There was a really good article on the 10B several years ago in Vacuum Tube Valley. Or was it Sound practices? Higly recommended reading. Dig it up.
Aside from the exceptional tuning front-end and all-tube circuits, I think the big difference may have been the six IF stages. Yeah, six. Far more than anything else you can buy. And I believe the filters might have been phase-linear, resulting is the cleanest and most selective IF bandpass possible. Another plus was that I think they used a discriminator circuit instead of the usual FM demodulator.
So it probably isn't the front-end or the audio back-end that makes the sound so clean. I'd wager the sonics are due to the linearity and bandwidth of the IF strip and demodulator circuits.
jh
Aside from the exceptional tuning front-end and all-tube circuits, I think the big difference may have been the six IF stages. Yeah, six. Far more than anything else you can buy. And I believe the filters might have been phase-linear, resulting is the cleanest and most selective IF bandpass possible. Another plus was that I think they used a discriminator circuit instead of the usual FM demodulator.
So it probably isn't the front-end or the audio back-end that makes the sound so clean. I'd wager the sonics are due to the linearity and bandwidth of the IF strip and demodulator circuits.
jh