I agree. The left channel stubbornly refuses to oscillate. I'm thinking there may be an outright defect in a component. I'd say the odds are close to 100% if I build up another of these boards I won't see this problem again.
I tried to look for oscillation in the regulator, but didn't find anything conclusive. The 13MHz tends to pollute everything once it starts, so it's hard to determine the source. Between the regs and the signal circuitry there's a heck of a lot of gain on that breadboard.
I tried to look for oscillation in the regulator, but didn't find anything conclusive. The 13MHz tends to pollute everything once it starts, so it's hard to determine the source. Between the regs and the signal circuitry there's a heck of a lot of gain on that breadboard.
I cut the gate traces right next to the input devices and installed 100 Ohm 0805 SMD resistors. I was surprised as heck that this made the oscillation much worse. It seems like I can can damp it out entirely by the judicious application of my finger.
I think the problem is my layout. I think there's capacitive coupling from the output stage to the gate of J2 and that's the issue. I might be able to disconnect the suspect trace tomorrow. We'll see.
This is great entertainment. Much more fun than politics.
I think the problem is my layout. I think there's capacitive coupling from the output stage to the gate of J2 and that's the issue. I might be able to disconnect the suspect trace tomorrow. We'll see.
This is great entertainment. Much more fun than politics.
Salas, about deciding the size of ubibs R1 resistors when feeding DCG-3 (double ubibs)
I have 150mA bias, so:
for negative boards 150mA+100mA= 250mA (R1=2.4 ohm)
For positive boards 300mA+100mA= 400mA (R1=1.5 ohm)
Is this correct?
I have huge sinks ( a-class amp case), so heat will not be problem.
What size transformers I need? Maybe 2x 60VA 2x18V outputs?
(Toroidy supreme audio v2 are tempting me)
I have 150mA bias, so:
for negative boards 150mA+100mA= 250mA (R1=2.4 ohm)
For positive boards 300mA+100mA= 400mA (R1=1.5 ohm)
Is this correct?
I have huge sinks ( a-class amp case), so heat will not be problem.
What size transformers I need? Maybe 2x 60VA 2x18V outputs?
(Toroidy supreme audio v2 are tempting me)
I too went for the supreme audio transformer (for my cherished but unfinished B1). They are very good. But they‘re very big too, you may want to make sure they fit into your design.
Apologies for my chattering but I couldn’t resist and maybe you will be glad to have this reminder...
Mills are very good. I put flexible footprint at the UBiB R1 area so you can use practical to find parts within reasonable size. Not that a higher Watt part is a problem, just not necessary in moderate mA settings cases where you can still find smaller/cheaper.
Most smaller ones stop availability at 10R. There are exceptions like the Takman REY75 1W list bottoming out at 2.2R for instance. For 1.5R it would take two in parallel i.e. 3R//3R.
Most smaller ones stop availability at 10R. There are exceptions like the Takman REY75 1W list bottoming out at 2.2R for instance. For 1.5R it would take two in parallel i.e. 3R//3R.
