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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Octal Akido HP amp as pre amp

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Be aware that the ebay board is not from Broskie the real Aikido guy. My experience is the Aikidos configured as an HPA don't necessarily play well with low Z 'phones. It very much depends on the phones. Some OTL HPAs use negative feed back to drive lower impedances, Broskies do not. Neg feedback might dilute the Aikido "goodness" An Hpa configured one might be OK as a line stage but won't be optimal.

Cheers, steve
 
Of course John B. uses gNFB for even 300 ohms load, see Aikido Headphone Amplifier. For 32 ohms that isn't possible with just gNFB and Aikido cathode follower, so have to use White cathode follower with gNFB. This is technically speaking, sonic wise don't know. I image you can sim and look at the harmonics distortion content for clues or is there already one you can look?

I got the sch for 8 ohms load with a pair of 6c19p but in SEPP mode, the harmonic is comparable to the full blown 25W amp. The above has no way to drive 8 or 16 ohms load anyway.
 
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Thank you so much Mr. Wirezz.

I think I will try CARY AE-1 modified by Mr. Koonw first. If the result is not good. I will consider Stereo Octal Akido.

From the simulation, sound is quite ok to me. I have bought all parts and ready to build.
 
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