How do you modify impedance on a speaker cabinet?

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Whoopysnorp

Whoopysnorp

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I have owned an Ampeg SVT-II bass head for a while, but didn't have a cabinet for it until yesterday, when I picked up a Peavey 410 TX for a couple hundred bucks at a pawn shop. I'm quite satisfied with the sound, but it seems like it could be a bit louder. The amp's highest impedance is 4 ohms, and the cabinet's impedance is 8 ohms. I've heard somebody mention modifying this very model of cabinet to run at 4 ohms. If I'm not mistaken, doing that would let the amp run at its full 350 watts RMS rating. Does anybody know what's involved in doing this?
 
I believe the stock speakers in your 410 cab are 8 ohms... which makes it really hard to do what you want...


Shred
 
If all speakers are 8 ohms, wire two speakers at the time in series. Solder the two pos wires and the two neg wires to the input jack and you have 4 ohms. this is called series/parallel wiring.

pos________+(speaker)-____+(speaker)-________neg

pos________+(speaker)-____+(speaker)-________neg




2 pos=====( input jack)======= 2 neg
 
If all speakers are 8 ohms, wire two speakers at the time in series. Solder the two pos wires and the two neg wires to the input jack and you have 4 ohms. this is called series/parallel wiring.
Click to expand...

Yes, that is series/parallel wiring, but it would net 8 ohms, not 4. Can't get 4 ohms from four 8-ohm speakers. You can get 2 ohms (all in parallel), 8 ohms (series/parallel), or 32 ohms (series). Honestly, the difference in the volume would be minimal changing to a 4 ohm cab.
 
Major Tom said:
Yes, that is series/parallel wiring, but it would net 8 ohms, not 4. Can't get 4 ohms from four 8-ohm speakers. You can get 2 ohms (all in parallel), 8 ohms (series/parallel), or 32 ohms (series). Honestly, the difference in the volume would be minimal changing to a 4 ohm cab.
Click to expand...

Thanks Tom, I stand corrected for the one cab. The series is additive and the parallel divides so you would return to 8 ohms. It would take both 4x10 cabs to get 4 ohms.
 
Major Tom said:
Yes, that is series/parallel wiring, but it would net 8 ohms, not 4. Can't get 4 ohms from four 8-ohm speakers. You can get 2 ohms (all in parallel), 8 ohms (series/parallel), or 32 ohms (series). Honestly, the difference in the volume would be minimal changing to a 4 ohm cab.
Click to expand...

Ah, OK. If the volume difference is minimal I'll just forget about it. Thanks guys.
 
On the other hand, it will not be damaging to anything to run it as is. It will not run as efficiently, but it will work fine. Just don't try and run it into a 2 ohm cabinet.


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