bridged amp and effect on resistance

[ncc74656 2]

if we bridge a stereo amp does the impedance of the amp change?

does the amp being bridged change the final impedance to the subs?

as an example would 2 4ohm SVC subs wired in parallel be seen as a 1ohm load by a bridged amp?

[frogcase2002 393]

Whatever you wire the subs to is what your ohm load is. 2 single 4 ohm subs would be 2 ohms in parallel

[ncc74656 2]

the way it was just explained is that because we are: "using 1 rail from each side of hte amp that the amp will further reduce the ohm load"

[ncc74656 2]

so because the "bridging" is using 1 rail of each channel, each rail will see half of the load. so a 2 ohm sub load being bridged would make each rail see 1ohm.

 

that is how its being explained.

[altoncustomtech 773]

so because the "bridging" is using 1 rail of each channel, each rail will see half of the load. so a 2 ohm sub load being bridged would make each rail see 1ohm.

 

that is how its being explained.

 

This is accurate, however that's not saying the LOAD itself is changing, just how the amplifier is seeing the load.

 

2 ohms is still 2 ohms, 1 ohm is still 1 ohm, but that's why a stereo amp is 2 ohm stable in stereo and 4 ohm stable bridged because when it's bridged each rail is essentially only seeing half the load.  The actual load doesn't change, only the way the amp perceives the load.

[95Honda 486]

Kind of...

 

It is simple ohms law, when you bridge, you double the output voltage.  When you double output voltage you increase the power 4x into the same impedance (E^2/R).  If an amplifier is only capable of X watts total, then you cannot get more than that under any condition.  Knowing this, when you bridge an amplifier, the overall load must not be any lower than what will draw maximum power at 2X the voltage of the un-bridged mode, i.e. you must have 2x the impedance. 

 

So it really isn't really that the each side is 1/2 the load, but that the output voltage has been doubled and when you do that you must also double the load impedance in order to not ask too much from the amp...

 

Additionally, there is no benefit to bridging unless it is to overcome a voicecoil configuration issue.  Output impedance of the amplifier is doubled, dampening factor is cut drastically.  In other words, the amp performance suffers...

[hdrox88 142]

Pretty cool having it explained like that.

[///M5 2,833]

Wow are there idiots at your store again. They've never told you anything right. Impedance is ONLY determined by the drivers (resistance as you asked about is pointless BTW). Just wanted to clarify if Honda's voltage description was confusing for any reason.

[ncc74656 2]

thats exactly what i thought and am trying to teach the new guys but my boss is teaching what i posted above.

[jcarter1885 995]

Put your boss's theory to test for him. Wire a 4 ohm driver to a two channel amplifier bridged, see what happens. Now get two 4 ohm drivers and repeat the process, amp should go into protect. If amp is stable to 4ohms bridged then the second test shouldnt last that long depending on amps protection features.

[frogcase2002 393]

Do you tell your boss he is wrong? Because it seems like he has been wrong about ALOT of stuff. . . . Should probably tell him to join this site

[///M5 2,833]

Fuck it just tell him he is a moron.

Easy to test. Measure the same woofers impedance 2x in a row. Pretend once it is connected to an amp that is bridged and once it is connected to a standard amp. Notice no difference. If he has ANY brain he will realize you are measuring the same woofers 2x in a row and whatever they are connected to doesn't matter.

[ncc74656 2]

i had that discussion, "i dont care if you dont believe it or if it does not makes sense to physics, that's the way it is" and the digging for books written in the 70's about audio began. mind you we were both unable to locate ANY supporting evidence to the claim that the "bridged speakers going to the bridged amp will lower the impedance"

[Jay-C76 333]

Use a meter to show the impedance.....meters don't lie.

If there's still an argument, then blindness is the issue not the ohms law.

[frogcase2002 393]

You mind saying where you work?

[///M5 2,833]

He works at Mach 1 IIRC. Obviously his boss is a complete and utter dipshit. Everytime he posts a question it is obvious the poor kid is being misled like crazy.

[frogcase2002 393]

Well at least he is on here and is getting some truth