I have a couple stupid speaker building questions

[kevinp.]

I can't think of a better place to ask them....

1. - Can you use high Qtc as a supplement to BSC? For instance, an RS270 in a 1cf sealed box. Nice 2db hump at 100hz with a nice slow taper...


2. - Multiple tweeters. Why not, again? I'm sure I'm going to hear all kinds of theories, like phase cancellation and what not, but won't they be very narrow and up so high as to not be noticable? I see the Axiom M80 measurements in soundstageav.com and looks really nice, although probably smoothed. What about 4 Dayton push-in Neos in a diamond config with a nice patch of felt in the middle? 4x power handling, +6 db and you don't have to use compression drivers or ribbons for high sensitivity.

[JonMarsh]

I can't think of a better place to ask them....

1. - Can you use high Qtc as a supplement to BSC? For instance, an RS270 in a 1cf sealed box. Nice 2db hump at 100hz with a nice slow taper...


2. - Multiple tweeters. Why not, again? I'm sure I'm going to hear all kinds of theories, like phase cancellation and what not, but won't they be very narrow and up so high as to not be noticable? I see the Axiom M80 measurements in soundstageav.com and looks really nice, although probably smoothed. What about 4 Dayton push-in Neos in a diamond config with a nice patch of felt in the middle? 4x power handling, +6 db and you don't have to use compression drivers or ribbons for high sensitivity.

You know, Kevin, this is DIY, not law or religion, so you're free to try anything you want. You know the old saying? About if you meet the Buddha on the road, kill him, because you can't follow someone else to your own path to enlightenment?

That said, since you asked, I'll respond- and I'll be gentler than Evil Twin. But maybe not much. :W

I think what I'll do is pose questions to enable you to answer your first questions.

First question, do you think you're likely to get a target response with boosted Qtc that will match the specific BSC requirements of a specific baffle and application? Second, do you want to listen to that boosted QTC and energy storage/resonance all the time in the low end? It won't be as bad as a poorly designed bass reflex system, but it sill probably won't be fun- unless that's your musical taste.

Another trick to do BSC without a BSC network is what Wilson Audio used in the X1 SLAMM - roll the main woofer off slowly so that it's output adds with that of the midrange unit being run only above 125 Hz with an 18 dB/octave high pass. See the old Stereophile review if you want to understand that better.

Second question, you can do anything you want with your tweeters. But I suggest someday buying one high quality tweeter (say, a dome SS, for example, or even just a Seas 27TBFCG), and building a simple 1500 Hz high pass (2nd or 3rd order) and listen to what it sounds like on pink noise, on axis and off axis from a normal baffle. Then try using that as your basis for comparison for anything you might do with a planar array, again listening with pink noise. If you can get the same harmonic coherency and dispersion as for the SS dome, then you're all set. If not, you'll be able to hear rather directly what you're giving up, and decide if that is worthwhile or not based on what ever other benefits you think you're gaining with the array.

Or you can ignore me and do whatever you'd like and have great fun, but possibly not great sound. :W

OK, take this with a grain of salt, I'm a little grumpy this AM because of work...

[kevinp.]

Thanks Jon -

My first question was based more on trying to fit that driver (or similar) into a small box rather than trying to implement BSC by shrinking the box, if you know what i mean.


the idea about the pink noise is a good one; I wouldn't have thought of that, and I might as well try it!

Thanks much, and that really wasn't too grumpy of a reply... (comparitively)

/duck

[cjd]

High Q alignments just don't sound good. This is an example of why straight frequency response isn't nearly the whole story.

Multiple tweeters can be fun - grab a couple cheapies of decent quality (the $5 press-fit jobs from PE work well) and put 'em on some boards where you can play with the distance between them. Move your head around, the tweeters around, further apart, closer together (still use pink noise or similar) - you can start to hear what kinds of problems exist with multiple tweeters.

C

[JonMarsh]

And if you rotate them at different speeds it produces even more interesting effects... oh yeah, they called that a Leslie tone cabinet- what I used to use with my Hammon organ. Interesting sound producer, not so recommended as a reproducer. :W