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REVIEW: S5 Electronics K12G Integrated Amplifier (Tube)

174.103.166.130

Posted on April 24, 2011 at 12:41:39
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
Model: K12G
Category: Integrated Amplifier (Tube)
Suggested Retail Price: $189
Description: Integrated Amplifier Using 10GV8 Tubes
Manufacturer URL: S5 Electronics
Model Picture: View

Review by JimOfOakCreek on April 24, 2011 at 12:41:39
IP Address: 174.103.166.130
Add Your Review
for the K12G


This is a review for the S5 Electronics K12G Integrated Amplifier Kit. This is an extremely low cost kit at $189. I know what you're thinking. For that price it must be a POS. However, I can tell you that this is one fine sounding amp when paired up with efficient speakers. Plus there are numerous well documented modifications on the Web that make this amp sound even better than stock. The amp uses 10GV8 tubes which are relatively cheap and put out about 8w/ch. The mods I performed include upgrading the caps to Auricaps, installed UF diodes, added snubber caps, upgraded the volume pot and a few other upgrades. I use this amp to drive a pair of DIY bass reflex speakers using the Tang Band W8-1772 drivers. The sound is amazing, deep deep bass and extended highs. But the most addictive quality is the musical involvement. Small jazz groups have that gritty realistic sound with a noticable 3D quslity to them. I hear details that I cannot hear with my Class D reciever. The K12G is a great project for a novice DIYer, an experimenter or someone on a limited budget. The stock kit is mounted on a plain board. I mounted mine in a wine box which requires more mods. BE WARNED: There are high voltages envolved in this kit. Understand the dangers before you start any tube project.


Product Weakness: The kit is primitive, mounted on a board. The DIYer must provide his own enclosure
Product Strengths: Inexpensive, unbelevable sound, very good platform for modifications


Associated Equipment for this Review:

Amplifier: K12G
Preamplifier (or None if Integrated): None
Sources (CDP/Turntable): PS Audio DAC & Computer
Speakers: DIY Tang Band W8-1772
Cables/Interconnects: Generic
Music Used (Genre/Selections): Jazz
Room Size (LxWxH): 24 x 16 x
Time Period/Length of Audition: 3 months
Type of Audition/Review: Product Owner


 

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RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 24, 2011 at 12:47:50
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004


I thought I would provide an image of my Wine Box enclosure for this amp.

 

RE: (strong)REVIEW: S5 Electronics K12G Integrated Amplifier (Tube)(/strong), posted on April 24, 2011 at 20:03:32
Æ
I built one several years ago, the original K-12M version. I didn't go overboard with modifications. I did however match and grade all of the components, replacing some of the cheaper capacitors and resistors and of course upgrading to gold plated RCA jacks and gold plated speaker binding posts.
My amp came stock with plastic tube sockets which I later upgraded to ceramic sockets at an additional cost, bummer! The amp had noticeable hum as assembled, until the manufacturer recommended/incorporated a few minor circuit modifications (fixes), After that it was dead quiet. The supplied volume potentiometer was an absolute piece of junk and caused severe mistracking between the channels. I replaced the supplied pot with a more precise one and all was good.
The amp doesn't like reactive loudspeaker loads and performs best into 8 ohms, maybe even as low as 6 ohms but nothing lower.
I took the amp to a local high end audio salon for comparison, not bad at all. In fact quite nice compared to some amps that cost considerably more.

 

Picture of my K-12 amp., posted on April 24, 2011 at 20:06:12
Æ



Completed amp.

 

RE: Picture of my K-12 amp., posted on April 24, 2011 at 20:07:00
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Another picture.

 

RE: Picture of my K-12 amp., posted on April 24, 2011 at 20:08:13
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The wood is Bubinga and Walnut finished with Tung Oil.

 

This thread should be moved to Tube/DIY, posted on April 24, 2011 at 21:59:52
Æ
This thread should be moved to Tube/DIY.

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 24, 2011 at 23:55:31
Æ



How was the wine? Any reason why you mounted all the transformers askew, not square or perpendicular to the wood box, or just for the looks?
Some people who have used wood tops experienced heating, scorching of the wood. Maybe a potential fire hazard!?!?

 

RE: (strong)REVIEW: S5 Electronics K12G Integrated Amplifier (Tube)(/strong), posted on April 25, 2011 at 00:53:19
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
Is this operating in all Class A? Triode? Pentode? I could not find the specs, but I assume it's the 6V tube with a different heater voltage.

 

RE: (strong)REVIEW: S5 Electronics K12G Integrated Amplifier (Tube)(/strong), posted on April 25, 2011 at 01:10:12
agattu
Audiophile

Posts: 606
Location: NW Washington & Southcentral Alaska
Joined: March 27, 2005
12G Stereo Integrated Tube Amplifier Specifications:
Input Impedance = 100k ohms
Output Impedance = 8 ohms
Output Power = Push Pull 8 Watts per Channel
The circuit is a Class A amplifier
Minimum Input for full output = .4 V
Frequency Response = 20 to 20,000 Hz
Total Harmonic Distortion at 1 Watt <1%

 

RE: (strong)REVIEW: S5 Electronics K12G Integrated Amplifier (Tube)(/strong), posted on April 25, 2011 at 01:12:28
Æ
Here is a link to the audioXpress review, in PDF format ( of the original amp). Maybe it will tell you what you want to know.
The amp did/does have its short comings, but since the kit is so easy to build, upgrades are easy to incorporate, do. The original amp kit tubes were 11MS8, since switched to 10GV8 tubes.

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 01:20:35
agattu
Audiophile

Posts: 606
Location: NW Washington & Southcentral Alaska
Joined: March 27, 2005
Nice job

 

Disagree. here is perfectly fine. It is a minor quibble anyway? why bother complaining?, posted on April 25, 2011 at 07:06:31
I just think it is an amp. this is an amp board.

 

Pretty nice. nt, posted on April 25, 2011 at 07:08:25
.

 

RE: Picture of my K-12 amp., posted on April 25, 2011 at 07:09:30
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
Beautiful!! You did a beautiful job. I made mine in a funky looking wine box. But you did a really beautiful job. Wow!

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 07:18:20
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
I orientated the transformers to give the most quiet performance possible without regard to appearance. The power transformer gets very very warm but not nearly hot enough to scorch the wood. The output transformers don't get nearly warm enough. The tubes get hotter than the transformers but still not enough to scorch (so far).

Weber makes some pretty darn good Riesling wine. My sweety and I enjoyed both the wine and music.

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 10:21:16
Æ



I wasn't referring to the heat of the transformers. . . . tubes of course. I had correspondence with someone else who used wood and he mentioned the problem of scorching.
My transformers never got terribly warm either except for when I connected up to a pair of loudspeakers that used piezo tweeters! The main power transformer got uncomfortably hot. I later modified the loudspeakers, inserting the necessary resistor in series with the piezo tweeters and that solved the problem.
Also the (R18) 470 ohm, 1 watt resistor in the power supply section ran terribly hot and began to discolor. I replaced it with a larger wattage and had no problems after that.

 

Absolutely, legalism is for the close of mind. *, posted on April 25, 2011 at 10:56:02
.

 

Very Nice! *, posted on April 25, 2011 at 10:58:08
.

 

Thanks., posted on April 25, 2011 at 11:08:43
Æ
NT

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 11:12:57
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
Just a quick note, my kit supplied tube sockets are ceramic. I beleive S5 has been shipping ceramic tube sockets with this kit for quite a while.

 

Thanks Nt, posted on April 25, 2011 at 11:30:37
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
Nt

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 12:31:25
Æ
Yes, you are correct. They did away with the plastic sockets long, long ago.

 

I enjoyed building Dynakits years ago, posted on April 25, 2011 at 14:29:31
E-Stat
Audiophile

Posts: 37464
Joined: May 12, 2000
Contributor
  Since:
April 5, 2002
Nice job. I might just have to find another kit project!

rw

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 16:36:34
Æ
How come you didn't provide the actual link to S5 Electronics instead of Tube Depot?

 

RE: REVIEW: S5 Electronics K12G Integrated Amplifier (Tube), posted on April 25, 2011 at 17:23:13
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
I didn't show the S5 Electronics link because I thought TubDepot had a better image of the amp (strangely enough).

 

RE: Check your spelling., posted on April 25, 2011 at 21:29:51
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TUB Depot? As in Hot tubs?
Ha!

 

RE: Disagree. here is perfectly fine. It is a minor quibble anyway? why bother complaining?, posted on April 25, 2011 at 23:23:34
Æ



". . . this is an amp board"
Yep, you are correct, an amp on a board!

 

One other thing. . . ., posted on April 26, 2011 at 14:44:11
Æ
Since I (deliberately) mounted virtually all of the components on the "wrong" side of the circuit board, my volume pot gain increases counterclockwise. A small but not terribly difficult inconvenience.

 

RE: One other thing. . . ., posted on April 26, 2011 at 15:19:16
JimOfOakCreek
Audiophile

Posts: 1301
Location: S.E. Wisconsin
Joined: August 23, 2004
I reversed evrything to the back of the board to mount it in the wine box as well. However I disconnected the volume pot from the board completely and used wires from the VC to the board.

 

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