Re: Hmm!
- From: "Trevor Wilson" <trevor@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 27 Apr 2008 10:27:10 +1000
"Iain Churches" <IainNG@xxxxxxxxxxx> wrote in message
news:Q9EQj.342739$147.94179@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I wonder what the DC resistance of a 250mA fuse might
be?
**Depends on the fuse. I just measured half a dozen 0.25 Amp 3AG fuses. They
ranged from 12 Ohms up to 15 Ohms. COLD. Expect hot levels several times
that figure.
I have just been speaking with a guy would told me that he
has replaced the fuse from the CT of the OPT of his tube
amp with a wire link, "because the fuse adds to the power
supply impedance and does not have a linear response"
**Smart man.
He could not quote any reference to substantiate this.
**Fuses act as non-linear resistors. They get hot and change resistance.
This is not an unknown phenomenon.
I wonder what the audio bandwidth impedance of a
250mA fuse might be? -)
**Depends on the impedance of the circuit it is placed in.
Compared to the cost of an OPT, the fuse seems to be a
good component for such a small investment.
**Sure, as long as the impedance of the transformer is significantly higher.
Personally, I don't like fuses placed anywhere after bridge rectifiers.
Beyond that point, they can influence sound quality.
Trevor Wilson
.
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