Elekit TU-8600R
300B SE tube power amplifier kit from Japan

The Elekit TU-8600, a 300B single-ended tube power amplifier kit released as a limited production model for 2017, ran out so quickly that we received many requests for reproduction from both domestic and oversea markets. Upon such request, we relized a revised version the TU-8600R, with minimal modification from TU-8600. Limited production, without tubes.

There are two versions of the kit - we stock both. The TU-8600R features Elekit's standard E and I core output transformers, whereas the TU-8600RVK uses Lundahl LL2770B C-core output transformers. This version is more expensive but worth the extra amount.

The kit is not supplied with valves as people generally have their own opinion on valve selection. The output valves are 300Bs, with 1 x 12AX7 and 2 x 12AU7s making up the full complement.

Elekit TU-8600R 300B SE tube power amplifier kit.

Power circuit enhancement
A high efficiency, low magnetic flux leakage R-core is used. The rectifier consists of schottky barrier diodes that require shorter recovery time. This results in a reduction in even negligible noise spikes. The windings of the power transformer include individual windings for the filament heater (A- Power), high voltage (B-power), and bias to stabilize the Negative Feedback (NFB) circuitry (C-Power). In addition, all power is stabilized to reduce residual noise as much as possible. This results in the noise level as low as less than 1/10 of that of TU-8300R.

Stable NFB circuit for great audio quality
To make the most of the 300B tubes, the characteristics of various parts and circuits, including OPT, have been improved. The NFB is applied to the cathode of the 300B by the third winding of the OPT as well as to the voltage amplifying stage. Consequently, the overall NFB is minimized as well as the chance for the transient response.

New active automatic bias adjustment adopted
For the 300B tube bias, the power supply is equipped separately, and a ”New active automatic bias” is used where the amp detects plate current and automatically adjust the grid voltage. This design earns TU-8600 the priviledges of both self-bias and fixed bias. In addition, current detecting circuit is moved from the cathode side to the B-power side resulting in even better sound quality.

Driving 300B tubes to full power
A very orthodox design is used for the voltage amplifying stage to bring out the outstanding characteristics of the famed 300B tubes. Of special note is that 12AU7(ECC82) is used in parallel for the 2nd stage to drive the 300B tubes to full power- resulting in 200Vp-p without clipping.

Tube-friendly design
Warm-up time for directly-heated and indirectly-heated tubes largely differ. In most designs, amp power-up starts heating both the directly heated 300B tubes (fast warm-up) as well as the indirectly-heated 12AU7 and 12AX7 (slower warm-up). In TU-8600R, the 300B tubes are heated after the indirectly-heated tubes have warmed up. A very tube-friendly design that will not overload tubes that have not warmed up fully.

Output level selection for headphones
For the headphone, you have 4 selections of output level to match your headphone.

Ample space for larger coupling capacitors
Capacitors can have a big effect on sound. TU-8600R use high quality conductive polymer hybrid electrolytic caps and polypropylene film caps. For those who wish to use other higher quality caps, there is ample space provided on the PCB for mounting larger caps.

Special version with Lundahl's transformers LL2770B
Besides the standard version, the kit will be also available with special adjustments for using a highest quality Lundahl LL2770B transformers for even better sound quality. This is the TU-8600RVK model.

• Circuit configuration, Single ended tube amplifier
• Used tubes (not included), 300B x 2, ECC83 x 1, ECC82 x 1
• Rated Output, 9,2 W + 9,2 W
• Rated input, 320 mV
• Residual noise, 36 µV (IHF-A)
• Frequency response, 7 Hz - 40 kHz (-3 dB)
• Input impedance, 50 kOhm
• Output impedance, 4
- 6,3 Ohm / 8 - 16 Ohm, Selectable by the rear switch
• Input, line x1
• Output, Speaker terminal gold-plated screw (banana plug usable)
• Power voltage, AC 100/110-120/200/220-240 V 50/60 Hz
• IEC Standard inlet
• Power consumption, 90 Watt.
• Dimensions, 385 x 217 x 325 mm
• Weight, 12,8Kg


Reviews :

review by Herb Reichert, Stereophile.

"The Elekit TU-8600R may look like a generic, old-school, single-ended 300B integrated amplifier, but its sonic character is clean, neutral, and precise in a distinctly 21st-century way. It doesn't sound at all warm or soft, but fast and vigorous, as transparent as any amplifier, and extremely captivating. My many months of auditioning it suggest that, with the right speakers, this humble amp kit could please discriminating listeners as much as any amplifier at any price. Bravo, Yoshitsugu Fujita.."

Price :

Elekit TU-8600R
(without tubes)

€ 991.74
€ 1200.00

Elekit TU-8600RVK
With Lundahl C-core output transformers.
(without tubes)

€ 1429.75
€ 1730.00


Remember that this is a DIY kit. It means that YOU will have to build it yourself using the assembly manual. The kit includes all electronic and mechanical parts (including housing) required to build a ready to work, high quality tube amplifier. It should take 5-6 hours to construct and it will need soldering. You should have some tools and soldering skills. Interconnects are not inclueded and the power cable is Japanese type, you will need a proper cable for your country.

A multimeter is not required but is really useful.
Detailed visual assembly kit instructions in Japanese language are included in package. An English language instruction will be send to you in pdf format after purchase.

Space for bigger coupling capacitors

TU-8600RVK Lundahl version

TU-8600RVK Lundahl version