A Speaker that Kicks Butt in Large Spaces

[freddi]

look at the difference at 1/24 octave between the old Karlsonette copy with small rectangular vent and the Acoustic Control coupler with its tapered rear profile and sizeable (~27 sq.in.) vent

one of the better response graphs I've seen was from a 0.8 scale K15 - might be good to have just a little bit of the lowpass board stick out to allow experimenting with front shelf depth.

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[freddi]

when I ran an early production BetsyK in the K12 (Karlsonette), it was surprising how loud the bass could be without much if any visible cone movement - but after the first song at a goodly (live) level (Paul Janda might argue..) BetsyK's leads fell out of the eyelets. I've run a Visaton BG20 in a slit-vent K12 copy with pretty good result and nice tone for a cheap (~$27 at Partsexpress) fullrange speaker.

Karlson's can have a lot of adjustments - lowpass/port position-type including de-Q-ing vents/aperture adjustments, etc.

Is your K15 model flexible enough to adjust only the rear chamber volume without bothering other parameters? - it would be interesting to see trends for certain drivers as the rear chamber is varied. It also would be cool to see trends with only the front chamber varied.

[GM]

Originally Posted by freddi

had to look at one of my blonde K15's - their stock vent is 8.875" tall x 4.5" wide.

Hey Freddy, WRT the 4.5" width, what about this vent update you sent me ages ago?

GM

[xrk971]

Originally Posted by freddi

when I ran an early production BetsyK in the K12 (Karlsonette), it was surprising how loud the bass could be without much if any visible cone movement - but after the first song at a goodly (live) level (Paul Janda might argue..) BetsyK's leads fell out of the eyelets. I've run a Visaton BG20 in a slit-vent K12 copy with pretty good result and nice tone for a cheap (~$27 at Partsexpress) fullrange speaker.

Karlson's can have a lot of adjustments - lowpass/port position-type including de-Q-ing vents/aperture adjustments, etc.

Is your K15 model flexible enough to adjust only the rear chamber volume without bothering other parameters? - it would be interesting to see trends for certain drivers as the rear chamber is varied. It also would be cool to see trends with only the front chamber varied.

When yo say only vary the rear chamber volume, do you mean keep the CSA of the back shelf gap and vent port constant? It can be done by adding a phantom volume to either the lower driver chamber and or the upper chamber or both. Or I can simply make the cabinet width change which alters volume and compensate by reducing the shelf gap CSA.

[IG81]

Originally Posted by freddi

I had a K12/Karlsonette copy, blocked its regular horizontal vent and introduced a rough rectangular vent with only around 7 sq.in. or so area - that seemed to cause quite a suckout. Vent placement probably matters somewhat besides vent area.

When I lowered the tuning on my SK8 by blocking ~2/3 of the vent with some dense foam, the expected effect happened around and below 100Hz, but the initial larger vent area seemed to fill more of that first large dip in the "W" region. I don't remember the exact figures, but tunings were ~67Hz down to ~60Hz or so. I preferred the lower tuning as it is more compatible to my room acoustics.

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IG

[GM]

Yeah, lowering Fb also lowered its 3rd harmonic dip and the lower you go, the deeper/wider it gets. Not many 'free lunches' in audio design.

GM

[GM]

What's needed is a hybrid K with a Danley DTS concept tapped horn mated to a high tuned K15 or similar.

GM

[xrk971]

What's a Danley DTS ?

[GM]

It's a type of tapped horn that offsets the driver to fill in its 3rd harmonic dip: Danley DTS-10 "Super Spud" DIY kit

GM

[freddi]

hi GM - in 1956, Karlson published an update of K15 narrowing the vent and both shelf gaps- - IIRC it had little effect on the bottom. A tight aperture gap can affect the tone. Carl experimented with a variety of apertures but did not publish response. K15 should be a lot cleaner than some horns.

here's a 15 inch Yorkville USC1 horn I purchased new compared to a simple K the size of K15 - note the horn's H2 is over 20dB higher than the Karlson and H3 10dB higher than the Karlson. The 1-sheet K was a lot lighter too. That Yorkville cost me quite a bit - never used it again after the testing. The Karlson type was loaded with an Eminence 18 which I bought for $90 having qts ~0.26, fs ~32 mms 103g

Yorkville description http://www.fullcompass.com/product/3...FWlo7Aod1gQABg

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