Hey Prasi . Before switching the boards on the first time , on your layout , am I correct in thinking that trimpot screw must be turned all the way counter-clockwise for minimum bias setting ?
Quiescent current can be set to 80mA (measured over fuse holder with fuse removed) , or 20mA over 1e emitter resistor ?
Quiescent current can be set to 80mA (measured over fuse holder with fuse removed) , or 20mA over 1e emitter resistor ?
I suggest using an ohmmeter to measure the resistance between pin1 and pin3 of the R36 trimmer potentiometer, after it has been stuffed and soldered to the PCB. Whichever setting gives the LARGEST resistance from pin1 to pin3, is the safest (lowest bias) starting point for bias adjustment. Measure it twice and reverse the probes for measurement #2. Patiently wait 30 seconds to allow the reading to settle.
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Hey Prasi .
Quiescent current can be set to 80mA (measured over fuse holder with fuse removed) , or 20mA over 1e emitter resistor ?
Hi Fredeb, 20mA measured over any one of the 1R resistor would be more convenient. 20mV delta V. Use bulb tester for initial 'firing-up'
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WOW!
inductor can be 10-12 turns wound on AAA cell with 1.2 mm magnet wire/ enameled wire
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progress
Managed to gain a little ground.
Got my boards mounted to the heatsinks and the front face mounted as well.
At last count that leaves 22 more holes to drill and tap.
Slow work takes time.
Managed to gain a little ground.
Got my boards mounted to the heatsinks and the front face mounted as well.
At last count that leaves 22 more holes to drill and tap.
Slow work takes time.
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Looking amazing flamethrower1 . Well done !
I finally have one channel biased and have been listening to one channel plugged into an old 6x9 driver lying on it's back . I'm going to assemble 6 boards . A pair for my dad , a pair for my friend and a pair for myself . May try some different parts on the last 2 boards to hear the difference .
I have an off board PSU - will draw a schematic of what I did there . I have bias set to ~18mA per output device . Offset seems.to be lowest at that point . Offset is hovering around 2.5mV . Input devices.are well.matched .
I finally have one channel biased and have been listening to one channel plugged into an old 6x9 driver lying on it's back . I'm going to assemble 6 boards . A pair for my dad , a pair for my friend and a pair for myself . May try some different parts on the last 2 boards to hear the difference .
I have an off board PSU - will draw a schematic of what I did there . I have bias set to ~18mA per output device . Offset seems.to be lowest at that point . Offset is hovering around 2.5mV . Input devices.are well.matched .
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I decided to build another amp.
Offer pcb / part kit
https://www.diyaudio.com/forums/swap-meet/376307-pass-ab-100-pcb-kit.html#post6767065
Offer pcb / part kit
https://www.diyaudio.com/forums/swap-meet/376307-pass-ab-100-pcb-kit.html#post6767065
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