Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on April 15, 2015, 03:29:28 am

Title: Tube Shields
Post by: TIMBO on April 15, 2015, 03:29:28 am

Hi guys, bought some 9 pin sockets that take a tube shield.
Can anyone give me a quick answer to their best use. Thanks

Title: Re: Tube Shields
Post by: sluckey on April 15, 2015, 06:41:25 am

I like tube shields on all little tubes that are in the signal path (except power tubes such as EL84, 6GW8, etc.). Especially on preamp tubes. No real benefit using them on a tremolo oscillator although I do.

Title: Re: Tube Shields
Post by: Fresh_Start on April 15, 2015, 06:55:58 am

Any amp where the preamp tubes are upside down. Maybe even sideways.

My Blues Jr. has a retainer for the EL-84 power tubes, although you can't use those shields on power tubes as Sluckey says.

Chip

Title: Re: Tube Shields
Post by: eleventeen on April 15, 2015, 11:09:58 am

I believe tube shields are more for retention than shielding, certainly when the tubes are hung upside down. You probably ought not use them on EL84's!

Title: Re: Tube Shields
Post by: TIMBO on April 15, 2015, 02:05:17 pm

Thanks guys, Its just that I noticed on datasheets it had mentioned the shields. http://pdf1.alldatasheet.com/datasheet-pdf/view/121279/GEC/12AX7.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/121279/GEC/12AX7.html)

Title: Re: Tube Shields
Post by: kagliostro on April 15, 2015, 02:56:00 pm

There were some shield, used in military equipment (if I remember well sometime Sluckey uses this kind of shield)

whose purpose was heat dissipation

something like this

(http://thumbs2.ebaystatic.com/d/l225/m/m76sTrKRmY3BhhbBMp5hCtw.jpg)

the inside has a particular configuration that increases heat dissipation, you can see it here

(http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/gfEAAOSwqu9U4~Qh/$_35.JPG)


K

Title: Re: Tube Shields
Post by: HotBluePlates on April 16, 2015, 05:42:36 pm

Quote from: TIMBO on April 15, 2015, 02:05:17 pm

Thanks guys, Its just that I noticed on datasheets it had mentioned the shields. http://pdf1.alldatasheet.com/datasheet-pdf/view/121279/GEC/12AX7.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/121279/GEC/12AX7.html)

That's only in reference to the amount of input capacitance (more with the shield).

I've never heard a difference with/without the shield, but only tried using them on lower-gain Fender-style amps.

Title: Re: Tube Shields
Post by: jojokeo on April 17, 2015, 12:35:49 am

Quote from: HotBluePlates on April 16, 2015, 05:42:36 pm

That's only in reference to the amount of input capacitance (more with the shield).

I've never heard a difference with/without the shield, but only tried using them on lower-gain Fender-style amps.

This must be where Gerald Weber gets his ideas about not using tube shields in his books because he thinks they rob tone due to the increased capacitances.

Title: Re: Tube Shields
Post by: Willabe on April 17, 2015, 01:31:27 am

It was from Ken Fisher in the 'The Train wreck pages' in Groove Tubes books and/or from Vintage Guitar Magazine.


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