by Brad Easton on February 2012

Back in the summer of 2000 I watched a friend build the K08T21 step by step, start to finish not knowing a lot about building speakers.  The process was fun to see for the first time and painstakingly long during the box building stage.  I was there for the first listen and was present for the first 3 months breaking them in.  Even from the first listen before being broken in you could tell these speakers were on a different level from speakers sold at bigbox stores at that time.  My friend was using klipsch cornwalls before building these and never went back (they are now a fixture in the dining room scarcely used). 

It took me about a year before I decided to go ahead and build my own speakers. So I ordered them from Sound Clearing House (formerly speakerpage.com) back in the summer of 2001 just like my friend did.  I spent every night after work for 2 weeks making them downstairs in the basement workshop. Before you know it they're up and running,  sounding smooth and clear as can be.  

Rumor around the web was the SCH owner started working at Aperion Audio and was too busy to keep the site going.  Which was unfortunate, the owner was one of the nicest guys you'll ever talk to and he designed great sounding speakers. 

The following was written on the cover letter that SCH sent me with the instructions on how to build the TOWER kit:

"The K08T21 is a full range tower speaker.  It exemplifies the modern approach of getting higher performance through minimalist design - the concept being that sound waves should originate from as simple and coherent a source as possible.  This approach uses fewer drivers that are higher quality and engineered to work well together as a unit.

With this method, the woofer presents the greatest engineering challenge since it is asked to handle a very wide range of frequencies.  We originally designed the woofer entrusted with this assignment in a well-known studio monitor system.  A large motor, including a long-throw voice coil wound on a Kapton former, results in tight, well controlled bass reproduction capable of extending in to the deepest registers.  The mica-filled, polypropylene cone and well-matched butyl rubber suspension produce a radiating surface that is simultaneously high in stiffness and internal dampening; the reward is a detailed ("clear") yet exceptionally well-damped ("smooth") sound character extending well up into the midrange.

The K08T21's tweeter, made by the European manufacturer Vifa and found in speakers costing up to $25,000, uses a large, damped chamber behind the radiating surface, allowing it to operate down into the midrange.  In conjunction with the woofer's extended midrange performance it is possible for the entire audio bandwidth to be handled in a high performance manner by just two drivers, creating a speaker with only a single crossover point.  The result is a much simpler, more unified sound wave source than speaker systems using more drivers.

Tower designs like the K08T21 meet dual objectives of nice styling and good engineering.  Cosmetically, the appearance is sharp while the enclosure occupies a minimal amount of floor space.  From an engineer's point of view the tower design gets the sound-producing part of the speaker at the proper height without the use of speaker stands while the larger air volume makes for low bass potential.

The K08T21 is a fine example of simplifying design through good engineering and high quality components in the service of higher performance."

 End of cover letter.

 I also ordered the DIY Speaker kit "K10S10" from Sound Clearing House to fill in the low frequencies. I currently use the speaker connections and do not use the RCA inputs as you can see in the picture below.  The x-over frequency is set as low as it can go at 40 Hz. This setup allows for seamless bass response between the sub drivers and the tower drivers.  I know what your saying....this isn't a true 2 channel system.  But you wouldn't know I'm using a subwoofer if you were listening to it blind.  I've heard this is the most accurate way to reproduce bass with 2 channel audio. Without the K10S10 subwoofer the K08T21's will lack the bass response to reproduce the low frequency thud you expect.

The following was written on the cover letter that SCH sent me with the instructions on how to build the SUB kit:

Subwoofers are required to play a Jeckel and Hyde role. In their home theater life, they shake the walls with frightfully loud, low, monstrous bass of special effects. Yet, during subtle music passages, they are asked to vanish, rendering, say, a cello so convincingly that you can believe your speakers have disappeared.

As Dr. Jeckel, the K10S10's 120 watt amplifier and mass loaded, progressive suspension, 10" woofer allows it to be a brute while as Mr. Hyde, it's well damped moving system and electronically equalize output results in tight, well controlled, natural sounding bass.

Several features permit it to fit into any system. Of course it has adjustable volume and crossover frequency control, allowing it to interface with any speaker system it's asked to work with, and high and low level stereo inputs allowing it to work with any set of electronics. And of course, it has auto on/off so that it will "standby" when it's not in use. But it also has two other less common features that are important.

  1. 24dB/octave rolloff slopes (rather than the more common 12dB/octave) insuring that midrange frequencies don't "leak through" to the subwoofer. These higher frequencies betray the subwoofer as a the source of bass information, destroying the illusion that the bass originates from your other speakers.
  2. Phase reversing switch, allowing you to get the subwoofer's output in phase with the main speakers regardless of the subwoofer's location

It all adds up to a strong performer that shines in any role its asked to play, from brutish special effects to the subtle nuances of music, with any supporting cast of electronics and staged in any living room.

 End of cover letter.

My 2 channel system has come a long way since 2000 with the addition of various DAC's. Not only do these speakers keep impressing me with the newer upgrades to my source components but....these speakers are still being used in some of YFS's listening rooms to this day and are comparable to many Rocky Mountain Audio Fest setups I've heard. Thank you to Sound Clearing House for making available a truly "high end" speaker that is still standing the test of time now that we're entering the realm of true HD audio. If you were one of the lucky ones that grabbed a Sound Clearing House DIY kit, I'm sure you know what I'm talking about. And Remember...Just because it's a DIY speaker, doesn't mean it doesn't sound really great.

Associated Equipment for this Review:

  • YFS CPU Prototype - HD Ref 1
  • YFS Custom Room Treatment
  • Musical Fidelity V-DAC
  • YFS Custom Direct Preamp and Custom 6L6 Tube Power Amp
  • YFS Custom Interconnects, Cables, and USB Cables

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