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15" ported horn
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 3096 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Topic: 15" ported horn
    Posted: 21 June 2010 at 5:57pm
Hi

just finished building the first prototype of this project. it is 70cm deep 57cm*57cm mouth. driver faces back of the cab where there is an access hatch with a phase plug attached. horn path goes round 90 degree bend and then straight to the front. chamber for driver is in the middle of the box with vents entering horn path about 15cm from the mouth.

it was designed to cover 70Hz to 320Hz. sounds pretty good compared to double 15" vented cab. got similar output with ultradrive set 2-3db lower for the horn. as the horn was 8ohm and the vented box 4ohm this makes it 5-6dB more sensitive as predicted by hornresp. sounded a bit faster and more defined - was able to pick out some detail on basslines that was just a constant drone on the vented cab. tried some vocal stuff through it and it sounded no worse than the vented cab. cone excursion was at least half for the same output.

as I have recently lost my microphone, laptop and camera phone to thieving ***** can't give any accurate info at this stage - perhaps if anyone in Bristol is interested they might come and measure it and help me tune the ports for a few beers???

cheers
Phil
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darkmatter View Drop Down
Old Croc
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Points: 2425 		Post Options Post Options   Thanks (0) Thanks(0)   Quote darkmatter Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2010 at 2:56pm
Very interested to see this as I need something similar. I wasn't sure whether to port it to 70hz or use a longer standard FLH and aim for 80hz. My only worry was that the port might make integration with subs harder.

Did you do the driver cutout slightly smaller than the 15" or did you leave the edges of the cone exposed and get the compression from the phase plug?

sorry to hear about the robbing bastads!
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snowflake View Drop Down
Old Croc
Old Croc


Joined: 29 December 2004
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Points: 3096 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 25 September 2010 at 12:38pm
Here are some screenshots from HR







HR can't model it exactly as the port re-enters the horn 12cm inside the mouth. the path difference is accounted for but not the changed loading on the port. exporting to akabak this is easily adjusted for and shows the bass response going about 5Hz lower. using the directivity tool in HR shows the on axis response much smoother from 400Hz to 700Hz and pretty flat up to 1kHZ. akabak shows similar response up high.
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Teunos View Drop Down
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Joined: 23 November 2008
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Originally posted by snowflake snowflake wrote:

Hi
it was designed to cover 70Hz to 320Hz. sounds pretty good compared to double 15" vented cab. got similar output with ultradrive set 2-3db lower for the horn. as the horn was 8ohm and the vented box 4ohm this makes it 5-6dB more sensitive as predicted by hornresp.
cheers
Phil
5-6db more sensitive? now that's something strange. a difference of 1 or 2db is possible, but no way the actual horn will be 5-6db more efficient than the hornresp sim.
Will it be used to 320Hz? i think it should be possible (if you used a reversed dome shape phase plug on the top hatch at which the woofer faces) but would like to know how it sounds. Pretty interesting.Wink


Edited by Teunos - 25 September 2010 at 1:33pm
Best regards,
Teun.
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snowflake View Drop Down
Old Croc
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Joined: 29 December 2004
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Points: 3096 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 26 September 2010 at 12:55am
"5-6db more sensitive?"
I mean that as one box was 4R and one 8R the 2-3 dB difference on the ultradrive was in reality a 5-6dB difference in 1W sensitivity between the two boxes - which agrees with the hornresp predictions.
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Teunos View Drop Down
Old Croc
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Joined: 23 November 2008
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Points: 1793 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 26 September 2010 at 10:20am
Originally posted by snowflake snowflake wrote:

"5-6db more sensitive?"
I mean that as one box was 4R and one 8R the 2-3 dB difference on the ultradrive was in reality a 5-6dB difference in 1W sensitivity between the two boxes - which agrees with the hornresp predictions.
Ok, Sorry, my badWink
Best regards,
Teun.
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snowflake View Drop Down
Old Croc
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Joined: 29 December 2004
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Points: 3096 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2010 at 11:58am
This is a photo from St Pauls carnvial. there are two unpainted boxes stacked in the middle. mirror man head is removable!
 
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Disco Stu View Drop Down
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EDIT WRONG THREAD SORRY!

Edited by Disco Stu - 01 October 2010 at 3:42pm
All you need to know is:
Sensitivity + Power Handling - Power Compression = Max Output

My acts:
www.myspace.com/thebowiexperience
www.myspace.com/scheisseelektronisches
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JD01 View Drop Down
Young Croc
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Joined: 23 August 2004
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Why did you vent that horn?
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_djk_ View Drop Down
Old Croc
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Points: 6002 		Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2010 at 3:19am
Do you have any idea how much mouth area a 40hz horn requires?

Horns with less than optimum mouth area benefit from venting.
djk
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JD01 View Drop Down
Young Croc
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Points: 819 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JD01 Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2010 at 4:40am
We are talking about a 70Hz horn, I guess it's used as a "kick cab". Porting such a horn is nonsense IMO, only plausible if the subwoofer below that is a bandpas.

Besides, a long horn does not need to have much mouth area as the quarter wave resonance will give some output around 40-50Hz. When stacking them, the effect will wear off and make way for "real" horn output. Works well with my selfmade horns...
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_djk_ View Drop Down
Old Croc
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Joined: 23 November 2004
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Points: 6002 		Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2010 at 10:03am
.

Edited by _djk_ - 03 October 2010 at 10:10am
djk
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