Hi all, I have a Brian Bell (Chip Amp) LM3886 kit which I'm building into a new enclosure for our lad. When I last used it I didn't bother fitting DC blocking caps because I knew my sources did not output any potentially damaging DC but I can't be sure that will always be the case in the future. There is no provision on the PCB's for a blocking cap and lack of space inside the enclosure means it would be difficult to fit them in.
What if I fit a couple of axial 1uF caps inside the separate passive preamp I'm assembling for use with this amp? I'm thinking about putting them between the volume pot output terminals and the signal output sockets. Is there any reason why this would not be a good idea?
What if I fit a couple of axial 1uF caps inside the separate passive preamp I'm assembling for use with this amp? I'm thinking about putting them between the volume pot output terminals and the signal output sockets. Is there any reason why this would not be a good idea?
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Fair point Andrew, I have a couple of quite large axial 1uF capacitors I was thinking about fitting inside the passive preamp but I could always buy in some smaller ones. I suppose either solution would work as both units will always be used together.
Found these on ebay - http://www.ebay.co.uk/itm/2x-DC-Fil...al_Components_Supplies_ET&hash=item2a24c067fc
I wonder what effect they will have on sound quality, probably not much.
Found these on ebay - http://www.ebay.co.uk/itm/2x-DC-Fil...al_Components_Supplies_ET&hash=item2a24c067fc
I wonder what effect they will have on sound quality, probably not much.
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A properly employed capacitor in a properly designed circuit will have for all practical purposes no audible effect on performance. The distortion introduced is so small that its consideration is academic.
Capacitor choice becomes much more critical in filter and tone control circuits where the capacitor has significant impedance inside the audible range (or within a decade).
There's nothing wrong with using nice film capacitors for coupling. They do have a different distortion profile than electrolytics.
Capacitor choice becomes much more critical in filter and tone control circuits where the capacitor has significant impedance inside the audible range (or within a decade).
There's nothing wrong with using nice film capacitors for coupling. They do have a different distortion profile than electrolytics.
Not if it's done right.
Calculate a pole that's at least lower than the input low frequency pole. Do not use a larger capacitor than necessary. You can bypass this electrolytic with a nice film capacitor in the neighborhood of 1 uF if you like.
Anything that happens below 2 Hz is sonically unobtrusive. 3 dB down at 2 Hz = 0.1 dB down at 20 Hz and phase shift in the audio range will be negligible too.
This is what I mean by "properly designed." If you understand and quantify your parameters, you can manipulate them to your needs too.
Commercial equipment employs this technique sometimes.
I looked at the math involved (never my strong point)
It's trivial algebra that can be calculated with an engineering calculator.
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