Powered Rack + Marshall 1960B cab tips

WillSchaeffer2000 · February 15, 2019 at 5:27 AM

Hey everyone, Iooking for some advice with hooking my Kemper powered rack into my Marshall 1960B 4x12 cab. I know this has been discussed from time to time in various threads on here, but I figured I’d get specific on my set up. Looking for what onboard output settings I should set/what Ohms to run the head into and any other suggested steps I should take to prevent volume, tone and of course possible cab overpowering.

I should mention Ive been using the rack through my studio monitors for a few months, so I’m familiar enough with operating it at this point. I’ve got some shows coming up and I have no experience plugging it into a cab for live use. Thanks!

Dogmatix · February 15, 2019 at 8:38 AM

Set your power amp boost to zero.

Use the cab’s 4 ohm input. It will work with 16 ohm as well but 4 ohm should be louder.

It shouldn’t reach maximum power unless you max out the volume which will probably be too loud. If it does the kemper will automatically cut itself off to protect itself.

Wheresthedug · February 15, 2019 at 10:02 AM

I would take the exact opposite approach

The Marshall cab is rated at 300w in mono. The KPA puts out 600w at 8ohm or less (ie 4 ohm in your case) but puts out 300w at 16ohm. As Dogmatix pointed out whatever you do will probably be too loud anyway but if you run at 16 ohms you will be withoun the power handling capacity of the cab without needing to worry about whether you are going to blow a speaker.

Dogmatix · February 15, 2019 at 11:49 AM

It will technically try to supply 1200 Watts at 4 ohms. The power amp boost is 6 dBs meaning if it’s at zero it will output 300 Watts.

4 ohms on a Marshall cab sounds better to me. Running the speakers in parallel gives better damping and more low end.

Though just running it at 16 ohms with the power amp boost max is also ok and perfectly safe.

Main thing is what sounds better.

Wheresthedug · February 15, 2019 at 2:13 PM

I don’t think it willtry to supply 1200w at 4ohms as its limited electronically to only supply 600w at 8ohm or below.

V8guitar · February 15, 2019 at 3:00 PM

I've run 16 ohms and 4 ohms in the same cab....I noticed virtually no difference soundwise.

I have my power amp boost on full.

You will blow your ears before you blow your speakers...

Wheresthedug · February 15, 2019 at 3:51 PM

Yes, I wouldn’t expect any difference soundwise with the Kemper as it's a class D power amp. There may be a sound difference when running a valve power amp with am impedence mismatch but I don’t believe there is any difference with Class D.

WillSchaeffer2000 · February 15, 2019 at 4:46 PM

So what I’m gathering is it’s same to either run it at 300w @16 ohms or the full 600w @4ohms, just watch the volume if I’m running it @4ohms?

paults · February 15, 2019 at 4:47 PM

Yes, you can run it either way.

Awesome_Elvis · February 15, 2019 at 5:19 PM

Quote from V8guitar

I have my power amp boost on full.

This is interesting, is this because of the volume not being loud enough or is it the way the volume reacts when you turn it up loud?

I never have turned my power amp boost up that loud before but I've noticed a few different behaviors when interacting with it.

V8guitar · February 18, 2019 at 1:45 PM

Quote from Awesome_Elvis

This is interesting, is this because of the volume not being loud enough or is it the way the volume reacts when you turn it up loud?

I never have turned my power amp boost up that loud before but I've noticed a few different behaviors when interacting with it.

I had some volume issues sometime ago ( turnout to be linked volumes issue) and I turned it full on. Never touched it since.

Never noticed any difference sound wise except more power....juts means I don;'t have to turn the volume knob quite so much..