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Tom Danley's TOWER OF POWER
Tom Danley's TOWER OF POWER
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Old 26th January 2007, 04:41 PM   #131
freddi is offline freddi  United States
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Tom Danley's TOWER OF POWER
Hi guys -

-like to get a handle on regular-syle large Karlson's front pipe and aperture to lower its apparant lumped tuning around the 3rd impedance peak without increasing bulk over K15. I did it with a 6" high 20 liter right angle stub somewhat like KenL's idea of a year or two ago connected to front chamber on coupler with 2"x19.5" slot above the reflector. This stub moved the 3rd Z peak of the same coupler from ~190Hz down to around 120 or so. K15 has the peak ~155Hz. Dunno if this stub was good distortion-wise at high input powers as my try was in added pieces. 85L rear chamber was ok for an 18" with qts ~0.25 and mms 103g.

I may be barKing up the wrong tree with a simplistic view of coupled-cavity peak juggling but can't crunch the math needed to do analysis. One engineer may provide some aperture inductance formulae in a few months to be put into basic or whatever (?)

Karlson's 1951 K15 box (K15 went to NYC Audio Fair in October 1952) is a loud player with lots of outout in its range for low cone motion with driver type of its time - low mass - low inductance. FWIW I've measured worse distortion in some horn. Below cutoff the cone motions seem better controlled than a reflex of its rear chamber size and tuning.

I don't think theres any midband gain - there's potential for ripple, balance issues and "reverb"- ha- certain baffle angles may work better/different than others.

maybe Tom can look at Karlson for what it is (whatever mix that may be)

IIRC, KenL's tall k had a dip -maybe Ken can join the conversation.. A slot might not be good for tapped horn (?)

hey Tom - you musta heard k15s

Freddy
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Old 31st January 2007, 01:52 AM   #132
cowanaudio is online now cowanaudio  Australia
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Default Tapped Horns (Back on topic)

To get this thread back on topic, I'd like to point you toward some measurements I've taken on some tapped horns I've built. Have a look at: http://diy.cowanaudio.com

Cheers

William Cowan
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Old 31st January 2007, 02:27 AM   #133
Lindahl is offline Lindahl  United States
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William,

How did you go about choosing a suitable driver for the tapped horn design? Can you talk about this process? Was it just a trial an error? What do I look for in a driver? I'd like to make a giant one, aiming to be flat to around 15hz. I'd guess a 15" driver would be suitable. I realize that this wouldn't be a high bandwidth design, but I plan on integrating with smaller sealed subwoofers at around 40hz. I'm just trying to get the most flat output for the buck in that lower region.
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Old 31st January 2007, 03:14 AM   #134
cowanaudio is online now cowanaudio  Australia
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G'day Lindahl

Driver choice is not much better than trial and error. We still get some surprises, so I'm not happy to choose drivers for people.

Initially aim for a Qt of 0.2 to 0.4 and an FS near your LF cutoff. That should get you close. The drivers I've found work well have a low VAS.

With a 15Hz LF cutoff, you should be able to see 60Hz before the first dip. I use an 18Hz dual 830500 design that is pretty flat to 70Hz.
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Old 31st January 2007, 04:24 AM   #135
freddi is offline freddi  United States
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Tom Danley's TOWER OF POWER
Hi William - my apologies on throwing the tread off (alhough in a sense, JK's K15 driver sat in its mouth)

its fascinating to see stories and poor plots on Jensen-stye transflex attempts online while a bit of tilt creating a positive flare gives beautiful plots on your speakers (when things are right).

if I feel better and can get plywood and B&D saw going down a guide then will give one a go. any hints on the 18 T-H? - would be cool with my theatre organ cd collection.

Cheers,
Freddy
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Old 31st January 2007, 04:51 AM   #136
cowanaudio is online now cowanaudio  Australia
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G'day Freddi

The 18Hz horn does work very well in room. Here is the near field response. In room it's pretty much flat. The rolloff above 60Hz requires a low crossover. I'll put some details on my webpage soon. It's BIG. It has the nick name "The Coffin" I think it's a bit big for that!

Cheers

William Cowan
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File Type: gif 18hzth.gif (12.5 KB, 1171 views)
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Old 31st January 2007, 04:58 AM   #137
freddi is offline freddi  United States
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Tom Danley's TOWER OF POWER
haha - it's a tad big - maybe a "coffindominium"? - does it have two drivers? - pic almost looks like one bigum

how sensitive is your Peerless 30Hz T-H? do T-H of this configuation like low vas driver with 89db spec?

Best,
Freddy

ps - please fix my Karlson!
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Old 31st January 2007, 05:24 AM   #138
cowanaudio is online now cowanaudio  Australia
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Yep, 2 12" Peerless XLS 830500's. Sens is a bit below 100dB/W/M for the two big tapped horns. The right 15" would work fine.

Cheers

William Cowan
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Old 31st January 2007, 05:06 PM   #139
freddi is offline freddi  United States
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Tom Danley's TOWER OF POWER
got a few 15" - fs 23-26, qt 0.32-0.26, vas maybe 14CF & 10CF - not sure if suitable - without understanding guess pipe would have to be built 1st :^)
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Old 31st January 2007, 05:49 PM   #140
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally posted by Tom Danley
GM, your down in the area of the shop as I recall, next time your out getting some of that good BBQ, give the shop a ring and stop by for a listen. They are starting to build a special walk in tapped horn which should be humorous. The customer wants 104dB from 15 to 20Hz at 250 Meters from the source and it has to run 24 / 7. Not really a home sized Tapped horn as it has 40, 16inch Drivers and 40 1Kw amplifiers in it.
Best

Tom Danley
A couple of weeks ago I was staying at the Aladdin during CES. They have an "indoor thunderstorm" in their shopping mall. The first thing you notice about their thunderstorm is that it sounds terribly anemic, because there's no low bass at all.

Something like that would be great for theme parks and hotels.

:: PB ::
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