[Michael V]

Hello,

I've been running a 15" augmentation woofer with B200's for a while now, and I'm starting to miss that last bit of extension in the bass.  For various reasons, I do not want to go active so high sensitivity will be needed.  I was just looking at the Warrior 18:

http://www.shredmuzic.com/product_p/813-022.htm

Fs:  30hz
Sensitivity: 101db
Qts: .75

Compared to my Hawthorne SI woofer, the Warrior's lower Fs and higher sensitivity suggest it will handle deeper bass.  Its Qts is lower, but still respectable (and according to some, perhaps even closer to the ideal).  I only need to augment up to 200 or 250 hz.

Does anyone have experience with this woofer, or advice on running 18" drivers in general?  Any reason to avoid 18's, aside from space? 

Thanks
Mike

[Kevin Haskins]

A larger woofer doesn't necessarily give you better extension.   In fact, in box subwoofers,  larger woofers give you a higher F3, with all other variables remaining the same.     Why?   Because you increase Sd (cone area), which increases Vas (effective air spring of the driver) and Vas is proportional to Vb which is the overall box size.    So... if you increase cone area by 25% you just increased the box size by the same amount in order to maintain the same bandwidth.   

High sensitivity runs counter to deep bandwidth.   Sensitivity is really only a combination of Mms & BL (moving mass & motor strength).   If you increase sensitivity you do so by increasing BL and/or decreasing Mms.    When you do so, it changes the unassisted cut-off, higher sensitivity drivers won't play as deep (all other factors equal) as a lower sensitivity driver.     Efficiency at lower frequencies is not changed though.   If you do a careful analysis of how much power it takes to get a certain SPL @ 25Hz, it is the same whether you use a low sensitivity driver designed to deliver that bandwidth (low Fs, Low BL) as it does if you use a higher sensitivity driver electronically equalized.   

So... hope I've not confused the matter.    What bandwidth are you trying to get?  Maybe we can go from there.   

[richidoo]

Thanks Kevin, some really good info there.

[Michael V]

Hi Kevin, thanks for your post!

I would say my goal is to be flat to 35 or 40 hz.  And, I should state: this is only for music, played at reasonable volumes - no locomotives or epic battle scene SPLs.

[nullspace]

Hey Mike --

There is no way on God's green earth that they're 101db/1W. Maybe in cone breakup they go that high, but I would expect piston-band efficiency to be around 92-94db/1W. I've had a couple different pairs of woofers from those guys come through my house, and none of them have been near as efficient as stated. In general, I'd say their posted theile/small numbers should be viewed as 'a rough approximation'.

That said, the ones I've had have done well as OB bass drivers, but biamping will probably be a necessity.

Regards,
John

[Kevin Haskins]

The guys who play with OBs can probably give you some personal feedback.    I'm going to design a couple OB speakers soon but I'm starting with the concept of bi-amping the system.   

[Michael V]

Hi John-

Thanks for the info, I was not expecting 101db but 92-94 is disappointing.  Are there any bass drivers you'd recommend for an all-passive setup like I've described?  I'm already resigned to a U-frame.

Thanks
Mike

[navin]

I've been running a 15" augmentation woofer with B200's for a while now, and I'm starting to miss that last bit of extension in the bass.

why not add a second Hawthorne 15"?

[Michael V]

Navin-

I never considered adding a second woofer, because where do you put it?

With an MTM arrangement, the woofer on top would not be rolling off much higher, without the help of the floor bounce approximating an infinite baffle.  I'd expect a hump in the mid/upper bass - above the point where the higher woofer rolls off - but with no benefit to extension.

W-frame or side-firing woofers conceptually are a non-starter.  Some companies employ them successfully, but I like my drivers on the same axis. 

Please correct me if I'm wrong on the above, or need clarifying.

Thanks
Mike 

[mcgsxr]

I believe most double helper woofer arrangements are configured WWF (!).

Where W is woofer, and F (could not think what else to use, as W was already used for woofer, and could not be reused as wide range driver) for full range driver.

Lots of folks are loving the Alpha 15, a pro 15 that has higher efficiency.

This whole issue, is why I chose to biamp, and thus woofer sensitivity is not a concern - there are other concerns, don't get me me wrong, just that already having a sub amp, it was the natural progression to trying OB bass.

I am using 1 x 12 per baffle at the moment, and other than air movement, the sound seems fine.

Would likely be better with 2x12 per side, to lower distortion, or even a pair of 15's per side...   

[navin]

Navin-I never considered adding a second woofer, because where do you put it?

I meant using both woofer below the widerange. 2 x 15" woofers = 30". +3" for wood + 4" for center of B200 = 37". Unless you listening axis is lower than 36" you should fine (a la Jamo 909).

[Michael V]

That's a possibility - the so-called WWF arrangement - but the upper woofer is still 16" from the floor boundary.  Since I'm concerned with getting the last octave the driver is capable of, wouldn't that amount of floor bounce cancellation mitigate a WW's benefits?

Why wouldn't an 18" driver be ideal?  If the Warrior's specs are 'optimistic', then what about some of Eminence's offerings that should be closer to their published sensitivity and Fs? 

To put it another way, is there a single bass driver that would meet all my (admittedly high) requirements?  Sensitivity to match the V200, bass extension flat to 35-40hz, and can be passively integrated with the WR driver on open baffle.

Thanks for everyone's input!

[Bob in St. Louis]

Michael,
How about two Augies "laying flat" (so to speak), with the b200 in the center but higher. Like the 'tripod' shape of the number 3 on a pair of dice.
{let me try to explain this way}:

 o    <-----b200
OO   <-----twin Augies


Granted the Augie SPL is 88, but they'd provide you with everything else you'd need. The Augies will get down to 27Hz as advertised.
I've talked to many fellows that use an Augie under a b200 and they have nothing but good things to say. Since you're not a home theater guy, you must be a little bit of a bass head to need more than one 15" per side.  aa

Bob

[Michael V]

Hi Bob -

Actually the 15" I'm using is the midwoofer from a Silver Iris, not an Augie.  I tried but did not have success w/ the Augies, so I'm exploring passive options that don't require biamping.

Any suggestions?

[richidoo]

Martin King frequently recommends the Eminence Alpha 15A for relatively high sensitivity woofer. It is more of an electric guitar speaker with Fs around 46Hz if I remember right. It is not a great hifi speaker, IMO, but people seem to love the Emerald Physics CS2 which uses a pair of them with heavy equalization from digital crossover. Take a look at the specs, or just try one, they are dirt cheap. Also you might like to check out some of Martin's articles about passive crossover OB projects, if you haven't already. quarter-wave.com

I am trying an active design using Peerless 830845 which are very accurate 12" drivers. I like Bob's idea of two on the floor, maybe U frame if still not enough. But with active, you just turn em up. It's easy, but not as rewarding as getting your passive working well. Good luck!
Rich

[Bob in St. Louis]

Any suggestions?

AAHHHhh, you're the guy that bought those!   Cool. I was wondering who got them.
Did you cap' the tweet-hole?
You could also play with wing design around the mid-woofers. That would get you some more bass, but if you get too carried away, it'll cost you some sound quality.
I've never tried to get an SI down to the numbers you're talking about (I cross mine at 80 for home theater), but would assume you could reach your Hz goals with some 'baffle building creativity'....not sure. 50Hz is obtainable, but the creativity needed to get to 35-40 may effect sound quality.
What was the issue with the Augie?

Bob

[nullspace]

Hi John-

Thanks for the info, I was not expecting 101db but 92-94 is disappointing.  Are there any bass drivers you'd recommend for an all-passive setup like I've described?  I'm already resigned to a U-frame.

Thanks
Mike

Hey Mike --

I would recommend checking out MJK's website for a primer on all-passive open baffle setups -- www.quarter-wave.com. Of the cuff, if you're thinking of a reasonable sized baffle, you're pretty much resigned to one or two Eminence Alpha 15As. I haven't heard them myself so I can't say how they sound, but spec-wise they're ideal.

Regards,
John

[Michael V]

Bob - you have me confused with someone else.  I bought the Silver Iris coax last year, did all the tweaks e.g. screenectomy, damping, etc.; then tried the Visaton B200 which I've used ever since.  I've gone through a few setups, but by far the most pleasing is the B200 fullrange with the SI woofer rolled off around 250hz. 

John & Rich - the Hawthorne woofer I'm using now similar to the Alpha 15 in MJK's article.  I did read his article, but need to give it a re-read.  I recall one of his statements is that an OB woofer should be 6-10db more sensitive than the fullrange driver.  Hence my original post about using the "101db" Warrior driver, or something better.

[Bob in St. Louis]

Understood Michael, sorry about the confusion.

[ttan98]

Hello,

I've been running a 15" augmentation woofer with B200's for a while now, and I'm starting to miss that last bit of extension in the bass. 

Some here may disagree with me, I don't believe the open baffle will give the deep bass you can get from a vented or sealed box.

Look at Emerald physics's CS2 it has an option for users of CS2 to purchase subwoofer to complement the CS2(it uses 2*15" woofers per side and equalized as well).

I suggest you like to look at GR research's active subwoofer. This way you would be able to squeeze the last drop of bass from your system. BTW this option is not cheap.