Basically vibration inside a hollow vacumn. The tail wags the dog!

Posted by mobiasloop (A) on October 27, 2014 at 07:58:41

In Reply to: What is the "sound" of microphonic tubes? posted by Nickel Core on October 26, 2014 at 13:20:04:

The rigidity of the internal construction of the tube, the posts and the mica washers/wafers. For instance compare a 12ax7a/7025 with a 12bz7. The 12bz7 was designed as a TV oscillator and sync seperator but it has the same gain as a 12ax7a, twice the transconductance and half the plate resistance BUT notice the stack of mica wafers (many more in the 12ax7) and the size of the posts supporting the structures of the tube. The 12ax7 is better damped. Also though we can't see them the heater maybe wound differently inside the cathode. All of this is a tail wagging the dog and it's a matter of DAMPING those tail wags. Acoustic feedback from the speakers, semi tractor trailers and trains near your home, heavy stampers (I have a daughter this is Miss congeniality but can't walk without shaking the house) all contribute. Moe
"...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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Follow Ups Full Thread

Topic - What is the "sound" of microphonic tubes? - Nickel Core 13:20:04 10/26/14 (18)

In addition.... - wheezer 11:07:51 11/03/14 (0)

RE: What is the "sound" of microphonic tubes? - Jim McShane 10:48:44 10/27/14 (0)

Basically vibration inside a hollow vacumn. The tail wags the dog! - mobiasloop 07:58:41 10/27/14 (0)

Depends what makes them microphonic - andy evans 01:56:26 10/27/14 (2)

The problem of course is... - Nickel Core 04:30:52 10/27/14 (1)

RE: The problem of course is... - Thomas Mayer 02:30:29 10/28/14 (0)

RE: What is the "sound" of microphonic tubes? - Ray Moth 16:36:02 10/26/14 (4)

RE: What is the "sound" of microphonic tubes? - deathtube 667 18:09:00 10/26/14 (2)

RE: What is the "sound" of microphonic tubes? - Tre' 18:55:36 10/26/14 (1)

RE: What is the "sound" of microphonic tubes? - deathtube 667 20:25:01 10/26/14 (0)

Awesome (nt) - Chip647 17:29:36 10/26/14 (0)

RE: What is the "sound" of microphonic tubes? - Tre' 16:26:02 10/26/14 (0)

RE: What is the "sound" of microphonic tubes? - Awe-d-o-file 16:07:06 10/26/14 (0)

if it's bad enough, they can actually cause feedback NT - Alpha Al 15:34:21 10/26/14 (0)

RE: What is the "sound" of microphonic tubes? - DAK 14:00:19 10/26/14 (0)

When I have gotten rid of my very microphonic tubes I hear an ease to the music - richardl 13:53:10 10/26/14 (2)

RE: When I have gotten rid of my very microphonic tubes I hear an ease to the music - Sherwood Forest 14:22:56 10/29/14 (1)

When they ring on and on, it is pretty bad - richardl 15:08:20 10/29/14 (0)

Follow Ups

Basically vibration inside a hollow vacumn. The tail wags the dog! - mobiasloop 07:58:41 10/27/14 (0)

Basically vibration inside a hollow vacumn. The tail wags the dog!

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