hi. i am looking for a 2 band tone control with transistors. i found lots of schematics on the net but i dont know how reliable they are. what do you suggest?
by the way ,which one sounds better ? a tone control with opamps or with transistors?
by the way ,which one sounds better ? a tone control with opamps or with transistors?
The WW schematic is OK, provided you realise that noise levels will be high, relative to modern designs, as there is no indication or provision of regulation, filtering of the power rail or suggestions for what to do about RFI or EMI if they become a problem in your board layout and wiring.
You will be on your own unless it is detailed in an article there, possibly relying on lots of bypassing, filtering and careful grounding. Personally, I would shield this or keep it separate in a freestanding preamp. The adjustment of R18,21 seems quite a strange feature. Is the setting explained in the text?
You will be on your own unless it is detailed in an article there, possibly relying on lots of bypassing, filtering and careful grounding. Personally, I would shield this or keep it separate in a freestanding preamp. The adjustment of R18,21 seems quite a strange feature. Is the setting explained in the text?
about line regulation i am planning to use a shunt regulator.About RFI or EMI , would a 47pf cap across base -collector of first emmiter follower transistor be helpful?
this is the article . http://www.keith-snook.info/wireles...1974/Baxandall tone control revisited DCD.pdf
this is the article . http://www.keith-snook.info/wireles...1974/Baxandall tone control revisited DCD.pdf
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I remember a very similar circuit in Practical Wireless, probably around 1976 ? It looked very similar from memory but just had the two conventional pots.
Anyhow... I couldn't resist seeing how this worked in simulation. Its very much of its time, probably sounds "nice" but ultimately lacks the precision that opamps bring to the response. The response here is with the pots centred, looks awful, but look at the scale. Perhaps not so bad in context.
Anyhow... I couldn't resist seeing how this worked in simulation. Its very much of its time, probably sounds "nice" but ultimately lacks the precision that opamps bring to the response. The response here is with the pots centred, looks awful, but look at the scale. Perhaps not so bad in context.
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this is a layout i made...correct part values are not specified yet on the silkscreen
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no i havent reworked anything yet. the only thing i did was to add 0.47u bypass capacitors to all electrolytic caps that pass signal,added base collector capacitor to first transistors,added rail bypass capacitors and 100ohm resistor at output. the writer used 25V supply rail and a boost cut of +-18db. i will have to recalculate values for +-10db boost/cut and maybe i use 30V for supply rail.
The original article is by M V Thomas and is available on line at http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1974/Baxandall%20tone%20control%20revisited%20DCD.pdf
--gannaji
Sorry, my mistake, the ref to original article is already given!
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The way the circuit is drawn isn't very intuitive. The left side of the 25uf cap (the output) is actually fully AC coupled, ground referenced and has zero volts DC present.
OOps, sorry - I had deleted my post before I saw your reply, Mooly. Yes, I realized it was AC coupled and made it rather pointless. Still not sure about low output impedance, though.
Its pretty average all round technically. Output swing is around -/+5 volts but that remains a constant down to a couple of k loading. I bet it sounds OK though.
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