which brand transistor was it, and was there a spike in your supplies.
though if there was spike lot more would have been affected.
Mr auriga2001
Circlophone is a tested circuit and fully balanced as far as current and voltages of each stage is concerned. I have made two prototype and two running stereo amplifiers BJT and MOSFET based and all are working fine at +/- 32V rail voltage. One set is permanently connected to my PC for more than a year. No problem at all.
May be in your case a component failure took place. The transistor might be fake.
I have used either CDIL India make transistors or other ST/Philips make transistors procured from RS.
Please check all active components for failure since it is a directly coupled circuit before replacement.
Circlophone is a tested circuit and fully balanced as far as current and voltages of each stage is concerned. I have made two prototype and two running stereo amplifiers BJT and MOSFET based and all are working fine at +/- 32V rail voltage. One set is permanently connected to my PC for more than a year. No problem at all.
May be in your case a component failure took place. The transistor might be fake.
I have used either CDIL India make transistors or other ST/Philips make transistors procured from RS.
Please check all active components for failure since it is a directly coupled circuit before replacement.
Mr Vincent77,
Welcome to Circlophone family.
Extremely good DIY work. Nice PCB layout.
I think you will need a large heatsink for higher rail voltages. You can use all aluminium Class A chassis to house your work.
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Thank you!
As promised, I made a box for my Circlophone:
I have some woodworking tools and machines at home, so I've built the box myself, using walnut wood with oak and meranti inserts, and plywood for the back and bottom panels. The color is natural, no dye has been used, only water-based polyurethane finish.
Because real wood grows or shrinks depending on humidity, precautions have been taken - for example, the top panel is only fixed in the central part, allowing it to grow on the sides without bowing.
This is how it looks inside:
There are big ventilation holes inside also, under the PCBs, invisible in the photo.
As an evolution to my first test, I have removed the small film capacitors that I had bypassing the local reservoir electrolytic caps. The power supplies are now separated per channel, and is using good quality Panasonic FR capacitors. The power transformer has secondary snubbers tuned with Quasimodo.
These modifications have improved the audio quality - it sounds great now, I'm very pleased with it.
I have added a relay module on the output that does turn-on delay, AC loss detection, DC protection and amp bypass (I'm using the same speakers with two different amplifiers).
I have reduced the power voltage to +/-18V, because my speakers don't need a lot of power. The heatsinks are just warm, +15°C above ambient.
One thing is missing: soft start for the big toroid transformer, I will add it when I have the time.
In conclusion, this is a great sounding project, I recommend it!
As promised, I made a box for my Circlophone:
I have some woodworking tools and machines at home, so I've built the box myself, using walnut wood with oak and meranti inserts, and plywood for the back and bottom panels. The color is natural, no dye has been used, only water-based polyurethane finish.
Because real wood grows or shrinks depending on humidity, precautions have been taken - for example, the top panel is only fixed in the central part, allowing it to grow on the sides without bowing.
This is how it looks inside:
There are big ventilation holes inside also, under the PCBs, invisible in the photo.
As an evolution to my first test, I have removed the small film capacitors that I had bypassing the local reservoir electrolytic caps. The power supplies are now separated per channel, and is using good quality Panasonic FR capacitors. The power transformer has secondary snubbers tuned with Quasimodo.
These modifications have improved the audio quality - it sounds great now, I'm very pleased with it.
I have added a relay module on the output that does turn-on delay, AC loss detection, DC protection and amp bypass (I'm using the same speakers with two different amplifiers).
I have reduced the power voltage to +/-18V, because my speakers don't need a lot of power. The heatsinks are just warm, +15°C above ambient.
One thing is missing: soft start for the big toroid transformer, I will add it when I have the time.
In conclusion, this is a great sounding project, I recommend it!
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