Tubes Asylum

Questions about tubes and gear that glows. FAQ

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

RE: Out of curiosity

Posted by unclestu on January 28, 2011 at 12:57:31:
They seem to be a late mC1 with the D getters, all the later long plates are halo style getters although I have seen one f91 with a D getter. The mC1 or f91/92 appellation should be located right above the date codes. If it is infact the mC1 they are quite valuable as are all Mullard long plates, but I find them excessively warm as I stated elsewhere. The f91 series is a totally different animal, significantly more open and airy sounding.

The f91's can be distinguished by the unusual construction on the top mica opposite each plate structure. There is a metal staple with a little coated wire extending from the outboard staple to the cathode.

Stu