18 April 2010

Elekit 6BM8 / ECL82 and 300B Tube Amp Kits

Over the past year, the good folks at TubeDepot have been expanding their line up of hi-fi tube amplifier kits.  They have been carrying the inexpensive S-5 electronics tube amp kits for many years now and it is one of these low-cost tube amp kits that got me started with tubes.  Late in 2009 TubeDepot added the OddWatt Audio OddBlock monoblock KT77 tube amp kits and that kit was followed up just a few weeks later with the Elekit TU-879S single-ended 6L6 tube amp kit.

Just a few days ago we were very pleased to see that they have added another pair of single-ended tube amplifier kits to their growing line up.

Elekit TU-870R Stereo Tube Amp Kit 
The smaller of the two kits is the Elekit TU-870R which is a small single-ended 6BM8 / ECL82 tube amp rated at about 2W per channel.  The 6BM8 (ECL82) tube contains both a power pentode and triode is a single glass envelope so only one tube is used per channel.

Elekit TU-870R 6BM8 / ECL82 Tube Amp Kit

The Elekit TU-870R kit comes complete with an enclosure and is neatly priced at $349.95US (April 2010).  The kit is available with a choice of 1a 20V or 220V power transformer.  With only 2W of output this kit will need to be matched with high sensitivity loudspeakers.

Elekit TU-8300 Stereo Tube Amplifier Kit
For those who are looking for more power output and true triode sound, there is the Elekit TU-8300 Stereo Tube Amplifier Kit which is based around 300B tubes.  The 300B is a directly heated power triode tube which was first introduced in 1937.  A 12AT7 (dual triode) is used to drive the 300B.  Power output is about 8W per channel.

Elekit TU-8300 300B Tube Amplifier Kit

The Elekit TU-8300 300B tube amplifier kit comes complete with an enclosure that includes a removable cover to keep curious hands and paws away from the hot vacuum tubes.  The 300B kit is priced at $1199US (April 2010).  The power transformer can be used with 100V / 120V / 220V / 240V mains.  

Tube Amplifier Kit Reviews:

16 April 2010

DIY HiVi Research Swans M1 Speakers

We got an email from Daniel Bolduc (Quebec, Canada) letting us know that he has followed up his DIY Swans Tempus Bookshelf Speakers with another DIY build of a HiVi Research speaker.  Daniel tells us that the speakers were built for his uncle who was very impressed with the Tempus speakers, but wanted something a little smaller and finished in a piano black high gloss finish.

HiVi Research Swans M1 Speakers
HiVi Swans M1 Speakers
Sticking with drivers from HiVi, Daniel proposed to build a DIY version of the Swans M1 Speakers. For the enclosure Daniel used a pair of ready made speaker enclosure from Parts Express.  I used a pair of the curved Dayton Audio 0.38 ft^3 enclosures with black piano gloss finish for my Fostex FX120 bookshelf speakers and the enclosures are well built and look great.

Dayton Audio / Parts Express Curved Speaker Cabinets
Dayton Audio 0.38 ft^3 Prefabricated Speaker Enclosures
The high gloss finish on the speaker cabinets will scratch easily so be sure to cover the area well so you don't scratch it with the router when cutting the port and driver holes.  The crossover schematic is shown below and Daniel wound his own inductors for the crossover.

HiVi Swans M1 Crossover Schematic
Hand Wound Air Core Inductors for Crossover
The drivers used in Swans M1 speakers are the HiVi F5 (5" bass / midrange) and the HiVi RT1C planer tweeter.

Mounted Crossover Circuits
The speaker project cost about $550CDN for the pair and Daniel estimates he invested about 55 hours.  I think Daniels build looks much better than the original Swans M1 speakers. 

Finished DIY HiVi Swans M1 Speakers
Daniel writes: "So far, I'm very satisfied with the M1's and my uncle is rediscovering his discography with the pair I built for him and is also impressed by the sound reproduction quality."

For full details, more photographs and a materials list for this DIY speaker project, see Daniel's Swans M1 speaker build

Related DIY HiVi Speaker Projects:

12 April 2010

Hybrid Headphone Amp - 12AU7 Tube / IRF510 MOSFET

Rogers has improved upon his 12AU7 (ECC82) Tube / IRF612 MOSFET Headphone Amplifier project from August 2008 with a new version, the NP-100v12, a DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier.  The 12AU7 / IRF510 headphone amplifier is powered from a rechargeable 12V sealed lead acid (SLA) battery which makes this an ideal project for novice builders as they don't have to worry about the high voltages typically associated with vacuum tubes.  The headphone amplifier circuit is very similar to the previous build utilizing a  single 12AU7 (ECC82) vacuum tube for the voltage gain stage which is followed by a IRF510 MOSFET follower stage which supplies current to drive demanding headphones.  IRF610, IRF611 or IRF612 MOSFETs will also work in this circuit.  The main difference between the updated headamp and the the original version is that a LM317 regulator (used as a constant current source (CCS)) is used in place of the load resistor to bias the MOSFET follower into class-A operation.

12AU7 Valve / IRF510 Mosfet with LM317 CCS Headphone Amplifier
12AU7 Tube / IRF510 MOSFET Headphone Amplifier
Included in the project documentation are printed circuit board (PCB) images and Eagle circuit board files so builders can easily make their own PCB for this project.  Being a fairly simple circuit, one could also easily build the headphone amp point-to-point on a 750 hole protoboard.  This simple headphone amplifier can be built for about $40-50 or less if you recycle parts and and enclosure.  For full details of this headphone amplifier, see the NP-100v12: DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier project page.

More DIY Headphone Amplifier Projects:

What's Playing: The Beatles - Love

10 April 2010

Giveaway #3 - Spears & Munsil High Definition Benchmark Blu-ray

After many years of good service I felt it was time to replace my aging CD and DVD players and a universal player seemed like a good choice.  After reading many glowing reviews I decided to give the OPPO BDP-83 Blu-ray Disc Player with SACD, DVD-Audio and streaming capabilities a try.  Included with the OPPO BDP-83 player was the Spears & Munsil High-Definition Benchmark Blu-ray to help with setup and calibration of the player.

Recently our good friends over at CANADA HiFi Magazine sent us a Spears & Munsil High Definition Benchmark Blu-ray and since we already have one we are offering it to our readers as Giveaway #3.

The winner of the Spears & Munsil High Definition Benchmark Blu-ray will be randomly selected from our RSS Email Subscription list on 17 April 2010.  In order to qualify for Giveaway #3, make sure you are signed up.  Note that the verification email often ends up in the spam folder so be sure to check there after you have signed up.  The randomly selected winner will be contacted by email for their shipping details.

Good luck.