How many ways to use a Kemper?

    So last weekend, my wife took the kids out of the house for a party and left me .... ALL ALONE! Hmmmm. What to do with 3 hours of time at home with no one else in the house :)


    So, just for some background, I play in a band with my Kemper DI into the PA. I am the rhythm player and sing lead. When I am at home, I generally play though headphones along with MP3's to practice (through my little ZED 10fx).


    When I bought the Kemper, I sold off my tube amp (VHT and 4x12), but still have my 2x12 cab. So I was wondering .... how does the kemper sound through an amp and speaker cab?


    First off, playing through my basement PA speakers (Klipsch KP301 3 - way 15") is not that inspiring. The eq is all off and doesn't sound that great. The headphones (HD280's) sound very good though.


    So, I re-route a channel of my QSC PLX3002 amp over to my VHT 2x12 cab, juice up the mixer and KPA and go through some rigs.


    Wow! First off, you really do need to turn the cab off when actually using a cab. This made a huge difference. The sound was incredible! I played until my ears rang and stuff started shaking out of the ceiling tiles :)


    I don't plan on changing my live rig. Going straight into the PA and using IEM's is still the best option for live, but I am here to tell you, I could really put some of my friends tube amp rigs to shame with my KPA and little 2x12 VHT cab (with an amp). The cab seems to give more texture and breakup to the rigs and warms up the sound compared to headphones or DI into my PA. Of course, having air moving at that volume also helps with the harmonics and interactions with feedback that you simply can't get without air movement, but the cab also gave a very different tonal quality to the KPA.


    As an aside, into 8 ohm, the PLX 3002 puts out 550W into a stereo load. I was only using half of that, so lets say 225W. My VHT 50ST was a 50W (supposedly) head and could reach the same volume and maybe even a bit more than my PLX3002. How does that work?


    It sure did sound good though. I might have to come up with a little amp to go with my 2x12 cab for those jam sessions I am sometimes invited to where there isn't a DI or IEM to be had ;)

    Beside of a perfect livemachine...


    I used it in the studio for Vocals (for fun and testing distorted industrial vocals)


    and
    with a Blues Harp (great!!!) [usually you play blues harp with an tube(-guitar-)amp with a liiiiitle overdrive for that bluesy sound]



    profiled a access Virus (synthesizer with some distorsionfx :))



    let´s see what could be interesting in the future

    Might have to look into the KPA power amp just for sit-ins. Sure will shock the devil out of my buddies with tube amps to be shredded by a digital head ;) I know that a year ago I would have laid out good money on a bet that my VHT could not be matched by ANY digital device in this universe.


    @Tandrin,


    Wow. Never even thought of profiling something like that.... but hey, why wouldn't it work?


    I wonder if CK has ever thought of making a profiling keyboard? CK?


    There USED to be profiling keyboards in the 1980s - they were called Samplers. Technology made them obsolete with keyboards that came with a sampled library in the on-board memory.

    Your PLX 3002 at 550watts is about twice as loud full open as your VHT 50ST at 50watts assuming you have the same Ohms.


    That is, the difference is about 10.4 dB


    I'm not a techie, but it could be the volume knob fooling you, meaning you might have the knob half way but that doesn't mean the loudness or wattage is half. This is due to the pots being logarithmic (or antilog) and if using differing ohms that could also throw off the loudness comparison.


    I had a number of differing watt amps at one point. 7, 15, 30, 50, 100 and the 15w shook the walls and hurt my ears. A 15watt can generate over 100 dB of loudness a foot in front of the speaker. Ever crank an AC30? That shit is LOUD.


    The difference between a 50w and 550w is about 115dB and 126dB from my reading so, both are ear damaging and probably beyond your ability to perceive the loudness difference with certainty if really turned up. I doubt that's the case. You're dropping them to lower levels.


    Point is, you may have your 550w actually turned down to a 40w or 45w level in terms of dB and the 50w wide open, hence, it sounds louder.


    Please feel free to massacre me if I'm wrong. I've always been curious about this, and have partial knowledge, but am now Mr. Safety Officer on my job and one part is testing areas for loudness for OSHA compliance, so I'll actually have to know some this stuff, lol. Plus the differing ways to measuring dB averages.

    Quote from paults

    There USED to be profiling keyboards in the 1980s - they were called Samplers. Technology made them obsolete with keyboards that came with a sampled library in the on-board memory.


    I got the M-Tron Pro by GForce. Who doesn't want to try the intro to Strawberry Fields just once, right? Now I use a Motiff Rack XS now and it's a wonderful thing, but it's static, not programmable for new samples like the Akai MPC's.


    I wonder what's new in the that vein of technology. I haven't kept up.

    Quote from db9091

    A 15watt can generate over 100 dB of loudness a foot in front of the speaker.
    Please feel free to massacre me if I'm wrong.


    ... You're correct Dennis, provided yo specify that the amp doesn't generate any loudness if not connected to a transducer.
    It's the latter than generates the loudness. SPL (the sound's volume in the room) depends on the cab's amplitude response, directivity and sensitivity. The higher these values, the more SPL you get. A 15 W amp can go much higher than 100 dB, provided it's connected to a cab with an high enough sensitivity. In fact, a 100 dB\1 W\1 m sensitivity means that a cab will produce 100 dB of SPL with just one watt from the amp. And if you measure it 1 foot away (Vs. 1 m) the value grows quadratically!


    Nope. I agree with your assessment from an engineering perspective completely ;)


    I can't fault your numbers at all. ~ 10db will generally sound 2x louder. I suspect that it isn't the volume knob so much as the fact that running through my mixer and amp I have a built in VU capability that my VHT amp did not have. I wasn't clipping the amp, so there was still room to go in output. It is very possible that my VHT got maxed and I didn't know it.


    I have heard an AC30 cranked. You are right. That is LOUD!


    I think that it has much to do with WHERE it is loud. Most of the wattage will get blown away on the bottom. It simply takes more umph to move low frequencies. The HF content is much easier for an amp to push to high SPL's.


    Sadly, most people don't understand SPL measurements. In your work, you likely use the A weighting (since that is what it is designed for ... hearing damage assessments that is). IMHO the C weighting is much more relevant when determining PA and pro sound equipment capabilities since it takes into account the lower frequencies much better.


    Using the A SPL weighting is why a 10" speaker can have an SPL rating equal to a 15" 3-way speaker. If it puts out enough HF, it gets an overall high average output. This does NOT mean that a 10" 2-way speaker can cover the same room as a 15" 3-way (as we all know), but lots of poor guys think so because of the SPL specs.


    I am still amazed at the capabilities of the KPA both as a direct in to a PA, and through an amp and cab. What a cool piece of gear!

    That's an interesting way to look at A and C. I'm aware they exist, but haven't read about them. Most of the noise at work come from high pitches. Quick air rushing from hoods, generators whining, etc. The lowest noises are one piston car engines knocking and that's still in the range of human speech, not bass.


    In the spirit of the Thread Title: my use of the Kemper is as a compensatory factor for my lack of coolness. It diverts attention away from my geek-ety and to this neat 50's looking piece-of-gear who's lights mesmerize folks while I murder all that is holy in guitar tones.

    Directivity (among the other elements I've quoted) also matters a lot in covering a room. If you measure SPL for a guitar cab, the overall energy just falls down quickly as you move the mic off-axis. So in a direct comparison with a cab gifted with a broader directivity, when in front of them they may produce the same SLP, but if you measure the sonic energy in a different spot of the room the broader-spreading cab will sound louder.


    The SPL "@ 1 m" definitely doesn't tell the whole story.


    We'll have to factor in frequency response as well. A cab that sounds as loud @ 1000 Hz but has got much more energy on highs or lows will be louder on the whole than a cab with a narrower frequency response.


    :)

    Yea, directivity is another issue that is not covered by most specs. Guitar cabs are notoriously directional. Even if you like the sound of a cab better than the sound of the PA for guitar sound, you just can't cover the area evenly with just a guitar cab.The highs in particular really dissolve quickly off-axis on most guitar cabs.The Kemper is like a dream come true for guitar players the world over. I just can't say enough good things about this piece of gear.I am going to keep my cab btw ;) Just too cool of an attachment for my Kemper rig for sit-ins.