setting gain via dmm

[soskie 10+ year member]

sub-1150 rms 4ohm dvc ( its wired to 8 ohms)

amp- 2x 400rms at 4 ohms (have sub bridged, so 800 rms)

Im trying to find out how many volts i should set the gain to.

Do I use the subs resistance or the amps?

Sqrt(Power*Resistance) = Voltage

Sqrt(800*8) = 80

Sqrt(800*4) = 56.56

Thanks in advance

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[rsgladwin85 10+ year member]

Why do you have it wired to 8ohms?

 

[bubbagumper6 5,000+ posts]

sub-1150 rms 4ohm dvc ( its wired to 8 ohms)amp- 2x 400rms at 4 ohms (have sub bridged, so 800 rms)

Im trying to find out how many volts i should set the gain to.

Do I use the subs resistance or the amps?

Sqrt(Power*Resistance) = Voltage

Sqrt(800*8) = 80

Sqrt(800*4) = 56.56

Thanks in advance

The answer is "yes"....because they are the same. The amp doesn't have resistance, the subs present an impedance load on the amplifier (in this case, an 8 ohm load), so that's the value you use for your calculation.

And to the second poster, he's probably got it wired to 8 ohm because his amp can't handle a 2 ohm bridged load...duh

 

[rsgladwin85 10+ year member]

The answer is "yes"....because they are the same. The amp doesn't have resistance, the subs present an impedance load on the amplifier (in this case, an 8 ohm load), so that's the value you use for your calculation.
And to the second poster, he's probably got it wired to 8 ohm because his amp can't handle a 2 ohm bridged load...duh

Then why not wire them in parallel to attain a 4ohm bridged load?

 

[justafifteen 10+ year member]

sqrt(watts*ohm)

For example, I want to send my AQ 870w at 2ohms, so

sqrt(870*2)

=

41.7ish volts

 

[soskie 10+ year member]

have it wired to 8 ohms because the only other way is 2omh and thats gonna be to much rms to my subs

 

[rsgladwin85 10+ year member]

have it wired to 8 ohms because the only other way is 2omh and thats gonna be to much rms to my subs

Each coil is 2ohms or 4ohms?

 

[soskie 10+ year member]

Each coil is 2ohms or 4ohms?

4ohms //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[wevie 10+ year member]

Each coil is 2ohms or 4ohms?

If the OP states his only two options are 8 ohms and 2 ohms, then obviously he has two four ohm coils. this thread isn't about how to wire the subs. its about how to use a DMM to set the gain.

 

[rsgladwin85 10+ year member]

4ohms //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

So you set it up to look like this: ?

View attachment 26520379

 

[rsgladwin85 10+ year member]

If the OP states his only two options are 8 ohms and 2 ohms, then obviously he has two four ohm coils. this thread isn't about how to wire the subs. its about how to use a DMM to set the gain.

You're right this is about helping him, and if his are dual 4ohm voice coils, he can attain a 4ohm load.

 

[soskie 10+ year member]

only have the one sub mate

 

[rsgladwin85 10+ year member]

only have the one sub mate

Ah, my bad. There would be the missing piece, or rather the one my mind fabricated. Sorry about that.

 

[Haunz 10+ year member]

A DMM is a nice toy to have, but setting gain levels by ear is the key.....

 

[soskie 10+ year member]

Ah, my bad. There would be the missing piece, or rather the one my mind fabricated. Sorry about that.

np, you tried to help.

Thanks everyone