Powered KPA & Passive Speakers

Yes, you need to be carefull. If the speaker can handle 300W and at full blast your putting out 600W that can be a problem. But really, be sensible with the volume levels and listen for speaker distortion and you should be fine. Both Cabs are used by many people on this forum without any Problems.

No, the Monitor out is for powered speakers. Your Kemper has a red Poweramp output on the back. This is for driving passive speakers.

Don't worry! The 600 Watts are not used permanently (even at a very loud overall-volumes) they are necessary for the headroom to transmit signal-peaks linearly. So you only need to be careful with very very loud clean signals with high slew rates and - as domsch1988 says above - try to avoid speaker distortion.

Quote from ViceVerses

Total noob but learning and researching. I apologise if it's just another one of those common questions but i'm currently quite confused!

Looking at a few various options for cabs/speakers to use and trying to understand all the numbers and stuff. 2 main passive options i'm currently looking at is the Mission Engineering Gemini 1P, and the Matrix FR12P.

Gemini 1P:
250W low frequency driver
50W 1″ high frequency driver
66Hz – 20KHz +_ 2dB Frequency Response
Passive Crossover 2.5KHz
8 Ohm Impedance

As the powered KPA is 8Ohm 600W, my current understanding is that i'd have to be careful with the volume (even if it is loud, I couldn't just be careless and whack the volume all the way up..), as the cab has half the power of the amp? Despite it stating it's partly designed for use with the powered KPA.

Again with the Matrix, it's 8Ohm with 300W, and i'm just looking to see if these are suitable to use or not. Another question, though this may come off as really stupid, could I just use the monitor out on the KPA into the speakers?

Thanks for any help, and any other suggestions are appreciated!

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Hello ViceVerses,

Along with the Mission Engr. Gemini 1P, I would also recommend you look closely at the XiTone 1x12 Passive monitor:

http://www.xitonecabs.com/mode…ive-1x12-wedge/index.html

According to the Mission Engineering site it is ideally matched for the Kemper Power Head - https://missionengineering.com…emini-1-p/?v=7516fd43adaa but it might not hurt to reconfirm with them.

Quote from Hurricane

Don't worry! The 600 Watts are not used permanently (even at a very loud overall-volumes) they are necessary for the headroom to transmit signal-peaks linearly. So you only need to be careful with very very loud clean signals with high slew rates and - as domsch1988 says above - try to avoid speaker distortion.

So the 600 watts rating is a peak rating? Was that confirmed by Kemper? I tried this forum to get an answer on whether the 600w rating is Continuous/RMS or a peak rating but received no response.

The recommendations I see say to use a power amp that has a RMS rating 2 times (or more) of the Continuous/Program Rating of the cabinet.

examples:
http://www.crownaudio.com/how-much-amplifier-power
https://www.crutchfield.com/S-…lifiers-buying-guide.html
https://www.sweetwater.com/insync/power-amp-buying-guide/

Quote from Grumpter

So the 600 watts rating is a peak rating? Was that confirmed by Kemper? I tried this forum to get an answer on whether the 600w rating is Continuous/RMS or a peak rating but received no response.
The recommendations I see say to use a power amp that has a RMS rating 2 times (or more) of the Continuous/Program Rating of the cabinet.

No, that doesn't have anything to do with Peak or RMS. This means that the Kemper has 600W as an Amp. By default it uses 300W max for driving the cab and the rest is headroom. You basically never ever want a digital poweramp to distort. It sounds nasty. That's why they are so high power. With the internal power increase setting you can lower your headroom for added volume.
While i'm not sure wether its RMS rating, i'd think it is. Every single serious audio Product is rated RMS. The only times i've seen peak mentioned is on cheap Stereos you can buy at walmart that produce "150W" of power.

None the less. From personal experience i can tell you, that 300W turned into volume by a half way efficient speaker is well past the point where your ears seriously hurt. It's not only really loud. You basically feel like someone is pushing a knife straight into your ear. I think you will give up from pain before your speaker gives up. Only case where it could be a problem is the poweramp accidentally putting out full power. But i wouldn't know why it should.

Very technical explanation: A solid state amp is always advertised in sine RMS ratings, with a relatively low "crest factor" (3dB), meaning the amp can't produce more voltage before it clips. Given that you're playing music through an amp, the crest factor of that music will be 6dB to 12dB (6dB tends to the heavy metal side of music, classical music goes even beyond 12dB). That 3dB extra will mean twice the power. So, when a speaker is rated 300W RMS (meaning the voice coil will melt), an amp rated 600W, playing music, will not be melting the voice coil. That's why everyone recommends to use an amp rated twice the power rating of your speaker, to get the most out of your speaker.

Offcourse you have to be careful not to clip the amp, as your sine waves will slowly transform to PWM, and your crest factor will creep to 0 dB (offcoure, 0dB will never be reached unless you are deaf ;)) Also, when using a passive crossover, all the high frequency harmonics introduced through this clipping will flow to the lower powered tweeter. Some speakers have a light bulb in series with the tweeter to act as a sort of passive power limiter (this works quite well!), if you don't: POP, goes my heart tweeter... Thats why, in larger PA systems, properly set limiters are crucial, and when that criterium is met, some audio engineers even go 4x the speaker power on the amp...

Also, this story is not true for tube amps. Why? dunno, no technical experience with it, but I think hangs together with the beautiful way they distort: that beauty comes with harmonics and extra power output (all tough with harmonic distortion). A solid state amp is just limited by it's voltage rails in terms of what it is able to output.

More musical explanation of all this: a solid state amps rating is for when you are playing fffff, without any rests, without decay. But in reality you will not always be playing fffff, there will be rests, and a guitar sound decays... With some genres (metal) thats a minimal effect, with other a very large effect (classical). But 3dB difference will allways be there...

Quote from domsch1988

No, that doesn't have anything to do with Peak or RMS. This means that the Kemper has 600W as an Amp. By default it uses 300W max for driving the cab and the rest is headroom. You basically never ever want a digital poweramp to distort. It sounds nasty. That's why they are so high power. With the internal power increase setting you can lower your headroom for added volume.While i'm not sure wether its RMS rating, i'd think it is. Every single serious audio Product is rated RMS. The only times i've seen peak mentioned is on cheap Stereos you can buy at walmart that produce "150W" of power.

None the less. From personal experience i can tell you, that 300W turned into volume by a half way efficient speaker is well past the point where your ears seriously hurt. It's not only really loud. You basically feel like someone is pushing a knife straight into your ear. I think you will give up from pain before your speaker gives up. Only case where it could be a problem is the poweramp accidentally putting out full power. But i wouldn't know why it should.

I don't think we can just assume 600w Continuous at 8ohms. It may very well be but it would be helpful for users to actually know if it is a continuous or peak rating so they can better match the Kemper power amp to a cab. Look at some of the active speaker offerings and you will find some are advertised as their peak power not the RMS/Continuous power.