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Class A amplifier kits split into two camps: solid-state Nelson Pass designs sold through the diyAudio Store for under $250, and single-ended tube kits from Bottlehead, Elekit, and budget import brand Nobsound that run from $180 into the thousands. Below are 9 real kits currently sold, with pricing verified this session — boutique audio runs well above general consumer-electronics pricing, so don’t be surprised by the top end.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | diyAudio Store ACA Mini Complete Kit | $180-$200 | Amazon |
| 2 | diyAudio Store Aleph J Essentials Kit | $90-$100 | Amazon |
| 3 | diyAudio Store Zenductor III BAF Edition | $200-$225 | Amazon |
| 4 | Nobsound KT88 Single-Ended Class A Tube Amp DIY Kit | $180-$210 | Amazon · eBay |
| 5 | Nobsound EL34 Class A Single-Ended Tube Amplifier DIY Kit | $280-$320 | Amazon · eBay |
| 6 | Bottlehead S.E.X. 4 Amplifier Kit | $850-$900 | Amazon |
| 7 | Bottlehead Stereomour II Single-Ended 2A3 Amplifier Kit | $1,450-$1,500 | Amazon |
| 8 | Elekit TU-8200R 6L6GC Single-Ended Tube Amplifier Kit | $780-$850 | Amazon · eBay |
| 9 | Elekit TU-8900 300B/2A3 Single-Ended Tube Amplifier Kit | $1,495-$3,280 | Amazon · eBay |
The picks, in detail
diyAudio Store ACA Mini Complete Kit
The Amp Camp Amp, Nelson Pass’s beginner-oriented Class A MOSFET design, sold complete through the official diyAudio Store.
- Nelson Pass Class A MOSFET topology
- Complete kit including boards and components
- Designed as an entry point for first-time builders
- Officially sold through diyAudio Store
- Widely regarded as the easiest Class A kit to build successfully
- Strong community support and documentation from the diyAudio forum
- Low power output (a few watts), best for efficient speakers
- Needs a separate chassis and power supply to finish the build
diyAudio Store Aleph J Essentials Kit
A kit of Nelson Pass’s Aleph J Class A JFET/MOSFET design, a step up from the ACA for builders wanting more refined sound.
- Nelson Pass Aleph J JFET/MOSFET topology
- Essentials-tier kit covering core boards and parts
- Popular among diyAudio community builders
- Compatible with widely shared enclosure plans
- Well-documented design with years of community build threads
- Considered a meaningful sonic step up from the ACA
- Essentials kit still needs a chassis, power transformer, and heatsinks sourced separately
- More assembly complexity than the beginner-focused ACA
diyAudio Store Zenductor III BAF Edition
A modern take on Pass’s classic Zen amplifier circuit, sold as a complete board-level kit through the diyAudio Store.
- Based on Nelson Pass’s Zen Class A topology
- BAF Edition board-level kit
- Single-ended Class A output stage
- Sold direct through diyAudio Store
- Modern reworking of a well-loved classic Pass DIY circuit
- Mid-price point between the ACA and the premium tube kits below
- Still needs external chassis, power supply, and heatsinking
- Lower power output limits speaker pairing options
Nobsound KT88 Single-Ended Class A Tube Amp DIY Kit
A budget import single-ended tube kit built around a pair of KT88 output tubes, the most affordable tube option in this roundup.
- 6N8P driver and KT88 output tube complement
- 16W x 2 rated output
- Single-ended Class A topology
- Includes 5Z3P rectifier tube
- Cheapest tube-based Class A kit in this roundup
- KT88 output tubes give more headroom than smaller-tube budget kits
- No printed step-by-step manual, diagram-based build only
- Fit and finish trail the Elekit and Bottlehead kits
Nobsound EL34 Class A Single-Ended Tube Amplifier DIY Kit
Nobsound’s EL34-based single-ended kit, a step above the KT88 kit in typical street price for this budget import line.
- EL34 single-ended Class A output stage
- Stereo HiFi amp configuration
- DIY solder-together kit
- Compact chassis footprint
- EL34 is a well-regarded, widely available output tube for future upgrades
- Still well under $350 for a complete tube amp kit
- Requires soldering skill and no formal instruction manual
- Build quality and documentation trail Bottlehead or Elekit
Bottlehead S.E.X. 4 Amplifier Kit
The current fourth-generation version of Bottlehead’s long-running Single-Ended eXperimenter’s kit, a 2-watt SET amp for headphones and efficient speakers.
- Two-stage, zero-feedback single-ended triode design
- Parafeed output topology
- 2 watts per channel
- Suited to headphones or high-efficiency loudspeakers
- Long track record and strong Bottlehead community support
- Parafeed topology gives extended bass and highs versus simpler SET designs
- 2 watts per channel limits it to efficient speakers or headphones
- Requires more build time than the solid-state diyAudio kits
Bottlehead Stereomour II Single-Ended 2A3 Amplifier Kit
Bottlehead’s step-up integrated amp built around 2A3 output tubes, a full-featured single-ended Class A tube amplifier.
- Single-ended 2A3 output tube topology
- Stereo integrated amplifier
- Higher power output than the entry-level S.E.X. kit
- Full Bottlehead build documentation and support
- More output power than the S.E.X. kit for a wider range of speakers
- 2A3 tubes are a respected classic for single-ended designs
- Among the priciest kits in this roundup
- Long, involved build compared with the solid-state kits above
Elekit TU-8200R 6L6GC Single-Ended Tube Amplifier Kit
A Japanese-engineered single-ended kit that runs 6L6GC, EL34, 6CA7, or KT88 output tubes, giving builders room to experiment with tube types.
- Accepts 6L6GC, EL34, 6CA7, KT88, or 6550 output tubes
- Triode, pentode, or ultra-linear switchable operation
- Ships with JJ 6L6GC and JJ ECC82 tubes included
- Elekit factory-quality kit documentation
- Multi-tube compatibility lets you experiment with sound without buying a new amp
- Elekit’s build manuals are noted as clearer than most import kits
- Priced well above the Nobsound budget tube kits
- Import shipping from Japan/UK distributors adds to lead time
Elekit TU-8900 300B/2A3 Single-Ended Tube Amplifier Kit
Elekit’s flagship single-ended kit built for 300B or 2A3 output tubes, the premium ceiling of this roundup.
- Accepts 300B or 2A3 output tubes (tubes sold separately)
- Premium transformer options up to Lundahl C-core
- Single-ended Class A topology
- Elekit factory-quality kit documentation
- Regarded as one of the best-engineered single-ended kits available
- 300B compatibility opens the door to a legendary output tube
- Most expensive kit in this roundup before adding tubes, which cost extra
- Premium transformer options push the price well past $2,000
Buying tips
- Solid-state Pass-design kits from the diyAudio Store (ACA, Aleph J, Zenductor) are cheaper and simpler to get running, but you’ll source a chassis, power transformer, and heatsinks separately — budget for that before comparing sticker prices.
- Tube kits need a chassis too in most cases, plus tubes themselves aren’t always included (the Elekit TU-8900’s headline price excludes 300B/2A3 tubes, which can add $365-$1,500).
- Match output tube type to your speakers before choosing — 2A3 and 300B kits (Bottlehead Stereomour, Elekit TU-8900) put out only a few watts, fine for high-efficiency horn or full-range speakers but underpowered for typical bookshelf speakers.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.