Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on January 18, 2012, 03:58:41 pm

Title: Have you ever used or seen a shield in the board like this ?
Post by: kagliostro on January 18, 2012, 03:58:41 pm: Does someone has used, in Audio Frequency, a shield like that in the attached image ?

can this be of some practical use ?

the designer may be is Larry (Larry Amps) but I'm not sure

(http://spinoo.free.fr/projetG5/Images%20Amplis/Larry/British%20Purist/brit.pur103.jpg)

Kagliostro
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: tubenit on January 18, 2012, 04:10:35 pm: I've not seen a shield on a board like that. However, I have seen and made a shield to do something similar before on a point to point wiring inside several Bogen amps.

With respect, Tubenit
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: tdvt on January 18, 2012, 04:34:21 pm: I just had my Pro Jr apart & there is a metal shield between the pots & the filter caps, grounded as I recall.

Not a great photo (not mine), but you can see it above the black filter caps, running from left of the input jack to the left end of the board

(http://lucky-cricket.com/files/Pro_jr_Recapped.JPG)
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: thermion on January 18, 2012, 04:52:11 pm: I've seen this kind of shield around the power transformer in an old masco-fanon PA head.
what are the little silver boxes on the board?
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: Willabe on January 18, 2012, 05:36:38 pm: Quote from: thermion on January 18, 2012, 04:52:11 pm
what are the little silver boxes on the board?

There relays. But if one burns up you would have to pull the whole eyelet board to replace it because he chose not to use a socket for it. :w2: :BangHead: :cussing:

Brad :laugh:

Edit; I should have added his work does look great.
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: Tom_Hull on January 18, 2012, 06:21:53 pm: hi ..

i seen them on the isolated reciever section in old tube stereos that i had ..off the chassis boxed around

and sheilds on tube sockets connections .....in the reciever section ,, sorry no pictures .

on my daughters amp i have something built for the preamp tubes isolating it from the pt ..but i took it off made the quick cap holder ..for the alamo,,temperary

tom
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: LooseChange on January 19, 2012, 06:47:41 am: That's a sun shield.. The amp is so cool it needs sunglasses. :-)
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: kagliostro on January 19, 2012, 07:32:58 am: Quote
That's a sun shield.. The amp is so cool it needs sunglasses. :-)

:icon_biggrin:

Kagliostro
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: stingray_65 on January 19, 2012, 09:01:09 am: Shielding like that in my opinion is used to correct a problem that could have been avoided with proper lead dress.

it is a patch at best.

Just my opinion, not saying its poor construction or that anyone who has used it built something sub standard, we all do what we have to to get by and make it work.
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: kagliostro on January 19, 2012, 09:53:07 am: Quote
But if one burns up you would have to pull the whole eyelet board to replace it because he chose not to use a socket for it.

may be he has reconsidered the relays placement in other amps

(http://spinoo.free.fr/projetG5/Images%20Amplis/Larry/Dino%20939/dino018-01.jpg)

Quote
Shielding like that in my opinion is used to correct a problem that could have been avoided with proper lead dress

yes, may be, or bay be is a sophisticated refinement for a boutique amp that wink to HiFi builds

about shields around pots and transformers I've seen before may be not on the board

Kagliostro
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: Willabe on January 19, 2012, 10:00:34 am: Yeah, maybe K.

He does do very nice work.

Brad :icon_biggrin:
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: birt on January 19, 2012, 12:21:21 pm: i have used a shield like that around an input that was really close to the mains/PT. it was a conversion build and this was the only possible place for that input. it works.
Title: Re: Have you ever used or seen a shield in the board like this ?
Post by: PRR on January 20, 2012, 09:18:23 pm: That's tone-stack caps, right? My Champ's oscillations changed when I just waved a pencil in that area. I just pushed the wires around to get distance; but a shield would work.