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Bottlehead Crack OTL Reviews

Nate L

What a pile did amp


Pros: Sounds gorgeous

Cons: Volume control not flexible in stock form but that's easily rectified

Fantastic amp. Easy and fun to build. Many opportunities to modify the amp. Vibrant on line community dedicated to the amp. Due to it being an otl amp, it's optimized for high impedance headphones. Don't bother with Grados, for instance. I don't view this as a con, but merely as a design characteristic. Truly synergistic with my HD600's. I've used film and teflon bypass caps to bypass all critical caps, and padded down the volume control as in stock form, it's way too loud by the 10 o'clock setting, also using beautiful NOS tubes. So no,,this isn't a stock Crack, but if you've got the DIY leaning, this is a great project.
Bill Way

Bottlehead Crack/Speedball OTL amp with Senn HD800s


Pros: gorgeous mids, nice extension top and bottom

Cons: doesn't quite have that "liquid" clarity of the best 'stats

This is a review of the Crack amp driving Sennheiser HD800s. I haven't had the chance desire to audition it with any other cans. The price is for the amp ($213) and the Speedball upgrade ($110).   I've had the combo for about two years, and have several hundred hours on it. The Crack is an OTL headphone amp kit, designed for high-impedance phones. Assembly is easy, the directions are excellent, and support on the Bottlehead forum from Dan Schmalle and his very active, knowledgeable customer base is superb. After living with it for a while, I added the Speedball power supply upgrade; it may have made a slight improvement - hard to say without being able to A-B it. I also...
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Awesome Tube Amplifier


Pros: Perfect for my HD600, boosts volume/bass/soundstage, very quiet background and no distortion at high volumes, fun to build as DIY

Cons: Not many features, only for high impedance cans, aesthetics could be better

This was an amazing and fun purchase for me. It was fun to build and it makes my HD600s sound great. Very simple design that does everything I need it to for my headphones. I don't believe I'll ever purchase another amplifier unless I fall in love with a low impedance headphone that needs amplification.

Amazing Value!


Pros: Incredible value, great soundstage presentation, ability to adjust sound via tube rolling, get to build it and customise it for yourself

Cons: Can't use it straight from the box :-), may take some tinkering to get the sound free from induced noise, performs best with high impedance cans

The Crack kit is easy to build and sounds incredible. Don't be scared of the DIY approach even if you're a beginner - it's fun and SO worth it!   Mine had some induced noise at first so I replaced the braided input cable with some shielded coaxial cable and it fixed it perfectly. I see that and potentially damaged/faulty tubes as being about the only real possible issue with this amp.   Once built (takes a day or 2 depending on how long you spend in one sitting) the final result is an amp with incredible staging and layering for the price combined with beautifully smooth and cohesive sound presentation. There's plenty of detail, but it's all cohesive and realistic - it...
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