could be what I'm hearing, but I have a feeling that the drivers do bottom out on occasion. Sometimes I push the thing incredibly hard, more than any normal person in the world would do, so I'm sure it's bottoming. I even play it louder (on occasion) than those people that have extremely bassy car systems that go around disturbing the entire neighborhood with their extremely obnoxious bass.
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Ah, so! That explains why you're experiencing such pesky sonic anomaly: dynamic compression as a result of plugging two ports on the B4+ (refer to Ed's comments to the effect elsewhere), which might also be taxing the K-2 amp spite of its total rated power output of 2400 watts (don't say that is not possible to use up all the power this amp produces because you just never know exactly what happened since peaks occur instantaneously!).

In your unique case it seems to pan out that way, particularly when you're using the Crown K-2 amp (lucky, lucky! ), so all the more reason to consider adding another B4-Plus (and another K-2 as well. Sorry! :b ) which am almost certain will solve the problem altogether, even with the two ports plugged.

Food for thought, eh?...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[Tom Vodhanel]

>>>But because of the way isobarik loaded drivers work together, different drivers probably is a bad idea

 

[frank manrique]

quote:
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If you bottomed the B4+, I would recommend the use of a very steep high pass filter set to around 15 Hz.

Frank, your approach to low distortion, dynamic bass is laudable and right-on.
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Oops! Totally forgot to mention low end filtering. Thanks!

Ed, am glad you are one of the few people who consider my approach at infrasonic bass reproduction as not being totally nuts...like many folks do!...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[Craig Chase]

Frank - Most people also think a Rolex is a stupid way to spend money, until they win the lottery....

 

[frank manrique]

quote:
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Frank - Most people also think a Rolex is a stupid way to spend money, until they win the lottery....
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Indeed!...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[Richard_M]

Hi David



Another alternative for an interim or long term solution is the use of a shelving filter.

The Behringer Ultracurve Pro DEQ2496 and Ultradrive Pro DCX2496 have the ability to program these types of Dynamic EQ filters as well as parametric EQ.



Basically you program the freq, threshold, slope, ratio, attack & release, once the input exceeds the threshold the DEQ filter cuts in and attenuates the output below the set freq by the amount programmed, it still allows for the audio to be output below the set freq just at a lower level, of course once the output is below the threshold the DEQ is disabled.

The plus with this type of setup is that you still get to have the full freq range available and if your sound track has a sudden dynamic gain (volume dependant) your sub has some protection.

In your setup an additional sub would be a definite advantage, this also brings about its own problems, therefore you will probably purchase some form of Parametric EQ anyway.