![]() ![]() ![]() The output impedance from the single transformer tap was commendably low for a single-ended-triode design, at 2.5 ohms, which resulted in frequency-response variations of +1.6dB/≡.2dB into our standard simulated loudspeaker (fig.1, gray trace). The input impedance was slightly but inconsequentially lower than the specified 100k ohms, at 60k ohms at low and midrange frequencies and 44k ohms at the top of the audioband. The output preserved absolute polarity ( ie, was non-inverting). The voltage gain into 8 ohms was low for an integrated amplifier and slightly different for the two channels, at 32.5dB left and 32.9dB right. I ran the amp for a couple of hours before attempting any tests. I made sure I installed the tubes in the correct sockets, though I didn't realize at first that the big 211s have a bayonet fitting: to engage the electrical contacts, you push down and twist. To perform the measurements on the Audio Note Jinro, I mostly used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 " As We See It" and for some tests, I also used my vintage Audio Precision System One Dual Domain. ![]()
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