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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: Gotta replace my tube rectifier with a SS rectifier, what are the best choices? posted by drummerwill on January 29, 2007 at 06:19:15:
Willie,Have you tried slipping a piece of ferrous - or other magnetic metal - between the volume pot and the rectifier filament winding? 5VAC doesn't put out much of an electrostatic field but the current is high. While you might not be able to permanently install the shield it is one way to determine is your diagnosis is correct. Another way is to power the rectifier from a DC source. This is a common hum diagnostic tool for preamp tubes, etc., that don't see B+ on the heaters. In your case you could try this but your test has to be carefully set up to prevent shock or destroying parts from shorting. A 6V lantern battery with an 0.5 ohm resistor would temporarily provide sufficient current to power the rectifier heater and could be more easily isolated from the chassis than a separate 5VDC supply - now that I think of it your rectifier will probably pull down the battery enough that you can eliminate the resistor (this might trash the battery but these can be found at Big Lots for $3 - and not more than $5 elsewhere, not too much to pay for diagnosis. But for safety sake you probably don't want to use your Mullard GZ34, etc., - a less costly rectifier just gives you a little more "economic safety.")
If this eliminates your hum (and somehow I don't think it will but your amp isn't in front of me) then you could cobble up a 5VDC supply that's sufficiently insulated/isolated to "float" the B+ voltage (and as far as I know the plasic cased bridge rectifiers probably have sufficient breakdown voltage to isolate them from ground as do most filter caps - a simple CRC pi filter would suffice IMHO).
Hope this helpsRob
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Follow Ups
- Re: Gotta replace my tube rectifier with a SS rectifier, what are the best choices? - Rob Mercure 08:05:42 01/29/07 (1)
- Re: Gotta replace my tube rectifier with a SS rectifier, what are the best choices? - drummerwill 12:53:58 01/29/07 (0)
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