NEW   Bruce shares a few notes on The Care and Feeding of LM317 and LR8 Integrated Circuit Regulators, Particularly in Valve Circuits.

DIY Audio Projects - DIY Hi-Fi for Audiophiles

DIY Audio Projects

Do-It-Yourself (DIY) Audio Projects - projects for audiophiles, hi-fi enthusiasts, music lovers, electronic hobbyists, woodworkers and those who like to learn, build and listen to music. This site exists to promote the hobby of DIY Audio. There is nothing for sale here. All project documentation presented on this site is free for personal non-commercial use. If you have a DIY Audio Project that you would like to share with others through this site, or if you have any comments, contact us or post a message on the DIY Audio Projects Forum. Questions about a specific projects can be sent to the project author noted at the top of the project page. If you are new to DIY Audio but want to learn more, take a look at our DIY Audio Book recommendations.

Last update: 21 July 2014

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DIY Audio Projects

These are some of our featured DIY audio projects. For more DIY projects, use the navigation menu on the left hand side of the page.

Gobo LM1875 Stereo Amplifier Kit Gobo LM1875 Stereo Amplifier Kit - 21 July 2014  Canadian Flag   NEW 
The Gobo Stereo Amplifier kit is a class-AB chip amp kit based around the LM1875 IC. This is a complete amp kit that includes all the necessary parts and enclosure to build a stereo amplifier. The LM1875 amp kit comes with audio-grade capacitors and toroidal transformer. The Gobo amplifier kit is easy to build, looks and sounds great. The amplifier kit is well suited to first time amp builders.

DIY 300B Single-Ended-Triode (SET) Hi-Fi Amplifier DIY 300B Single-Ended-Triode (SET) Hi-Fi Amplifier - 24 March 2014  Greek Flag
This DIY 300B triode amplifier project was completed by Stamou Tasos who is from Greece. As a thank you for the 300B amplifier schematics, Stamou has shared his implementation of the 300B single-ended tube amplifier schematic by J.C. Morrison. The 300B SET amp uses a 6SN7 direct coupled driver stage and an all low mu triode array. The power supply filtering sections have been duplicated for each channel for this 300B triode amplifier and premium parts are used throughout. The audio output transformers are Lundahl LL1623. This is a great sounding 300B triode amplifier that I am sure DIYers will find very rewarding.

4S Universal Preamplifier for 12A*7 Tubes 4S Universal Preamplifier for 12A*7 Tubes - 15 December 2013  USA Flag
The 4S Universal preamp is a Super Simple Single Stage (4S) line level Hi-Fi preamplifier 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 sound and gain considerably. The preamp uses a 6CA4 tube rectified power supply which is very quiet. The Universal preamp is fun as it allows tube rolling to compare various tubes in your stash. This is a great simple preamplifier unit to bring out the most in your power amps.

Op-amp based RIAA Preamplifier for MM and MC Phono Cartridges Op-amp based RIAA Preamp for MM / MC Phono Cartridges - 1 Sept 2013  USA Flag    Low Voltage 

This project by Bruce is for a relatively simple but high performance RIAA phono preamplifier that can handle both moving magnet (MM) and low output moving coil (LOMC) cartridges. The preamplifier circuit uses a Burr-Brown OPA2134 operational amplifier (op-amp) for the active RIAA filter. The power supply makes clever use of a Meanwell DCW03A-12 DC to DC converter to produce a regulated symmetrical power supply. The RIAA preamplifier can be built for about $100US including a modest enclosure. Bruce reports that this is a "surprisingly nice sounding preamplifier".

Fostex FE103En DIY Bass Reflex Bookshelf Speakers / Nearfield Monitors Fostex FE103En Bass Reflex Bookshelf / Nearfield Monitor Speakers - 14 Apr 2013  Canadian Flag
Gio has put together a small bookshelf / monitor speaker using a single inexpensive fullrange speaker driver. The enclosure is a 6.9 L bass reflex cabinet tuned to about 95 Hz that follows the speaker box plans included with the driver datasheet. The loudspeakers use a single Fostex FE103En fullrange driver with no crossover circuit. The speakers work well as nearfield monitors and combined with a subwoofer the speakers can be used for home theater duties.

DIY 6DJ8 (ECC88) Tube Headphone Amplifier DIY 6DJ8 (ECC88) Tube Headphone Amplifier - 24 November 2012  USA Flag
This low power tube headphone amplifier project comes from Bruce Heran. The simple tube headamp uses one 6DJ8 (ECC88) tube per channel. The amplifier circuit is push-pull and biased into class-A operation with a CCS. Gain is sufficient that no driver stage is required for the tube amp. The 6DJ8 tube headphone amplifier is suitable for use with many Hi-Fi headphones. Output power is over 100 mW between 32 ohms to 300 ohms. The response is 20 Hz to 28 kHz within 0.5 dB and the wide band signal-to-noise is -84 dB.

Mini Block Ultra-Linear Class-A Push-Pull EL84 (6BQ5) Valve (Tube) Amplifier DIY EL84 Push-Pull (Class-A, Ultra-Linear) Amplifier - 30 September 2012  USA Flag
Bruce Heran of OddWatt Audio outlines the design and construction of monoblock Push-Pull EL84 (6BQ5) valve amplifiers. The Mini Block tube amps use a 5751 twin triode to drive the EL84 push-pull output stage which is biased into class-A operation, ultra-linear mode. Output power is 5.8 W @ 2% (0.25% @ 1 W) and the response is 10 Hz to 44 kHz within 0.2 dB. Bruce reports that the Mini Blocks are more powerful than the Poddwatts and seem to have more detail while retaining all the good characteristics of the Poddwatt amps.

Fostex FE206En Double Bass-Reflex Speakers Fostex FE206En Double Bass-Reflex Speaker Project - 17 September 2012  Australian Flag

Mark has put together his second set of the Fostex FE206En double bass-reflex speakers. The speaker box plans are from the datasheet that was supplied with the drivers. The loudspeakers use a single Fostex FE206En fullrange driver and no crossover. The sensitivity of the drivers is about 96 dB / 1W / 1m, so the double bass-reflex speakers are well suited for use with flea and low power tube amps. The two chamber box design extracts good bottom end from these low displacement drivers. The speakers will be used in a home theater so for a non-reflective finish the speaker enclosures are painted with a undercoating paint for a stipple like finish and flat black paint. Mark reports that the speakers are an excellent mate for use with his 2.5W 6EM7 SET amp.

DIY Stepped Attenuator Volume Control DIY Stepped Attenuator Volume Control - 21 June 2012   USA Flag

In this DIY attenuator project Matt uses an inexpensive ladder type stepped attenuator to make a passive stereo volume control. The switched attenuator comes fully assembled and uses 1% precision metal film resistors on a make before break 2-pole (stereo) 24-position switch. Checking noise, Matt found that the stepped attenuator has a noise figure which is about 26dB lower than a PEC hot molded carbon potentiometer of the same value. This attenuator project is simple to build and should save you some money if you are in the market for a passive hi-fi volume control.

DIY Hi-Fi Phono Turntable DIY Hi-Fi Phono Turntable - 26 March 2012   Hungarian Flag

Nandor a very talented DIYer from Hungary has built this fabulous looking Hi-Fi record player. The DIY turntable project uses the platter and the direct drive motor assembly and controls from a Dual 701 record player. The tonearm is built from scratch following a magnetically Stabilized design which means that there are no fixed pivot points or bearings. The turntable plinth is made using stacked layers of plywood. A DIY record weight rounds out this challenging DIY record player project.

DIY Shielded RCA Interconnect Cables DIY Shielded RCA Interconnect Cables - 22 February 2012  Germany Flag

Tom has put together an instructional guide to construct simple line-level RCA interconnect cables. The cables use shielded instrument wire and is very simple to construct requiring only some basic soldering skills. The required parts are easy to source and a pair of these shielded RCA cables can be built for as little as $10. Use these simple DIY cables to upgrade your stock and inexpensive interconnects.

Parts-Express.com - Project Showcase Index - [External Link]

Check out the Parts-Express.com - Project Showcase Index for a wide range of DIY Loudspeaker projects. The showcase features over 50 DIY speaker projects that have been built by other DIY audio enthusiasts. Each speaker project includes complete drawings to illustrate construction of the speaker enclosure, crossover schematics, a full parts list and photographs of the finished speaker project.

Shown in the photo to the left is the TriTrix MTM TL DIY speaker project. For those who are not great with woodworking, the TriTrix is available as complete kit.

DIY (12AX7 / 12AT7) Tube RIAA Phono Preamp DIY (12AX7 / 12AT7) Tube RIAA Phono Preamplifier - 1 November 2011  USA Flag
The latest project from Bruce's workbench is the Groovewatt, a tube RIAA phonograph preamplifier design. The preamp uses a solid state HT power supply and DC for the heaters. Gain is 45 dB, sufficient for use with a high output MC cartridge. The design uses two 12AX7 SRPP gain stages, passive RIAA equalization and a 12AT7 cathode follower.

DIY 12AU7 / IRF510 Headphone Amplifier DIY 12AU7 (ECC82) / IRF510 Headphone Amplifier - 12 April 2010  USA Flag    Low Voltage 

Rogers has built an improved version of his popular and simple low voltage 12AU7 / IRF612 Headphone Amplifier (5 Aug 2008). The new version allows novice builders to experience assembling and listening to their own headamp. The headphone amplifier is similar to the previous version in that a single 12AU7 (ECC82) vacuum tube is used for voltage gain and an IRF510 MOSFET follower stage is used to provide current to drive demanding headphones. The hybrid tube and MOSFET amplifier operates off a 12V SLA battery so there are no high voltage concerns. The main difference from the original version is that a LM317 regulator is used as a CCS to bias the MOSFET into class-A operation instead of a load resistor. The project includes PCB image files and can also be built on a protoboard. This simple headphone amp can be built for about $40-50.


Tang Band D4-1 DIY Back Horn Speaker Kit Tang Band D4-1 DIY Back Horn Speaker Kit - 10 March 2010  Canadian Flag    KIT 

The D4-1 DIY Back Horn Speaker Kit put together by Tang Band is very simple to build, sleek looking and sounds great. The DIY speaker kit comes complete with all the parts and tools required (except for a soldering iron) to build a great looking, little rear loaded single driver horn speaker system. There is no cutting or finishing (painting / staining) required to complete the speaker kit. The small horn speaker kit goes together much like ready-to-assemble furniture. The end result is an attractive and compact horn speaker that sounds great and is fun to build.

DIY 6L6 / 5881 Single-Ended (SE) Tube Amplifier DIY 6L6 / 5881 Single-Ended (SE) Tube Amplifier - 9 February 2010  Thai Flag

This fantastic looking tube amplifier was put together by Mr. Chey in Thailand. The DIY enclosure is constructed from aluminum sections and the audio output transformer covers are built using copper clad board. The circuit is very simple, a single-ended output stage using 6L6 or 5881 tubes, driven by 6SJ7 or 6SD7 cutoff pentodes. Mr. Chey is very pleased with the results and has replaced his solid state amp with this beauty. Nice work!

DIY KT88 Push-Pull Monoblock Tube Amp Kit DIY KT88 Push-Pull Monoblock Tube Amp Kit - 30 November 2009  Canadian Flag    KIT 

A build and review of the Odd Block KT88 Series 1 Tube Amp Kits. The monoblock tube amp kit uses an SRPP input stage with 5751 driver tubes and a push-pull output stage with KT88 power tubes. A constant current source (LM317HVT voltage regulator) is used to force the output stage into class-A operation. A solid state power supply is used. The tube amp kit comes with a nice steel enclosure and the power output is about 25 watts. The amplifier circuit is very simple with minimal parts in the signal path. The result is a very nice sounding tube amplifier kit that performs well.

DIY TDA2050 Hi-Fi Chip Amplifier DIY TDA2050 Hi-Fi Chip Amplifier (chipamp) - 5 July 2009   German Flag   UPDATED  (16 April 2012)
A small hi-fi chip amplifier (chipamp) project put together by Thomas in Germany which he calls his "Mini Gainclone". The amp uses a STMicroelectronics TDA2050V chip capable of producing about 25W into 8 ohms. The circuit is very simple and constructed on a protoboard. The power supply uses a 120VA torroidal transformer and generally follows the "snubberized" Gainclone power supply design. A black steel Hammond enclosure rounds out the amp. Thomas reports that the small chipamp can hold it own against various high quality amplifiers he has used.

DIY Low-Inductance Speaker Cables DIY Low-Inductance Speaker Cables - 19 May 2009  USA Flag    Recommended 

Adam has put together another fine looking set of Do-It-Yourself (DIY) Speaker Cables for his DIY 3-Way Hi-Vi Tower Loudspeakers. The cables are very simple to construct and are comprised of 16 gauge wires that are twisted together in alternating directions. The cable geometry results in a very low-inductance speaker cable with an equivalent wire gauge 10 so insertion losses are also low. High quality gold plated banana plugs, TechFlex and a laser etched decorative Oak Sleeve round off a very nice looking cable that rivals the performance of high quality commercial cable offerings.

DIY KT88 Push-Pull Tube Mono Block Amplifiers KT88 Push-Pull Mono Block Tube Amplifier Project - 29 October 2008  USA Flag   UPDATED  (9 Oct 2012)
Bruce's second follow up to his original "OddWatt" project are the "Odd Blocks", a pair of KT88 Push-Pull Mono Block Tube Amplifiers. Like the Oddwatt 225, the mono blocks are scalable and can be used with a number of octal tubes (KT77, 6CA7, EL34, 6L6GC, KT88, 6550, KT90). Like the previous projects the driver stage is an SRPP but this time with the 12SL7 tube. The output stage is a Class-A UL SIPP using KT88 tubes. LM317HV Regulators are used for the cathode CCS.