8 ohm and 4 ohm

[LuckyScott]

My question is can I use one cab that is 8 ohm and one that is 4 ohm.
I got a 4X10 that is 8 and a 2X10 that is 4.
Coming out of a GK fusion amp

 

[Drredplate]

The load on the amp will be less than 4ohms.
What is the minimum impedance the amp can drive?
Also the 4 ohm cab will draw twice the power of the 8ohm.
Will the 4ohm cab be up to it?

 

[agedhorse]

I wouldn't recommend that combination even if your amp can safely drive loads below 4 ohms.

The 210 will receive twice the power of the 410, and each driver in the 210 will receive 4 times the power of each driver in the 410.

There are situations where mixed loads work fine, but yours isn't one of them.

 

[LuckyScott]

Thank you. That’s what I was thinking, just wanted to make sure

 

[agedhorse]

Always best (and cheapest) to ask BEFORE damaging something.

 

[bholder]

once that magic smoke is out .. ...poof ...

 

[Sparkl]

It would work if it were the other way around - a 4ohm 410 and 8 ohm 210. Then each driver would see the same load.

Does the GK Fusion support a 2 ohm load though? If memory serves, the newer S series Fusions are able to take loads down to 2 ohm but the older ones only go down to 4 ohm. Same goes for the original Fusion 550.

 

[whitelines]

In theory, if your drivers are all the same, you could rewire your cabs and make the 2x10 into 8 ohms and your 4x10 into a 4 ohm cab.
If they are not the same make and model, don’t do this.

 

[nonohmic]

It would work if it were the other way around - a 4ohm 410 and 8 ohm 210. Then each driver would see the same load.

Does the GK Fusion support a 2 ohm load though? If memory serves, the newer S series Fusions are able to take loads down to 2 ohm but the older ones only go down to 4 ohm. Same goes for the original Fusion 550.

2.7. And yes they can.

 

[agedhorse]

In theory, if your drivers are all the same, you could rewire your cabs and make the 2x10 into 8 ohms and your 4x10 into a 4 ohm cab.
If they are not the same make and model, don’t do this.

I would like to see the math supporting this...

 

[monti2889]

Combining a 4ohm and 8ohm load in parallel will yield a total load of about 2.67ohm. most gk amps that I have experience with, are stable down to 4ohms. So this combination in parallel, would not load the output of the amp enough. Most likely you'll cause thermal shutdown, but if the thermal shutdown circuit fails, the next piece to go would be the output stages of the amplifier.

 

[rickdog]

In theory, if your drivers are all the same, you could rewire your cabs and make the 2x10 into 8 ohms and your 4x10 into a 4 ohm cab.
If they are not the same make and model, don’t do this.

I would like to see the math supporting this...

Right, that doesn't work. But there's a hint of a useful idea here: if the 4 ohm 2x10 has two 8 ohm drivers in parallel (seems likely) it could be rewired with them in series, making it a 16 ohm cab. That would play well with the 8 ohm 4x10, making a 5.7 ohm load for the amp and adding some speaker area.

But I doubt the small increase in SPL would be worth the trouble. I suppose the stack might look more impressive

 

[whitelines]

I would like to see the math supporting this...

you're right it falls apart even on the 2x10. If the 2x10 is 4Ohms, assumedly in parallel, changing it to series would make it 16.
brain fart...

 

[whitelines]

Right, that doesn't work. But there's a hint of a useful idea here: if the 4 ohm 2x10 has two 8 ohm drivers in parallel (seems likely) it could be rewired with them in series, making it a 16 ohm cab. That would play well with the 8 ohm 4x10, making a 5.7 ohm load for the amp and adding some speaker area.

But I doubt the small increase in SPL would be worth the trouble. I suppose the stack might look more impressive

I have a rare (70s?) ampeg G-60 6x10 that I believe is wired like this. Sold as a guitar cab I think but sounds great on bass.