Bridging 4 channel loose SQ fact or myth

[Lizardking 10+ year member]

Does bridging a 4 channel amp really affect SQ? I've read and heard this many times and I've read that its a myth.

Personal experience is that when I ran the Zapco 4.0 it seemed that the sound was much warmer and true before I bridged it. When I bridged it I gained output but it seem like I lost something.//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif Thanks for any info..

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[Joe92GT 10+ year member]

When I bridged my alpine 4 channel, I definitely gained output. However, I hated the way it sounded. The mids became really harsh, it just did not sound good. I bi-amped it instead, now its much better. Really, I should just buy a more powerful amp. Your probably in the same boat as me.

 

[Trey803 5,000+ posts]

one of two things happened

1) you ended up clipping the amp

2) you ended up overpowering the speakers

you wont lose sq by bridging

 

[Trey803 5,000+ posts]

repost

 

[Rich B 5,000+ posts]

Does bridging a 4 channel amp really affect SQ? I've read and heard this many times and I've read that its a myth.

I think it depends on the quality of the power supply whether its possible to lose sound quality when its bridged down to 2 channels.

Probably a good rule to follow would be to only expect a 4 ch. amp to sound good bridged into 2 ch.'s when its from a reputable company and its at least their midline pricewise.

 

[faulkton 5,000+ posts]

you might die if you try that.

 

[wesl56 10+ year member]

Probably a good rule to follow would be to only expect a 4 ch. amp to sound good bridged into 2 ch.'s when its from a reputable company and its at least their midline pricewise.

//content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif

 

[squeak9798 5,000+ posts]

It's a myth

 

[Boulderguy 10+ year member]

Not a myth. By bridging into the same load you're effectively doubling the load & hence increasing the output. You do this at the expense of headroom.

No such thing as something for nothing.

 

[squeak9798 5,000+ posts]

Not a myth. By bridging into the same load you're effectively doubling the load & hence increasing the output. You do this at the expense of headroom.
No such thing as something for nothing.

If anything, you would be gaining "headroom" as the potential power output increased, yet (in all likelyhood) the percentage of that power actually being used decreased.

It's a myth.

 

[Kenny Pollock 10+ year member]

My first thoughts are that you might have been overpowering the speakers? That for sure would make me hate my speakers.

 

[T3mpest 10+ year member]

Techically your are "losing SQ", because distortion is doubled. However, it goes from 100x lower than what you can hear only 50x... Odds are if your music was harsher, you were simply pushing the components harder than you were before.

 

[Boulderguy 10+ year member]

If anything, you would be gaining "headroom" as the potential power output increased, yet (in all likelyhood) the percentage of that power actually being used decreased.

It's a myth.

Nah, disagree. Increasing the output only brings you closer to the rail's max, thereby lowering potential headroom.

If you keep volume on 2/10, that's another story - but why bridge then?

 

[squeak9798 5,000+ posts]

Nah, disagree. Increasing the output only brings you closer to the rail's max, thereby lowering potential headroom.
If you keep volume on 2/10, that's another story - but why bridge then?

Who said anything about the volume ?

With a 1:1 gain ratio (setting the gain with a 0db track, for example), your average power output is only going to be about 10% of the amplifier's power. With a 3:1 ratio (using a -10db test tone), that rises to about 30%.

If you, for example, have an amp that outputs 50w x 4 @ 4ohm and 100w x 4 @ 2ohm;

sqrt(50*4) = 14.14V

sqrt(100*2) = 14.14V

Rail voltage stays the same.

You aren't loosing any headroom. , if anything you're going to gain headroom as in all likelyhood the percentage of used to available power is going to decrease.

 

[Boulderguy 10+ year member]

Who said anything about the volume ?
With a 1:1 gain ratio (setting the gain with a 0db track, for example), your average power output is only going to be about 10% of the amplifier's power. With a 3:1 ratio (using a -10db test tone), that rises to about 30%.

If you, for example, have an amp that outputs 50w x 4 @ 4ohm and 100w x 4 @ 2ohm;

sqrt(50*4) = 14.14V

sqrt(100*2) = 14.14V

Rail voltage stays the same.

You aren't loosing any headroom. , if anything you're going to gain headroom as in all likelyhood the percentage of used to available power is going to decrease.

It's not about the rail voltage changing, it's about exceeding the maximum output capacity of the amp. There is a fixed ceiling. By doubling the RMS you cut the margin in half - that's reduced headroom.

It's not about avg output, that doesn't consider clipping. Using your example above, if the RMS @ 4ohm is 50x4 then let's assume clipping occurs at say 150x4. Now up your output at 2ohms to 100x4 - you just lost half your headroom. The max output won't magically increase.

Avg output can still increase well into clip, but who wants to do that?

The only reason volume becomes an issue is if we're assuming lower input for the 2 ohm example. But nobody bridges an amp & doesn't try to use that power, that would defeat the purpose.

Do an A/B test, someone had to prove it to me that way.