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Post subject: small signal tube shields
Posted: Thu May 29, 2014 2:04 pm
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Here's probably a stupid question, but I still wanna know.
I've never noticed any stray signals thru my amps with the tube shields removed........ so I leave them off under the theory that better ventilation/cooler running tubes last longer sounding better.
Or do the aluminum shields actually help dissipate heat?


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Post subject: Re: small signal tube shields
Posted: Thu May 29, 2014 4:50 pm
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I'd leave them on. Not only for EMF shielding effect, but the spring loaded bayonet shields help keep the tubes aligned in the socket. Esp during transit. They also protect against slight damage to the pins. 12AX7 and 12AT7 really do not run that hot, if your amp has adequate ventilation for the rectifier and output tubes --- this will be adequate for the shield-covered signal tubes.


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Post subject: Re: small signal tube shields
Posted: Fri May 30, 2014 2:06 am
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Why not rip out the metal-mesh screen stapled to the underside of the cabinet's top? You're sure to save at least 25 or 30 grams in weight which will make the amp much more comfortable to lift and move.

:lol:

Leo put those tube shields there for very sound reasons and it cost him money to do that. If they weren't absolutely necessary to the amp's performance he'd have put those bucks in his pocket instead.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: small signal tube shields
Posted: Fri May 30, 2014 4:50 am
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Thanks guys.
One more quircky question pertaining to preamp tubes (ax7's @ at7's).
When ordering high output tubes at the premium price (measuring at or above specs), does the tube wear out quicker........or lose its output just because it's operating harder?
Or is meeting spec mainly a function of how well the tube is constructed/aligned?,


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Post subject: Re: small signal tube shields
Posted: Fri May 30, 2014 6:16 am
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Provided the circuit around each tube is within specs, the stronger testing tube should last longer. Minus, excessive physical jarring.


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Post subject: Re: small signal tube shields
Posted: Fri May 30, 2014 6:17 am
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Only the 12AT7 ( phase inverter , close to output tubes ) work harder with Power Outputs tubes


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Post subject: Re: small signal tube shields
Posted: Fri May 30, 2014 9:27 am
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yomammaaho wrote:
Or is meeting spec mainly a function of how well the tube is constructed/aligned?,


Correct.

The better-built tube (type of materials and quality of assembly) performs more efficiently and lasts longer.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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