Lineup;
YES! That is the right way to do it....... unless you are willing to take the risk of making fire crackers 😉
I have blown up some LYNX in the beginning. The version published does work, and performs very good for the intended job. I have comfirmation that several 100's have been build over the years, most of them still playing in disco's, bands and homes without any problems 🙂
YES! That is the right way to do it....... unless you are willing to take the risk of making fire crackers 😉
I have blown up some LYNX in the beginning. The version published does work, and performs very good for the intended job. I have comfirmation that several 100's have been build over the years, most of them still playing in disco's, bands and homes without any problems 🙂
it´s terrible! My opinion is, there was oscillations 
! You must recalculate zener rezistors and test amplifier with regulated PS with current limitation!Bo, I am sorry, i saw it right now. Your zener rezistors are calculated correctly. What is the OPA?
masteramp said:
Yes, they are isolated with self adhesive pads and nylon bushings, and I measured all BCE-legs to chassis before starting it up.
P-A;
I did not connect speaker output to ground. I connected GND to ground (or virtual ground or whatever you call the common rail). And no, I did not have fuses on the input supply
but I have purchased them now, and I will use them for as long as I live. 🙂But when measuring the other card, the GND on the input supply is not connected to the GND on the output supply. How come?
Learning by burning!
/Bo
This is to minimize noise at the input. In the QAG it is shown how to connect the Grounds for best result.
😉
PMA said:
PMA, you don't really think so, do you?
If you do, I would have misjudge you 😉
I can not give as perfect answers like you do, PMA.
But I try my best to show interest in peoples issues.
Even when other just ignore 'stupid questions'.
And for this I am well respected by the vast majority at this forum.
But not by everybody, which would be an impossibility.
Lineup Regards 🙂
bomellberg said:
Yes, they are isolated with self adhesive pads and nylon bushings, and I measured all BCE-legs to chassis before starting it up.
P-A;
I did not connect speaker output to ground. I connected GND to ground (or virtual ground or whatever you call the common rail). And no, I did not have fuses on the input supply
But when measuring the other card, the GND on the input supply is not connected to the GND on the output supply. How come?
Learning by burning!
/Bo
Bosse, see page 7 in Jan's directions "Connect the Power Supply GND to both the Supply GND and the Input GND
terminal."
Jan, it's a bit confusing that you have two nets which aren't connected to each other. To make it more clear you should have different ground symbols for power ground and signal ground.
Jan, perhaps you should mention the good idea to use fuses in stategic places.
Well, actually Jan does mention the fuses when performing the pre-test. I just didn't use them.
Also, I did follow the pre-test instructions, connecting the Power Supply GND as well as the input GND. There is a very clear picture showing this.
Again, what I did which is different from the QAG:
1. Soldered the output devices before pre-test.
2. Didn't use fuses on the +V and -V to the input stage.
3. Connected GND on the supply to the output stage.
Otherwise I followed Jan's excellent instructions.
I will try the other channel tonight. Since the output devices are soldered in place, would it be sufficient to desolder the base-resistors to decouple them from the pre-test, or do I need to desolder the output devices?
Best regards,
/Bo
Also, I did follow the pre-test instructions, connecting the Power Supply GND as well as the input GND. There is a very clear picture showing this.
Again, what I did which is different from the QAG:
1. Soldered the output devices before pre-test.
2. Didn't use fuses on the +V and -V to the input stage.
3. Connected GND on the supply to the output stage.
Otherwise I followed Jan's excellent instructions.
I will try the other channel tonight. Since the output devices are soldered in place, would it be sufficient to desolder the base-resistors to decouple them from the pre-test, or do I need to desolder the output devices?
Best regards,
/Bo
Usually, we put something like 3 ohm - 10 ohm power resistor into each +V and -V power supply lead. This prevents any damage even in case your power transistors are soldered in a PCB.
Something very important:
Power supply must contain at least TWO 100nF ceramic or foil capacitors paralell to output!
I recomend to place two 47uF (or more) capacitors to a Lynx PCB between V+/GND and V-/GND.
If you do´t use 100nF capacitors, the oscillations are very probable!
Power supply must contain at least TWO 100nF ceramic or foil capacitors paralell to output!
I recomend to place two 47uF (or more) capacitors to a Lynx PCB between V+/GND and V-/GND.
If you do´t use 100nF capacitors, the oscillations are very probable!
masteramp said:
I have these (foil capacitors), but they are not mounted yet. Are they really that important for the amp, even though the output stage is not connected yet?
Yes, that is very importat for most of amplifiers. When I tuned my smaller version of Lynx, i saw on my oscilloscope large differences between supply with and without theese 100nF capacitors. Is posible, your amplifier will oscillate after add 100nF, but oscillations will be smaller and your amplifier won´t blown up. Key to stability are as well C102, C103 and C109.
Adequate sollution:
Adequate sollution:
Attachments
OK, I'll add them before checking out the other channel.
Thanks for the illustrative schematic!
Best regards,
/Bo
Thanks for the illustrative schematic!
Best regards,
/Bo
The LYNX already has C112, C113, C114 and C115 (100nF) as decoupling capacitors. Plus an extra 100nF within the zener-regulation. Do you think I need 2.2uF?
/Bo
/Bo
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