basic questions about horns

ddashk · 16th November 2009, 02:24 PM

hi i am a product design student. i am messing about with building a passive horn for an mp3 player. i have built a few horn by eye and to tractrix curves. my question is what curve/ speaker combo will be most efficient to be powered by for example an ipod. ideally some generic type of speaker for now until i get it all sorted. cant afford to waste any money. thanks any help greatly appreciated

Glowbug · 16th November 2009, 05:46 PM

How much can you spend?

You really need some kind of external amp, the Ipod isn't going to be able to directly power a set of horns from a line-level output.

ddashk · 16th November 2009, 08:27 PM

im not avoiding an amp because of the money. i want to use the horn as the amp. im sure the ipod is more powerful than a gramophone. at the moment i have a tractrix horn about 500mm long and an old speaker i had under my desk. its a mylar diaphragm 87mm dia. 8ohm 8-10w. its a decent listening volume in a quiet room. im sure i can get more with different/bigger horns and a speaker more suited to the ipod

PeteMcK · 16th November 2009, 09:32 PM

iPod Measurements
as you can see from the above site, you'll need high impedance drivers, ...or an amp for max efficiency - this can be as simple as a source follower - Project 83 - MOSFET Power Follower.
as far as the horn goes, the size limits the bandwidth, so to cover the audio spectrum you'll need multiple horns, which means multiple drivers...
an approach which might work is a high efficiency full range driver, in a ported box with a front horn - ask on the 'full range' forum, there are plenty of designs floating around there...

ddashk · 16th November 2009, 10:27 PM

thanks for the reply.. how high impedance should the driver be. is 32 0hm about right as this is what the earbuds are. also on that site they mention that the headphone jack is 5 ohm and the line out 100 ohm. would i be better to use a hacked dock to use the line out?

ddashk · 20th November 2009, 10:25 PM

i remember i used to have a a broken guitar amp. i had a 3.5mm jack wired onto the speaker. it was much louder than i thought it would be. so i looked up the spec sheet for the speaker nd bought the closest generic item i could. its 203mm 8ohm and 91db sensitivity. because of the size of the speaker the horn is huge. it think its getting to the point where its loud enough. im gonna work my way through some more horn curves to see which works best. does anyone know what curve was used for old gramophones?

16th November 2009, 02:24 PM	#1
ddashk diyAudio Member Join Date: Nov 2009	basic questions about horns hi i am a product design student. i am messing about with building a passive horn for an mp3 player. i have built a few horn by eye and to tractrix curves. my question is what curve/ speaker combo will be most efficient to be powered by for example an ipod. ideally some generic type of speaker for now until i get it all sorted. cant afford to waste any money. thanks any help greatly appreciated

16th November 2009, 05:46 PM	#2
Glowbug diyAudio Member Join Date: Feb 2006 Location: Hillsborough, NC/McLean, VA	How much can you spend? You really need some kind of external amp, the Ipod isn't going to be able to directly power a set of horns from a line-level output. __________________ Jim J.

16th November 2009, 09:32 PM	#4
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	iPod Measurements as you can see from the above site, you'll need high impedance drivers, ...or an amp for max efficiency - this can be as simple as a source follower - Project 83 - MOSFET Power Follower. as far as the horn goes, the size limits the bandwidth, so to cover the audio spectrum you'll need multiple horns, which means multiple drivers... an approach which might work is a high efficiency full range driver, in a ported box with a front horn - ask on the 'full range' forum, there are plenty of designs floating around there... __________________ “In the beginner's mind there are many possibilities, but in the expert's mind there are few” Shunryu Suzuki

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16th November 2009, 08:27 PM	#3
ddashk diyAudio Member Join Date: Nov 2009	im not avoiding an amp because of the money. i want to use the horn as the amp. im sure the ipod is more powerful than a gramophone. at the moment i have a tractrix horn about 500mm long and an old speaker i had under my desk. its a mylar diaphragm 87mm dia. 8ohm 8-10w. its a decent listening volume in a quiet room. im sure i can get more with different/bigger horns and a speaker more suited to the ipod

16th November 2009, 10:27 PM	#5
ddashk diyAudio Member Join Date: Nov 2009	thanks for the reply.. how high impedance should the driver be. is 32 0hm about right as this is what the earbuds are. also on that site they mention that the headphone jack is 5 ohm and the line out 100 ohm. would i be better to use a hacked dock to use the line out?

20th November 2009, 10:25 PM	#6
ddashk diyAudio Member Join Date: Nov 2009	i remember i used to have a a broken guitar amp. i had a 3.5mm jack wired onto the speaker. it was much louder than i thought it would be. so i looked up the spec sheet for the speaker nd bought the closest generic item i could. its 203mm 8ohm and 91db sensitivity. because of the size of the speaker the horn is huge. it think its getting to the point where its loud enough. im gonna work my way through some more horn curves to see which works best. does anyone know what curve was used for old gramophones?

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