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Posts by Donald North

Hopefully sooner. I may be able to build the first one in 2-3 months.
You need to adjust the hum nulling potentiometers each time you swap 2A3s. With no music playing, set the volume control to 0 and use your most sensitive headphones. Carefully listen and adjust until it is inaudible.When using TRS headphones the -6dB setting changes the secondary grounding from the - end to the center tap, thus reducing the output voltage by one half or 6dB. Output impedance is also reduced from 8 to 3 ohms. This settings is useful for low impedance...
A head-fier recently brought the KEF Muo to our office to compare to the Turbo X and S. When listened individually I was surprised to find that the Muo operates as a mono speaker. They have some explanation for this on their website. You need two for stereo.
Right now it is around 7-8 months.
They're Switchcraft D3F and D4F. You can order them through Mouser.com
Think of the Stratus as an integrated amplifier for headphones. The preamp duty is handled within the amplifier by the 6N1P. Now if you were to listen to vinyl through the Stratus, then you would need an external phono stage preamp.
Bypassing the internal volume control and using an external active preamp is not a good idea, in my opinion and experience. You will be adding more gain to the signal path, when there is already plenty with most sources and reducing the usable range of the volume control before it is too loud with dynamic headphones. You will also be adding noise. Of course you are welcome to try by turning up the Stratus volume control to maximum, thereby effectively taking it out of the...
Thanks, the design is not yet final and there are some more features I am considering to add to further improve performance. Stay tuned
I just received the Audio Note input transformer samples. I do not know their price yet. Once I receive it I can calculate the amp price difference.
The 20A amp needs to be driven from a low source impedance, be it a DAC/disc player with variable output or active preamp. Volume attenuator can be analog or digital. Transformer volume control can also be used but not a traditional resistive passive preamp because their output impedance will be too high and cause high frequency attenuation.
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