Plan request: A Traped horn to go from 35(ish)-120 w/RCF L18P200 - diyAudio
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Old 20th February 2011, 04:19 AM   #1
tobiazz is offline tobiazz  Denmark
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Default Plan request: A Traped horn to go from 35(ish)-120 w/RCF L18P200

Hey Guys

I have 2 of the RCF L18P200-N drives laying around and i would like to build a traped horn to put them in, if its posible to get one cap to go from 35hz(ish) to 120hz and around a 100-101db spl minimum in the bandpas it would be soooo sweed!

They have good power handling (800w AES) and a large xmax (9,8mm) and i can get 2 more pretty cheap

Is this posible ? is there a designe that will do this or am i looking at making a new designe?

Cheers Toby


(sorry for my bad english)
Same post on speakerplans.com...
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Old 20th February 2011, 07:13 AM   #2
OscarS is offline OscarS  United States
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stock sensitivity is 96 db/1W/1m. A 5-dB increase won't happen while staying reasonably flat from 35ish all the way to 120 in a tapped horn. You want an increase in sensitivity, FLH in groups of 4 is the way to go. But you won't get down to 35Hz unless you use a massive horn length. Hoffman's Iron Law. It would be nice if we all could simply specify the -3dB corner frequency AND an arbitrary sensitivity and have the laws of physics conform around us.
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Old 20th February 2011, 08:38 AM   #3
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Quote:
Originally Posted by OscarS View Post
stock sensitivity is 96 db/1W/1m. A 5-dB increase won't happen while staying reasonably flat from 35ish all the way to 120 in a tapped horn. You want an increase in sensitivity, FLH in groups of 4 is the way to go. But you won't get down to 35Hz unless you use a massive horn length. Hoffman's Iron Law. It would be nice if we all could simply specify the -3dB corner frequency AND an arbitrary sensitivity and have the laws of physics conform around us.
With the right 96 dB speaker a TH can do 101 dB one watt one meter at 35 Hz and around 104 dB at 120 Hz.

The DSL TH-118 does, at 40 x 22.5 x 28 inches is not particularly massive.
A quarter wave length of the FC in a TH design does not require a huge mouth, so can be folded in to a relatively small enclosure.
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Old 20th February 2011, 10:33 AM   #4
djk is offline djk
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There may be a better solution, but here is one (5mH inductor added):

Click the image to open in full size.

RCF - L18P200-N
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Old 20th February 2011, 03:29 PM   #5
OscarS is offline OscarS  United States
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Quote:
Originally Posted by weltersys View Post
With the right 96 dB speaker a TH can do 101 dB one watt one meter at 35 Hz and around 104 dB at 120 Hz.

The DSL TH-118 does, at 40 x 22.5 x 28 inches is not particularly massive.
A quarter wave length of the FC in a TH design does not require a huge mouth, so can be folded in to a relatively small enclosure.

Well I feel dumb. Really. I had been used to modeling using only 2V input in Horn Resp due to me simulating some "mobile audio" speakers recently. Let me see what a correct 2.83V input shows now.
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Old 20th February 2011, 10:00 PM   #6
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Originally Posted by OscarS View Post
Well I feel dumb. Really. I had been used to modeling using only 2V input in Horn Resp due to me simulating some "mobile audio" speakers recently. Let me see what a correct 2.83V input shows now.
The less the Re of a speaker, the louder it will show in Hornresp.
Some "4 ohm" speakers really are more like 3 ohms.

Most amps do not quite double the power at 1/2 the impedance, so a four ohm speaker may not actually play 3 dB louder than an 8 ohm.
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Old 22nd February 2011, 01:49 AM   #7
tobiazz is offline tobiazz  Denmark
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Djk what design is that?

Also on speakerplans.com i have been sugestet the cyclobs (CB-18) you thing that the l18p200 will work on fullpower 800w in that one?

I know that the sens is low at 96db/1w but it should bee posiblel i think
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Old 22nd February 2011, 09:17 AM   #8
djk is offline djk
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"Djk what design is that?"

That is a design I did for an 18 Sound woofer that I modified slightly for your RCF driver.

"Also on speakerplans.com i have been sugestet the cyclobs (CB-18) you thing that the l18p200 will work on fullpower 800w in that one?"

I think it should work OK, you notice that I was the one that suggested the Cyclops over there (I'm _djk_ over there).

"I know that the sens is low at 96db/1w but it should bee posiblel i think"

It looks like the TH adds about 5dB, so it should do what you need it to. The AkAbak script I posted is of one TH, a pair would smooth out a bit. Here is one, two, and four or a 40hz 15" design just to show how things change.

Click the image to open in full size.
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Old 22nd February 2011, 07:27 PM   #9
bjorno is offline bjorno  Sweden
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FYI,

Alternative designs using the RCF L18P200-N driver:

b
Attached Images
File Type: jpg RFC-L18P200N_T-TQWT.JPG (594.3 KB, 593 views)
File Type: jpg RFC-L18P200N_T-TQWT_music-Home.JPG (740.3 KB, 564 views)
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Old 22nd February 2011, 08:58 PM   #10
tobiazz is offline tobiazz  Denmark
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djk sorry did not notis that you were on speakerplans ;P

The grafs you are showing is that your design or the cyclobs?

Also du you have the plans for that design of yours?

bjorno how dos that design look? it seems to run out of xmax to soon?
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