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ADA Power Amps => B200s => Topic started by: Mxzx on February 06, 2014, 03:43:24 PM

Title: Marshall Cabs
Post by: Mxzx on February 06, 2014, 03:43:24 PM
I just got a B200s off of Ebay, and was wondering if I can run two 16 ohm 4x12's through it?  I don't have the manual for it, but seller says it can do 100w into 8 ohms, or 135w at 4 ohms?  I do have a JCM-900 that has the stereo switching in the back that I think brings each pair of speakers to 8 ohms, so I can always to do a single cab.

Thanks
Title: Re: Marshall Cabs
Post by: rnolan on February 06, 2014, 08:46:06 PM
The B200s does about 124w rms into 4 ohms and probably about 80w rms into 8 ohms.  You'll do damage if you use a 16 ohm load.  It will pair well with the JCM-900 in stereo with each pair 8 ohms.  You can re wire the 16 ohm cabs to be 4 ohms or run both in parallel off one side of the B200 (ie 16 + 16 in parallel = 8).  4 x 16 ohm cabs are typically wired with each pair in parallel and then the series between the 2 pairs = 16 ohm box (or each pair in series and parallel between the pairs).  If you change the wiring to be all parallel  16 + 16 + 16 +16 = 4 ohm.
Title: Re: Marshall Cabs
Post by: Mxzx on February 07, 2014, 05:20:05 AM
Cool, thanks for the info.

I think I'll just run it into one -900 cab in stereo.

Title: Re: Marshall Cabs
Post by: rnolan on February 07, 2014, 06:45:11 AM
Sounds good  :thumb-up:
Title: Re: Marshall Cabs
Post by: MarshallJMP on February 08, 2014, 07:25:39 PM
You can use 2 16 ohm cabs if you want,won't harm a thing,just the power will be lower.Around 50-60W /side.

JCM900 cabs have either mono 16 or 4 ohms input or  2 x 8 ohms stereo.Are both cabs JCM900 models?
Title: Re: Marshall Cabs
Post by: rnolan on February 08, 2014, 08:41:22 PM
Hey MJMP, that's good to know, I didn't think the B200 would be happy with a 16 ohm load, how would it react to 2 ohm load ?
Title: Re: Marshall Cabs
Post by: MarshallJMP on February 12, 2014, 12:53:02 PM
2 ohm will be too low,it won't like that.
Title: Re: Marshall Cabs
Post by: Dante on February 12, 2014, 05:04:22 PM
This analogy works for me when it comes to amps into speaker cabs:

Ohms are like water in a hose. If you have a garden hose, you can plug it into a garden hose or a fire hose (something larger). You can NOT plug the garden hose into a drinking straw (something smaller). So, if we use the same logic here: If you have an amp that pushes 8 ohms, you can plug it into a cab that will handle 8 ohms (or 16 ohms = something larger).

It will not be good to plug your 8 ohm amp into a 2 ohm cab (which would be like the firehose into the drinking straw = something smaller).

Hopefully, that helps more than it hurts