RFI
Yes, since my filtering - inspired by the W4S sensitivity, I'm also in hi-fi heaven. There's a lower level of grain and transients are totally unblurred - for want of a better expression.
Is the iron wire coated or bare?
I'm currently playing with iron wire for making chokes - its considerably cheaper than copper and is nicely resistive. With its lower skin depth it gets even more lossy as the frequency goes up. I'm getting highly worthwhile improvements in soundstage depth and decay tails seem to go on forever...
Yes, since my filtering - inspired by the W4S sensitivity, I'm also in hi-fi heaven. There's a lower level of grain and transients are totally unblurred - for want of a better expression.
Is the iron wire coated or bare?
Its coated with what seems to be green PVC although for some reason my camera doesn't do the colour justice its turned rather turquoise. While I'm using it for mains, I'm a little uncertain of its insulation rating so I've also wrapped some tape around the coils for good measure.
its turned rather turquoise. While I'm using it for mains, I'm a little uncertain of its insulation rating so I've also wrapped some tape around the coils for good measure.Attachments
Hi Aucosticraft,
thanks for your wishes and for the
suggestions.
I needed some more rest. But the choke manufacturer
woke me up to say that he is not able to get 2mH
on a reasonable size ferrite ring and about 2Amp ratings.
So he gave up and canceled the order.
Hi Abraxalito, I just checked your blog and finally
reached Murata chokes. Kindly suggest some which will
be good for the filter circuit and for the power supply of
the phono preamp. The Murata chokes are cheap.
I just have to import them. I have the other parts ready, only
the chokes are missing.
Regards
Roushon.
thanks for your wishes and for the
suggestions.
I needed some more rest. But the choke manufacturer
woke me up to say that he is not able to get 2mH
on a reasonable size ferrite ring and about 2Amp ratings.
So he gave up and canceled the order.
Hi Abraxalito, I just checked your blog and finally
reached Murata chokes. Kindly suggest some which will
be good for the filter circuit and for the power supply of
the phono preamp. The Murata chokes are cheap.
I just have to import them. I have the other parts ready, only
the chokes are missing.
Regards
Roushon.
The first question in selecting a suitable choke is - what's the power draw of the equipment? I guess for a preamp, its low so choose a choke with a low current rating - the Murata PLA10 range starts at 0.3A which should be plenty. Lower current-rated chokes give better noise rejection (and absorption). I agree with Aucosticraft, put the choke on the mains side of the transformer - that's where they're designed to go. If I were you, I'd also add some steel or iron wire chokes prior to that filter like the ones shown on my blog.
Murata aren't the only manufacturer of CM chokes, they just happen to be the brand I've used in the past so I'm more familiar with them. The link jacco has posted to Schaffner also includes at least one part with good specs. Wurth is yet another good manufacturer. For a multi-stage (i.e. wide bandwidth) filter I don't think its worthwhile winding your own LF choke (that's the L4 on my hand-drawn schematic on the blog). A couple of days ago I put a sample LF choke on my newly acquired LCR meter and was surprised to discover how much loss it introduces even at low frequencies (below 100kHz). This is a worthwhile characteristic and one which depends on having multiple layer windings - i.e. the lower current chokes are best.
Murata aren't the only manufacturer of CM chokes, they just happen to be the brand I've used in the past so I'm more familiar with them. The link jacco has posted to Schaffner also includes at least one part with good specs. Wurth is yet another good manufacturer. For a multi-stage (i.e. wide bandwidth) filter I don't think its worthwhile winding your own LF choke (that's the L4 on my hand-drawn schematic on the blog). A couple of days ago I put a sample LF choke on my newly acquired LCR meter and was surprised to discover how much loss it introduces even at low frequencies (below 100kHz). This is a worthwhile characteristic and one which depends on having multiple layer windings - i.e. the lower current chokes are best.
80dB at 3KHz for the 5-stage filter of the Metronome Elektra PS, with $3 each CM chokes.
(the fancy precision power plate resistors Mr Giner picked are pricy pricey though, white/green things in the pic http://www.metronome-technologie.com/admin/pop_up_image.php?num=279&ordre=3 , no big deal for a powersupply that retails for €11K).
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Thanks!
Got busy with some more health related issues...hopefully
it is now over.
I am on the look out for ready made chokes by Murata or
some other company. Thanks Abraxalito for the
suggestions. I will also add the iron coil but
I need to read your blog more carefully about
core size and number of turns etc.
Found a source of the CMC in Singapore
(sg.element14.com) but the shipping is a lot. Found
another source in India (JPED Electronics, Vikhroli) also
but they do not entertain retailer and in fact was very
arrogant. Asked for VAT TIN, but I think individual can not
have such numbers. Or can we? I do not know. My Indian
friends here can say.
I will inform once I find a suitable source.
Regards
Roushon
Got busy with some more health related issues...hopefully
it is now over.
I am on the look out for ready made chokes by Murata or
some other company. Thanks Abraxalito for the
suggestions. I will also add the iron coil but
I need to read your blog more carefully about
core size and number of turns etc.
Found a source of the CMC in Singapore
(sg.element14.com) but the shipping is a lot. Found
another source in India (JPED Electronics, Vikhroli) also
but they do not entertain retailer and in fact was very
arrogant. Asked for VAT TIN, but I think individual can not
have such numbers. Or can we? I do not know. My Indian
friends here can say.
I will inform once I find a suitable source.
Regards
Roushon
Roushan check if Indian Vishay can help you. http://www.vishay.com/docs/34015/ihb.pdf
may be vishay is available here.
may be vishay is available here.
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