{"product_id":"elekit-tu-4523-45-2a3-kit","title":"Elekit TU-4523 — 45\/2A3 Single-Ended Power Amplifier Kit","description":"\u003carticle\u003e\n\u003cp\u003e\u003cem\u003eTubes are not included. Shipping from late October\u003c\/em\u003e\u003c\/p\u003e\n\u003ch2\u003eThe Other End of the Triode Family\u003c\/h2\u003e\n\u003cp\u003eIf the \u003ca href=\"https:\/\/secretchordanalogue.au\/products\/elekit-tu-8900-kit\" title=\"TU-8900\"\u003eTU-8900\u003c\/a\u003e is where Elekit lets a 300B and a 2A3 argue over who gets to fill the room, the TU-4523 is where the conversation gets quiet. This is the 45's amplifier: a single-ended, class-A kit built around the most delicate of the classic directly-heated triodes, with a manual switch that lets you drop back to a 2A3 whenever you want a little more scale.\u003c\/p\u003e\n\u003cp\u003eThe 45 first appeared in 1930s American radio sets, was pushed aside for decades by tubes that could simply make more noise, and has spent the last twenty years being quietly rediscovered by listeners who care more about texture than headroom. It has a well-earned reputation as the sweetest-sounding tube in the 45\/2A3\/300B family — and the most limited. The TU-4523 is Elekit's purpose-built home for it, sharing its 2A3 socket with the \u003ca href=\"https:\/\/secretchordanalogue.au\/products\/elekit-tu-8900-kit\" title=\"TU-8900\"\u003eTU-8900\u003c\/a\u003e so the two kits meet in the middle, while each pushes off in its own direction: the TU-4523 toward finesse, the TU-8900 toward drive.\u003c\/p\u003e\n\u003ch2\u003eWhy Choose the TU-4523 Over the TU-8900?\u003c\/h2\u003e\n\u003cp\u003eBoth kits share Elekit's now-familiar formula — automatic tube-type detection, DC-heated filaments, MOSFET-regulated B+, and a proper NFB\/non-NFB switch for tone-shaping without a soldering iron. Where they part ways:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eA different pair of tubes entirely.\u003c\/strong\u003e 300B\/2A3 versus 45\/2A3. The 2A3 is the shared middle ground; the 45 and 300B are the two extremes either kit lets you reach for.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBoutique components as standard, not as an upgrade.\u003c\/strong\u003e The TU-4523 ships from the factory with Lundahl output transformers, Takman resistors and an ALPS R27 potentiometer built in — components that are optional upgrades on the base \u003ca href=\"https:\/\/secretchordanalogue.au\/products\/elekit-tu-8900-kit\" title=\"TU-8900\"\u003eTU-8900\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA smaller, lighter, cooler-running amplifier.\u003c\/strong\u003e At roughly 9.8kg and drawing 42W (45) or 65W (2A3), the TU-4523 asks less of your shelf, your power bill and your room in summer than the 11.2kg, up to 95W TU-8900.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMore headroom to modify the sound yourself.\u003c\/strong\u003e Elekit has deliberately left extra board space for larger coupling capacitors (up to 22mm × 44mm), and added a second selector so speaker impedance can be matched separately for 45 or 2A3 operation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA closer relationship with its most famous historical role.\u003c\/strong\u003e The 45 is a lower-powered, lower-voltage tube than the 300B, so the TU-4523's whole design — voltages, cathode resistors, board layout — is tuned around getting the most out of a tube that was never meant to be loud in the first place.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eIf you already know you want the biggest, most authoritative single-ended sound Elekit builds, stay with the \u003ca href=\"https:\/\/secretchordanalogue.au\/products\/elekit-tu-8900-kit\" title=\"TU-8900\"\u003eTU-8900\u003c\/a\u003e. If what drew you to SET amplification in the first place was the promise of the most transparent, most \"in the room\" midrange going — and you can live with roughly 2.5W to get it — the TU-4523 is built for you.\u003c\/p\u003e\n\u003ch2\u003eTU-4523 Full Specifications: 45 vs 2A3\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eWith 45 Tubes\u003c\/th\u003e\n\u003cth\u003eWith 2A3 Tubes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eTubes required\u003c\/td\u003e\n\u003ctd\u003e2 × 45 + 2 × 12AU7 (ECC82\/6189)\u003c\/td\u003e\n\u003ctd\u003e2 × 2A3 + 2 × 12AU7 (ECC82\/6189)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCircuit\u003c\/td\u003e\n\u003ctd\u003eClass A, single-ended, self-biasing\u003c\/td\u003e\n\u003ctd\u003eClass A, single-ended, self-biasing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax. output (8Ω, 1kHz, THD10%)\u003c\/td\u003e\n\u003ctd\u003e2 × 2.5W\u003c\/td\u003e\n\u003ctd\u003e2 × 4.5W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput at 1% THD (8Ω, 1kHz)\u003c\/td\u003e\n\u003ctd\u003e2 × 1.5W\u003c\/td\u003e\n\u003ctd\u003e2 × 3W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRated input\u003c\/td\u003e\n\u003ctd\u003e660mV rms\u003c\/td\u003e\n\u003ctd\u003e800mV rms\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVoltage gain\u003c\/td\u003e\n\u003ctd\u003e19dB (NFB) \/ 27dB (non-NFB)\u003c\/td\u003e\n\u003ctd\u003e19dB (NFB) \/ 26dB (non-NFB)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDamping factor (8Ω, 1kHz)\u003c\/td\u003e\n\u003ctd\u003e6\u003c\/td\u003e\n\u003ctd\u003e8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eResidual noise (IHF-A, 8Ω)\u003c\/td\u003e\n\u003ctd\u003e12µV rms\u003c\/td\u003e\n\u003ctd\u003e15µV rms\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended speaker impedance\u003c\/td\u003e\n\u003ctd\u003e6–16Ω\u003c\/td\u003e\n\u003ctd\u003e4–16Ω\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFrequency response (−3dB)\u003c\/td\u003e\n\u003ctd\u003e10Hz – 90,000Hz\u003c\/td\u003e\n\u003ctd\u003e10Hz – 90,000Hz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRated power consumption\u003c\/td\u003e\n\u003ctd\u003e42W\u003c\/td\u003e\n\u003ctd\u003e65W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eShared Across Both Tube Types\u003c\/h3\u003e\n\u003cp\u003eRCA line-level input (≈50kΩ input impedance); gold-plated binding-post speaker outputs (banana-compatible); 3-pole 6.3mm headphone output with adjustable level via a rear shorting pin; universal AC115V\/230V power input (set at assembly); dimensions 356 × 214 × 320mm; weight approx. 9.8kg (assembled, excluding tubes and power cord).\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eSpecifications per Elekit's official TU-4523 documentation and subject to change without notice.\u003c\/em\u003e\u003c\/p\u003e\n\u003ch2\u003eSourcing 45 Tubes for Your TU-4523\u003c\/h2\u003e\n\u003cp\u003eEvery Elekit SET kit ships without tubes, and that's usually a minor detail — a matched pair of current-production 2A3s is inexpensive and easy to find. The 45 is a different story, and we'd rather tell you that up front than have you discover it after the kit arrives.\u003c\/p\u003e\n\u003cp\u003eThe 45 never went back into mass production the way the 2A3 and 300B did. Today it's effectively a specialist tube: the main current-production source is \u003cstrong\u003eEmission Labs\u003c\/strong\u003e (Czech Republic), whose standard and mesh-plate 45s run roughly £300–£450 a matched pair through UK\/European dealers and can be somewhat more through US retailers — noticeably more than an equivalent 2A3 pair, and worth budgeting for separately when you're costing out this kit. Fittingly, it's an Emission Labs 45 pictured in Elekit's own TU-4523 literature. Genuine vintage-original 45s (RCA, Sylvania, National Union and others) can still be found through valve specialists and vintage-radio dealers, but pricing is condition- and rarity-dependent and supply is finite, so we'd generally point first-time 45 owners toward current production.\u003c\/p\u003e\n\u003cp\u003eNone of this affects the 2A3 side of the amplifier — those tubes remain as affordable and plentiful as they are in the TU-8900. It's only the 45 half of this kit's dual personality that comes at a premium, and we think it's a premium worth knowing about before you buy rather than after.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eAsk us about tube pairing options — we're happy to help you source a matched set for either tube type.\u003c\/em\u003e\u003c\/p\u003e\n\u003c\/article\u003e","brand":"Secret Chord Analogue","offers":[{"title":"Default Title","offer_id":53903873638683,"sku":"SCA-4523-NT","price":2473.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0785\/0134\/7611\/files\/2A3_OK.png?v=1788830413","url":"https:\/\/secretchordanalogue.au\/products\/elekit-tu-4523-45-2a3-kit","provider":"Secret Chord Analogue","version":"1.0","type":"link"}