Enclosure designs for Burro Speakers

[pjanda1]

That certainly is an interesting cabinet design. I am a bit skeptical, and I'd love to hear one. It is simple enough, that for most folks it would probably be much less expensive to have the wood cut locally. Shipping would be an absolute bear. I'm sure you've got a local cabinet shop that would do an excellent job for less than I'd have to charge.

In general, I think space is more the issue than skill. The folding baffle is neat because you can have the panel's precut easily (even on a home depot panel saw), and then one can screw it together in the living room. If, however, you've got the space, all you need are some cheap tools. A lack of skill doesn't stop me!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[Poultrygeist]

Last weekend I attended a woodworking class on building kitchen cabinets with the Kreg Pocket Hole Joinery System. It's got to be the easiest method on earth to contruct a strong box from plywood. This system has to have great application in speaker cabinet building. After cutting your plywood you can literally put a cab together in five minutes. Is anyone using this to make speaker cabs? I was so pumped I ordered my Kreg kit off ebay as soon as I got home from the class.

[freddi]

hey pjanda - a few minutes ago I fired up the fresh BetsyK mounted into the first Karlson 12 (introduced October 1954) - she kicked like a mule and rocked better than my Klipschorn on old 60's spy-rock - I probably didn't have enough power with my Monarchy SM70 and cds coming out though a Promitheus TVC - cone excursion at a very loud level was not even 1/8" peak to peak - but by the second cut I lost a tinsel joint to the cone - Misco imo needs to get a tougher solder connection - the cone movement was very small and I very happy for a few faint moments. The impedance curve looked good too with nearly equal amplitude for the 1st and 2nd peaks - I took a screen shot and the enclosure has a damping strip which allows some juggling of input Z.

if I can pull BetsyK (cramped space and I lack appropriate screwdrivers) then I'll see if she'll resolder like the first one I popped (that one was under high motion - this one was under a high load)

I'm impressed!

Karlsonette drawing by Greg B. from my horrid sketch
http://img228.imageshack.us/img228/8...sonetteib7.png

[pjanda1]

Wow! I've run them (my personal pairs, not those I sell) at double or triple Xmax for hours on end and I haven't broken one (often 20-30hz sine waves for break-in). This does open up an interesting opportunity though. Your pair is one of those early crippled ones where some current passes from tinsel to tinsel through the cone, which is why you measured those high Qes numbers. If you try and fix it, use a little nylon washer where it passes through the cone and that should correct the problem. Of course, you'd have to do it to the other one too to have a pair. FWIW, all the new production units have washers around the leads, so I suspect they are also more immune to snapping. It's funny that you should have tinsel lead problems. I'm planning to run some sweeps of my 15" OB woofers tomorrow, and those leads (basically the same as your BetsyK's) don't inspire great confidence at OB excursion levels.

BTW, if you can't fix them easily let me know. I'll see if I can work out a recone.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[freddi]

I think (hope) the voice coil's good - but my vision doesn't converge well anymore for soldering so it'll be hit or miss if I can get it back into the cone's eyelet - BetsyK made a lot of noise - not just movement - Karlson will hold that cone motion down so power can be applied - it may (?) have helped if I'd had used a more powerful amp - say 60w -- it sounded like a band in a club !
re:washers - I've ~zero mobility to get stuff - how do they work to help the leads at the cone junction? - wonder if there's some sorta goop which would retain the lead and not cause response problems?

[Mosquito]

Hi Freddi , this drawing of a Karlsonette seems to have an internal net volume of around 3cu. ft (85dm3) and looks like is more for a 12 incher. Do you feel that it is roughly suitable for a 8 " BetsyK as well?
Regards
JJT

[freddi]

I doubt if the rear chamber has more than 1.5 cubic feet - if that - Front chamber on Karlson couplers in general are around 1/2 the rear chamber volume. 12" in K12 generally rolloff subjectively higher than what I heard from BetsyK - if one were building a K12, then it might be good to retain the 12" cutout and make an adapter plate for smaller drivers.

This was the first k12 from late 1954 - later K12 canted the front panel forwards and used a 6-slit distributed vent. I like the early one as it sounds
more like K15 .

give me a minute and I'll pull Julian Hirsch's old (1955) Audio League graph of two twelves and one 8 in Karlsonette -
here we go:

[Mosquito]

Thanks for the answer. It leads to suppose a good performance on it , for the Betsy K.
Any chance to see a freq response plot ? (3rd. octave in room will be fine)
Regards
JJT

[freddi]

I don't have any equipment hooked up and might not for while until I buy a new preamp for my mic - a graph might not look great but the sound is fun - a Behringer "Truth" speaker will make a decent graph but sounds pretty poor imo -- Best wishes, Freddy

[brsanko]

Here's a nice compound horn design I worked up. They're pretty big but the sound would be big too. I have included the hornresp model so you can see the performance you could expect. As you can see they are pretty flat down to 50Hz and have useful response down to 40Hz. They exceed 115db at Xmax and if like you said the do okay at over 2X Xmax then they should hit 123db down to 45Hz if you put them in the corners(that figure is for one speaker!) If anyone is interested in plans let me know. Or I could build them if anyone is interested as well.