Aikido

I started working on Aikido. Aikido is a great topology (noise cancellation). It can be used for headphone amplifier/line stage/pre-amp, etc. See picutres.


I plan do do a class-A power amplifier based on Aikido input stage and MOSFET output stage - called MOSKIDO ;)

Cheers,
Matej

Battery Powered PSU - Daja

Today I've finally completed Battery Powered PSU (named Daja). Its is fully automatic (no switches at all, triggered by client - 12V trigger) based on relays. When not used battery are being charged. Charging is advanced using several stated: batery revival (trickle charge), current limited charging, voaltage limited charing and finally float charge. No maintainence is needed. Connectors are RCA and all fully fused.

See pictures with comments.

Cheers,
Matej

Aikido

Now DAC output stage is a "simple" SRPP. It sounds nice, but.... it can be made better. After lots of investigation I decided to go Aikido way. It is really great design and very flexsible. I might try Moskido as well.

I've removed digital PSU out of DAC and mounted new PSU. Now everyhing is nice and clean. No bruuum and background noise. Great!

SLA battery chager (UC3906) prototype works. I plan to built 4 on them on a board and put SLAs in nice separate chassis. I will use RCA conectors (standard and thay have good connections).

Matej

Coupling caps

After quite some investigation I will most likely go for Mundorf Silver/Oil. Possible candidaces are: Audience Auricap and Audio Note Copper Foil (Silver Foil are way too expensive). Since I have WIMA MKP at home, I will try these as well (for fun - they should be very transparent and thin).

Value is determined by C = 1/(2*pi*R*f), where f is a roll-off frequency. Coupling cap forms a high-pass filter with resistor and impedance of the next stage (power amplifier). I recommend values 470nF and larger.

Matej

It plays... to cry for!!!

Last days I've done and learned lots of things, experiments, playing with the osciloscope, etc.

However today I've installed my new HT PSU and the sound is to cry for: soundstage is wide, instrumets got played by musicians, everyhining is so much real and alive.

SiC diodes, EPCOS 220uF LL caps, 2k2 resistors (2W) in CRCRC configuration bypassed with terrific WIMA MKP4 4,7uF.

Got to go now... litstning to the music :)

Matej

Optocoupler volume control

Audio level control with resistive optocouplers

DIY Audio thread (very looooong).

Use low noise PSU (SLA battery) and add capacitor (good 100uF low-LSR; consider Murata 47uF ceramic) in parallel to LDR LEDs.
I recommend usage of Silonex NSL-32SR2S (sorted, matched).

Matej

On SLA PSUs...

"... you power it with unregulated +/-12V SLA batteries and use plenty of fast capacitance across the battery terminals and bypass caps at the IC pins ..."