Dear friends,
Almost ten years back, I started a thread "Bigun's TGM8 with single Supply", https://www.diyaudio.com/community/threads/biguns-tgm8-with-single-supply.250380/ . Post #21 contains the final circuit.Three of our members constructed that amplifier with good reviews. After seeing lineup's 6Tr Lateral amp, I wanted to try my hand again.
The result is as below.
I retained Q-1,2&3 and the circuit around them same. There is a good improvement in Distortion and its profile.
Taking the guide for Dummies of minek for olg, I followed the method religiously and the result is as below.
I require help in improving the Gain and Phase margins. The .asc files are enclosed.
Almost ten years back, I started a thread "Bigun's TGM8 with single Supply", https://www.diyaudio.com/community/threads/biguns-tgm8-with-single-supply.250380/ . Post #21 contains the final circuit.Three of our members constructed that amplifier with good reviews. After seeing lineup's 6Tr Lateral amp, I wanted to try my hand again.
The result is as below.
I retained Q-1,2&3 and the circuit around them same. There is a good improvement in Distortion and its profile.
Taking the guide for Dummies of minek for olg, I followed the method religiously and the result is as below.
I require help in improving the Gain and Phase margins. The .asc files are enclosed.
There s a lot of things that can be improved but the first one is to moderate the TMC local NFB,
use a 330pF + 68pF and a 4.7k resistance, current values are just a recipe for poor stability.
use a 330pF + 68pF and a 4.7k resistance, current values are just a recipe for poor stability.
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Hi Gannji.
To simulate the OLG just use a big inductance, say 100TH, in serial with R6 (wich is 1k on the schematic), and remove any AC voltage source in this path, just keep one AC voltage source at the amp input.
To simulate the OLG just use a big inductance, say 100TH, in serial with R6 (wich is 1k on the schematic), and remove any AC voltage source in this path, just keep one AC voltage source at the amp input.
Make a try and see if the curves are the same than the ones you got with your first method, but that should be
very accurate, that s the method i use generaly for this kind of simulation.
very accurate, that s the method i use generaly for this kind of simulation.
That s about accurate, the OLG is actually close to 100dB with this kind of design, only thing that seems not accurate is this peaking at high frequency, remove the output RL filter for OLG simulations.
Edit : There s usually no need of an output RL filter with a capacitive coupled amp, the output capacitor has generaly
enough parasistic inductance and resistance to keep the amp stable on capacitive loads.
Edit : There s usually no need of an output RL filter with a capacitive coupled amp, the output capacitor has generaly
enough parasistic inductance and resistance to keep the amp stable on capacitive loads.
I tried to sim this amp, including square waves, see 3 attachments.
I guess the shape of the olg() graphs is this way, slightly different that I'm used to, but this amp is also
different....
My phase margin was 51 degrees, worse than in your post, but square waves look better.
I'm sure more tuning can improve it even further.
I guess the shape of the olg() graphs is this way, slightly different that I'm used to, but this amp is also
different....
My phase margin was 51 degrees, worse than in your post, but square waves look better.
I'm sure more tuning can improve it even further.
Thank you, dear minek!
Last two days, I had been trying to do the tuning. I started off with Bonsai's post:
https://www.diyaudio.com/community/...-a-power-amplifier-method.406145/post-7522505 .
With TPC disabled, C6=47p, F/Mag/Ph = 1.12MHz/ -23 / -70.
With c6=68p, F/ Mag/ Ph = 1.2Mhz/ 26 /75.
With C6=81p, F-Mag-Ph = 1000khz-28-77,
With C6=100p, F-Mag-Ph = 812khz-30-79.
TPC enabled:
C6=100p, C5=330p, R19=3k3, F-Mag-Ph = 1.05Mhz-27.7-70.4
C6=100p, C5=330p, R19=2k2, F-Mag-ph = 1.07Mhz -27.6-67.7
C6=100p, C5=330p, R19=4k7, F-Mag-Ph = 1.03Mhz-28.0-72.7
With Output L short removed, ------------- = 1.07Mhz-27.7-73.5.
TMC, ie C6=100p, C5=330p, R19=4k7, R19 connected to Output,
- - - - - - - - - - - - - - - - - - - - - - F-Mag -Ph = 1.07Mhz-27.8- 77.8
The concerned olg, Sq wave test, and Dis files for the last case are enclosed.
For comments please.
Last two days, I had been trying to do the tuning. I started off with Bonsai's post:
https://www.diyaudio.com/community/...-a-power-amplifier-method.406145/post-7522505 .
With TPC disabled, C6=47p, F/Mag/Ph = 1.12MHz/ -23 / -70.
With c6=68p, F/ Mag/ Ph = 1.2Mhz/ 26 /75.
With C6=81p, F-Mag-Ph = 1000khz-28-77,
With C6=100p, F-Mag-Ph = 812khz-30-79.
TPC enabled:
C6=100p, C5=330p, R19=3k3, F-Mag-Ph = 1.05Mhz-27.7-70.4
C6=100p, C5=330p, R19=2k2, F-Mag-ph = 1.07Mhz -27.6-67.7
C6=100p, C5=330p, R19=4k7, F-Mag-Ph = 1.03Mhz-28.0-72.7
With Output L short removed, ------------- = 1.07Mhz-27.7-73.5.
TMC, ie C6=100p, C5=330p, R19=4k7, R19 connected to Output,
- - - - - - - - - - - - - - - - - - - - - - F-Mag -Ph = 1.07Mhz-27.8- 77.8
The concerned olg, Sq wave test, and Dis files for the last case are enclosed.
For comments please.
Attachments
At a superficial glance - as much as you like.
No solution has been found, RC circuits placed at random do not add quality.
Does your input transistor have at least some gain?