Thanks Rudi. How close do I need to match the 2SA/2SC pair for Hfe? Is 155/184 close enough for the 2SA/2SC pair Q19/20? Otherwise I may need to buy even more 2SA/2SC
surely 170 for 2SA and 184 for 2SC - Or do you need the higher value 2SC for the other pair?
Can I ask how many you have gone through?
I bought 50 of each as measured them all. There are only 2 2SA around 170. The rest are all around 155. And I need 4 pairs.
double insulated is Class11
That is designed and built and tested and guaranteed to NOT allow mains to electrocute the user.
And it is a condition of that DESIGN and BUILD, that it must NOT have an Earth.
Here is the ambiguous statement that could lead to a VERY DANGEROUS construction if implemented by a Beginner that did not realise what he/she was incorporating.
The least you can do is expand on what you said to make the "SAFETY" part appropriately important.
Or.
simply remove the potentially fatal advice.
Seems like it would be easier to find a diode of the proper characteristics in a TO220 package and mount it on the back of the power transistors using the same screw along with some thermal paste in between. The diode would help clamp the power transistor evenly to the heat sink, and the leads would be much easier to solder. I would opt for putting one on every output transistor, though, even if not used, to maintain an equal thermal environment for each transistor.
Alternatively, glue a SMD packaged diode on the collector lead of each transistor. The collector lead is connected to the heat plate of the transistor, so heat should conduct to the collector lead a diode very quickly.
or glue a sot23 transistor to the Collector/Drain lead.
Then wire the transistor as a virtual diode.
Two wires take the tempco signal back to the amp board.
Then wire the transistor as a virtual diode.
Two wires take the tempco signal back to the amp board.
What is the best option for the input DC blocking cap? It should be 3.3 to 3.9uF according to Andrew? I haven't been able to find any quality polypropylene caps that would fit 15mm lead spacing on Rudi's board.
If your preamp output is capacitor coupled or otherwise DC output protected, you shouldn't need a cap here. I have lived without an input cap for almost 40 years without losing a moment of sleep.
Thanks Pooge. But I will be using the VCPre with the FC-100 and one of my sources is direct coupled, hence the possible need for suitable DC blocking caps.
Paul, I do not know any suitable polypropylen capacitor either.
I am either using polyester capacitors (for example: VISHAY MKT1822) or WIMA MKS4, which uses a PET foil.
Best regards - Rudi_Ratlos
I am either using polyester capacitors (for example: VISHAY MKT1822) or WIMA MKS4, which uses a PET foil.
Best regards - Rudi_Ratlos
Hi Andrew, I was referring to this post in the original GB thread as cited in the builders manual :
http://www.diyaudio.com/forums/group-buys/209075-roenders-fc-100-rev-1-group-buy-20.html#post3160282
OK, now I see.
The time constant around 85ms to 100ms suits me. But it must also suit the abilities of the amplifier.
That was the point I was making.
Stating capacitance alone without the resistance value tells us nothing. It's a filter and both parts of the filter require specification.
The time constant around 85ms to 100ms suits me. But it must also suit the abilities of the amplifier.
That was the point I was making.
Stating capacitance alone without the resistance value tells us nothing. It's a filter and both parts of the filter require specification.
Solved bias issue by exchanging all the 0281/0302's. I was complaining last year about my bias was rising slowly with temperature and becoming suddenly unstable.
I have discovered that my transistors has some diode problems also quite high Vfe. The old ones has Vfe diode around 0.520V and the new working ones are very close to 0.500V.
It seems that Onsemi has some problem in the past with thermaltrack diodes.
I have discovered that my transistors has some diode problems also quite high Vfe. The old ones has Vfe diode around 0.520V and the new working ones are very close to 0.500V.
It seems that Onsemi has some problem in the past with thermaltrack diodes.
If YOU consider your speakers as "expensive" then YOU decide if you want to protect them.
It has nothing to do with the amplifier type, nor it's design.
It has nothing to do with the amplifier type, nor it's design.
Excuse me that saw your question so late.
The Aluminum angles are self made (like everything of the case except the heatsinks).
I cut them of a big one in pieces of 20mm and drill the holes.
The first test I did with the speaker protection and later I took it out.
Regards
Andreas
The Aluminum angles are self made (like everything of the case except the heatsinks).
I cut them of a big one in pieces of 20mm and drill the holes.
The first test I did with the speaker protection and later I took it out.
Regards
Andreas
- Status
- Not open for further replies.