{"title":"Headphone Amplifiers","description":"\u003cp\u003eBottlehead offers vacuum tube headphone amplifier kits for headphones with high and low impedance.\u003c\/p\u003e","products":[{"product_id":"crack-1-1-otl-headphone-amplifier-kit","title":"Bottlehead Crack 1.1 OTL Headphone Amplifier Kit","description":"\u003cp class=\"p1\"\u003eThe Crack is a legendary OTL (output transformerless) headphone amplifier kit, purpose-built for high-impedance headphones like the Sennheiser HD600 and HD650, as well as AKGs and Beyerdynamics. Its single-ended triode design delivers rich midrange, spacious soundstage, and a uniquely engaging tube character. Designed with first-time builders in mind, the Crack offers a fun, rewarding build experience—and sonic performance that rivals amps several times its price. Add the Speedball to elevate your Crack’s dynamics, clarity, and resolution.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe Crack uses a universal power transformer. International customers will need to supply their own power cord, but the kit can be wired for different voltages using instructions in our detailed manuals.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThis product has a universal power transformer and can be used worldwide by following the wiring instructions in the manual. Please note that \u003cstrong\u003einternational customers will need to provide their own power cord.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cem\u003eWe're now including the square version of our badge in each amplifier and preamplifier kit. If you prefer the word mark version, please note that in your order.\u003c\/em\u003e\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":52093288382833,"sku":"HPK-CRACK-1-1","price":375.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/Crack_Hero.jpg?v=1775342057"},{"product_id":"crackatwoa-headphone-amplifier","title":"Crackatwoa Headphone Amplifier Kit","description":"\u003cp\u003e\u003cspan style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003eCrackatwoa is a premium version of the direct coupled Crack circuit - it \u003c\/span\u003etakes everything you love about the original Crack and dials it up. With an upgraded power supply and the Speedball constant current source built in, it delivers greater dynamic impact, tighter bass, and improved resolution—while maintaining the OTL magic that made the original a classic. Perfect for high-impedance headphones (200 ohms or higher - think \u003cspan style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003eSennheiser HD600\/650\/800, Beyerdynamic 250 and 600 ohms headphones, etc.)\u003c\/span\u003e and experienced builders seeking even more from their tube amp.\u003cspan style=\"font-family: -apple-system, BlinkMacSystemFont, 'San Francisco', 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; font-size: 0.875rem;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cem\u003eWe're now including the square version of our badge in each amplifier and preamplifier kit. If you prefer the word mark version, please note that in your order.\u003c\/em\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":52093288415601,"sku":"HPK-CRACKATWOA","price":965.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/crackatwoa-headphone-amplifier-kit-5644141.jpg?v=1754731609"},{"product_id":"stat-electrostatic-headphone-energizer","title":"Stat Electrostatic Headphone Energizer","description":"\u003cp\u003eThe Bottlehead Stat is a zero global feedback, class A tube electrostatic headphone amplifier that features both 580V Stax Pro Bias and 230V Stax Normal (legacy) bias jacks. There is a single input, a balance control, and level control. It has a universal power transformer. Because of the high voltages present inside the chassis this product is only offered in assembled form.\u003c\/p\u003e\n\u003cp\u003eNo global feedback is used in this design, which provides a smooth, open sound. We have listened to Nectar Sound, Stax and Koss ES headphones and they all work as expected. To further enhance this design, each differential stage uses our Bottlehead C4S constant current source. These provide a very high impedance under the cathodes of each differential amplifier, providing very tight AC balance in each stage.\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":52102752403825,"sku":"HP-STAT","price":1699.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/stat-electrostatic-headphone-energizer-1050760.jpg?v=1752975574"},{"product_id":"mainline-1-1-headphone-amplifier-kit","title":"Bottlehead Mainline 1.1 Headphone Amplifier Kit","description":"\u003cp class=\"p1\"\u003eMainline is Bottlehead’s flagship headphone amplifier, designed for the discerning audiophile. This fully balanced, single-ended amp delivers low noise, stunning resolution, and wide dynamic range—making it an ideal match for top-tier headphones like the Sennheiser HD800, Focal Utopia, and ZMF line. With a versatile circuit and precision stepped attenuator, the Mainline is a statement piece both in design and sound.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe Mainline has a universal power transformer and can be used worldwide by following the wiring instructions in the manual. Please note that \u003cstrong\u003einternational customers will need to provide their own power cord.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cem\u003eWe're now including the square version of our badge in each amplifier and preamplifier kit. If you prefer the word mark version, please note that in your order.\u003c\/em\u003e\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":52109623918961,"sku":"HPK-MAINLINE-1-1","price":1435.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/mainline-11-headphone-amplifier-kit-5576652.jpg?v=1752975574"},{"product_id":"sex-4-kit-for-headphones-speakers","title":"Bottlehead SEX 4 Kit for Headphones \u0026 Speakers","description":"\u003cp\u003eSay hello to the new Single Ended eXperimentation (SEX) kit!\u003c\/p\u003e\n\u003cp\u003eThe SEX 4 has a ton of changes under the hood. For starters, it uses two 6FM7 tubes and a refined circuit to drive more than double the power of the SEX 3. We’ve heard from builders that they’re increasingly using preamps and digital sources, so we’ve removed the volume control. This plus the roomier chassis provides ample opportunity for experimentation.\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eSpeaking of experimentation, we’ve added a useful experiment to the stock kit. Sitting front and center is a new switch. Flipping it \u003c\/span\u003e\u003cspan\u003econtrols the\u003c\/span\u003e\u003cspan\u003e amount of local, plate-to-plate feedback \u003c\/span\u003e\u003cspan\u003eapplied\u003c\/span\u003e\u003cspan\u003e in the \u003c\/span\u003e\u003cspan\u003ecircuit\u003c\/span\u003e\u003cspan\u003e. What does that mean? The higher feedback allows the SEX to act as a low-gain power amplifier with \u003c\/span\u003e\u003cspan\u003etighter\u003c\/span\u003e\u003cspan\u003e mid- and low-end performance and a blacker background. Switching to lower feedback mode gets you performance closer to a traditional desktop tube headphone amp. You should see more warmth, emotion, and character.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eIn either feedback mode, the SEX 4 feels a lot more controlled than the SEX 3 in the bass department, and the lower gain option mates solidly to a Moreplay and avoids hair trigger volume control issues. We’ve built a bundle so you can buy both the SEX 4 and the Moreplay at a discount.\u003c\/p\u003e\n\u003cp\u003eSEX 4 has a universal power transformer and can be used worldwide by following the wiring instructions in the manual. Please note that \u003cstrong\u003einternational customers will need to provide their own power cord\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eWe're now including the square version of our badge in each amplifier and preamplifier kit. If you prefer the word mark version, please note that in your order.\u003c\/em\u003e\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":55747018359153,"sku":"COMBOK-SEX-4-0","price":885.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/more-sex-combo-5145595.png?v=1757954364"},{"product_id":"sex-4-moreplay-bundle","title":"More SEX Combo","description":"\u003cp\u003eWe built the SEX 4 to be the perfect companion to our popular Moreplay preamplifier. We're offering the two as a bundle at a discount. After all, everyone could use More SEX. In this kit you'll get:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca rel=\"noopener noreferrer\" title=\"Bottlehead SEX 4 Kit\" href=\"https:\/\/bottlehead.mom\/products\/single-ended-experimenters-kit-4-0-for-headphones-sensitive-speakers\" target=\"_blank\"\u003eThe all-new SEX 4 amplifier kit\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003ca rel=\"noopener noreferrer\" title=\"Bottlehead Moreplay Preamplifier Kit\" href=\"https:\/\/bottlehead.mom\/products\/moreplay-preamplifier-kit\" target=\"_blank\"\u003eOur best-selling Moreplay preamplifier kit\u003c\/a\u003e\u003cbr\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eGet 10% off the \u003ca rel=\"noopener noreferrer\" title=\"Moreplay Upgrade Kit\" href=\"https:\/\/bottlehead.mom\/products\/moreplay-upgrade-kit\" target=\"_blank\"\u003eMoreplay Upgrade\u003c\/a\u003e and \u003ca rel=\"noopener noreferrer\" title=\"Bottlehead Power Cord Kit\" href=\"https:\/\/bottlehead.mom\/products\/bottlehead-power-cord-kit\" target=\"_blank\"\u003ePower Cord kit\u003c\/a\u003e if you buy them with the combo! \u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eWe're now including the square version of our badge in each amplifier and preamplifier kit. If you prefer the word mark version, please note that in your order.\u003c\/em\u003e\u003c\/p\u003e","brand":"Bottlehead","offers":[{"title":"Default Title","offer_id":62394534494577,"sku":"BUNDLE-MORESEX","price":1219.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/files\/more-sex-combo-8153832.png?v=1759027208"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/6408\/6641\/collections\/headphone-amplifiers-7492030.jpg?v=1775564978","url":"https:\/\/bottlehead.mom\/collections\/headphone-amplifiers.oembed","provider":"Bottlehead","version":"1.0","type":"link"}