Kemper Amplifiers for dummy’s

Birdsofprey

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Ok, so many of you seem to praise the sounds and quality of Kemper amplifiers. I get it however doing the early research my ( possibly dumb) question is why 600 watts! Appears like extreme overkill. I think of this using a Hughes & Kettner Tubemeister 36 head through a Blackstar 2x12 cab. This is my “ house rig” in my dining room. Just wondering why such a high wattage rating which btw always seems to be the norm with rack gear. Thanks Ken
 

Boogie

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You aren’t comparing apples to apples. A class D amp and a class A or AB amp derive their power differently and the manufacturers use specmanship to sell, not compare the output stage. My FRFR cabs have amps rated at 2000w peak and they are adequate for live applications and not overkill at all.
 

Birdsofprey

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So a wattage rating tube or solid state does or does not reflect what our ears hear overall? I do somewhat understand the class A, A/B thing however didn’t know the rack stuff is considered class D. I’ll have to learn more about that.
 

Boogie

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So a wattage rating tube or solid state does or does not reflect what our ears hear overall? I do somewhat understand the class A, A/B thing however didn’t know the rack stuff is considered class D. I’ll have to learn more about that.
It’s not about the mounting format, it’s the fundamental amp design. But to answer your first question…no. If they publish an SPL (sound pressure level in dBm) spec, that’s a different story, but that doesn’t happen with an amp, more of a speaker thing.

Comparing amps via specs has always been an impossible task.
 

RickP

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You’ll see this a lot. The speakers I use with my Axe Fx III spec 500 and 700 watts, split (biamp) into one coaxial 12” speaker (Atomic CLR Neo II and RCF NX12SMA, respectively). As the others noted, it’s about the same volume as my 50 watt HXDA 1x12 combo although it can stay clean to a higher level… the function of a heavier duty speaker. If you need to play very loud and clean, this is where the more PA-like fidelity of these type amp/speaker combos shine. The speaker in a tube amps breaking up is often part of its sound.
 
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LSchefman

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As a tube amp gets louder, the distortion gradually rises, but that's part of its charm. A solid state amp will stay clean until it breaks up, and then the sound is most unappealing, so solid state amps tend to have more wattage in the output stage, and handle all of the breakup - in this case, modeled amp breakup - in the preampfification stage.

There are other differences in the way tubes operate as well, and of course, tube amps use transformers that have their own operating characteristics, depend on speaker breakup for part of the tone, etc.

As Boogie says, a 600W rating doesn't necessarily mean all that much. A lot depends on how they measure it - Peak? IHF? RMS? Etc.

One thing about a solid state amp is that it should sound pretty much the way it does at high volume levels, at lower volume, since it's designed not to have the coloration of output tubes and transformer saturation. Tube amps often don't sound the same at lower volume.

As you can see, a modeled amp depends on the model for its tone characteristics, not so much the amplification.
 

markd21

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When I went Helix and was looking for an "FRFR" monitoring system I had a hard time wrapping my head around the concept. I was perplexed by the same thing as you - why so much power?

Then it hit me. The models were the whole signal chain without volume. It was literally like a recorded guitar chain. Until boosted BACK through something the tone was nonexistent. The "color" of the amp was in the model. I needed a high headroom amplifier to properly reproduce the colored tone from the model - kinda like sitting in a killer studio with massive far-field monitors.

More power equals more headroom. More headroom equals a more accurate representation of what you are boosting in volume. Considering your amp model includes power section coloration along with speaker/mic coloration, you want that "extra" wattage. You are thinking of sound reinforcement vs. guitar amplification.

Hopefully that clarifies the water a little...
 

DreamTheaterRules

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Thanks, your last sentence pretty much sums it up, I was just curious why there was such a disparity in wattage ratings.
I've said this more than once here. My 18 Watt Bogner > 2x12 is as loud or louder than my 1000 watt QSC CP8. My Archon would dust it, and my former Mark V would probably disintegrate the plastic cabinet of the CP8.
 

Birdsofprey

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You’ll see this a lot. The speakers I use with my Axe Fx III spec 500 and 700 watts, split (biamp) into one coaxial 12” speaker (Atomic CLR Neo II and RCF NX12SMA, respectively). As the others noted, it’s about the same volume as my 50 watt HXDA 1x12 combo although it can stay clean to a higher level… the function of a heavier duty speaker. If you need to play very loud and clean, this is where the more PA-like fidelity of these type amp/speaker combos shine. The speaker in a tube amps breaking up is often part of its sound.
So Rick could one use there guitar (stage) amplifier like an attenuator being set the sound you may love even if it’s not at very high volume, mike the cab and in essence use the pa as your final/balanced volume? It appears all the best tone when we use various guitar/amp combos aren’t always at high amp volumes. Would your pa keep the tone but allow you to control volume? Thanks for your explanation btw.
 

DreamTheaterRules

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You need another CP8?
That is officially my stage monitor. If I choose to get one to use as an "amp" I'm going upstream a bit. I really want to try the Atomic with some RCF's in the $500-1K range. One of my buddies who does sound systems keeps telling me to go up to an NX but it's over $1700 retail and you all know how I feel about that much on an FRFR. LOL
 

Boogie

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So Rick could one use there guitar (stage) amplifier like an attenuator being set the sound you may love even if it’s not at very high volume, mike the cab and in essence use the pa as your final/balanced volume? It appears all the best tone when we use various guitar/amp combos aren’t always at high amp volumes. Would your pa keep the tone but allow you to control volume? Thanks for your explanation btw.
That is specifically one of the magic features of a Kemper. I use FRFR cabs for most of my needs but I tried using my Boogie MkIII as a power amp for a while. Worked well, but I preferred the consistent sound thru the wedges and send a signal directly to FOH.

rig-cold-zoom.jpg
 

RickP

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So Rick could one use there guitar (stage) amplifier like an attenuator being set the sound you may love even if it’s not at very high volume, mike the cab and in essence use the pa as your final/balanced volume? It appears all the best tone when we use various guitar/amp combos aren’t always at high amp volumes. Would your pa keep the tone but allow you to control volume? Thanks for your explanation btw.

That is specifically one of the magic features of a Kemper. I use FRFR cabs for most of my needs but I tried using my Boogie MkIII as a power amp for a while. Worked well, but I preferred the consistent sound thru the wedges and send a signal directly to FOH.
@Birdsofprey As @Boogie notes, it is one of many ways you can do it. My experience is with the Axe FX line, but it’s very similar with Kemper. Here are a few options:

1. FRFR- These “full range flat response” speakers are essentially guitar PA systems. While guitars have a limited frequency range, the effects available in a modeler greatly expand those possibilities, above and below. The FRFR can handle that clearly, much like a PA does, but the cabinet is more designed for the shorter, wider throw of a stage monitor. One of the biggest advantages of a modeler-FRFR setup is that they tend to be extremely consistent venue to venue and stage to stage, as it’s much like the listening relationship of a good set of near/mid field monitors in the studio, for most of the same reasons.

2. Into front of amp- You can use a modeler like a glorified pedalboard, using your amp for tones (generally no amp/cab sim in the preset). Guys like Steve Vai and John Petrucci use the Axe Fx this way.

3. The “4CM”- This is the 4-cable method, where you run some effects into the amp input, and some in the FX loop. This also uses the amp as the tone generator (preamp, power amp, speakers), but places effects where they work best. You mic the amp.

4. Using the amp as power amp only- if your amp has a power amp input, you can replace the preamp with the amp model from the modeler, and use the tube power amp and speaker of your amp to power the sound. Again, you’d mic the amp.

4. All PA- The most non-fuss method, good for extremely small stages (or “silent” ones), or for really lazy guitarists :). You send your amp/cab modeler signal to the FOH/Monitor boards, and they give you your sound back through your floor monitor or IEMs. Some love this, and sometimes it’s all you can get! It’s workable, but not my fave. Get good IEMs if you go this route… cheap ones will wreck your hearing.


There are more ways you can mix and match, and you can even send the FOH a completely different sound than you’re hearing, if it works better that way (kind of like listening in the studio with effects while the track goes down dry). By now, you’re probably regretting you asked, but it’s a real rabbit hole to dive down if your of a mind to explore it!
 

bodia

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That is officially my stage monitor. If I choose to get one to use as an "amp" I'm going upstream a bit. I really want to try the Atomic with some RCF's in the $500-1K range. One of my buddies who does sound systems keeps telling me to go up to an NX but it's over $1700 retail and you all know how I feel about that much on an FRFR. LOL
Right on. I was just curious as I grabbed a Kemper Power Cabinet which makes my CP8 obsolete. Would send it your way if you wanted/needed it.
 

Em7

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Unlike a class AB or class B amp, a Class D amp is theoretically 100% efficient (i.e., no energy is wasted to heat). However, I do not trust the ratings of most class D amps. Even though a class D amp is theoretically 100% efficient, it cannot exceed its power draw from the outlet into which it plugged. A simple test can be made using a Kill A Watt device. Power drawn equals voltage supplied by the outlet multiplied by current (amperage) drawn by the amp. I suspect that a lot of class D amps are rated for the maximum power the amp can handle without going into clipping, but then the designer limits the amount of drive so that amp never comes close to this power rating in use. A 120V/15A receptacle has a maximum power rating of 1800W. A 120V/20A receptacle has a maximum power rating of 2400W, and a 120V/30A receptacle (very rare to find) has a maximum power rating of 3,600W. If these modern devices were drawing the amount of power they claim to draw, bands would be blowing breakers at gigs on a regular basis.
 
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DreamTheaterRules

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Right on. I was just curious as I grabbed a Kemper Power Cabinet which makes my CP8 obsolete. Would send it your way if you wanted/needed it.

Shoot me a PM and let me know how much you want for it. But I'm really more interested in either A) a power amp to drive one of my cabs... thought about the Seymour Duncan 170, but more about a Fryette PS-2, since it could cover modeler>PS>cab but also allow me to use it with my amps to turn them up more and control the volume. Or B) the Power Cabinet... or ...
 

Birdsofprey

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Thank these are informative responses and I’m learning even if it’s a slow process well worth asking those whom have had experience with various products. Not to get off subject but I remember when some of the first modeling amplifiers came out. I happened to hook onto the Line 6 product line. At first I would run through all the amplifier models and try to “hear” if they really nailed it. After getting bored with that
I just kept changing the setting until I was happy with the sound. Didn’t matter what the amp model was. As often discussed here on the form if your happy with the sound doesn’t matter how or which equipment your using call it a good day.
 
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