Mattstat's response covered most of the advantages of offset driver arrangements.
As GM mentioned, the enclosed volume between the drivers creates a short parabolic horn.
The sonic effect of the "horn" is a rising upper response, followed by a steep cancellation dip, followed by lesser peaks and dips at higher frequencies.
This can be seen in the raw response of these Fulcrum Acoustic offset driver cabinets:
Larger drivers have more enclosed "horn" space, the first peak and dip will be at lower frequencies than smaller drivers.
In the example above, a pair of 21" are on top, 15" center, 12" on the bottom, the primary cancellation frequency rising from ~450Hz to 800Hz.
For comparison, this is the response of one of Fulcrum Acoustic's 2x18" in a standard "flat" arrangement:
Used as a subwoofer, the offset driver's first upper peak increases sensitivity, requiring less power and reducing voice coil heating, while the upper cancellations may reduce some harmonic distortion, but require more out of band corrective equalization.
Used as a mid range, the offset driver arrangement upper cancellations and peaks limit the usable bandwidth.
The reduced center to center distance in the offset driver arrangement may widen horizontal dispersion.
Art
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My guess is that the over arching goal of that pro-sound subwoofer design was to reduce the size of the frontal area of that box as much as possible so they can stack more woofers into small spaces. Looks like a pretty good solution.
https://www.linkwitzlab.com/LX521/Description.htm
Is it one of the Linkwitz's? It has the force cancellation you're seeking.
Is it one of the Linkwitz's? It has the force cancellation you're seeking.
thanks everyone for the replies.
I asked this question to understand if I can stack two Karlson K15 , one on top of the other in a symmetrical way but with the front chambers communicating. my prototype has a different shape than the original one. Karlson's flaw is the two W-shaped cancellations and decreasing spl. If to all this I also add the cancellations caused by two opposing speakers then the negative effects add up, causing a disaster.
I asked this question to understand if I can stack two Karlson K15 , one on top of the other in a symmetrical way but with the front chambers communicating. my prototype has a different shape than the original one. Karlson's flaw is the two W-shaped cancellations and decreasing spl. If to all this I also add the cancellations caused by two opposing speakers then the negative effects add up, causing a disaster.
The peaks and dips caused by the offset driver loaded in the Karlson aperture enclosure are inherent in the design, a "flaw" or a "feature", any way you stack it 😉
How many "W" peaks and dips can you count in this scaled down 8" driver Karlson ?
https://www.diyaudio.com/community/threads/karlson-response-peaks-and-dips.380731/
How many "W" peaks and dips can you count in this scaled down 8" driver Karlson ?
https://www.diyaudio.com/community/threads/karlson-response-peaks-and-dips.380731/
if using a single fullrange speaker is not a priority then you can create a two-way speaker. in this way the problems remain confined to the low frequencies because the remaining frequencies are produced by a speaker fixed to the K-tube which has no problems with drops or peaks, this is what I know until proven otherwise.
The graph below shows the measurement of my K12 prototype in a large room compared to a measurement in a small room.
The graph below shows the measurement of my K12 prototype in a large room compared to a measurement in a small room.
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Hey Art - I want a really good - stellar "K10" perhaps a Karlsonator 10 but maybe old school - reasonably smooth graph - how would you do that task ? - want cleat punchy sound - maybe EQ'ed at Fb. K-tube internal /or on top. Augment the 10's with sub. I'd dead broke as income has dropped 66% so relegated to some custom EM10 bored for coax with 80oz magnet - B102 (newer model) - maybe P-Audio S?N10C if not ruined by mice. Your Dad's large area distributed vent made for a better graph than some K's.
Freddi,
Sorry to hear your income dropped.
A "reasonably smooth graph" from a Karlson would require a lot of EQ at multiple frequencies, but that would only correct response at one measurement position.
A miniDSP has a dozen filters, enough for a good start on a Karlson 😉
Sorry to hear your income dropped.
A "reasonably smooth graph" from a Karlson would require a lot of EQ at multiple frequencies, but that would only correct response at one measurement position.
A miniDSP has a dozen filters, enough for a good start on a Karlson 😉
bad thing about the income - now I won't be able to pay taxes so will entirely lose my only income (gas well royalties - they are paying 1 dollar per well per 24hr day currently)
oh - I don't need that ridiculous amount of eq for music -
This old EV18B did ok - height could be cut to 36" - run an internal tube with my 1.4" Beyma CD
BUT - i rather two 10 inch Ks plus a subwoofer - if I ever get back into my house there's the old Edgar Monolith which would make a helper woofer to about 40Hz and other stuff.
Your Dad's "K8" are contenders for a real good 2.1 system - wish I had his input for a "K10" ;^)
oh - I don't need that ridiculous amount of eq for music -
This old EV18B did ok - height could be cut to 36" - run an internal tube with my 1.4" Beyma CD
BUT - i rather two 10 inch Ks plus a subwoofer - if I ever get back into my house there's the old Edgar Monolith which would make a helper woofer to about 40Hz and other stuff.
Your Dad's "K8" are contenders for a real good 2.1 system - wish I had his input for a "K10" ;^)