Bottlehead Crackatwoa OTL tube headphone amplifier build

[Veri]

Pretty sure many people here believe tube amp is outdated and obsolete technology of no value in audio.

That's a great description, almost like you get it

 

[SIY]

@lordGwyn really appreciate your work and great amps. TBH I am confused why you would post this stuff here though where most people will never appreciate it because they base their entire lives off SINAD. Pretty sure many people here believe tube amp is outdated and obsolete technology of no value in audio.

Don't forget the part about us eating babies because they're too noisy.

 

[L0rdGwyn]

@smodtactical thanks, I post on a number of forums, each has its own value for me, I like to share what I love doing. While my own listening preferences don't necessarily follow the SINAD metric, I enjoy the knowledge, experience, and discussion ASR brings. Tubes are fun and if done right sound great, so I think they have their place in the audio world.

 

[charleski]

Pretty sure many people here believe tube amp is outdated and obsolete technology of no value in audio.

They glow and they look cool! Nothing wrong with looking cool.
It is possible to get fairly respectable performance from tubes, but requires meticulous attention to detail in both the design and build. Here's a long article on the sort of design and build elements required:

Ultra-low distortion valve hybrid amplifier - Valve Radio

This site is devoted to vintage electronics -- radios and audio amplifiers. It is not about restoring and collecting vintage items, but rather about modifying them in attempt to improve performance and bring it closer to modern standards.

www.valveradio.net

The author claims to achieve a THD+N of around -86dB just below clipping, which is quite satisfactory. But it should be noted that he's using pentodes running single-ended and unlikely to be putting out more than about 5W. That would be fine for a headphone amp though.

 

[Tom C]

@lordGwyn really appreciate your work and great amps. TBH I am confused why you would post this stuff here though where most people will never appreciate it because they base their entire lives off SINAD. Pretty sure many people here believe tube amp is outdated and obsolete technology of no value in audio.

Hey! I resemble that remark.

 

[smodtactical]

@smodtactical thanks, I post on a number of forums, each has its own value for me, I like to share what I love doing. While my own listening preferences don't necessarily follow the SINAD metric, I enjoy the knowledge, experience, and discussion ASR brings. Tubes are fun and if done right sound great, so I think they have their place in the audio world.

ASR don't deserve a genius and gentlemen like you.

 

[L0rdGwyn]

ASR don't deserve a genius and gentlemen like you.

I'm no genius, but thanks for the compliment! Lots of smart ones here on ASR, opinions vary, just how it is in audio.

 

[pkane]

ASR don't deserve a genius and gentlemen like you.

We, knuckle draggers, don’t understand or appreciate technology.

SINAD — yum yum! No SINAD — bad!

 

[netsullivc]

Can't wait! Everyone is going to see how poorly it measures and everyone will scramble to justify their

 

[netsullivc]

I really wish the crackatwoa was measured as recently received a newly released K15. A/B across the Bottlehead vs Fiio headphone amps both obviously driven by the same K15 dac module. While the K15 clearly has superior power output the resolution and detail out of the OTL is leagues ahead of the ASR style excellent measuring K15… go figure? One note, being OTL, tubes and headphones make a big big difference - change of tubes and the Crackatwoa falls behind the K15 amp section - hence the fixation of tube rolling with the designs. I wish to suggest that possibly while ASR currently measures some very important aspects of audio equipment possibly the measurements are not yet fully capturing all the key aspects that lend itself to a satisfactory audio experience. As an analogy until Nasa had an x-ray telescope in space they weren’t able to fully measure and define celestial bodies that they theory and ground based observations and suggested existed, if you follow me.

 

[ObjectiveSubjectivist]

I wished bottlehead was more available in Europe, pity

 

[Phatfish]

Stunning build! I'm about to start one myself (5th bottlehead build, so I'm a certified fan boy). Anything you would do different in terms of cap upgrades or anything else you've upgraded since? Thx!

 

[L0rdGwyn]

Well I moved on from this amp a long time ago, but no I was happy with how it turned out. I wouldn't recommend polishing the top plate, as maintaining that finish on aluminum is a real drag. Better would to have it properly chromed.

 

[Phatfish]

Well I moved on from this amp a long time ago, but no I was happy with how it turned out. I wouldn't recommend polishing the top plate, as maintaining that finish on aluminum is a real drag. Better would to have it properly chromed.

Thanks for responding. I've been doing a satin type finish on my kits with a orbital sander and a clear coat. Been quite happy with it. What is your go-to amp these days?

 

[L0rdGwyn]

Thanks for responding. I've been doing a satin type finish on my kits with a orbital sander and a clear coat. Been quite happy with it. What is your go-to amp these days?

I design and build all of my own amplifiers custom nowadays. I also have a DIY project out called Aegis. That same design was released as a commercial product under ZMF Headphones in collaboration with Cayin. Likely we will have another release next year. So I use any of those nowadays.

 

[Phatfish]

I design and build all of my own amplifiers custom nowadays. I also have a DIY project out called Aegis. That same design was released as a commercial product under ZMF Headphones in collaboration with Cayin. Likely we will have another release next year. So I use any of those nowadays.

Impressive looking amp! I love all the tube options, output jacks and impedance options.
Would you mind sharing your preferred closed high impedance ZMF headphone you've used with this kit? Or did you always use an open one?

 

[L0rdGwyn]

Since I collaborate with the ZMF, I have many of their headphones, open and closed. With a transformer coupled amp, like Aegis, Caldera Closed is very nice. With an OTL, I like Atrium Closed.