Kemper Power Rack - Connecting two cabinets/fullstack

  • Hi guys,


    I wondered how/if I could connect my Kemper Power Rack to a fullstack/two cabinets.

    So I have a 2x12 Mesa Roadster Cab. 140W, 8 Ohm In and parallel out

    Also I do have a Marshall JCM 900 1960 4x12 300W with a 4 Ohm and 16 Ohm input.

    How can I connect both cabs to the Kemper at the same time? Kemper Power Amp into Mesa 8 Ohm Input --> Parallel Out to 16 Ohm Marshall Input?

    Will this work in terms of impedance without causing harm to the power amp?
    Thanks a lot!

  • Here's the internal power amps load capabilities.

    manual page 92:

    "The Built-in Power Amplifier

    The optional built-in power amplifier allows you to connect your PowerHead or PowerRack to 4, 8, and 16-ohms guitar cabinets, as well as unpowered full-range cabinets. It is cabled to the MONITOR OUTPUT internally, so all features of the MONITOR OUTPUT are applied to the internal power amplifier as well."


    Here's a discussion about it, myself I don't think it's worth the risk, but this gets over my head a bit.

    https://www.thegearpage.net/bo…d-16ohm-together.1418822/

  • EDIT: I was using the formula for resistance. It only works for impedance calculation when both speakers have the same impedance.

    The discussion on the gear page link above had the same figure as what lbieber listed, 5.33. I was waiting for forum members to post here to see what the correct answer was for sure. I'm always learning something new, and many times just like this, the information is applicable to more than just the profiler. You should see all the screen shots of info I've taken from the forum over the past five years, thank you all for sharing your knowledge.

  • The formula I found for Parallel impedance on multiple websites:


    I = 1 / (1/X1) + (1/X2)


    I = 1 divided by (1/8) + ( 1/16)


    I = 1 divided by 3/16


    I = 1 divided by .1875


    I = 5.33333333


    BTW - if the two cabinets DO have the same impedance, the same formula simplifies to one half of the impedance of one of the cabs:

    Two 8 ohm cabs in parallel = 4 ohms.


    https://calculator.academy/speaker-impedance-calculator/


    https://audiouniversityonline.…e-with-multiple-speakers/


    https://www.speakerimpedance.c…_parallel&page=calculator

  • Just out of interest, what are you trying to achieve?

    Adding another speaker will look good, but will alter the sound as the cabs will sound different. They won't be any louder or give a much wider spread unless you split them. If you did that, you will have an unbalanced sound...