MADE IN JAPAN

ELEKIT TU-8600S

300B SE TUBE AMPLIFIER

HIGH QUALITY DIY (DO-IT-YOURSELF) KIT

ELEKIT TU-8600S

300B SE TUBE AMPLIFIER DIY KIT

TU-8600S IS LIMITED PRODUCTION MODEL

TU-8600S is a third generation of TU-8600 series, a 300B single-ended tube amp kit released as a limited production model for 2017 and 2018. Receiving many requests from both domestic and oversea markets, we are again reproducing it as a revised version TU-8600S with some modification to the parts layout on the PCB from TU-8600R. And again it is a limited production model.

In 2019, TU-8600 was selected as the Stereophile Recommended Components, the first kit amp picked and reviewed by Sterophile. The new TU-8600S amp has a lot more improvements from its predecessors TU-8600 (2017) and TU-8600R 2018-19).

Some highlights:

  • Mr Fujita, the famous amp designer, slightly modified the B+ power supply section, while keeping the same amplification circuit to further enhance the sound quality and the stability of the amp.
  • Mr Lundahl from Lundahl Transformers, world-wide know designer and manufacturer of output transformers redesigned the OPTs with the know-how from LL2783C to make LL2785B/60mA for the new TU-8600S.
  • The noise level of TU-8600 is very very low... amazing design indeed!
  • TU-8600S 300B is not a HiFi amp. HiFi amps will only give you dramatic, high and low sound, missing the nuances and intricacies that TU-8600S can provide for you. Some people says that's the HiEnd...

TU-8600S FEATURES

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.
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 system
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-8600S 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-8600S, 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
The headphone volume settings and the color settings of the power LED can be changed by moving the jumper location on the PCB.
Ample space for larger coupling capacitors
Capacitors can have a big effect on sound. TU-8600S 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.

TU-8600S

Headphones output level selectors

TUBES

Powered by directly heated 300B power tubes, ECC82 and ECC83.

HEADPHONES

Four selectable sound levels to match your headphones

AUTO BIAS

New active automatic bias adjustment system for better sound quality

IMPROVES

Improved power circuit and stable NFB system for better quality

TECHNICAL SPECIFICATION
CIRCUIT CONFIGURATION Single ended tube amplifier
STOCK TUBES 300B x 2, ECC83 x 1, ECC82 x 2
RATED OUTPUT 9,2 W + 9,2 W (THD 10%)
RATED INPUT 270 mV
RESIDUAL NOISE 36 µV (IHF-A)
FREQUENCY RESPONSE 15 Hz - 40 kHz (-3 dB)
INPUT IMPEDANCE 50 kΩ
OUTPUT IMPEDANCE 4 Ω - 6,3 Ω / 8 Ω - 16 Ω
Selectable by the rear switch
INPUT TERMINAL LINE x 1
OUTPUT TERMINAL Speaker terminal gold-plated screw (banana plug usable)
Headphone terminal 6,3 mm jack
POWER VOLTAGE AC 100/110-120/200/220-240 V 50/60 Hz (3P inlet)
POWER CONSUMPTION 90 W
DIMENSIONS W 385 x H 217 x D 325 mm
WEIGHT Approx. 12,8 kg (excl. power cord)

TU-8600 REVIEWS

Great fun with construction should be ended with a great listening. Look what the people which heard it says about.
  • ...musically and sonically satisfied me as much as if they cost $26,000....

    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.
  • First off, the kit arrived with everything nicely bundled and the parts sorted and arranged into their own bags. Very tidy and professional – no surprise, this is Elekit. The 32-page manual deserves special mention. This is likely the best audio documentation I’ve ever seen. Novice builders especially should take note: look at the little icons on the PCB, look at the drawings in the manual – look for clues. If something seems complex, you’re not looking.
    Noam Bronstein | Wall of Sound, Part 2
  • As music pours out of Elekit’s new amp through my speakers, I’m smiling, and remembering that some things are much more than the sum of their parts. Some things just work, and those who have heard the mighty 300B tube perform its magic through full-range drivers understand this. That’s why you’re reading this review, naturally.
    Noam Bronstein | Wall of Sound, Part 1

PRE-ORDER

Due to imited production we now accepts pre-orders. Estimated availability - late
July 2020 for standard version, late September 2020 for Lundahl's version.

DIY - DO IT YOURSELF

Please remember that this is a DIY kit. It means that YOU will have to build it yourself using assembly manual. The kit includes all electronic and mechanical parts (including tubes and housing) required to build a ready to work, high quality tube preamplifier. It should take 4-5 hours to construct and it will need soldering. You should have some tools and soldering skills. There is not included interconnects and the power cable is Japanese type, you will need a proper cable for your country.

TOOLS REQUIRED

Although building this kit is not hard, you will need some skills and tools. A multimeter is not required but can be useful.

  • Phillips screwdriver
  • Diagonal cutter
  • Longnose pliers
  • Scissors
  • Scotch tape
  • Hexagonal wrench
  • Soldering iron
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