Thanks for the replies!
So would the 22k shunt resistor be placed in the same position as the original schematic i.e. just after the 220 resistor to input, or do I place it before the 4.7uF cap?
If I instead just used a cap from input to ground 1) what would the value need to be and 2) could I do without the shunt resistor then? Going for minimal parts here
- John.
P.S. What is the minimum wattage that can be used for the resistors in this schematic? Cheers!
So would the 22k shunt resistor be placed in the same position as the original schematic i.e. just after the 220 resistor to input, or do I place it before the 4.7uF cap?
If I instead just used a cap from input to ground 1) what would the value need to be and 2) could I do without the shunt resistor then? Going for minimal parts here
- John.
P.S. What is the minimum wattage that can be used for the resistors in this schematic? Cheers!
arold19 said:
You always have to have a DC reference voltage on +in. In this case it has to be 0V. So no matter what you connect where you have to connect +in to GND through a DC path (just a resistor). There are more considerations but for now: Connect 22k from +in to GND. Use the 33k pot.
If you use input cap you really don't need the 220 Ohm res. This res helps only if you have a pot connected directly (no cap) to the +in. If that's the case add the 220 res.
In other words use Peter's schematic (no caps), or use the one above and add the 22k between GND and +in and you can safely remove the 220 res.
One last newbie question (promise )
As I have said, I will be using my gainclone with a 50k ALPS passive pre. I will also be using it occasionally with an active-pre (modded quad 34).
Any suggestions on which path I should travel regarding either using that 4.7uF input cap and shunt resistor to protect from possible DC, OR Peter's circuit which has that 22k shunt and the 220 input resistor instead but no input cap? I've heard that caps are best avoided in the signal path wherever possible, so this sugests I that perhaps I would be better served (sound quality wise) by going for 220 + 22k resistor path instead?
Sorry but I really don't have enough electrical knowledge (yet!) to work these things out for myself, and I can't afford to keep trying out different components as this must shorten the life of the chip (the heating of the soldering iron on the chip pins when changing components?).
Cheers everyone!
- John.
)As I have said, I will be using my gainclone with a 50k ALPS passive pre. I will also be using it occasionally with an active-pre (modded quad 34).
Any suggestions on which path I should travel regarding either using that 4.7uF input cap and shunt resistor to protect from possible DC, OR Peter's circuit which has that 22k shunt and the 220 input resistor instead but no input cap? I've heard that caps are best avoided in the signal path wherever possible, so this sugests I that perhaps I would be better served (sound quality wise) by going for 220 + 22k resistor path instead?
Sorry but I really don't have enough electrical knowledge (yet!) to work these things out for myself, and I can't afford to keep trying out different components as this must shorten the life of the chip (the heating of the soldering iron on the chip pins when changing components?).
Cheers everyone!
- John.
If in doubt use the input cap. Resistors in any configuration will not block DC.
However, you could measure the DC coming from your source or preamp and if it is zero, you won't need the input cap on the amp.
If you have not yet seen it, may I suggest you take a look at my Gainclone FAQ page before building anything.
However, you could measure the DC coming from your source or preamp and if it is zero, you won't need the input cap on the amp.
If you have not yet seen it, may I suggest you take a look at my Gainclone FAQ page before building anything.
Hi Nuuk!
I've indeed been to your fantastic website many times - a constant course of inspiration (I particularly love your valve buffered gainclone - awsome!).
I'll do as you suggest in your FAQ for measuring DC offset - one question. You say to use 10 ohm resistor - watt wattage should this be please?
That's it! Start building my first gainclone tomorrow - woohooo!!!!
I've indeed been to your fantastic website many times - a constant course of inspiration (I particularly love your valve buffered gainclone - awsome!).
I'll do as you suggest in your FAQ for measuring DC offset - one question. You say to use 10 ohm resistor - watt wattage should this be please?
That's it! Start building my first gainclone tomorrow - woohooo!!!!
question for Peter.
Nobody tried lower values for 22k,680? (higher current feedback)
for instance 10k, 320?
less resistor quality dependable?
Most pre-amps, cd-players have output impedance < 500 ohm so driving it may not be a problem, on the contrary i think, less sensivity causes less influence by unwanted external distortions.
Nobody tried lower values for 22k,680? (higher current feedback)
for instance 10k, 320?
less resistor quality dependable?
Most pre-amps, cd-players have output impedance < 500 ohm so driving it may not be a problem, on the contrary i think, less sensivity causes less influence by unwanted external distortions.
Thanks for all the replies again guys! This forum is the bizzo
OK - one last question (slight return!): I need to measure whether there is any DC coming from my source - A Rotel RCD02 CD player and DPA PDM series two DAC. Nuuk, is this the same kind of procedure which you mention for the amp?
I have a digital multi-meter but lack the knowledge of exactly how to take these measurements - I'm sure it's so easy I'll kick myself
Best regards,
- John.
OK - one last question (slight return!): I need to measure whether there is any DC coming from my source - A Rotel RCD02 CD player and DPA PDM series two DAC. Nuuk, is this the same kind of procedure which you mention for the amp?
I have a digital multi-meter but lack the knowledge of exactly how to take these measurements - I'm sure it's so easy I'll kick myself
Best regards,
- John.
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