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Tubes Asylum: REVIEW: S-5 Electronics K-12M Amplifier (Tube) by olen

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REVIEW: S-5 Electronics K-12M Amplifier (Tube)

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Model: K-12M
Category: Amplifier (Tube)
Suggested Retail Price: $139.95
Description: Tube Amplifier Kit
Manufacturer URL: Not Available
Model Picture: View

Review by olen on December 10, 2001 at 20:55:16
IP Address: 64.170.113.83
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for the K-12M


I bought this little amp from S-5 Electronics for $139.95 plus $10 shipping, when I called to order it they guy said they don't take credit cards, so I sent a personal check; 2 weeks later I had a small package at my door. Recently I saw a post with a link to a VERY similar looking amp from Antique Electronics Supply (http://www.tubesandmore.com/)go to "kits" it has a different model # and a yellow PCB.
First off I did NOT build the stock version of the amp.
Second it does NOT come with an enclosure, you mount everything to a 8"x10" pine board.
It uses 4- 11MS8 tubes (triode and pentode) similar to a 6BM8 but with 11.6V heaters.
After I opened it and checked the parts I went to Home Depot to get an enclosure and a decent power cord. I bought a 10"x10"x4" steel enclosure($15), a 10/3 power cord($6), a Leviton plug($7), and a power switch($4). I went to Radio Shack for a new fuse holder and 1N4006 diodes. I also had in my parts bin insulated RCA jacks, banana posts, poly coupling caps, wire, and lots of nuts and bolts.
The enclosure is big enough to fit everything inside so the only things sticking out are the switch and tubes. These tubes get hot! I mounted everthing on the reverse side of the PCB except for the tube sockets. I then used the nylon standoffs from the kit to mount the PCB to the enclosure, with only the tubes sticking out the top. I'd recommend an aluminum chassis because the thick steel is tough to drill. I also eliminated the global feedback cicuit. When I finished assembling the amp I hooked it up and I got a fair amount of hum (in the speakers and the power transformer) I figured it was the minimal filtering on the power supply. But when I moved it up stairs to my bedroom system the hum on the speakers was nearly inaudible, but the power transformer hummed like flouresent lights.
The sound:
It takes a long time to warm up, at least an hour. Then the treble settles down, and the midrange is much better than expected. It actually sounds good! The bass sounded a little thin, but this could be any number of things: elimination of the feedback, and most of my speakers are rather bass shy (I usually use a powered Dynaudio sub). The eight watts it puts out sound much bigger, but I was using pretty efficient speakers(91dB).
Summary:
It's cheap, and the stock version could be built in few hours, and it sounds good. I recommend it to anyone on a budget, but don't let any kids or pets near it without making a cover.


Product Weakness: UGLY!
Product Strengths: PRICE!


Associated Equipment for this Review:
Amplifier: The one I'm reviewing!
Preamplifier (or None if Integrated): none
Sources (CDP/Turntable): modified Cambridge CD4
Speakers: Homemade RS1197+Dynaudio D28/2S tweeter
Cables/Interconnects: Monster zipcord
Music Used (Genre/Selections): Lots (Erykah Badu to Paul Simon to Wes Montgomery)
Room Size (LxWxH): 15 x 25 x 8
Room Comments/Treatments: none
Time Period/Length of Audition: 2 days so far
Other (Power Conditioner etc.): homemade surgeprotector
Type of Audition/Review: Product Owner




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Topic - REVIEW: S-5 Electronics K-12M Amplifier (Tube) - olen 20:55:16 12/10/01 ( 0)