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Driver Specs

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Though I'd sure like you to visit my website, I figured I should toss a spec sheet up here. The BetsyK is V1, the redline, and the specs on the left. The other is the Betsy, as the Qts would indicate. Thanks to the forum updates I can post the full res jpg! It didn't fit last year when I introduced the drivers.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 

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I had a few drivers built with no whizzers. Right now they are special order, and those that are interested may want to check with Godzilla for info on his tweeter. Here is a comparative chart of the Betsy with and without a whizzer. Look at the specs: you can see that the plain dustcap weighs more than the normal whizzer! Also of note is the sensitivity difference between the two. Despite the whizzerless driver having a higher Mms and a correspondingly higher Qts, the computer figures it to be a more efficient driver! Thing's ain't always what the numbers would have you believe. . .

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 

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Hi Paul

I had a look at your website.

On the "speakers" page, it looks like you've got the colors mixed up in this piece of text: "Specs: V2 (red line) is the Betsy. V1 (blue line) is the BetsyK." Shouldn't that be "Specs: V2 (blue line) is the Betsy. V1 (red line) is the BetsyK." It's here: Wild Burro Audio Labs - Fullrange Speakers - The Betsy & Betsy-K Drivers

Also, I'm curious as to why the Betsy-K has much higher mechanical damping than the Betsy if the only difference is a stronger motor. Longer gap with ferrofluid maybe? Hmm - that would imply a bigger x-max too. You mention 2mm for Betsy, but I didn't see a spec for Betsy-K.

Regards - Godfrey

p.s. There - now you know somebody's at least paying attention ;)
 
You are right about the reversed colors/descriptions. I should really get to work on the website, but then what would we talk about? I would assume the Mms difference is due to an x-max difference. No ferrofluid here. I'll check in with the engineers when I get a chance. I'll also see about some off axis curves. No promises.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
I haven't tried phase plugs. I'm sure they would make a difference, but whether or not it is significant enough to be worth the trouble is probably a personal decision. I've got bigger fish to fry: more speaker projects, continued turntable work, and a never ending pile of new projects. (I picked up an Akai M8 tonight!). The whizzer and dustcap are connected, so anyone removing the dustcap should be careful!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
I've been neglecting you guys for too long. The Betsy and BetsyK have different voice coils. The Betsy has a Kapton former. It has a little longer Xmax (shorter front plate) at 2.7 mm. The BetsyK has a Nomex form and a 1.9mm Xmax (I usually just say 2). It's larger magnet would saturate the thinner front plate. FWIW, nobody knows why we are using different formers. Perhaps some listening tests are in order . . .

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
It's larger magnet would saturate the thinner front plate.
Is that bad? Wouldn't it have a similar effect to a shorting ring, but with distortion reduction all the way down to frequencies that shorting rings can't help?

I'm thinking if the plate's saturated, the flux won't be so strongly modulated by the VC current. :confused:

Then again, there didn't seem to be much interest in shorting rings anyway...
 
BetsyK is a very good speaker - mine were among the first. Each one had what I think may have been cold solder joints as the tinsel rattled loose from the eyelet - Its difficult to see here but there's a little knob of solder on the tinsel where it pulled out from the eylet when I played it for the first time yesterday in the early Karlson 12 with a Monarchy SM70. Cone excursion wasn't even 3/16" p-p but it was loud and rocking and bass more coherent than my Klipschorn. The cone would have jumped a lot more imo in reflex tl and probably blh and not reached the same spl - one reason I may not go with GB's TL simulated in MJK's software. A Karlson can be superior.

I think just the vibrations loosened it. Hope I can see to poke the lead back into the eyelet!
http://img692.imageshack.us/img692/1848/pulledfromeyelet.jpg

a bit more HF extension could be nice in later WBA drivers - I'd like some 12" WBA as Eminence's 12LTA doesn't have the extension
and Super10 doesn't possess dynamic capability for bass (I'll assume 12" FR are considered ludicrous on this forum)

are you working up some new stuff?
 
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Umm..Err...

Hi Freddi,

I saw your post at AA about a K-Betsy-K and was going to ask you about it but since your here I can get to you and Paul at the same time :^)

Can you and the guys at the Karlson forum help with Karlson design optimised for the Betsy?

Also, what do you think about a "tarted-up" Motorola KSN-1005, 1141, 1176 as a helper tweeter?

BTW. Did the 8K I sent you have any features that you haven't seen before? I tried a bunch of drivers with it without success.

Hey Dave!

I just got 2 t-amp modules (sonic impact) and they sound fantasatic with the BKs bi-amped with some tweets I bought from a guy here ( C-Audio). Looks like a set of self- powered speakers is a good idea. Can you email me the plans for the towers? Thanks bro!

Bill H.
 
Bill,

You may have seen it, but Godzilla used to use (maybe still does, I don't know) piezos with the Pioneer B20. You'd probably be using them up a little higher with the BetsyK, so it would certainly be worth a shot.

Re: the T-amp, I like them for OB's because of the built in rolloff. If, however, you have a cabinet that you want to take a little lower, you might consider swapping the input caps for something larger. In stock form, they'll only let you get down to 60hz or so before rolling off. The upside is that the high pass reduces excursion, and thus distortion, while increasing dynamic range.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
Freddi,

There actually isn't an easy way to do it. I can only do a bigger motor with a bigger voice coil, which given this cone's stiffness, would limit high frequency extension. It would be more of a widebander. I know that would probably be perfect for you, but I'd need a few more interested folks to justify the development costs. But, aren't you looking for more high frequency rise to mate well with the Karlsons? A lower Qts won't net you much (in any) more HF. If you want, I could look into doing a shorting ring as a custom unit. That would probably make a bigger difference in your application.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
Tweakk,

Thanks for your kind words. To respond to your earlier exclamation, there is an Alnico motor I could use. The problem is that it would limit mechanical Xmax to less than I am comfortable with. I actually think others have used the same motor in fullrange, bass reflex applications. But, single driver OB would be an even bigger stretch. Again, there are some development costs too, so I'd need to see some wider interest.

I'm continuing to explore another motor avenue that may be exciting to both of you, but it will be considerably more expensive. We're so far behind schedule on it that I hesitate to say more at this point.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
dang it - just had a good wide-dynamic recording of percussion & flutes playing nicely - it is cut so low that my transformer volume control was up all the way, I went out of that room and my 5 disc changer slipped into a Nokie Edwards recording with very little dynamics but cut much higher - that heated BetsyK to cooked level and fried her coil to a smelly state. Damn those low dynamic recordings cut to 0dB or higher !!! At least my re-soldered joint held in the eyelets :( I can't easily mount a Fostex FE206EN in a stock 8K Karlson due to the way its stamped frame is manufactured. Maybe I better buy a single disc transport
 
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