rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Feb 28, 2006 4:53:49 GMT
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Post by PinkFloyd on Feb 28, 2006 23:33:09 GMT
Nice one Rick, very handy indeed.
Mike.
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Post by derekrumble on Apr 27, 2006 13:27:42 GMT
Hi Rick, thanks for your hard work. A question for you - how does the volume pot, in the X Cans 3, fit into this picture?
Hope this makes sense.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Apr 27, 2006 17:39:57 GMT
 yeah,makes good sense.I would fly a guess and say the volume control fronts R6. You never want a variable resistance going to a capacitor unless you are trying to make a variable filter or tone control because it is the combination of R/C that sets the hinge point.Change "R" and you change the filter. So this means the only place where you can stich a variable resistor is before the fixed resistance of R6 or it would throw off the entire input filter. As "another guess" this says R6 has to have a high value in order for the input attenuator to operate without unduly stressing the preceeding stage (the source) which means it too must have a "highish" value which is also the input impedance setting point. so assuming a 10K volume pot R6 would be 100K.This would mean a 10K input impedance for the amp.If the input impedances is 50K then R6 would have to be 500K,if 100K then R6 1Meg,etc., in order to maintain a good ratio of impedances. Long winded way of saying the schematic does not show the volume control but my best guess is it goes before the first resistor shown in the schematic 
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Post by derekrumble on Apr 28, 2006 8:13:39 GMT
I have cpmpared the xcans v2 schematic alongside the x10d v3.. quite a similarity it seems to me - although I am no electronics expert. In the xcans2 the vol pot is in the same position as R4 and R5 in the x10d - but if c3 reamains in the xcans3 then there would be a problem along the lines of the filter issue you explained?
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Apr 28, 2006 16:09:35 GMT
R4 is shown in this schematic as a fixed resistor with C3 across it.
If R4 were instead a pot (volume control) then it would be fine as long as the capacitor is not attached to the wiper everything is cool and actually makes sense.
This would then make the R6 "fixed" resistance the input impedance setting resistor and the R4 "volume control" the impedance seen by the input low cut and RFI filter network.
Fixed resistance at both ends of the input network,standard potentiometer attenuator to the first stage of the amp
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