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Tube use? 24->300V large cap charger with 300V 150mA reg
Tube use? 24->300V large cap charger with 300V 150mA reg
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Old 6th April 2021, 05:39 PM   #121
NickKUK is offline NickKUK
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Join Date: Dec 2019
So.. Tracing back the noise - I can see that the Isense doesn't worry about the leading transient however the NPN does I believe. So I've added some snubbage

The output from the boost section is good and seems clean enough, the only variants in wave form is the variation from the PWM itself which is controlling the current but has an accumulative cycle and then decides it needs to have a fractionally larger gap - this occurs at 7KHz so it's easy to spot.

Now then..

Screenshot 2021-04-06 at 18.31.46.png

Top is output into the load. Middle is output from the maida mosfet... and the bottom is the output from the SMPS.

So it appears that currently the mosfet is setup to allow uA through.. which isn't enough to correct.. so the 600mA is going through the D1 diode as it keeps it 20V separation.. so a little more current is needed through the regulator

Edit.. Turns out that that R1 is too large and that prevents the regulator from starting. The regulator is now starting up.. and the slow start should take about 900ms - the SMPS is already at 260V.. Let's see what happens after dinner

Last edited by NickKUK; 6th April 2021 at 06:04 PM.
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Old 6th April 2021, 07:08 PM   #122
NickKUK is offline NickKUK
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Better..

Screenshot 2021-04-06 at 20.07.33.png
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Old 6th April 2021, 08:28 PM   #123
NickKUK is offline NickKUK
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Simulation time 1.2 to 2.8 seconds gives:

Screenshot 2021-04-06 at 21.25.39.png

Better FFT sim performance that could do with some additional tweaking.. if that means I can get 20uV ball park figure then I'll be extremely happy.
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Old 7th April 2021, 08:09 AM   #124
NickKUK is offline NickKUK
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So I've put the model onto the large amp model.. left it running overnight, now it's just reached 1.2 seconds so it'll need today to continue running and we should then have a few seconds of amp startup and operation to assess.

Screenshot 2021-04-07 at 09.09.39.png
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Old 7th April 2021, 11:16 AM   #125
NickKUK is offline NickKUK
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Join Date: Dec 2019
Screenshot 2021-04-07 at 11.36.31.png

Spicy appetiser from the large model.. this has a 10KHz 3.16V input signal and a 30Hz 3.16V input signal on the other channel. This is from the top of the output tubes on one channel.

It still needs to run for several more seconds to get a real output but this is looking promising.
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Old 7th April 2021, 12:51 PM   #126
NickKUK is offline NickKUK
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Update - same run... at 3.2 seconds or so.. still need a stretch of 3 seconds after it's warmed up to get a really decent FFT out of it.

Screenshot 2021-04-07 at 13.49.26.png
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Old 7th April 2021, 02:37 PM   #127
NickKUK is offline NickKUK
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From the pre-out - 2 to 4 seconds. Looking very transparent as a power supply (yes I know the amp needs work).

Screenshot 2021-04-07 at 15.24.13.png
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Old 7th April 2021, 06:00 PM   #128
NickKUK is offline NickKUK
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Ok last ones for today I suspect. 4.5 to 5.8 seconds:

At the headset load 32ohm. Left channel 10Khz 3.16V input, right channel is 30Hz 3.16V:

Left
Screenshot 2021-04-07 at 18.55.06.png

Right
Screenshot 2021-04-07 at 18.56.06.png

So apart from my amp's signal path not being anywhere near clean, the power supply (which I'm concerned with) looks very promising.

I still think the real value would be +20dB on that but until it's built you known nothing John Snow..
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Old 7th April 2021, 08:28 PM   #129
NickKUK is offline NickKUK
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Yee gawds.

Right channel is getting better by the second..
Screenshot 2021-04-07 at 21.27.11.png
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Old 8th April 2021, 07:14 AM   #130
NickKUK is offline NickKUK
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Left and right - 5.0 to 12 something seconds of simulation time.

Screenshot 2021-04-08 at 08.08.14.png

Screenshot 2021-04-08 at 08.12.10.png

I think I could live with that. Some cross talk, I think it's onto tubing the amp a little better to lower the harmonic chorus that's currently in effect.
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