[Luigi]

Can anyone help here? Now that I'm reasonably happy with top end augmentation of the Visaton B200 with the Fostex FT17H tweeter, Im wanting to boost the bottom end with a 15-inch driver.

I have a few in mind - thanks to a couple of recommendations - but am wanting to know  what TS requirements I really NEED to fulfil. For example, people say a high Qts is good, but why and how high? The Eminence Alpha 12 Qts is around 0.77 and the Alpha 15 is 1.26. Is the latter too high?

Is there anything else I need to consider? My plate amp is the Kiega 5210. What I'd like to do ideally is get high sensitivity drivers so I can drive the speaker full range with my main amp (though not sure the existing amp will handle that, but I'd at least like to have the opportunity to try that).

TIA for any suggestions.

[lankester]

Hi Luigi,

My partner and I have just finished a long project.  Finding a decent bass driver for an open baffle is very difficult.  There are a couple out there but they are very expensive.  We decided to design and them have them manufactured to our own specs.  We took delivery of our first pair and after listening to and measuring them, we are delighted with the result.

Our new baby is called the Capilano Audio 15" bass driver specifically designed to be used in an open baffle configuration.  Very reasonably priced.

I would be happy to send pics and specs and graph at your request.  Sorry if I am not allowed to solicit on this site but I could not help myself after reading your post. 

Capilano audio is a small cottage business that builds open baffle speakers one at a time using exotic hardwood veneers and high end field coil drivers like Supravox.  The B200 driver you are using is a wonderful sounding driver to use in open baffle designs.  It is hard to beat in the value for dollar category.

Let me know if you would like the pics and specs emailed to you.

[mcgsxr]

lankester - you are allowed (mostly) to solicit here, but you should add the requisite information about your company to your signature, so that folks know who you are, who your firm is, and how to contact you etc - please add your website to your signature.

Luigi - I have used different OB subs with the b200's, and can offer some advice.

1 - your Kiega amp is perfect, you will do well with that baby.
2 - by biamping (one amp for mains, one amp for subs) you take the high efficiency out of the equation, and it gets easier to find good subs that can match the b200 on OB
3 - 0.5-0.9 is probably the sweet spot for QTS - any lower, and you will need significant EQ - any higher, and you run the risk of boomy, peaky bass response, isolated around the FS
4 - speaking of FS, you want as low as you can find, as below FS, on OB, there is little bass
5 - XMAX - you want some of this too, especially as you go with lower efficiency drivers - you can apply more power, to match the output of the b200's, but only if your subs have enough travel to use all the power without bottoming out
As for good 15 inch drivers, I can think of a few that I know people are happy with, and one that I have used myself (OK, I have the 12 inch version, but the 15 is good, according to folk's I know).

In no particular order (ie the order of which I thought of them!)

Hawthorne Silver Iris Augie - http://www.hawthorneaudio.com/drivers.htm
Mach5Audio MAW-15 - http://www.mach5audio.com/product_info.php?cPath=48&products_id=53&osCsid=a46a9a2e6c54d15d937171c76d02db5d - run this using only 1 voice coil, and the effective QTS doubles, giving you a 15 with FS of 26Hz, QTS of 0.64, and XMAX of 13mm in each direction... for US$74.70
Parts Express IB15 - http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-455

Those would be the best 15's I can think of off the top of my head.

I would be interested to learn more about these other 15's that lankester has!

[Luigi]

Thanks for taking the time to reply you two. I really appreciate the input. It makes my search that much easier if I'm not fumbling in the dark.

[markC]

If you are able to set-up infinite baffle, i.e a crawl space, laundry room or largish closet that shares a wall with your listening room, then the P.E IB 15 is killer. I've got 2 of them in parallel and they are far better than any boxed sub I've heard.

[D OB G]

Hi Luigi,

It seems to me that for conventional augmentation, the low frequency hump produced by a driver Qts above 0.7 has a low frequency cut off due to Fs, and a higher frequency transition to a flat response due to the system Q.  Therefore a different sized baffle is required (for the baffle loss component of the frequency response) for a flat frequency response according to the system Q.

It seems to me that there is an art as well as a science in matching baffle size to system Q, as well as the issue of ultimate low frequency response, to obtain a flat frequency response without any hump, dip, or underdamped result.

An alternative approach, that you might like to ponder, is one I have provided in the thread "an OB design".

David

[mcgsxr]

The PE subs can of course be used via IB, but their specs also lead me to believe they would be good OB subs, for those without the requisite space for the IB.

Of course, if I ever got off my A$$, I would have heard MarkC's IB by now!  Actually, it has always been my kids that have disabled those visits, but eventually I MUST HEAR IB BASS!

[giacomorocca]

Does anyone has ever tried B200 drivers in an Infinite baffle situation or is it a moron idea?

[markC]

Never tried B200's in an IB set-up, but I believe a lot of the magic of the sound has to do with the back wave of the driver.

[Dmason]

Giacomo,

 the only "moron" question is the one not asked...

I think the B200 would be superb in an infinite baffle, simply because it is spec'd that way, AND because it sounds so good. I just ordered my first pair in almost two years, and apparently these are slightly different, better compliance, and coil tolerances, according to Simon at Visaton. I am looking forward to hearing them.

Last weekend I was listening to the DarkStars, over at "Jiffyboob" s place, still sounded great.

Meantime, this is Andy Lankester's site: www.capilanohornspeakers.com   and be sure to look at the nice 6V6 monoblox he has. Those would sound yummy with the B200. Andy will be posting more about his new custom bass drivers, which, from the outset look like EXACTLY what we are after!!!

[scorpion]

Indeed, it will be very interesting to know about the Capilano Audio 15" OB bass driver.
We somewhat lack alternatives today !

/Erling