how to bridge an amp

[Jay_G]

I think the term is bridging.

I bout a 400watt 4 channel amp today and i am only planning on running 2 6x9's off it.

now im not totally sure but i think even with only 2 channels hooked up it will only supply 100 watts to the channels.

i have heard some people briging amps for subs n stuff is it possible to do it for the 6x9's and run 200watts to each 6x9?

so how do i do it?

[tomee]

imo id recommend not to bridge ur 6x9's.... not worth it imo
just run ur 6x9's off a channel each..

stick with bridging to subs :)

[Jay_G]

ok then so how do i bridge chanels for a sub :)

???

[mirage]

the amp should tell you on the casing or manual if it is bridgable, basically it combines 2 channels into 1 by using the positive of one channel and the negative of the other. The casing or manual will tell you which to use from which if it is indeed safely bridgable.


That said, 6x9's do not need over 100W to get loud so i wouldnt bother, as running each of a bridged channel means you will have to adjust the gain and frequency cut off for each speaker seperately.

[Jay_G]

The manual doesnt say a single thing about bridging the amp.

so basicly i would wire the 2 channels up in series one wire coming form the +tive and one from the -tive and a wire interconnecting the other +tive and -tive terminals?

can you do this with all amps or is ther a possibility i could blow it up?

[steevo]

this is what your teminals should look like when bridged,The positive from one channel to the negative of the other channel (the pic below is for one sub but for two use do the same to the other channel

Channel 1-2

+ - + -
I_______I
Bridged

Channel 3-4

+ - + -
I_______I
Bridged

[GTS_215KW]

Originally posted by Celica_RA40
The manual doesnt say a single thing about bridging the amp.

so basicly i would wire the 2 channels up in series one wire coming form the +tive and one from the -tive and a wire interconnecting the other +tive and -tive terminals?

can you do this with all amps or is ther a possibility i could blow it up?

in a bridgeable amp, the + of one channel and the - of the other channel are both reference, so you would not have to connect them together as it is done internally.

in a bridgeable amp A channel +pos is a normal wave and A channel -neg is the reference. And B channel has its reference on the +pos terminal and the -neg channel has an inverted wave.

in normal operation, ie. unbridged, they both produce the same music which is in phase.
Proof:
let the music amplitude be X, since for channel A the voltage across its terminals from +pos to -neg is V = (X - 0) = X

for Channel B it is V = (0 - (-X)) = X
it is -X because the neg terminal on channel B is inverted. so overall they play the same.

in a bridged configuration you would connect the +pos of Channel A and the -neg of Channel B to the speaker terminals. Now the voltage across the terminals (once again from +pos to -neg) is:
V = [X - (-X)] = 2X
ie. double the voltage across the speaker.

Power = V^2 / R

with the same speaker (or load), bridging theoretically quadruples (2^2) the power being disapated through the speaker. emphasis on theoretically there since it depends on how efficient the amps are.

sorry but i seemed to have digress a bit there.

anyway the point is not all amps are bridgeable (non-bridgable amps have the same +pos and -neg signal on both channels, and chances are they will have a floating ground so dont connect the two grounds together).

if bridging isnt mentioned in the manual, it would be a good assumption that the amp isnt bridgeable.

(PS. i wrote my post with respect to a two channel amp which bridges into one channel, just double everything for a four channel which bridges into two and etc etc)

:)

hope dat helps