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natehansen66 31st May 2011 05:04 AM

Betsy K OB's with 15's and a MiniDSP....
3 Attachment(s)
Hey, I'm Nate and this is my first post on DIY Audio. The audio bug bit me back in October with some pawn shop Klipsch's and a receiver........7 months later here I am!

Betsy K's on a 12" wide baffle, sitting on 8" deep U-frames. The frames are holding 15" woofers of unknown 'em from Paul (thanks Paul!). I wrapped the frames in burlap to make a 'back', to allow me to stuff with polyfill (interesting ideas from Oh yeah, the tweeters on the back of the Betsy baffles are from some old junk Sony speakers, with cap crossovers of about 8500hz, wired out of phase.

My computer is my source, toslink out to a Xiang Shiang tube DAC, and from there to a MiniDSP (I plan on getting a MiniDigi to cut out the DA middleman). Powering the Betsy's is a MiniAmp, in BTL configuration putting out 25 watts. I've got a 200 watt Adcom driving the 15's. 15's have a hi-pass of 20hz @ LR12db slope, and a low-pass at 150 @ LR48db slope. The Betsy's have a crossover of 150 with a LR48 db slope.

I'm learning the whole measurement deal, and right now all I've got to work with is a Rad Shack SPL meter and REW. I took a quasi-gated measurement of the Betsy's, and eq'd accordingly. I eq'd the woofers from my listening position.

So.........after all that how the hell does it sound? Pretty damn good! Much better than my Klipsch References. The Klipsch's are really the only other decent speakers I've heard.........and maybe for now that's a good thing! With these OBs nearly the whole front of my room is the soundstage, and it seems to have depth at times beyond the window. The rear mounted tweeters help define the image, and give me just a little more on top. This whole combo is killer. The bass is quite good, down to about 50hz or so. I've got an old Def Tech sub that I fire up sometimes to cover below that, but I don't like the thud-thud-thud sound anymore.

Anyways I'm lovin' the Betsy's Paul thanks again man!

norman bates 31st May 2011 11:23 AM

nice job !!!!!!!!!!!!!!!!!!!!


pjanda1 31st May 2011 07:13 PM

Great work! I think the combo of dsp and power on the woofers is a great help. These woofers, BTW, are from big old 80's Jensen speakers. Maybe CS-something-or-the-other? Folks looking for high-Qts 15's for OB use who are willing to experiment a bit should be able to find such things on craigslist and the like. The miniDSP is quite fun too, isn't it? They keeping coming out with more and better software. Like you, I just need my measurement technique to catch up to the DSP capabilities!

Wild Burro Audio Labs - DIY Full Range Speakers

natehansen66 1st June 2011 04:38 AM

Yeah the miniDSP many different adjustments. I ran my Behringer analog crossover for a while, then took that out when I burned up an amp (due to my impatience, doh). I used a plate amp for the woofers, and used a cap at line level for the Betsy's. Sounded MUCH better, I can't believe how noisy that Behringer was!
After getting the DSP, and putting my Adcom back on the woofers, things went to a whole 'nother level. Having the woofers in stereo makes a huge difference, and cutting the Betsy with a steep slope opened things up even more.

sprinter 3rd June 2011 11:08 PM

This is extremely close to what I've had in mind, MiniDSP and all, and the FR driver is the only piece I still haven't acquired. I know that Paul has recommended the regular Betsy for OB and the K model for enclosures.

How has the K worked out in OB for you?

To Paul and the other experts, how would you expect the K to work in OB assuming active crossover? Or is the standard version still preferable for that?

natehansen66 4th June 2011 05:04 AM

1 Attachment(s)
So I had this all typed out but with a cat in my lap managed to delete it..........anyways.....

I think the reason the OB Betsy is recommended is due to its higher qts, it can play lower on an open baffle before the dipole rolloff. The pic is a measurement of my K's, from about 1 meter, sans crossover and eq filters (I've read that spl meters aren't all that accurate at the frequency extremes......). She's flush mounted in a baffle about 12" wide, 1.5" off center, and about 9" from the top. Using the miniDSP I've got a low shelf from about 300-400hz down, and a cut around 5-6 Khz. Not ideal I know, but it sounds good to me!

I'd like to cut the Betsy's higher and do away with the low shelf, but my woofers sound horribly muddy any higher than 180hz......

pjanda1 4th June 2011 04:18 PM

Betsy vs BetsyK with a helper woofer depends greatly on the application. If you are trying to get the fullranger down to 150hz, you need the Betsy and a big enough baffle, like 20+ inches. If you are using a baffle the size of Nates (12"), the dipole cancellation will dominate the lower end rolloff, and you'll end up with something like that graph with either speaker.

The Betsy has two other advantages: slightly longer Xmax and it is cheaper. The BetsyK is a couple db more sensitive, so that will help those with lower powered amps. Some might prefer the looks of the larger magnet structure when it is on an OB.

Finally, it is good to think about what other sorts of speakers you are interested in. If you are interested in trying a box of some sort, then the BetsyK is nice as it has the flexibility. If you are interested in loosing the helper woofer (or not having one to begin with), you need the Betsy.

So, you can make the decision based on any number of things. If it helps, I'm currently out of stock on the Betsys and the BetsyK's are on sale.

Wild Burro Audio Labs - DIY Full Range Speakers

natehansen66 4th June 2011 04:38 PM

hmmm, how do I edit posts?

I've been playing around with my system this morning, and after doing some more measurements of my Ks that baffle roll off has been bugging me....

A few measurements and a little driver specific eq (very minimal on the Betsy's, just a couple cuts at 3.3 khz and 5.8 khz) later I moved my crossovers up to 250 hz........and the muddiness I've noticed with the woofers earlier is entirely gone! These speakers are sounding better than ever, with better mid-bass and the Betsy's seem to be opened up more.

I can't say enough about the miniDSP, within an hour my speakers sound entirely different. The Betsy's kill too!

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