Higher inductance issue

sonu · 13th February 2005, 08:29 AM

My friend has made an 18" Under hung type Woofer with 20mm xmax with 2magnets of 220mm & magnet height of 60mm. it has not been tested yet), he claims it can handel 1500W of Power & has 4Layer 4" coil with 26swg wire & 20mm winding height for 6 Ohms. But the inductance is very high to be 7 mH. The cone & suspension is very good, and looks like the Bl of the magnet structure would be high.

I wonder what would be the frequency response of the sub if the inductance is so high, and can it really handle 1500W of rms power.

Ron E · 13th February 2005, 12:38 PM

High inductance woofers don't model properly in most T/S software because the easily accessible equations assume inductance is negligible. High Inductance causes a peak in response and then a rolloff above that.

Snickers-is · 14th February 2005, 12:03 PM

And some of the few programs that handles this kind of simulation does it wrong.

sonu · 16th February 2005, 06:21 AM

Ok.. but If the inductance is so high it would be quite slow, as it stores quite energy in the coil, and how to know would it even drive upto 300Hz properly, is there any programme/spredsheet which would give the reactance / rollof frequency depending on the inductance.

And what about the power rarting of the Coil & how is handling wattage calculated.

thoriated · 16th February 2005, 02:23 PM

The rising impedance due to larger inductance shouldn't hurt its power rating per se, although it will require more voltage at higher frequencies to approach a given level of thermal dissipation because of this.

simon5 · 17th February 2005, 04:14 AM

With WinISD, if you have the T/S parameters of your woofer, it can approximate the high frequency rolloff of your driver.

Snickers-is · 17th February 2005, 07:38 AM

I have tested that, but it did not seem very reliable.

hunter audio · 17th February 2005, 03:14 PM

hi

26 swg copper coils are used by eminence too - these drivers will sound boomy and heavy - lacking transient responce and dynamic ability

it will be slow and poor in phase responce the coils are very heavy and even with dual 220 x 20 mm mags i doubt the bh curve will be good

another thing ? underhung - has he used common mild steel or 1008 ? - if not 1008 the magnets will not saturate the magnetic gap evenly

giving rise to heavy non linearite ie the + ve stroke & the - ve stroke will not be same

suranjan das gupta

transducer design engineer

sonu · 18th February 2005, 02:25 PM

We are going to test it within a day or two, for which i need a sealed box, which is under construction. I am setting up my system with SW.
But still no one has answerd my main issue of power rating which can be handled by this coil.
I want to get assured of the power rating it can handle, cause i am gonna power it with a 2000W Bridged amp.

Mr Surjan Das, I have read most of your replies in forums, I need your email address....

my mail address is matrix_electronics@yahoo.com.

hunter audio · 18th February 2005, 03:04 PM

hi

power handling capacity totally depends on your cooling efficiency

parts used - not only in the voice coil material

but else where too

and then your design capability

in lay terms ability to reduce distortion in the entire transducer

since you are manufacturer your self , i can only provide a leading thought - already my partner is very angry with me on - letting out too much - as he says

suranjan das gupta

transducer design engineer

tubu_cruise@yahoo.co.in

13th February 2005, 08:29 AM	#1
sonu diyAudio Member Join Date: Apr 2004 Location: maharashtra	Higher inductance issue My friend has made an 18" Under hung type Woofer with 20mm xmax with 2magnets of 220mm & magnet height of 60mm. it has not been tested yet), he claims it can handel 1500W of Power & has 4Layer 4" coil with 26swg wire & 20mm winding height for 6 Ohms. But the inductance is very high to be 7 mH. The cone & suspension is very good, and looks like the Bl of the magnet structure would be high. I wonder what would be the frequency response of the sub if the inductance is so high, and can it really handle 1500W of rms power.

13th February 2005, 12:38 PM	#2
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	High inductance woofers don't model properly in most T/S software because the easily accessible equations assume inductance is negligible. High Inductance causes a peak in response and then a rolloff above that. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

14th February 2005, 12:03 PM	#3
Snickers-is diyAudio Member Join Date: Nov 2004 Location: Rakkestad	And some of the few programs that handles this kind of simulation does it wrong. __________________ Live sounds better than HiFi.

17th February 2005, 04:14 AM	#6
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	With WinISD, if you have the T/S parameters of your woofer, it can approximate the high frequency rolloff of your driver. __________________ DIYaudio for President !

17th February 2005, 07:38 AM	#7
Snickers-is diyAudio Member Join Date: Nov 2004 Location: Rakkestad	I have tested that, but it did not seem very reliable. __________________ Live sounds better than HiFi.


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16th February 2005, 06:21 AM	#4
sonu diyAudio Member Join Date: Apr 2004 Location: maharashtra	Ok.. but If the inductance is so high it would be quite slow, as it stores quite energy in the coil, and how to know would it even drive upto 300Hz properly, is there any programme/spredsheet which would give the reactance / rollof frequency depending on the inductance. And what about the power rarting of the Coil & how is handling wattage calculated.

16th February 2005, 02:23 PM	#5
thoriated diyAudio Member Join Date: Nov 2003 Location: flyover country	The rising impedance due to larger inductance shouldn't hurt its power rating per se, although it will require more voltage at higher frequencies to approach a given level of thermal dissipation because of this.

17th February 2005, 03:14 PM	#8
hunter audio diyAudio Member Join Date: Dec 2003 Location: calcutta	hi 26 swg copper coils are used by eminence too - these drivers will sound boomy and heavy - lacking transient responce and dynamic ability it will be slow and poor in phase responce the coils are very heavy and even with dual 220 x 20 mm mags i doubt the bh curve will be good another thing ? underhung - has he used common mild steel or 1008 ? - if not 1008 the magnets will not saturate the magnetic gap evenly giving rise to heavy non linearite ie the + ve stroke & the - ve stroke will not be same suranjan das gupta transducer design engineer

18th February 2005, 02:25 PM	#9
sonu diyAudio Member Join Date: Apr 2004 Location: maharashtra	We are going to test it within a day or two, for which i need a sealed box, which is under construction. I am setting up my system with SW. But still no one has answerd my main issue of power rating which can be handled by this coil. I want to get assured of the power rating it can handle, cause i am gonna power it with a 2000W Bridged amp. Mr Surjan Das, I have read most of your replies in forums, I need your email address.... my mail address is matrix_electronics@yahoo.com.

18th February 2005, 03:04 PM	#10
hunter audio diyAudio Member Join Date: Dec 2003 Location: calcutta	hi power handling capacity totally depends on your cooling efficiency parts used - not only in the voice coil material but else where too and then your design capability in lay terms ability to reduce distortion in the entire transducer since you are manufacturer your self , i can only provide a leading thought - already my partner is very angry with me on - letting out too much - as he says suranjan das gupta transducer design engineer tubu_cruise@yahoo.co.in

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