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>> Breadcrumb ://DIY AUDIOFILE

DIY 6EM7 Single-Ended Triode (SET) Amplifier

By | July 6th, 2015|Categories: DIY AUDIOFILE|Tags: , |

This unique looking hi-fi amplifier was put together by Matt in a vertical wooden chassis that has been styled after early vacuum tube equipment of the 1920s.  The amplifier uses a single 6EM7 tube per channel.  

 6EM7 Single-Ended Triode (SET) Amplifier
 6EM7 Single-Ended Triode (SET) Amplifier


The 6EM7 tube has two dissimilar triodes in one envelope.  One is a high gain, low power unit intended as an amplifier or oscillator, and the other is a higher power unit originally intended to drive the magnetic deflection coils on the back of a CRT.  Together the tube sections are well suited to create a nice little audio amplifier with just one 6EM7 tube per channel.  The clean output power from the 6EM7 SET amplifier is 2.2 Watts per channel and the frequency response is consistent with the advertised performance of the Edcor audio output transformer (40Hz to 18kHz).Read the full article

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Fostex FE206En Rear-Loaded Horn Speakers

By | September 2nd, 2014|Categories: DIY AUDIOFILE|Tags: , |

Once again Mark tries on the Fostex FE206En high sensitivity fullrange driver, but this time in large rear-loaded horn loudspeaker cabinets. The horn speaker cabinet plans are from the FE206En driver datasheet.

Fostex FE206En Rear-Loaded Horn Speaker Cabinet
Fostex FE206En Rear-Loaded Horn Speaker Cabinet

Each horn speaker cabinet is made up from thirty-six pieces of 21 mm thick pine plywood.  Australian beeswax is used on the outside of the horn cabinet and heavy cedar oil was applied to the mouth of the horn.

The sensitivity of the FE206En driver is greater than 96 dB / 1W / 1m, so the rear-loaded horn speakers are very well suited for use with very low power tube amplifiers.Read the full article

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Gobo LM1875 Amplifier Kit

By | July 28th, 2014|Categories: DIY AUDIOFILE|Tags: , , |

The sharp looking amplifier below is the Gobo Stereo Audio Amplifier from boxkedkitamps.com which is sold as DIY kit.  We have completed a review of the Gobo LM1875 stereo amplifier kit which is available on the main site.  The Gobo kit is a class-AB chip amplifier kit that uses the LM1875 IC. The LM1875 amplifier kit includes all the required parts and enclosure to build a complete stereo amplifier. 

Gobo LM1875 Stereo Amplifier Kit
Completed Gobo LM1875 Stereo Amplifier Kit



The kit comes with a very detailed step-by-step instructions that make it possible for a first time amp builder with only soldering skills to complete the kit.  The amplifier kit comes with good quality parts like audio-grade capacitors from Nichicon Muse, Panasonic and WIMA.  The linear power supply for the amplifier kit makes use of a audio-grade toroidal transformer from Antek.Read the full article

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Elekit TU-8200 Tube Amplifier Kit (SE 6L6)

By | April 23rd, 2014|Categories: DIY AUDIOFILE|Tags: , |

Over the past several years I have been enjoying an Elekit TU-879S Stereo Tube Amplifier Kit paired up along side of Fostex FE206E high sensitivity speaker drivers in Dallas rear-loaded horn enclosures.  I put a number of hours on the Elekit TU-879S, enough to fully consume the stock EH 6L6 tubes and to cycle through a number of power tube sets before deciding on JJ EL34 blue glass tubes.  Throughout this time the Elekit TU-879S amplifier has been reliable and a good performer sonically so it was disappointing to hear that the popular TU-879S tube amp kit had been discontinued. 

Elekit TU-879S with Fostex FE206E Rear-Loaded Horn Speakers
Elekit TU-879S with Fostex FE206E Rear-Loaded Horn Speakers


However, there is good news – the follow-up tube amplifier kit to the Elekit TU-879S, the Elekit TU-8200 is now available from TubeDepot (USA) and VK Music (Canada).  The renowned Elekit designer, Mr.Read the full article

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300B Single-Ended-Triode Amplifier

By | March 28th, 2014|Categories: DIY AUDIOFILE|Tags: , |

300B Single-Ended-Triode (SET) Amplifier Project

The DIY 300B triode amplifier shown below was completed by Stamou Tasos (Greece).  The 300B triode amplifier was built following the 300B single-ended (SE) tube amplifier schematic by J.C. Morrison.

DIY 300B Single-Ended-Triode Hi-Fi Amplifier

DIY 300B Single-Ended-Triode Hi-Fi Amplifier

For this single-ended (SE) 300B triode amplifier build Stamou has used premium parts, Lundahl audio output transformers and a DIY chassis. The 300B Single-Ended-Triode (SET) amplifier circuit uses a direct coupled 6SN7 driver stage. The output stage is a SE 300B triode and the maximum power output is about 8 Watts per channel.Read the full article

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4S Universal Preamplifier for 12A_7 Tubes

By | December 16th, 2013|Categories: DIY AUDIOFILE|Tags: , |

The 4S Universal preamp is a Super Simple Single Stage (4S) line stage preamp that works well with the entire range of 12A_7 tubes – 12AU7, 12AV7, 12AY7, 12AT7, 12AZ7, and 12AX7. You can change the tube type to vary the gain of the preamplifier by quite a large margin. 

4S Universal Preamp for 12A_7 Tubes
4S Universal Preamp for 12A_7 Tubes

The preamp uses a 6CA4 tube rectified power supply which is very quiet. The preamplifier is built using point-to-point construction techniques and into a die cast aluminum enclosure from Pomona.  The attenuation control is on the output of the preamp.Read the full article

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Cheap Open Baffle Speakers (COBIES)

By | July 15th, 2013|Categories: DIY AUDIOFILE|Tags: |

Bruce has put together a pair of Cheap Open Baffle Speakers – the COBIES.  Relative to most DIY speakers this open baffle project will be quite easy to build.  One of the main design goals for Bruce was to keep the total parts cost under $150US.  The open baffle speaker project was inspired by the “Big Air” open baffle system by Jim Strasser.  

Cheap Open Baffle Speakers
COBIES – Cheap Open Baffle Speakers

Each open baffle uses a GRS 12PF-8 woofer and two Goldwood GT-25 paper cone tweeters.  One tweeter is mounted on the rear of the baffle pointed upwards about 45 degrees.Read the full article

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DIY Nearfield Monitor Speakers with Fostex FE103En

By | April 16th, 2013|Categories: DIY AUDIOFILE|Tags: , |

Fostex FE103En DIY Bass Reflex Bookshelf Speakers

These small computer desktop speakers were built using the in-expensive Fostex FE103En fullrange speaker drivers following the bass reflex enclosure box plans that were provided with the FE103En datasheet.  The enclosure volume is noted as 6 L and tuned to 95 Hz but the the gross volume was calculated to be 6.9 L and the box tuning frequency to be about 97 Hz.  The Fostex FE103En drivers are 100 mm in diameter and have a rated sensitivity of about 89 dB / 1 W / 1 m.Read the full article

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6DJ8 Tube Headphone Amp

By | November 26th, 2012|Categories: DIY AUDIOFILE|Tags: , , |

We are always on the lookout for good headphone amplifiers and here is a great simple tube design that will work with a wide range of headphones.  This tube headphone amplifier design comes to us from Bruce Heran.  The tube headphone amplifier is designed along the lines of the Oddwatt power amplifiers with the exception that this headamp does not require a driver stage. The headphone amplifier uses only one 6DJ8 tube per channel in a push-pull configuration.  All the circuit gain is in the single output stage.Read the full article

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Push-Pull EL84 Mono Block Amps

By | October 3rd, 2012|Categories: DIY AUDIOFILE|Tags: , |

 Mono Block Ultra-Linear Class-A Push-Pull EL84 Tube Amplifier Project

Recently Bruce has been enjoying his PoddWatt amplifier and the EL84 tube sound that he has revisited the original OddWatt amplifier project, tweaked it and put together an improved EL84 push-pull amplifier.  Like the previous EL84 projects the Mini Block amplifiers use a EL84 self-inverting push-pull output stage that is biased into class-A operation.  The big difference is that the amplifiers are built as mono blocks.

Mini Block Push-Pull EL84 (6BQ5) Valve Amplifiers

Interior – Mini Block EL84 Push-Pull Amplifiers

The input circuit is a 5751 SRPP.  The ouput uses the ultra-linear connection and output power was 5.8 W @ 2% distortion and less than 0.25%  at 1 W.  The measured frequency response was 10 Hz to 44 kHz within 0.2 dB.   Bruce reports that the Mini Blocks have slightly more output power than the Poddwatts and seem to have more detail while retaining all the good characteristics of the stereo Poddwatt amps.  Full details are available on the Mini Block Ultra-Linear Class-A Push-Pull EL84 (6BQ5) Valve (Tube) Amplifier Project page.… Read the full article

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