Aikido meets Zen

kacernator · 20th July 2011, 11:53 AM

Hi,

I am building single ended mosfet amplifier. I am not electrical engineer.

How do I adjust idle current?
Also would it be possible to convert the output stage to DC coupled version?
Or do you know some better schematics of single ended output mosfet stage which inverts the phase?

Thank you.

alex mm · 20th July 2011, 01:33 PM

....... may be will help you Moskido - Hybrid Aikido/MOSFET amplifier

Regards Alex.

kacernator · 20th July 2011, 01:41 PM

I know that thread as I have already built two moskidos. But that thread is about push-pull variant mainly.

I have spare parts and building this single-ended version as headphone amplifier.

alex mm · 20th July 2011, 02:28 PM

...... try this for final headphone amplifier and Aikido in front like preamplifier
HeadWize - Project: The Zen Headphone Amplifier by Marcello Pellerano . I have use marcelo's amplifier with Sennheiser HD555 from some time with good results .

kacernator · 20th July 2011, 07:36 PM

But does this Zen headphone amplifier invert the phase? Because aikido stage already inverts.

kacernator · 20th July 2011, 07:52 PM

I found it, it does invert.

WuYit · 20th July 2011, 09:49 PM

Common cathode / source / emitter stages invert the phase. Why is it important?

kacernator · 06:48 AM

Idle current should be adjusted by the upper resistor in CCS mosfet (150k).

Should I make source resistor higher value (like 2 ohm) as it woudl be better for headphones?

Do you know why is feedback taken before output capacitor and not after as it would reduce output cap distortion?

WuYit · 21st July 2011, 10:54 AM

You could change the 0.56 Ohm resistors to around 10 ohms. Roughly I = 1.2 / R
Feedback does not reduce cap distortion.
What tubes are you having?

kacernator · 21st July 2011, 11:31 AM

I am using 6SL7 and 6SN7 tubes. Alternate option is to use ECC83 and for output ECC82 (or ECC88). If no feedback would be used, you can use lower gain input tubet, but I think it will sound better with feedback - will see after the build is finished, it will take one week or so, as I have little time in next few days.

I will use 2.2 Ohm source resistors and adjust the upper resistor in CCS to set current.

21st July 2011, 06:45 AM	#8
kacernator diyAudio Member Join Date: Jan 2008	Idle current should be adjusted by the upper resistor in CCS mosfet (150k). Should I make source resistor higher value (like 2 ohm) as it woudl be better for headphones? Do you know why is feedback taken before output capacitor and not after as it would reduce output cap distortion? Last edited by kacernator; 21st July 2011 at 06:48 AM.

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20th July 2011, 01:33 PM	#2
alex mm diyAudio Member Join Date: Mar 2006 Location: ROMANIA ,	....... may be will help you Moskido - Hybrid Aikido/MOSFET amplifier Regards Alex.

20th July 2011, 01:41 PM	#3
kacernator diyAudio Member Join Date: Jan 2008	I know that thread as I have already built two moskidos. But that thread is about push-pull variant mainly. I have spare parts and building this single-ended version as headphone amplifier.

20th July 2011, 07:36 PM	#5
kacernator diyAudio Member Join Date: Jan 2008	But does this Zen headphone amplifier invert the phase? Because aikido stage already inverts.

20th July 2011, 07:52 PM	#6
kacernator diyAudio Member Join Date: Jan 2008	I found it, it does invert.

20th July 2011, 09:49 PM	#7
WuYit Banned Join Date: Oct 2010	Common cathode / source / emitter stages invert the phase. Why is it important?

21st July 2011, 10:54 AM	#9
WuYit Banned Join Date: Oct 2010	You could change the 0.56 Ohm resistors to around 10 ohms. Roughly I = 1.2 / R Feedback does not reduce cap distortion. What tubes are you having?

21st July 2011, 11:31 AM	#10
kacernator diyAudio Member Join Date: Jan 2008	I am using 6SL7 and 6SN7 tubes. Alternate option is to use ECC83 and for output ECC82 (or ECC88). If no feedback would be used, you can use lower gain input tubet, but I think it will sound better with feedback - will see after the build is finished, it will take one week or so, as I have little time in next few days. I will use 2.2 Ohm source resistors and adjust the upper resistor in CCS to set current.

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