6BK7B cathode follower questions

Posted by mobiasloop (A) on April 1, 2015 at 14:41:25

I have a preamp that originally used a 12ax7 as a cathode follower. The tube is cascaded: ie both sides are tied in parallel. After reading up on cathode followers in a Naval Preferred circuits Manual, I have decided to use a 6BK7B or a 5687 instead of the 12ax7. Have any members used these tube as a cascaded cathode follower? I'm also interested in applying a negative voltage to the cathode. I would like to hear from any members who have had any experience with speeding up the negative traveling waveform. All I need is .775 RMS AC volts out into an output transformer that is (1200 to 600 ohm impedance). Is a white cathode follower faster in it's square wave fall time than a standard (non totem poled) cascaded cathode follower? Tektronix used a 6DJ8 cascaded cathode follower in a scope preamp with a negative voltage (-125V) applied to the cathode through a 5watt 22K resistor. There was CONSIDERABLE CURRENT DRAW. It would seem to me that transconductance affects rise-fall time or am I wrong? Thanks, Jim
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare

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Topic - 6BK7B cathode follower questions - mobiasloop 14:41:25 04/01/15 (19)

RE: 6BK7B cathode follower questions - Caucasian Blackplate 16:42:04 04/01/15 (18)

RE: 6BK7B cathode follower questions - mobiasloop 04:58:31 04/02/15 (17)

RE: 6BK7B cathode follower questions - Caucasian Blackplate 11:23:29 04/02/15 (4)

RE: 6BK7B cathode follower questions - mobiasloop 11:29:00 04/02/15 (3)

RE: 6BK7B cathode follower questions - Caucasian Blackplate 11:33:11 04/02/15 (2)

RE: 6BK7B cathode follower questions - mobiasloop 11:00:00 04/07/15 (1)

RE: 6BK7B cathode follower questions - Caucasian Blackplate 11:10:05 04/07/15 (0)

Output Z / Cable Capacitance - Triode_Kingdom 05:53:39 04/02/15 (11)

RE: Output Z / Cable Capacitance - mobiasloop 06:49:25 04/02/15 (10)

RE: Output Z / Cable Capacitance - mobiasloop 07:03:42 04/02/15 (9)

RE: Output Z / Cable Capacitance - Triode_Kingdom 18:22:04 04/02/15 (3)

RE: Output Z / Cable Capacitance - mobiasloop 06:12:50 04/03/15 (2)

RE: Output Z / Cable Capacitance - Triode_Kingdom 09:30:21 04/03/15 (1)

RE: Output Z / Cable Capacitance - mobiasloop 13:05:01 04/03/15 (0)

RE: Output Z / Cable Capacitance - Caucasian Blackplate 11:35:18 04/02/15 (1)

RE: Output Z / Cable Capacitance - mobiasloop 11:50:46 04/02/15 (0)

RE: Output Z / Cable Capacitance - mobiasloop 10:25:34 04/02/15 (2)

RE: Output Z / Cable Capacitance - Caucasian Blackplate 15:04:45 04/03/15 (1)

RE: Output Z / Cable Capacitance - mobiasloop 15:58:12 04/03/15 (0)

6BK7B cathode follower questions

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