Series or Parallel??!!

If you run them in series, you'll have an 8 ohm load

 

Just run the SM900 in stereo mode; each channel will easily handle 4 ohms. Then you can balance levels between the cabs---they'll definitely sound different. Don't run biamped or bridged.

Forget about series, because it requires a special cable. And you'd always have to be careful to never plug them in parallel, which is the most common way.

Forget about replacing the speakers. It will cost too much, and you would need the exact same model speakers. Otherwise the cab won't be tuned for the speaker, and it may be bad news.

 

If you run them in series they will show as an 8ohm load to your amp.

HOWEVER,

in order to do that you need a special cable or box.

Something like this will work.





Joe.

 

You're still better running them on separate amp channels, because they'll probably have different volume anyway, and you'll need to balance them.

If you run them in series, you will be limited to 400w (the weaker cab), because max current flow through the 600w cab would be too much for the 400w cab. Besides, the amp will only push 650w into 8 ohms (running bridged). Why bother?

You can get 400w per channel at 4 ohms. That'll be plenty for either cab.

 

At an 8ohm load you'll only draw about half the wattage you'd get if you were drawing at 4ohm. Not a very efficient way to go, you may want to go with Rick's advice.

 

Or better yet, get another poweramp. Then you can drive one cab with the Carvin and the other with your poweramp. Yeah, if money was no option. ...

 

Some companies might make a series speaker box, but I still think it's the WRONG thing to do.

 

www.bayoucables.com makes one

 

He already has two power amps in the SM900.

 

+1. Also, the high voice coil inductance of the 1x15 will attenuate the high frequency output of the 2x10. Series wiring is a bad idea all around.

 

Right...thanks Rick. I definately agree with your setup suggestion. Hopefully he takes your advice. Those series boxes can cause trouble, but I figured I'd give him the link to Bayou if he decides to go that route.

 

It's good to know Bayou makes that. I've only ordered cables from Butch.

Thanks for that bit, Bill...I had no idea, but now that you mention inductance, yes, of course.

 

What does inductance have to do with it Bill?

Thanks.



Joe.

 

The first speaker in the chain is a big coil in series with the next speaker. A coil (inductor) blocks high frequencies. So the speakers hurt each others' high end.

BTW, There's a technical error on page 9 of the SM900 manual (I downloaded it to check facts for this thread). In discussing different-impedance speakers in parallel, they say:

"However, if speaker impedances are not all equal, the lowest impedances will get the most power. For example, if you connect an 8Ω and a 16Ω speaker to an amp output of 30 watts, the 8–ohm speaker will receive about 20 of those watts (and be twice as loud as the 16-ohm speaker)."

The first statement is correct: the power will be split unevenly.

The second statement, however, is false. Double the power will increase volume only by 3dB. (Double the volume would be about 10dB---which equals 10 times the power.)

 

Only very slightly if the drivers are the same. But the average fifteen has twice the Le value of the average ten, so the fifteen will kill the highs from the tens.

 

Ah, the big-honkin-coil phenomenon.