Elekit TU-8600S Tube Amp Kit - Lundahl Version

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USD $‎2,199.95
A Stereophile Recommended product, the Elekit TU-8600S Tube Amp Kit with Lundahl Output Transformer (LL2785B) upgrade is back! Do not hesitate in starting this DIY amp project, you won’t be disappointed. 
From Stereophile (Herb Reichert): "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 distincty 21st-centary 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."

Stereophile Recommended Components 2020
From Wall of Sound: "There isn’t any question that I’ll be buying this amplifier. I missed out on the 8300R, and I won’t let that happen again. My understanding is that orders are already outpacing supply, and this is listed as a limited production model. So its success is virtually a given. Elekit continues to raise the bar in the fairly-priced high-end game...this is a tremendous offering. A commercial Japanese-made amp of this calibre would (and does) sell for several times that much. This is a Wall of Sound Gold Star amp, if there ever was one."

The Elekit TU-8600S is a Single Ended DIY Stereo Tube Amp Kit. Always in pursuit of great sound quality beyond the typical 300B amp, Elekit have updated and improved the amplification, power, and feedback circuitry with this new design. The result is an amplifier with amazing sound quality and super low noise, that can also be used with headphones. Incredibly, the noise level is as low as 1/10 of TU-8300R.


Tube sets for this kit can be ordered below.
Upgrade PackagePremium PackageUltimate Package

We also offer Mundorf coupling capacitor upgrades for the TU-8600S amp. You can order a 4-pack of caps below:
Mundorf MCap Supreme EVO Kit
Mundorf MCap Supreme Silver Gold Oil Kit

TU-8600 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. 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 privileges 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-8600, 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-8600 uses 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.

■ Safety tube cover


Vacuum Tube Stereo Power Amplifier
Tubes Required: 300B x 2, 12AX7 x 1, 12AU7 x 2 (Not included. Order full tube sets here)
Output Stage: 300B tubes, Class A single ended, active bias adjustment
Voltage Amplification Stage (Input stage): 12AX7 (ECC83), 12AU7 (ECC82)
Heater/Filament Power: DC voltage (LDO used)
Plate voltage: MOSFET + BJT ripple filter (for Left and Right separately)
Rated Output (8ohm load, THD 10%): 9.2W + 9.2W
Rated Input: 320mV rms
Frequency response (-3dB): 7Hz - 40,000kHz
Residual noise (IHF-A, 8ohm load): 36μVrms
Inputs: 1 Line input (RCA)
Output Terminal: Gold-plated speaker binding terminal (Banana plug)
Headphone Impedance: 8-600ohm , unbalanced
Universal Power Voltage: 110-120V AC OR 230V AC 50/60Hz
Power Consumption: 90W
Dimensions: W385 x H217 x D325
Weight: Approx 12Kg

Additional Information and Downloads

Update/Modification: Page 8, step 20 mentions 5pcs of 4700uF/16V capacitors. They have been upgraded to 8200uF/16V rated. Download PDF update here.

About Elekit

Elekit (EK Japan Co. LTD) has been producing electronics kits since the early 1970's. While their main focus has always been educational kits, more recently they started to offer hifi audio amplifier kits. Included are some fantastic DIY vacuum tube amps and headphone amplifiers.

Warranty Information and Return Policy

Since this is an electronic product that is assembled by the user, we cannot provide a warranty like those found for regular pre-assembled electronics. Instead, Elekit can provide a counseling service. If there is a problem in the product please contact ELEKIT. However, throughout the instruction manual there are many check points, and we kindly ask you to make sure to pay attention to those check points as most of the time your problem can be solved if you follow them closely. We can not accept returns of any kit that has been started.

EK JAPAN CO., LTD Tofuro-minami 2-19-30, Dazaifu-shi, Fukuoka, 818-0105 Japan Phone: +81-92-923-8235 Fax: +81-92-923-8237 Website: http://www.elekit.co.jp Email: info@elekit.co.jp

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