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The Purple speaker: an $18, 8" fullrange!

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#61
Thanks again for your help Paul

I have a a lot of work to do here I think. I am looking at your OB/amp project thread and thinking along the lines of buying the Jensem 15" drivers and using a similar U baffle to yours.

Thanks for the offer of helping with the design but I think I`ll stick to tried and tested format.

How do the Purples sound in your U baffle?
Cheers
Alan
 
#64
Hi Paul,

I've ordered 4 of your purple speakers, and have a few quick questions.

I assume a nominal impedance around 8 ohms? I might run two in parallel and my amp is rated down to 4 ohms.

I saw the whizzerless (is that a word?) graph in your post. Have you graphed the driver with whizzer? The reason I ask is I'm considering running a tweeter with a first order crossover, and am curious as to the frequency I might crossover. 8 khz, 10 khz, etc.?

They were priced at a point where I can play a little before I finalize plans...

Thanks!

John
 
#66
John,

They are 8 ohm speakers. Comb filtering is the potential problem with running two per side (the phase difference between the two speakers resulting in deep and frequent nulls in the frequency response above a frequency determined by driver spacing). Some folks claim the problem isn't audible. I'd be curious to see someone play with it, as I frequently have folks interested in running two per side and I'd be happy to sell more speakers!

I can try and dig up a graph with whizzers. But if you are running a tweeter, I'd either cut them into dustcaps or use a phase plug (diy or Planet10). May as well give the tweeter something to do, and avoid the imperfections of the whizzer! The crossover will be application specific. For example, if you're running a really efficient tweeter and a single cap, you might choose a higher than technically perfect electrical crossover point in an effort to bring the actual in line with the Purple. But assuming equal efficiency, whizzerless, you're looking at 7-8khz. With a whizzer, I'd say 12-16khz, depending on which whizzer you choose.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
#78
Which whizzer did you use? Still can't figure out which to use on mine. 😛

The directionality of the BetsyKs is inconvenient to me, in my small, heavily obstructed room. By no fault of their design of course. Is it possible that using a smaller whizzer will decrease directionality, and improve HF behavior? And allow me to equalize out HF rolloff?

- keantoken
 
#79
there was a 3 page thread started in march on what a whizzer does, very informative with graphs before and after whizzer removal. Yet other threads people like large or small whizzers, but not 8" whizzers for some reason. My an10 has a tiny whizzer, but I've never hooked it up. People seem to like the huge whizzer on the 12lta also, and people seem to like the whizzer on the fe166e and fe167e, and some like whizzers on even smaller drivers.

Here's the link.....

http://www.diyaudio.com/forums/full-range/185012-whizzer-intelligibility.html

The whizzer on an 8" helps dispersion from 2khz-4khz. If you cut off the whizzer (on a flat coral 8a anyway), the drivers response climbed from 1.5khz around 6khz, then fell off above that.

Otherwise the phase is wonky, especially where the whizzer and cone are both operating.

And yea, to me an 8" full ranger (even with a whizzer) is maybe 2 people wide dispersion up to past 5khz at 12' (using 8" whizzer no phase plug and a different 8" with phase plug).

p.s. those purples seem to have had an excellent freq response.

Norman
 
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