*** AN UPDATE to the performance of the phono stage is written by me several postings below here: ie, further on in this particular post, not in a separate one.
Hi all, I just wanted to share my latest project, something I've been saving for and wanting to build for some 18 months. It's an Elekit TU 8500 valve preamp, direct from Japan, complete with all assembly instructions in Japanese! Fortunately, the instruction sheets are so beautifully put together from beginning to end, as well as the fact that I've been building kits on and off for decades, that I had no issues with the build as such. It did mean I had to double check some items for orientation, but that was no big challenge at all, really just precautionary. It's certainly not a kit I would recommend to beginners, but if you have good soldering skills and can at least follow picture directions, then you should have little problem with this one.
The sheer quality of the boards and casework is truly admirable, as everything aligned to perfection and once I fired it up and checked the 140V and 12V+- test points all was well. This preamp is SILENT(!), thanks to a classy R-Core transformer often found in much more high end gear and a comprehensive DC power supply. Even the phono stage needs full volume through headphones to hear even the slightest of noise at a very very low level, the line stage is for all intents and purposes completely silent.
** This TU 8500 preamp is far quieter than a $3700NZ TRI KT88SE Integrated amplifier that I owned and loved for five years!
Board layout is exemplary and I had a great time being a bit OCD in aligning all my components in straight lines and resistor values facing the same direction .. unless they were mirrored I even went to the extent of filing down the board joins, as they all come connected together and require breaking off, sort of like breaking tiles, not as nerve-wracking as you might think, as they snap off easily. The solder flowed effortlessly with every joint and I double checked each one to make sure it was shiny and perfect.
Some weeks before receiving the kit in the mail, I had bought up both the upgrade op-amps for the phono stage and from Parts Connexion, the upgrade Amtrans resistor kit and two Mundorf Evo capacitors, supposedly for the phono stage coupling to the line stage .... until after ordering them, found out that I also needed two more for the line stage itself, DOH! I umm'd and ahh'd a bit, before remembering that I had some high grade polypropylene caps (630V) that I had bought for a Trevor Lees preamp some years back, so I used two of these in the phono stage and the Mundorf Evo's in the line stage. You can see them easily in the pictures below. I also replaced the stock 0.1uF caps in the phono stage with two Black Gate 0.1uF NP caps, something I've done with other amps to very good effect, these tiny capacitors are super clean and transparent and are brilliant as power supply bypass caps in the right circuits, as Martin Collums discovered to his great delight when reviewing a series of these brilliant high quality capacitors several years ago. The kit also comes with quite a number of quality low ESR capacitors for use outside of the power supply. Great stuff.
The TU 8500 lit up from first switch-on and has functioned perfectly ever since, a week later. I've already put some 30-40 hours on it and the bass has most certainly filled out in the last 10 hours or so, taut, dynamic and organically alive. I'm also very impressed with the phono stage, very clean, quiet and detailed, with excellent dynamics as well, although the Black Gate caps will take quite some further time to run in, as usual, as well as the big polypropylene caps. The upgrade op-amps also seem excellent, OPA2227P x 2.
Initially, I used the stock supplied Chinese 12AU7s and had an absolute ball listening through headphones to hours of an iTunes downloads folder! So much fun and even though the preamp was brand new and there was some extra warmth from the stock 12AU7s, I could imagine that many folks would be happy just to leave them in there and listen to music, particularly with Mp3's and AAC tracks.
Still, I was keen to hear how my top grade Psvane 12AU7-T's sounded in here, so the next day in they went. Yes, well, this is why we pay extra for top class bottles! Transparency and speed, extension top and bottom, openness and 3D space. Highly recommended! The Ziggy Stardust and the Spiders From Mars Live soundtrack album has never sounded this good!
I did pop in a couple of Mullard valves that I thought were of the right species (the preamp can accomodate both 12AU7 types and the lower MU 12AT7s), but it turns out I had mislabelled the ECC88s as 12AT7s ... they are not! No wonder they glowed very brightly (see pics below)! They were a bit soft and warm anyway and once I'd realised my mistake, I replaced them with the Psvanes and all was well, no harm done. 12V into a 6V heater may not have gone so well. Last task is to find a cable tie that will stick to the base for the main's cables from the transformer.
I bought my TU 8500 from an eBay site, it shipped on Dec 22nd, suggesting it could be late Jan/early Feb before it arrived and instead it sped here in four days (after clearing their store) and took another five or six days to get to my PO, including redirection (we'd moved house). No issues over freight speed! The Parts Connexion also posted free of charge for the resistor kit and caps, well done them, about 10 days arrival time.
If you'd prefer to buy in Australia, there is a Gumtree site that will post from WA for $65, bringing the price to around $740AU, minus the upgraded parts which they don't keep in stock; Hammersley, Sterling Area. That would take you up to around the $800/820 mark including the upgrades.
The eBay site I bought from was here and included a voucher code for some $40AU off the list price: japanmegamall (4167)
All in all, a very highly recommended 'kit' that performs way above it's station and price range. I am extremely happy with my TU 8500 and would now really love to build the TU 8200 headphone/speaker amp this year, with it's upgraded parts.
Sorry about the bluish/green light in some of the pics.