Problem Statement - You want a quality integrated tube amplifier, but no means to afford one. No problem, just build your own ! Assuming you have decent soldering skills, and are not instruction-intolerant (sadly, that rules out my teenage daughter), the Elekit TU-8600R lets you enjoy quality on the cheap. You will need about four full days to build one, but the effort is well worth it.
The Elekit TU-8600R is a 300B single-ended integrated tube amplifier kit from the nice folks at Elekit of Japan. The TU-8600R is neither a basic kit nor design, and has parts quality and design features found in high-end models.
The power transformer is a high-quality R-core type, with low magnetic flux leakage. The solid state rectification uses Schottky fast recovery diodes. The power supply circuit includes ripple filters and plenty of regulation stages. An active automatic bias adjustment system means no fiddling with bias pots, and optimal sound quality at all times.
Parts quality is generous with plenty of Japanese branded resistors and capacitors. The PCB thoughtfully provides sufficient space for you to install large boutique coupling capacitors too. After all, isn't that the whole point of DIY, the freedom to express yourself ?
The TU-8600R's circuit is based on a single 12AX7 input tube, which then feeds dual 12AU7 tubes. The latter's two triode sections are wired in parallel to drive the 300B power tube. The output transformer has speaker taps for both low and high impedance speaker loads (selectable by a switch on the rear). A headphone socket allows you to enjoy your Elekit with your favourite pair of cans. Jumpers on the PCB allow you to adjust the headphone output level, and the colour of the power LED.
Although the TU-8600R is an integrated amplifier, there is only one set of RCA inputs. This could be a deal-breaker for some, although you could purchase or build an input switching box to get around this.
Elekit gets first prize for having the best instructions I've ever received with an audio-oriented kit. The instructions rely on very clear diagrams and steps to guide you every step of the way. The PCB is marked clearly and even reminds you when components are required to be installed on to the reverse side of the board. Plenty of due care and consideration went into ensuring that the assembly is as painless as possible.
The sheer parts count and complexity of the PCB makes this project highly unsuitable for a first-time build. The soldering of the transistors was the most delicate part of the build, as the solder pads are dangerously close. I would also highly recommend that a temperate controllable iron be used.
In my case, I chose to upgrade the stock resistors to Takman Carbon film ones, and the coupling capacitors to Amtrans AMCY Golden Black. I also bypassed the volume pot and wired the input jacks directly to the main PCB. The input sensitivity will be high, but if you are able to adjust the output level on your source (e.g. a DAC with volume control), you should be fine.
|Starting off at the professional assembly area a.k.a. dining table.|
|The Takmans are too large to fit and the legs have to be bent in a curved fashion to fit the board.|
|Soldering of the resistors is complete.|
|Plenty of space for upgrading the coupling capacitors.|
|This is the top side of the board. The main circuit is on the underside.|
|Testing phase. I made a boo-boo here.|
The only mishap suffered was when I wired the input wiring to the wrong solder pads. I happily soldered them to the input pads. They should have been wired to the output pads instead (Elekit refers to them as output pads in the sense that they receive the output from the potentiometer).
The power and output transformer connect to the PCB via push-on Molex connectors. Since the stars were aligned, I decided to run in both the stock output transformers and the Lundahl ones which are optional.
One criticism I have is with respect to the sheet metal covers. They have a fair amount of ring, and degrade the sound quality. This was very noticeable when I installed both after my run-in process was completed.
Paired with Genalex 300B tubes and a variety of 12AX7 and 12AU7 tubes from my stockpile, I gave each set of output transformers about 10 hours of run-time before I did any critical listening. I used my Totaldac DAC (using digital volume control) and icOn4 Pro as preamplifier, and my Vivid Giya G4 speakers.
The Elekit is highly detailed, fast and open. The tone is light and clear, so if you are seeking the vintage 300B tone (warm, full and midrange-centric) you should look elsewhere. Despite the low power on tap, vocals and smaller works were an absolute treat with the Vivid. While the midrange was not overly liquid, the presentation was clearly in the tube amp camp.
Soundstaging and imaging was holographic with pinpoint placement and excellent depth and width. The bass control and dynamics were satisfactory, but this is not the reason why you choose a single-ended tube amp. I believe that given the right set of loudspeakers (i.e. high efficiency), the Elekit would have no problem bringing the house down.
Swapping in the Lundahl transformer is the point where the Elekit is transformed from competent to world-class. The gains in detail retrieval, control over both ends of the frequency spectrum and refinement make the Lundahl a solid investment proposition. Elekit supplies the stock transformer even if you opt for the Lundahl, so you could always upgrade in the future, only losing out on having additional shipping costs.
The Elekit is good enough to be your end-game amplifier unless you suffer from equipment polygamy (which Audiophile doesn't ?). I was heartened to find such high quality at an affordable price, knowing that many would be able to enjoy its fine musicality.
There is a sense of rightness to the Elekit, and there is the invaluable ability to dial it in precisely to your taste through judicious choice of parts.
It comes in at an attractive price tag, so the only real downside is that you need to spend the time and effort to build it yourself. However, most Elekit dealers would offer a build service for a fee, or be able to refer you to someone who could. Best Buy and Highly Recommended.
Elekit TU-8600R Integrated Amplifier
Price - POA
Elekit kits are available from :-
1 Pemimpin Drive
#08-11, One Pemipin