LM4780 for SubW

samsagaz · 15th September 2004, 06:14 PM

hey guys, will be an LM4780 (bridged) good for an Subwoofer?

will be this comparable with Class D Amps?

i read the Class D Amps are the best for Subwoofers, but a lot of hard to design it too

please someone help me

Upupa Epops · 15th September 2004, 06:55 PM

What power do you need ? With one 4780 you can get 120 W / 8 Ohm, with two pieces more than 200 W / 4 Ohm.

samsagaz · 15th September 2004, 07:09 PM

well i need at least 300-400 Watts

its the description of the woofer that i maybe ill use

Tempest combines a low Fs (18.6 Hz), medium Vas (317L), and medium Q (0.38) with an incredibly long throw (16.9mm one way) for a subwoofer driver capable of huge deep bass output. And with a 750W power rating, you can use all that displacement, too. We've run a LOT more power through this unit than what we've rated it for. Tempest should be able to take a beating!

will be great to use 4 IC in bridged mode

Upupa Epops · 15th September 2004, 07:21 PM

In normal connection is " border line " practically somewhere between 250 - 300 W / 4 Ohm, 'cos rails must be +/- 40 V max. . Bigger power you get only with lower load impedance.

samsagaz · 16th September 2004, 02:58 PM

wich relation existe between the amount of bridget ICs and power supply?

i mean, can i bridge 10 ICs for example?

soundNERD · 17th September 2004, 01:28 PM

No, you cannot. You can only bridge 2 chips (or 1 4780 - bridge the 2 amps in it). The reason is because bridging means that the positive of two amps drive half of a speaker.

What you can do is parallel 2 sets of 5 amps then bridge them. That would give you amazingly low impedence drive.

samsagaz · 17th September 2004, 01:38 PM

sounds nice

some math !formula" to determine how much V and Amps i need in the power supply?

peranders · 17th September 2004, 02:48 PM

Why don't you use this Excel file?

http://www.national.com/appinfo/audi...gn_Guide13.xls

http://www.national.com/appinfo/audi...sign_Guide.pdf

peranders · 17th September 2004, 02:52 PM

Seriously, it's easier to design an amp for max 10 KHz or a bit less than that and use MOSFET's. Driving MOSFET's up to 100-200 Hz requires almost nothing in power, nor in complexity.

samsagaz · 17th September 2004, 03:50 PM

thanks dude

15th September 2004, 06:14 PM	#1
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	LM4780 for SubW hey guys, will be an LM4780 (bridged) good for an Subwoofer? will be this comparable with Class D Amps? i read the Class D Amps are the best for Subwoofers, but a lot of hard to design it too please someone help me

17th September 2004, 02:48 PM	#8
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Why don't you use this Excel file? http://www.national.com/appinfo/audi...gn_Guide13.xls http://www.national.com/appinfo/audi...sign_Guide.pdf __________________ /Per-Anders (my first name) or P-A as my friends call me

17th September 2004, 02:52 PM	#9
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Seriously, it's easier to design an amp for max 10 KHz or a bit less than that and use MOSFET's. Driving MOSFET's up to 100-200 Hz requires almost nothing in power, nor in complexity. __________________ /Per-Anders (my first name) or P-A as my friends call me

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15th September 2004, 06:55 PM	#2
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	What power do you need ? With one 4780 you can get 120 W / 8 Ohm, with two pieces more than 200 W / 4 Ohm.

15th September 2004, 07:09 PM	#3
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	well i need at least 300-400 Watts its the description of the woofer that i maybe ill use Tempest combines a low Fs (18.6 Hz), medium Vas (317L), and medium Q (0.38) with an incredibly long throw (16.9mm one way) for a subwoofer driver capable of huge deep bass output. And with a 750W power rating, you can use all that displacement, too. We've run a LOT more power through this unit than what we've rated it for. Tempest should be able to take a beating! will be great to use 4 IC in bridged mode

15th September 2004, 07:21 PM	#4
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	In normal connection is " border line " practically somewhere between 250 - 300 W / 4 Ohm, 'cos rails must be +/- 40 V max. . Bigger power you get only with lower load impedance.

16th September 2004, 02:58 PM	#5
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	wich relation existe between the amount of bridget ICs and power supply? i mean, can i bridge 10 ICs for example?

17th September 2004, 01:28 PM	#6
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	No, you cannot. You can only bridge 2 chips (or 1 4780 - bridge the 2 amps in it). The reason is because bridging means that the positive of two amps drive half of a speaker. What you can do is parallel 2 sets of 5 amps then bridge them. That would give you amazingly low impedence drive.

17th September 2004, 01:38 PM	#7
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	sounds nice some math !formula" to determine how much V and Amps i need in the power supply?

17th September 2004, 03:50 PM	#10
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	thanks dude

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