Wattage meter setting matching cabinet impedance.

  • This has been the most confusing post of all time on this site.


    First, I dont understand why the Kemper is posting the wattage incorrectly. Calculating wattage is baby sh*t compared to what the Kemper is already doing. Unless they are NOT measuring anything and just going off the volume knob and an assumed load. Just so people can have a ball park idea of how much power they are using.


    Second, I dont understand why people are annoyed that someone asks for it to be usable. They put it in there and with 10 minutes of code could make it function better. Why not do it?


    Whats next? Covid is not real and the world is flat? Guitars are really sticks of wood that shoot sub atomic particles at the far right to reprogram their brains?


    :wacko:

  • The code isn't the problem. The problem is that the Kemper would need to know the impedance of the cabinet. Cabinets don't have the means to transfer the information back. The only way is to use a multimeter, which is not built into the Kemper.

  • Hey Dynochrome


    I've found that to unleash an inventor/designer/engineer on a problem, you need to articulate the need

    Would like to see a setting that matches your cab impedance so that the watt meter show accurate without having to divide.

    ✔️👍

    and the use case

    I think everyone is missing what i was asking. When you play an 8 ohm cab and the Kemper power meter reads 50W that means it's actually about 25 watts. I would like it to actually read 25W in that case.

    ✄ - ✂ - ✄ - ✂ - ✄ - ✂ - ✄ - ✂ - ✄

    ✔️👍


    and get out of the way and let them figure out how to do it.


    I don't know why anybody else feels compelled to undermine the validity of your feature request, or what value it brings to suggest it's not possible.

  • The code isn't the problem. The problem is that the Kemper would need to know the impedance of the cabinet. Cabinets don't have the means to transfer the information back. The only way is to use a multimeter, which is not built into the Kemper.

    Power = Voltage * Current

    Power = Voltage^2 / Impedance

    Power = Current^2 * Impedance

    With some adjusting for power factor, crest factor, etc.


    There are two easy ways to measure the power:

    1) Measure the Voltage and Current at the output of the Kemper.

    2) Measure the Voltage OR Current at the output and calculate power from the cabinet impedance.


    Method #1 is probably the best way. It will be more accurate and does not require any knowledge of the cabinet impedance.


    To use method #2, the Kemper would need to measure the cabinet impedance (as you suggested) or have the user enter the impedance manually (as the OP is requesting). Of course you will not get a true power reading since you do not know the phase angle between the voltage and current and therefore cant calculate power factor.


    So yes, the CODE is the PROBLEM. The Kemper engineers just need to let you edit the cab impedance. Assuming this is the method they are using. I do not know or even own a power Kemper ... yet 8o So I could just put down my crack pipe and be quiet. But what fun is that?

  • Ikm pretty dumb when it comes to electronics but the manual states thate the power amp delivers X watts at Y impedance. Presumably this is because current in the Power Formula is dependent on voltage and impedance. Therefore, power would change with impedance.

    Impedance is mainly frequency dependent.

  • I'm more curious about your cabinets, than anything. Four 16 ohm cabinets in series-parallel? Four 4 ohm cabinets in series?

    You can wire 8 & 16 ohm speaker cabs in many ways. One way is two eight cabs paralleled (4 ohms) + 2 eights in series with the other 2. (8 ohms total)

    Or 4 cabs all wired 16 ohms (my setup) 2 in parallel (8 ohms ) plus another pair in series (16 ohms total). These are connected by a simple hand wired speaker box. When you pay big outdoor shows where the sound isn't bouncing around, I need much more power. I am not the only player that runs 4 cabs off of their kemper power amp. I could name at least a few artists that use the Kemper the exact same way I do on stage with internal amp. I like looking at the meter and making sure I am not coming too close to the 160 watt continuous power rating of the amplifier because I have come close before and luckily nothing happened but in August in on a hot night it might. Not a big deal, just a request. I thought it would be a easy fix.

  • Impedance is mainly frequency dependent.

    True, a speaker’s quoted impedance is only a nominal value (measured at kHz I think) as each speaker has its own impedance curve. However, even the current power meter only uses a fixed nominal impedance so presumably the OP’s request shouldn’t be any less accurate than at present.

  • True, a speaker’s quoted impedance is only a nominal value (measured at kHz I think) as each speaker has its own impedance curve. However, even the current power meter only uses a fixed nominal impedance so presumably the OP’s request shouldn’t be any less accurate than at present.

    True, and also most power meters read RMS AC voltage. Back (way back) in the day when I worked in engineering at Electro-Voice we used 1kHz for impedance and most distortion spec's. When EV was eventually acquired by Mark IV Industries and Midas/Klark Teknik, DDA and Dynacord became sister companies they started up the Mark IV Pro Audio Group, where I worked for seven years servicing and supporting the KT lineup and Midas/DDA consoles. Those were the days!