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Old 22nd December 2005, 15:28   #1
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Default The H bridge concept & Building an amplifier

hi team bhp

If i have an amplifier of 100watt rms into 2 channels
can any one tell me what will be the output in watt rms if
i connect these 2 channels in B bridge configration.

will it become 2 times(200rms) or 4 times(400rms)

ny help will be greatful
thankz
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Old 22nd December 2005, 18:18   #2
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its h bridge nor b bridge sorry :-)
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Old 22nd December 2005, 19:14   #3
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100W/ch at 4ohms would give 200W/ch at 4 ohms if the amp is stable at 2 ohms (in stereo).
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Old 22nd December 2005, 22:11   #4
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hello naven

here is a small derivation which says that i will get 4 times output that is 400watts instead of just double that is 200wats
POWER = VOLTAGE*VOLAGE/RESISTANCE
P=V*V/R
In the h bridge configration the voltage is doubled across speaker ( basic concept of h bridge)
power is proportional to square of voltage so when voltage is doubled due to h bridge the power will increase by a factor of square of 2, that means 4

can any one tell if i am right
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Old 23rd December 2005, 11:29   #5
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Quote:
Originally Posted by navin
100W/ch at 4ohms would give 200W/ch at 4 ohms if the amp is stable at 2 ohms (in stereo).
I agree. However in a typical situation, a bridged ampifier gives about 175% in bridged mode. So a 100W X2 @ 4ohms
with roughtly translate into 175WX1 @ 4ohms
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Old 23rd December 2005, 17:45   #6
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Quote:
Originally Posted by amit1101
POWER = VOLTAGE*VOLAGE/RESISTANCE
P=V*V/R
amit you are gonna hurt yourself. :-)

P is also = I*I*R. that is where typical amps trip up. current capacity.

Sam, my home brew 200W/ch 8 ohms home amp dumped over 500W in bridged mode into 8 ohms. Then again it has a 1200VA trany and 120,000uf of filter caps. The fact is I use about 10W of this 30kg beast. the rest is for show!
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Old 23rd December 2005, 17:57   #7
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Default 4 channels bridged to 1

Well let me have the best of it...
So guys, can someone tell me if i can bridge a 4 channel amp which is manufactured by the company to run 4 channel and 2 channels to do 1 channel.
IE, Connect on single sub and derive the complete power to a sub. Well I am sure u can have two speaker setup on these easily but is the 1 channel setup advisable and recommended. If yes, how is it done.

Hope i am clear.
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Old 23rd December 2005, 18:04   #8
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Quote:
Originally Posted by general_neo
Well let me have the best of it...
So guys, can someone tell me if i can bridge a 4 channel amp which is manufactured by the company to run 4 channel and 2 channels to do 1 channel.
IE, Connect on single sub and derive the complete power to a sub. Well I am sure u can have two speaker setup on these easily but is the 1 channel setup advisable and recommended. If yes, how is it done.

Hope i am clear.

Hello General,

To tell you the truth - NO you arent clear

But i gather you want to bridge 4 channels into 1. No amplifier i know of does that yet.
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Old 23rd December 2005, 18:34   #9
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Default I*i*r

Quote:
Originally Posted by navin
amit you are gonna hurt yourself. :-)

P is also = I*I*R. that is where typical amps trip up. current capacity.

Sam, my home brew 200W/ch 8 ohms home amp dumped over 500W in bridged mode into 8 ohms. Then again it has a 1200VA trany and 120,000uf of filter caps. The fact is I use about 10W of this 30kg beast. the rest is for show!
hello navin
here is the derivation in i square r format
suppose u have a normal amp , its a push pull amp and operates at +/- V rms volts
impedance of u r speaker be R ohms
during positive cycle the currrent through speaker is +V/R rms
during negative cycle the currrent through speaker is -V/R rms
total power is I*I*R where I= V/R rms
V*V/R watts ...........................................(1)

now u make an H bridge
since the voltage across speaker is now doubled the current will aslo double
bcoz V=I*R
thus in bridge
current during positive cycle is +2V/R
current during negative cycle is -2V/R
now power by I*I*R
(2V)(2v)/R
4*V*V/R watts ...........................................(2)

now the power in equation 2(bridge) is 4 times that of equation 1(normal)

amit
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Old 23rd December 2005, 18:51   #10
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amit101 - look at navins statement again: CURRENT CAPACITY is the key. We're talking about amplifiers that run off a 12V battery and have a limited power supply to say the least. Current will double only if the power supply is capable enough to supply the juice
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Old 23rd December 2005, 20:55   #11
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Quote:
Originally Posted by Sam Kapasi
Hello General,

To tell you the truth - NO you arent clear

But i gather you want to bridge 4 channels into 1. No amplifier i know of does that yet.

I am sorry..
If i were in ur place reading my post, I would be shellin u with abuse... heheheh!!!

U answered my question... but i tried reading my own post and it doesnt make any sense at all.

U must be a genius to understand what i was looking for...

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Old 23rd December 2005, 21:34   #12
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gen neo, geez. you cant do that. think when you bridge an amp the +ve's are used across both channels. once you have done that how do you connect 2 bridged amps?
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Old 23rd December 2005, 22:54   #13
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Quote:
Originally Posted by navin
gen neo, geez. you cant do that. think when you bridge an amp the +ve's are used across both channels. once you have done that how do you connect 2 bridged amps?
I consider myself moderate, when it comes to audio setup. I raised the question becoz i didnt believe such a thing cud be done. But how ever When the tread started, i felt somebody was talkin about it and wanted to clarify. Neva know wats in and wats out. Thanks for the intel...
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Old 25th December 2005, 18:57   #14
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Quote:
Originally Posted by Sam Kapasi
amit101 - look at navins statement again: CURRENT CAPACITY is the key. We're talking about amplifiers that run off a 12V battery and have a limited power supply to say the least. Current will double only if the power supply is capable enough to supply the juice
there is no limit on the voltage u can obtain from a car battery
we use a circuit called chopper boost up circuit which can avail us 250 volts dc very easily
u must have noticed coils in amp. those are passive filters but mainly they are the paart of this chopper ckt.
if there was no choppers we would have to keep big big transofrmers at our back with amp. :-)

Last edited by amit1101 : 25th December 2005 at 18:59.
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Old 25th December 2005, 21:55   #15
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there is a limit on the power supply on most power amps.

P=V*I=I*I*R Even is V=250 you still have to dump amps. it is the current capacity which limits most amps.

Last edited by navin : 25th December 2005 at 21:57.
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