To shield or not to shield.

[buzzfreeNOT]

Ok the last few parts are ordered! One last thing though, are the tube shields necessary for an amp that will probably never be moved around?
Is the shield only to physically protect the tube or does it also shield noise?
I went to angela and could not get the ceramic/gold 9 pin sockets with a shield. I figure "so what" the amp will be stationary but then i figure that maybe vibration will work them out. Any thoughts?
18w combo TMB.

[Icetech]

I have never used a shield in like 15 years of tube amps.... never had a problem, and i rarely move my amps also...

[Mr_dB]

In my opinion, the main purpose of preamp tube shields is to keep the tubes in their sockets when you're moving the amp around.

[ab3640au]

An amp builder friend of mine built a custom 2x12 combo cabinet, but found that the magnet bell from one of the speakers (one was a Celestion Blue; the other a G12M) was almost touching the preamp tubes. He found that the amp hummed a lot with the shields off, but was quiet with the shields on. Therefore, in extreme situations like that one, the shields might serve a worthwhile purpose, other than holding the tubes in place.

Barry M

[rjgtr]

Shields can be useful when your preamp tubes are close to a transformer or speaker (as already noted). Also in a high gain amp, the first one or two tubes can be a little sensitive. Fortunately, the 18 doesn't have a high gain preamp, even in the TMB format.

[buzzfreeNOT]

Thanks for the advice. This amp will be parked in one place and probably never move, so i'll go with the unshielded

[Plexi]

It can make a difference,just depends on the amp,and positions of transformers,or how the amp is laid out etc.. Some amps, like some Carvin models don't use shields.

As for the 18.. I would use the shields,. On other amps you can also see they use a metal flat shield.. Between the tubes and transformer.

Richie

[zaphod_phil]

I personally haven't found a need for tube shields on lower gain amps like 18watts. They also somewhat hinder cooling of the tubes. I wouldn't be surprised though if they might help reduced noise and oscillation with some TMB builds.

[GaryM]

If you do use a shield, it's most important on the first (V1) position since any humming or extraneous noises are amplified the most if introduced here.

Flourescent lighting, faders, overhead fans, and other transformer-based interference can all be problematic and shields can help reduce the noise.

Heat retention really isn't a problem with preamp tubes, IMHO.

[novosibir]

I've noticed, that when I'm using my wireless telefon near the amp, then the disturbances out of the speakers are louder with shielded preamp tubes. So I'd suspect, that they also can act as an antenna. However it was a shock mounted tube socket and therefore not grounded.

Larry G

[rjgtr]

You know I always buy the preamp tube sockets with the sheilds anyway. Even if I don't use them because it doesn't really cost any more.