Elekit TU-8600R 300B Power Amplifier / Headphone Amplifier Kit

1,899⁰⁰

Description

>>> Please note that tubes are not included in this kit <<<

"A world-class, four-star 300B tube amp that should cost $20,000 but will cost you only about $2,000 because you've assembled it yourself"
^{Herb Reichert Stereophile Magazine March 2019}

The TU-8600R is a 300B single ended audio power amplifier kit. This is a special edition for the diyAudio store that includes upgraded 2% REX50G Takman resistors.

The 8600R has been reviewed by Stereophile and is now a Stereophile recommended component.

We are currently offering it in these configurations:

Deluxe Special Edition (SE). This is the TU-8600R, upgraded Takman resistors and a pair of Lundahl transformers for ($1,874)
A "Super Deluxe SE" version which additionally upgrades to a Japanese TKD 2CP601S stepped attenuator ($1,899)
The Lundahl Transformers (Pair) are also available for purchase by themselves, and are compatible with both the original TU-8600 and the current model TU-8600R ($650)

Features

Power circuit enhancement

High efficiency, low magnetic flux leakage R-core transformer
Schottky barrier diodes for shorter recovery time
Individual windings for the filament heater (A power), high voltage (B power), and bias to stabilize the negative feedback circuitry (C power)
All power stabilized to reduce residual noise as much as possible, resulting in a noise level as low as 1/10th of the TU-8300R

Stable NFB circuit for high quality audio

Improvement to various parts and circuits including OPT to make the most of 300B tubes
NFB applied to cathode of 300B by the third winding of the OPT as well as to the voltage amplifying stage
NFB is minimized as well as transient response

New active automatic bias adjustment

Bias power is supplied separately
New "Active automatic bias" used where the amp detects plate current and automatically adjusts the grid voltage, rendering the TU-8600 both self-biasing as well as having fixed bias.
Current detecting circuit moved from cathode side to the B power side for better sound quality

Full power use of 300B tubes

Orthodox voltage amplification stage to make the most of the 300B's outstanding sonic characteristics
12AU7 (ECC82) used in parallel for 2nd stage to drive the 300B tubes to full power resulting in 200Vp-p without clipping

Tube friendly design

Warm up times for directly heated and indirectly heated tubes differ. Most designs warm up both at the same rate.
The TU-8600 heats up the directly heated 300B tubes after the indirectly heated 12AU7 / 12AX7 indirectly heated tubes have warmed up.
This is a very tube friendly design that will not overload tubes that have not warmed up fully

Output level section for headphones

There are jumpers on the board to allow for headphone impedance matching

DIY friendly design

The TU-8600 comes with high quality polymer hybrid electrolytic caps and polypropylene film caps, however extra space has been designed into the PCB for audiophiles to add (larger) after market caps

Safety

The TU-8600 operates at very high voltages, and includes a safety cover

Specifications

Tubes: 300B x 2, 12AX7x1, 12AU7x2 (TUBES ARE NOT INCLUDED)
Rated output: 9.2W + 9.2W (10% THD)
Rated input: 320mV
Residual noise: 36uV (IHF-A)
Frequency response: 7Hz-40kHz (-3dB)
Input impedance: 50kΩ
Output impedance: 4-6.3Ω, 8-16Ω selectable
Input: Line1 (2 x RCA)
Output: Gold plated speaker output terminals (banana plug compatible)
Power input: 100/115/200/230V 50/60Hz (IEC inlet)
Power Consumption: 90W
Dimensions: 385x217x325mm (including projections)
Weight: ~12.6kg assembled

I built one. Thank you Herb Reichert!!!!!!

I've always been intrigued by 300B SET amps. Over the years I've built a number of kits from AudioNote Kits and Bottlehead. Herb's Stereophile review made me commit. This is the best packed, picked, instructed kit I have made. Like Herb's, mine is the upgraded version, but I built it myself. It was an easy and fun build. My only caution is for newbies with little soldering experience. Watch some YouTube videos and practice first. In places the PCB is densely populated and the solder pads are close together.

Now for the best part. As Herb stated in his review, pair the TU-8600R with the right speaks and they sing. It's just mind boggling. You just built a $20,000 amp $2,000. There's nothing else to say!!!!!!

What a vacuum joy

After a long while of soldering, three months at least, I finished my second diy project - A Elekit TU8600 tube amp. I told all my friends that there are 2 things in audio I wouldn’t touch. 1 is vinyl the another is tube powered amp. Obviously, I break the latter one now. Faced a bunch of parts, I had a doubt that “can I really get it done?” However, the manual was clear & straight forward, even there’s no photo instructions like the amp camp amp did. Used a long while because I wanted to enjoy the processing. Part by part, step by step. For me it’s a great satisfaction to see it stuffed full. Watch those tubes light up the first time. It’s really some strangest feeling. Describing the sound texture isn’t my best. All I can tell is really a big difference with all equipment I have. And I understand why there are a lot of tube-philers after decades of solid state occupied the market. I need to thanks Victor Kung for helped me some up grade parts, even I didn’t install them all now. But after A period of time to listen. I’ll put them all for a deep comparison. I, definitely, believe this’s not the only one vacuum thing in my life.