I agree, in my youth I assembled class A. What is interesting is that the radiators are hot in idle time, and as soon as the signal arrives they become warmer, so it’s not scary to make a little more quiescent current. 60 degrees. My Krell was also like an iron (I redid it a little on the advice of one craftsman), it became warmer. Moreover, there will be protection for each channel separately for temperature rise. The constant output component is approximately 0.08-0.1mV on each channel.
Hello . As I said without a signal, I set a quiescent current of 25 mV at a temperature of 60 degrees for 1 hour. I connected a preliminary Krell (I have not yet fully implemented my volume control) and a CD player. When listening to music at a decent volume, the temperature of the radiators dropped to 46 degrees at a quiescent current of 23mV. I think that without problems it is possible to raise the current a little. By the way, I removed additional radiators, steel was not needed, since the temperature decreased on the real signal. With shorted inputs, a hiss is barely audible when you put your ear close to the HF dynamics, with an open input, it increases slightly with a small background at a distance of 10-15cm. While on wiretapping and face-to-face with Dartzil. Report later. But I want to note that I did not expect such a quality from a Chinese assembly, my 3 strips with a 30cm woofer cracked down easily.
Well, since everyone is silent, I will continue. Decided to make fun of the amplifier. Brought it up to 70 degrees (thermocouple control of the FLUKE 187 multimeter) at 30mV (additional cooling radiators removed). I drove 2 hours on various music at a volume above average. It's okay - IRON plays well. I want to notice somewhere at a quiescent current of 20 to 30 I didn’t feel a difference in sound, but lower I feel the bass is blurred, but the amount remains. I found aluminum plates 300x40x12, all the same I will screw them to the main ones. Great weekend to everyone.
Yes I read it. When I was making a pre-amplifier with a display and a relay volume control, I could not overcome the background for a long time, although I grounded both the power supply and the controller and did everything I could. Even the transformers (there are two of them, 2x24v was required) shielded. As a result, I disconnected everything from the case, left the ground from the input sockets - complete silence.
Dear Paroxod,
I have just few questions:
1. Does the hiss occur just when you have just one channel connected?
2. How you made grounding?
Regarding the components: I have tested (1) "finished" board, I have built the amplifier (2) from the stratch with components from CDIL/ISC purchased from Reichelt and also (3) "components from the reputable" supplier - Farnell (ON-Semi).
Surprisingly, CDIL/ISC was better. Both THD meassurements and listening inpression were better. Chinese "finished" board was also better than that from "reputable" source.
I wanted to understand why and have used my curve tracer to test individual transistors. CDIL/ISC components have meassured signifficantly better. All-in-all, "reputable suppliers" are a myth, at least in this particular case.
Also, there is a short thread here at this forum indicating that CDIL 2SA970/2SC2240 are indeed low noise.
It is late here and I am going to sleep now. Later on I will continue to show the results of my comparison of transistors.
I wish you all a pleasant week end.
I have just few questions:
1. Does the hiss occur just when you have just one channel connected?
2. How you made grounding?
Regarding the components: I have tested (1) "finished" board, I have built the amplifier (2) from the stratch with components from CDIL/ISC purchased from Reichelt and also (3) "components from the reputable" supplier - Farnell (ON-Semi).
Surprisingly, CDIL/ISC was better. Both THD meassurements and listening inpression were better. Chinese "finished" board was also better than that from "reputable" source.
I wanted to understand why and have used my curve tracer to test individual transistors. CDIL/ISC components have meassured signifficantly better. All-in-all, "reputable suppliers" are a myth, at least in this particular case.
Also, there is a short thread here at this forum indicating that CDIL 2SA970/2SC2240 are indeed low noise.
It is late here and I am going to sleep now. Later on I will continue to show the results of my comparison of transistors.
I wish you all a pleasant week end.
Indeed, this is the medicine that worked for me too. I also strictly applied star grounding - all grounds to a single point.... left the ground from the input sockets - complete silence.
Berlusconi hello, I barely hear the noise (almost inaudible) by putting my ear tightly to the tweeter (with short inputs), when the inputs are open I hear noise at a distance of 10-15 cm and this is normal. Interestingly, it does not change when I connect the ground to the case, while it is turned off, since I will have it connected separately from the attenuator boards through a 10-ohm resistor, each separately.
Now, connect the input to some good, well grounded source. Do you hear the noise then?
