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REVIEW: Krell ksa 100 s Amplifier (SS)

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Model: ksa 100 s
Category: Amplifier (SS)
Suggested Retail Price: $5500
Description: 100 w class a
Manufacturer URL: Krell
Model Picture: View

Review by jbmcb on January 03, 2005 at 12:02:31
IP Address: 12.148.60.177
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for the ksa 100 s


So, I decided I wanted one crazy audio component in my system. I don't count the Sonic Frontiers Line-1 'cause it's actually quite useful, loads of features and very reliable. I upgraded my speakers from Magnepan MG-1.4's to MGMC1's for the start of a multichannel system, but I'm setting it up as an add-on to my stereo system, which I will keep analog. I decided I wanted more power than the NAD 214 I had could put out (80Wpc @ 8 Ohms, 160 @ 4 Ohms) It was a great amp, and could drive just about anything, but I wanted more power. After lurking on eBay and audiogon for a while, I saw a Krell KSA-100S for sale nearby, for a very reasonable asking price. I took it, especially since I wouldn't have to pay for shipping.

Construction:

Jeeze, this thing is HUGE. I was at CES once and saw some crazy amplifiers in the 500-1000W range, thinking only *really* powerful amps were that big. Nope, at 100W into 8 Ohms, this thing weighs a ton and almost doesn't fit onto my pretty audio rack. The sides are solid heat sinks. The front is the old-school Krell machined gray and black steel look. It looks like something from a post-industrial Sci-Fi movie, something that would be powering a laser cannon on a star destroyer. No coincidence, I think, that the name Krell comes the movie Forbidden Planet :)

Features:

Well, as far as amplifiers go, it's feature packed :) The back panel has a pair of big handles, which you will have to use if you want to move the thing anywhere. The heat sinks on the sides will cut your hands off if you try to hold it from the bottom. There are two single-ended RCA inputs, and two balanced XLR inputs, and a switch to select from between the two. The amp is supposed to come with shunt plugs to put in the balanced inputs if you use the RCA jacks. If you don't, you get a TON of noise coming out of your speakers. Mine didn't come with the plugs, but I'm running with homemade balanced cables, anyway. Supposedly, inside there are a ton of pots you can tweak with if you are brave, to set various biasing and gain levels and such. I'll leave those alone for now, or at least until I can dig up a service manual for this thing. The front panel has a bias indicator, that tells you how much power the thing is dissapating. See, it is a Class A amplifier, which means the output transistors should work at full power all the time. This would be *really* wasteful, and, if the thing wasn't a great big heat sink, would cause the amp to glow orange with waste heat. The "S" in the KSA-100S name stands for "Sustained Plateau Biasing" which means the amp only draws as much power as is needed for a particular input level. So, for instance, if you have your volume knob up half way, your speakers might requrie 50W to play at that level, and that's how much the amp will draw. And the cool LEDs will light up on the front of the amp to indicate that power level. Turn up the volume all the way, the amp starts throwing out 100W, and jackpot! All the LEDS light up. And your room starts to heat up :) So, you get a cool indicator of how much power the amp is putting out, along with a nice blue power LED. There's a power button, which starts the amp with a whole bunch of clicks and clunks as various safety interlocks make sure the amp doesn't blow up your speakers as it turns on. After about a minute, after charging up all the caps and firing up the transistors and whatnot, the amp is ready to use. Another switch turns the LED meters off, if you don't like LEDs on when using your amp. With all these controls you'd wish you had a remote. Wait, you get a remote! :)

Remote:

Well, it turns the amp on and off, and turns the meter on and off when the amp is on. That's it. That being said, it's really cool looking, I think it's aluminum, and is pretty dense. It's larger than my preamp remote, which has about 4x more buttons on it. If you want to turn your amp on and off from the couch, it does a bang-up job.

The Sound:

Compared to my NAD-214, it plays a LOT louder. Supposedly it only puts out another 20-40W per channel, but at the same level on my preamp it plays maybe 50% louder. I've heard Krells are very conservatively rated, wattage-wise, so I wouldn't be suprised if this thing is dumping 250W into my 5-Ohm MGMC1's. I haven't noticed it sounding particularly better than my NAD-214's, but the sheer amount of power this thing can put out compared to my 214 probably makes a fair, direct comparison not possible.

Conclusion:

It's a *Krell* It's big. It's overengineered. It'll probably run until the heat-death of the universe, or at least until the electrolyte in the caps boils away. It's a tank. It's something Darth Vader uses to blow up asteroids. It will probably drive any speaker any sane person would want to listen to. I can't fathom how Krell could come out with two whole amplifier product lines after this thing, I'm not sure what you could improve on. Maybe if amplifier development mirrored the computer business, at this point, ten years after the introduction of the KSA-100S, this thing should fit in your pocket and draw a tenth the power. But then it wouldn't be a Krell :)


Product Weakness: It's huge and weighs a TON. Probably eats gobs of power, too, but still more efficient than pure class-A amps. Subsequently, it needs breathing room as well.
Product Strengths: Built like a tank. Super-powerful. It looks like it will last forever. You can probably use it to prop up your Hummer to do brake work if cinderblocks aren't strong enough.


Associated Equipment for this Review:
Amplifier: Krell KSA-100S, NAD-214
Preamplifier (or None if Integrated): Sonic Frontiers Line 1
Sources (CDP/Turntable): Audio Alchemy ACD-1, Project 6.1 'table
Speakers: Magnepan MGMC1
Cables/Interconnects: Homemade
Music Used (Genre/Selections): Classical, Jazz, Ambient, Rock
Type of Audition/Review: Product Owner




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Topic - REVIEW: Krell ksa 100 s Amplifier (SS) - jbmcb 12:02:31 01/3/05 ( 22)