Elekit TU-8600S 300B Single Ended Triode Power Amplifier/HPA Kit
>>> 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-8600S is a 300B single ended audio power amplifier kit, replacing the old TU-8600R model.
We are selling a special edition for the diyAudio store. This special edition includes:
- Lundahl LL 2785B transformers, PCB board and HV connector
- 81 x 1/2W 2% REX50G Takman resistors
- TKD 2CP601S potentiometer with conversion kit
The 8600S has been reviewed by Stereophile and is now a Stereophile recommended component.
- TU-8600R Product Leaflet
- Review of TU-8600R in March 2019 Stereophile magazine
- Stereophile recommended components list
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
- The TU-8600 operates at very high voltages, and includes a safety cover
- 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
After the great customer support from Elena and Jason, the kit arrived in The Netherlands. Perfectly packed, clear instructions and all parts complete. The instruction manual is of a very high quality ( respect! ) and building the amp was not very complex and a lot of fun to do. You need a bit of solder skills and the right material though. Unpacking the big Lundahl trafo's was a special moment, they are beauties. After finising the kit and putting in a complete Genalex tube set, i first listened with a cheap headphone to be sure everything worked fine. Sound was a bit muffled ( brand new tubes ) in the beginning but it was already very promising. I could not resist and connected it to my Klipsch Forte III and Lumin A1 to listen how it sounds and see if i had enough power. Well....more than enough! After connecting the TU-8600 i let it play for days to break in all parts, no critical listening, just background music. Last night i was listening with my girlfriend and we sat on the couch for hours, number after number, album after album and we could not stop. I'm 42 and had all kinds of equipment at home. Only transistor amps and my last on was a 2x30 Watt class A of 14K. None of these made me cry of musical emotion...this one did which was a revalation. Stage, immense detail, dense natural spooky real sound, articulation of voices, bass speed, power & detail...all there at any volume. Also when you play at low volume all is there which is very important for me, i don't want to play loud all the time to hear all details. The only thing i changed were the ECC82's which are Philips Miniwatt's now to give the sound a bit more 'body' but that's more personal taste. I'm very very happy with this amp, and it feels like an endpoint now. What you read in the reviews is true, it is that good. A big thanks to the designer of the amp and diyaudiostore. You made me a happy man.
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!!!!!!
I've had the base TU8600 with Mundorf silver oil caps added for 2 years now. Everything pretty much settled. Was looking to buy those transformers only but never saw available until now (thanks Jason)
Anyway, the improvement was immediate no break in needed. As I've read before just more of what the 8600 is good at clarity, soundstage, tonal balance and accuracy.
Worth the dough!
This 300B kit resulted in sound quality that retired amps from my listening room that cost several fold more. The build instructions are so clear that experienced builders and newcomers should enjoy the soldering.... and the end product offers performance that can’t be over-sold
still in assembly,buteverything looks great, and the instructions are the best I've seen. I have high hopes and plan to power Altec 9844B's
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.
Like the previous reviewer, I decided to build this kit based on the outstanding review in Stereophile. I also went with the upgraded version--Lundahl transformers, Mundorff caps, Shuguang 300Bs. And, like the previous reviewer, I'd sound a note of caution about the soldering; oversoldering, a common beginner's error (it certainly was mine), will definitely cause problems in some areas where the PCB is densely populated. I think I'm reasonably good with a soldering iron and I still had to redo a couple of connections.
That said, the instructions are excellent and the polarity markings on the PCB make proper orientation of the components foolproof. Just take your time.
I built it not sure whether it would drive my medium-efficient monitors but thinking I would be happy if it performed well with headphones, which I listen to a lot. And it does, but speakers not so much; there's just not enough power for even low-mids, let alone bass. So I started nosing around for high-efficiency DIY speakers, which, long story short, led me to the pair I am now using: Audio Nirvana 8" full range speakers with ferrite magnets in very simple ported bass reflex cabinets made out of plywood. They definitely look homemade, because they are, and they're still breaking in, but they sound fabulous.
This experience has opened up a whole new way of thinking about stereo gear for me: low-powered amplification, high-efficiency speakers. I won't go on about this here, but I'd be happy to hear from anyone similarly inclined. And to wrap up, the Elekit TU 8600R is a fabulous amplifier and easy to build as long as you're careful and have a light touch when the PCB gets crowded.
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