Discussion: Bridging Reduces Sq

[roger]

I came across that statement on another forum today. I wanted to know what the local gurus think. I personaaly cannot say with any assurance that it does or does not. I know that bridging reduces headroom, but sound quality???

what say ye? Does bridging two channels to one reduce sound quality??

[SR]

yes it does
ratings on amplifiers are given at 4 ohm stereo loads.........ie thd
when an amplifier is bridged
effectively its the same as running the amp at 2 ohm stereo and thd rises when the amplifier is loaded at 2 ohm

this is the case for most amplifiers unless the amp is a high current amp which theoretically has been designed backwards ie designed to run lets say at 1/2 ohm stereo with the same thd and freq response as a comparable 4 ohm amplifier say .05 thd
however when this amp is loaded at 4 ohm the thd now drops to say .005 thus making the high current amplifier a cleaner playing amp at 4 ohm
amps are designed to play at lower impedance loads to give the user a better bang for their buck however quality is sacrificed
most if not all the pro competitors in sound q run their amps at 4 ohm and tnd to run more amps rather than loading to 2 ohm to keep the system playing as clean as possible
however if you are using dedicated high current amplifiers then the loads can be run down to 2 ohm or even 1 ohm without sacrificing sound quality

[Sully]

There's also a change in the damping factor when using a lower load. This could affect the quality if it's used for a subwoofer.

[roger]

well, i always thought wrt to the dampening, that it comes into play when an amp is driven to its limits, and is really a better indicator (to me) of the power supply capabilities. So i cannot see the dampening affecting sq when the channels are bridged, and the playing level is normal.

as for the thd, again while i understand what you are saying sr, is the difference in thd between 0.5% and 0.005 audible? now the point may be thru that amps run cleaner at 4ohms stereo than 2ohm bridged, but does it have do do more with the combining of the left and right signals than thd.

[nigel1977]

damping is a measure of how well the amp can control its output at a given load.

when you bridge an amp, lets say a 75x2 @ 4 ohms amp.. when you bridge the amp into 4 ohms, it the same effect as if you ran the amp 2 ohms stereo. so expect the damping to drop.
the mere fact that the amp looses a measure of its ability to comtrol its output means that there is less cone control, attack and decay of audio notes will be degraded. etc etc. sq isnt as you will find out isnt just about how something sounds... its about placement, definition.
expect that when you bridge an amp, based on the amplifierd design circuitry, that entire bandwidth may be affected.

you'll have no problems with the zapco studio series though. yeah i dun know yuh busnisess

[roger]

hahahahaha....

OMG news travels fast!!!!

after thinking about it, and ready over the explanations i understand now about bridging and sq

[SR]

seeing dat allyuh so concern with bridging
ORION HCCA
talk dun

[roger]

^^didn't think of them....

i should have

[nigel1977]

if yuh cud get

[roger]

i gud get........................trust meh!

[~snYper~]

seeing dat allyuh so concern with bridging
ORION HCCA
talk dun

oh gorsh!!!!

Yuh take the words straight outta meh mouth.........u just hadda say you luv the HCCA's eh.....neva heard anything better!!!

[roger]

[chosen1]

bump for a real ole school but still relavent topic....

[silent_riot]

Lots of guys in the lanes today bridge amps.
Tbh, there is a lot more to pay attention to, i.e. installation and tuning, than worrying about amp distortion.

[FD3S]

Lots of guys in the lanes today bridge amps.
Tbh, there is a lot more to pay attention to, i.e. installation and tuning, than worrying about amp distortion.

Endorsed. From my experience I prefer the increased headroom gained from bridging. My system improved in impact and dynamics and I have yet to hear what increased thd and decreased damping factor sounds like. Maybe you need to have ears like bat to hear that

[Gladiator]

Bridging the amplifier output changes the reference point of the output signal from Ground to an inverted copy of the signal... therefore the Voltage across the load is doubled and the power increased.

In a class AB amp, the crossover distortion contributes to the thd of the signal. If you bridge two channels into one, you sum the distortion of the two output stages and double the thd.

Another factor to consider is that most output devices exhibit more thd with increased temperature and increased output causes increase in temperature. Output devices are not thermally matched in most amplifiers and may exhibit non linearity as temperature varies. When bridged, due to the fact that more output devices determine the final signal characteristic, the chances of greater non linearity in reproduction and increased distortion is increased.

High current amplifiers produce massive amounts of heat when bridged into low impedance loads. They are just overdesigned to handle the high current and heat. The general characteristic of a tansistor/mosfet shows increased thd with heat. therefore IMO high current amplifiers are not a solution to low thd in bridged applications.

I personally use 4 ohm loads for best SQ and although 0.05% thd cant be heard by some.... you will notice the difference in bridged outputs as compared to normal stereo operation into 4 ohm loads.