Putting a new BJT type pair in the current mirror takes repeating the offset trim procedure of course. Even if it was just another pair of the standard type it would have had somewhat different Vbe & HFE than the previous.
I plan my move for today, at night, and it will be quite immediate judgement since I’m making that change on my first unit that fully burned in.
My second one with LDRs is started to run yesterday and sound changes hourly. I listened to it about 4 hours by now and it is perfectly fine for my ears. Very airy and kind of more detailed vs. v47 Goldpoint. One issue that I need to solve is a clicking pops when I turn volume switch knob up or down. Should fine appropriate bypass cap.
My second one with LDRs is started to run yesterday and sound changes hourly. I listened to it about 4 hours by now and it is perfectly fine for my ears. Very airy and kind of more detailed vs. v47 Goldpoint. One issue that I need to solve is a clicking pops when I turn volume switch knob up or down. Should fine appropriate bypass cap.
Unfortunately, I plan to upgrade unit with step attenuator first. My LDR one will be the next in line. LDR unit just started its journey and I’ll be listening to it for a month or so. Let’s see what will be with Goldpoint step attenuator one. I’m very very happy about its sound and hope to hear some changes. I’ll report soon.
I will put the dam1121 DAC and the DCG03 in one case. As USB is my only source and the DCG3 seams to be a good output stage ( as a headphone and Pre Amplifier) I think it is a good idea (?).
Regard the volume control:
The idea is to manage that within the DAC. I think the volume control within the dam1121 didn't touch the audio data itself, so is bit perfect.
Are my ideas comprehensible and, above all, correct?
If so what to do with the DCG03? Is it a good idea to leave the DCG3 always full throttle?
Or is it better to reduce the DCG03 volume at a fixed certain level?
If yes, how?
greetings
Regard the volume control:
The idea is to manage that within the DAC. I think the volume control within the dam1121 didn't touch the audio data itself, so is bit perfect.
Are my ideas comprehensible and, above all, correct?
If so what to do with the DCG03? Is it a good idea to leave the DCG3 always full throttle?
Or is it better to reduce the DCG03 volume at a fixed certain level?
If yes, how?
greetings
Definitely doable to combine some DAC and digital control in the same box with this amp and result in a noise free whole. You wouldn't have to do something special regarding the DCG3 itself. Has been done by some members before but maybe the most characteristic and compact example has been demonstrated by Croatian member yoke. More box space to easier dissipate the Class A heat is a good idea nonetheless. Its not made of butter of course and its Panasonic caps are 105C but cooler is better for long term peace of mind. See posts #1937,1938,1946,1949,2035,2200.
It says in the pdf instructions it can't be set to unity gain. Wasn't its purpose at all. Although at times two its still robust. Maybe there is some way to modify its blocks or over-compensate its open loop gain curve to achieve buffer mode stability but it will not be much the same circuit anymore. I haven't tried that anyway.
Little more 2ndH is possible due to less HFE and 8% less open loop gain than with the BC560C (especially the one from the kit which is very high HFE). But also less noise that maybe its not an immediately audible change since the preamp wasn't noisy before. If you go near your tweeters can you hear bit less system hiss? Anyways let it play for some hours or more and if no extra detail comes through due to bit more quiet, then no reason to stay with this test type if it will not eventually open up.