Non ADA Gear > Speakers & Cabinets

Watts and Ohms and Cabs and Oh My!

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rnolan:
So if the GBs are 8 ohm and CBs are 16 ohm, you can wire one GB and one CB per side in parallel (+ve to +ve, -ve to -ve) which will give you ~ 11 ohms per side. The amp will output less into the higher load (90 w into 4 ohms, maybe 55 w into 11 ohms ?) and run in stereo like that. And mono for the cab will be 5.3 ohms so ok for the poweramp for one channel (80ish watts into 5.3 ohms ?).  However some cab stereo/mono cab switching set ups also include some other circuitry in the switch for impedance matching.

vansinn:
Yep to all above wiring considerations.
As Nolan stated, dunno if there might be additional components to consider.
You could make us a pic from the inside of the jack/switching/wiring area..

MarshallJMP:
Ok in your case MC ,this would mean;

Mono 16 ohm input: 10.6 ohms
Mono 4 ohm input: 2.66 ohms ==> DON'T USE THIS !!! your amp won't like that.
Stereo each input:5.33 ohms

Now this how a Marshall cab is usually wired.So to make sure plug in a cable and use and ohm meter to measure the resistance of each possibility.The dc resistance will always a bit lower.
If you can post your measurements here so we can check them.

Because of the mismatch in impedances the GB will take 2/3 of the power and the CB 1/3 of the power.

McLeanAB:
Hey there MJMP!

Here's what I'm doing... I'm going from only one channel output on my Stealth power amp (I'm assuming 4ohms) to the 16ohm input on the back of the Marshall input jack.  MONO.

So everything is safe for the moment, yes?

Here's what I think I'm gonna do... trade out the 8ohm Greenies for two 16ohm Greenies... OR, just go up and get the 75 watt Creambacks G12H's at 16ohms each and use the cab in stereo.

Thanks again for all the info!

McLeanAB:
Okay, gentlemen...

It seems I might land some 16ohm 25 watt Greenbacks to compliment my 16ohm Creambacks in my Marshall 1960 cab...

Since the ohms will all match, running mono from my Stealth at 90 watts and seemingly 4 ohms, can I run stereo from the Stealth at 90 watts per side and not blow the Greenies?  When the cab is in stereo, it's 8ohms per side (even though the Stealth is 4ohms which is okay).

So back to my first question:  how are watts 'distributed' across the speakers?  If it's 90 watts per side, with a 90 watt total between the GB and CB, will it be safe and distribute only 25 to the GB and the other 65 to the CB?

Let me know, as I'd love to have a stereo cab!

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