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S-5 Electronics DIY Tube Amplifier Kits

S-5 Electronics DIY Tube Amplifier Kits

The inexpensive vacuum tube (valve) amplifier kits made by S-5 Electronics are an ideal way to get introduced to vacuum tube audio. However, don't be fooled by their low cost. As many builders of these kits have found, these low cost tube amplifiers can sound better than amplifiers that cost many times more. All of the kits are a push-pull tube amplifier that supply from 8W to 16W of power (depending on the kit). The tube amp kits were designed by George Fathauer and the various versions have come with 11MS8, 11BM8 and 10GV8 triode-pentode tubes, with the newer kits using the 5670 triode and 6005 pentode tubes.

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Purchasing a Tube Amp Kit

The various S-5 Electronics Tube Amplifier Kits can be purchased online from TubeDepot. We have used TubeDepot on several occasions in the past and are very satisfied with their service. The prices noted below are as of October 2009.

The above kits are also available in mono kits if you would like to build a pair of mono-block amplifiers. The mono kits also make excellent guitar amplifiers.

NEW   If you are looking for a tube amplifier kit than can deliver more power and higher performance, take a look at the OddWatt mono-block KT77 tube amp kits. The mono-block kits are $599 each but the kits do come with a nice chassis, safety / protective cover and very good quality components. Here is our review of the 5751 SRPP / KT88 Monoblock Tube Amp Kits.

NEW   The Elekit TU-879S Stereo Tube Amplifier Kit also makes for a good fist tube amplifier. The kit is a simple and clean single-ended (SE) design for 6L6 output tube. This is a versatile amplifier which will be able to handle just about any octal based power tube - 6L6, EL34, KT77, 6550 and KT88.


Finished Tube Amplifier Kits and Reviews

The projects links below are reader submitted build logs of these tube amplifiers kits. The build logs provide construction tips, a review and some contain modifications and measurements. Also, take a look through the S-5 Electronics Tube Amp Kit Photo Gallery for more finished kits. If you have built one of these kits, please send us an email and feel free to upload photos to the Gallery. We are very curious about the K-16LS kit.

S-5 Electronics K-8LS Tube Amp Kit S-5 Electronics K-8LS Tube Amplifier Kit - 15 December 2007  USA Flag
Bruce Heran has completed one of the new S-5 Electronics K-8LS Tube Amplifier Kits. Unfortunately, the results are not impressive at all (see the oscilloscope and frequency response measurements). Another reader has also confirmed the poor low frequency response measured by Bruce. If you have any experience with the new S-5 electronics tube amp kits, please contact us.

K-502 Tube Amp Kit K-502 Valve Amplifier Kit - 9 July 2007  UK Flag

Given the low cost and great sound of these tube amp kits, it is no surprise they are popping up everywhere. This is Scott's build of the inexpensive K-502 tube amp kit. It features a fantastic looking enclosure and uses a stepped attenuator for volume control.

K-502 Tube Amplifier Kit and The DelSol Speaker K-502 Tube Amplifier Kit and The DelSol Speaker - 5 April 2007  Canada Flag

This is Barry's build of a K-502 Tube Amplifier Kit and The DelSol Speaker which uses the Aura NS3-194-8E fullrange driver. The enclosure for the K-502 Tube Amp Kit is wood and Plexiglas. Together these two projects make a great looking Hi-Fi unit. Nice work Barry!

S-5 Electronics Tube Amplifier Kit More Modifications for the K-12M Tube Amp - 25 January 2007  USA Flag

Another S-5 Electronics K-12M Tube Amplifier Kit! This is Bruce's build of the popular and inexpensive Tube Amplifier Kit. Bruce has completed several modifications which include many of VoltSecond's mods, new input and coupling caps, a beefed up power supply and upgraded output transformers wired in Ultra Linear (UL) Mode.

S-5 Electronics Tube Amplifier A Case for the K-12M Tube Amplifier Kit - 9 November 2006  Australian Flag

This is Mark's build of the S-5 Electronics K-12M Tube Amplifier Kit. In fact, Mark has built three of these fantastic kits! His modifications include snubbers, a beefed up power supply and upgraded power and output transformers.

K-12M Integrated Tube Amplifier K-12M Vacuum Tube Amplifier Kit - 2 January 2005  Canadian Flag
At $139US for the kit, this is the cheapest Tube Amplifier kit on the block. However, don't let the inexpensive price tag fool you, as this tube amp can go head to head with amps that cost $800. With its very modest price tag, this kit is an affordable step into the wonderful world of vacuum tube audio. I have provided information about my experiences with the K-12M kit as well as several modifications and upgrades that I have tried out.

S-5 Electronics Tube Amp Kit Schematics

S-5 Electronics K-12M Tube Amplifier Schematic
Schematic for the S-5 Electronics K-12M Tube Amplifier Kit.

S-5 Electronics K-12G Tube Amplifier Schematic
Schematic for the S-5 Electronics K-12G Tube Amplifier Kit.

S-5 Electronics K-8LS Tube Amplifier Schematic
Schematic for the S-5 Electronics K-8LS Tube Amplifier Kit.


Additional S-5 Electronics Tube Amp Kit Resources

Tube Amplifier Kits at TubeDepot
Online supplier of the various S-5 Electronics kits and other Tube Amp Kits.

S-5 Electronics Tube Amp Kit Photo Gallery
A photo gallery of completed S-5 Electronics Tube Amplifier Kits. Feel free to upload photos of your tube amp.

audioXpress review of S-5 Electronics K-12M Tube App Kit - (PDF 348kB)
An in-depth review of the S-5 Electronics K-12M kit published in the November 2002 issue of audioXpress.

VoltSecond's Modificaion of a K-12M
The K-12M modifications outlined by VoltSecond are well thought out and have received positive reviews by several others who have implemented them. This page is a must read if you own one of these tube amplifier kits.