A question about impedance?

[dthor68 10+ year member]

Lets say you have a 2 channel amp that you want to use to power 1-10" woofer. You bridge the amp, positive channel 1, negative channel 2. By bridging you get 400 watts at 4 ohms. What kind of sub do you need, a 4 ohm or a 2 ohm?

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[germanyt 10+ year member]

That amp is probably not best suited for a subwoofer but you would need either a single 4 ohm coil or a dual 2 ohm coil. The dual 2 could then be wired to 4 ohm.

 

[big scott]

you have to read the manual and see what it says.

it may be 2 ohm or 4ohm.

 

[germanyt 10+ year member]

you have to read the manual and see what it says.
it may be 2 ohm or 4ohm.

I assumed he was fairly certain of 400 at 4ohm.

 

[dthor68 10+ year member]

Its a little bet I got with a co-worker and yes, definitely 400 watts at 4 ohms.

 

[germanyt 10+ year member]

Its a little bet I got with a co-worker and yes, definitely 400 watts at 4 ohms.

Then yes a single 4 ohm coil or dual 2 ohm. Depending on the amp and your electrical you could run a 2 ohm load on a 4 ohm amp but not something a beginner or novice should try.

 

[Slo_Ride 5,000+ posts]

Subwoofer Wiring Diagrams, One 2 ohm Dual Voice Coil (DVC) Speaker

You can play around with that to get the gist of things.

 

[dthor68 10+ year member]

$10.00 richer! He thought that when you bridged the amp, the ohms doubled. So a 4 ohm would be 8, a two ohm would be 4. So in order to get 4 ohms you would need a 2 ohm sub. He was so sure that he had me questioning myself!

 

[germanyt 10+ year member]

$10.00 richer! He thought that when you bridged the amp, the ohms doubled. So a 4 ohm would be 8, a two ohm would be 4. So in order to get 4 ohms you would need a 2 ohm sub. He was so sure that he had me questioning myself!

That doesn't quite make sense but yes he is incorrect. The sub doesn't changed the value of the amp. You choose a sub that fits the specifications of the amp, or vice versa. A 2 channel amp that is 2 ohm stable for each channel would bridge at 4 ohm so could put 2 2ohm speakers, one on each channel, or 1 4 ohm speaker bridged.

Edit. Wanted to add that you could also wire each channel to its own 2 ohm coil.

 

[wew lad 5,000+ posts]

tell him to read this: Bridgeable Amplifiers

i just learned something about bridgeable amps i didnt know before

 

[germanyt 10+ year member]

tell him to read this: Bridgeable Amplifiers
i just learned something about bridgeable amps i didnt know before

Been so long since I saw a BCAE link I forgot it existed. Thanks for posting it.