DIY VACUUM TUBE AUDIO PROJECTS
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Documented below are a number of DIY tube amplifier and tube preamplifier projects. Please make yourself aware that most of these tube projects involve leathal voltages that can kill you! If you are a novice to vacuum tubes, the K-12 / K-502 tube amplifier kits make a great first tube amplifier project. If you have a DIY tube project that you would like to share on this site, please contact me.
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EL84 Push Pull Tube Amplifier Project - 22 October 2007 
Bruce latest project, the "OddWatt" is a EL84/6BQ5 Push-Pull Tube Amplifier. The driver stage is an SRPP with ECC802S tubes, while ultra linear operation is used for the output stage with Sovtek EL84 tubes. LM317 Regulators are used for constant current sources (CCS) of the output stages. 12VDC is used for the tube heaters. |
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K-502 Valve Amplifier Kit - 9 July 2007 
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. |
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KT88 Single Ended (SE) Tube Amp - 11 June 2007 
Alex has pulled together a single ended tube amp based around the popular KT88 valve. EL34 tubes can be used in place of the KT88 tubes. The preamplifier tube is a inexpensive 6N1P, but the 6DJ8 / ECC88 / E88CC family of tubes can also be used. The power supply uses a 5U4 dual rectifier. |
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The "Beauty" - 12AX7 Tube Preamp - 1 May 2007
Bruce has put together a 12AX7 Tube Preamplifier to accompany his LM3875 Chip Amp. He has named the tube preamp "Beauty" as it sweetened the sound of his LM3875 Chip Amplifier. For the enclosure, Bruce used a readily available plastic and aluminum project box from Radio Shack. Similar to what Mark discovered with this economical tube preamplifier kit is that you get a very quiet preamp that can compete with ones that cost much more. |
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K-502 Tube Amplifier Kit and The DelSol Speaker - 5 April 2007 
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 plexiglass. Together these two projects make a great looking hi-fi unit. Nice work Barry! |
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5687 LED Biased Tube Preamplifier - 1 March 2007 
Vincent has pulled together a fine looking preamplifier that is based around the 5687 twin triode. Each channel uses both sections of a 5687 vacuum tube with LED biasing used on each section. To keep potential hum at a minimum, the heater filaments are supplies with DC. To further minimize the potential for unwanted noise, the power supply is external to the preamp section and consists of a RCA-83 mercury rectifier and two 50H chokes. Very nice work Vincent. |
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12AX7 Tube Preamplifier Kit - 12 February 2007 
This is Mark's build of a simple and inexpensive tube preamplifier kit. The preamp kit is based around a common 12AX7 dual triode. What makes this kit inexpensive is that power comes from a switch mode power supply, fed from a 17 volt DC wall wart! Mark's modifications to the kit include snubbers and upgraded capacitors. The end result is a simple DIY tube preamplifier that sounds great and will keep some money in your pocket for the next project. |
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More Modifications for the K-12M Tube Amp - 25 January 2007
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. |
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A Case for the K-12M Tube Amplifier Kit - 9 November 2006
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. |
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SE 50EH5 Tube Amplifier - 14 May 2005
Having completed my first tube amplifier project, I decided to go back to the basics for my next project and construct a very simple Single Ended (SE) amplifier. This SE amplifier is based around the 50EH5 power pentode. The component count in this amplifier is very low and the result is a small (1.4W) neutral amplifier that sounds very good. The total costs for this project were less than $15US! |
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K-12M Tube Amplifier Kit - 2 January 2005
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. |