Mission accomplished after over a year.

[Hari Iyer]

Sachin, You can check if the tube is microphonic by gently tapping the tubes with a pencil with the preamp on. If they are microphonic it will send the tapping sound to your speakers with a howl.

 

[Rajiv]

Sachin, You can check if the tube is microphonic by gently tapping the tubes with a pencil with the preamp on. If they are microphonic it will send the tapping sound to your speakers with a howl.

Hi,

The 4P1L is microphonic, but if mounted properly and Viren has done that in the amp (I own one) microphony is not a problem.
The Lyrita DHT pre is very good if you want to experiment with the sound try different rectifier.

Tapping a tube with a pencil can lead to catastrophic results. You can crack the glass or if the tube goes microphonic the resulting howl can fry your tweeters.

Regards
Rajiv

 

[Hari Iyer]

Hi,

The 4P1L is microphonic, but if mounted properly and Viren has done that in the amp (I own one) microphony is not a problem.
The Lyrita DHT pre is very good if you want to experiment with the sound try different rectifier.

Tapping a tube with a pencil can lead to catastrophic results. You can crack the glass or if the tube goes microphonic the resulting howl can fry your tweeters.

Regards
Rajiv

Nope, gentle tapping on the tube with pencil is safe and a recommended method to check microphonic. I have done this couple of times to all my 12AU7 and 300B tubes safely with out any problems.