Pumpkin preamp - ordered by Steen , official making thread - Page 113 - diyAudio
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Old 19th January 2008, 05:19 PM   #1121
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Quote:
Originally posted by Zen Mod



use that EI and place it in separate box ; 600VA donut is really overkill ....... even for Pumpkin

both transformers you show are probably too large ( physically and inducing hum wise) to be in same box with active electronic
Keeping the trafo in another box is not very high in the WAF - how effective is it to do a aluminum partition or an aluminum cyclinder to surround the trafo (using a tin can? ) - in terms of reducing noise? Or is it the fact that the trafo is bolted to the chassis that causes problems?

I don't mind having a larger single chassis and keeping the trafo as far away from the channel pcb as I can. But I guess if its no go - then I'll use one of those desktop computer power supply boxes to house the power circuit.

her shann
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Old 19th January 2008, 05:28 PM   #1122
Manu is offline Manu  Europe
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My (humble) experience is that Al is not really (or really not) good in shielding trafos radiations.
Distance is far better, or some iron-sheet.

I had good experience with little piece of wood for méchanical decoupling from chassis.

Manu
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Old 19th January 2008, 05:35 PM   #1123
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Quote:
Originally posted by Manu
My (humble) experience is that Al is not really (or really not) good in shielding trafos radiations.
Distance is far better, or some iron-sheet.

I had good experience with little piece of wood for méchanical decoupling from chassis.

Manu
How about copper sheets?

her shann
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Old 19th January 2008, 05:39 PM   #1124
Magura is offline Magura  Denmark
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Quote:
Originally posted by Manu
My (humble) experience is that Al is not really (or really not) good in shielding trafos radiations.
Distance is far better, or some iron-sheet.

I had good experience with little piece of wood for méchanical decoupling from chassis.

Manu

Whatever material you choose for the shielding, keep in mind that it's a matter of thickness. Steel can offer the same shielding as aluminum, but require less wall thickness.

Anyhow, you need more than a tin can to make any significant shielding. I did some testing on the subject, for a 1000VA torodial trafo you need approx. 12mm steel to get the magnetic field under control adequately for placing it next to a sensitive circuit.


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Old 19th January 2008, 05:47 PM   #1125
Manu is offline Manu  Europe
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Copper don't hurt but is not so efficient against magnetic radiations. Actually only u-Metal is.
If magnetic strays is the problem. Distance cures it completely. Depending on how strong the radiations are (how big the trafo, but not only) a of course. So " ... both transformers you show are probably too large ( physically and inducing hum wise) to be in same box ..." (Zen Mod)


Manu
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Old 19th January 2008, 05:54 PM   #1126
Magura is offline Magura  Denmark
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Quote:
Originally posted by Manu
Copper don't hurt

Manu

That sure depends if you ask your wallet......as it will be hiding under the sofa, shaking in fear, if you even mention heavy gauge copper these days


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Old 19th January 2008, 05:57 PM   #1127
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Magura : you're right.

So : copper is expensive
and : uMetal or any steel-iron alloy difficult to source and expensive.

But :
Distance is for free

manu
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Old 19th January 2008, 06:02 PM   #1128
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Quote:
Originally posted by Manu
Magura : you're right.

But :
Distance is for free

manu

Free.....and a lot lighter! The boxes I ended up making for shielding the before mentioned 1000VA trafos, are even heavier than the trafos themselves, tipping the scales around 12kg a piece for the shields.

Unfortunately distance is an opposite liniar function of WAF


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Old 19th January 2008, 06:21 PM   #1129
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Quote:
Originally posted by Magura

WAF
I thought Mrs Magura beside that she is beautifull she is also very compréhensive.

May be she could give hershann some hints how to wheedle is wife.

Manu
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Old 19th January 2008, 06:25 PM   #1130
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