May be you can use midlebrook method with less precision than tian probe. If you don't know how to measure phase margin and gain margin in ltspice, you should not comment my simulation is wrong
Hi Bimo,
The Turtledove is singing beautifully. Very, very nice! Thanks for sharing this design with us. It played from first start up. Looks great on the scope. I have it playing right now on my A/B system. Compared it to the Honey Badger and Peeceebee so far. Holds it own very well and I just have it on a so-so PSU. 160VA 30-0-30vac transformer and 6X4700 caps. Even with this small PSU it sounds really, really good. I will be recommending this one to my friends.
Blessings, Terry
The Turtledove is singing beautifully. Very, very nice! Thanks for sharing this design with us. It played from first start up. Looks great on the scope. I have it playing right now on my A/B system. Compared it to the Honey Badger and Peeceebee so far. Holds it own very well and I just have it on a so-so PSU. 160VA 30-0-30vac transformer and 6X4700 caps. Even with this small PSU it sounds really, really good. I will be recommending this one to my friends.
Blessings, Terry
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Thank you, if you enjoy this amplifier.
Can I put this pictures to my blog? Can you take some pictures of the scope?
Bimo, something is not right. The graph shows the gain @ 1KHz is some 6db. Open loop. It can't be the case... too low to be truth... in this case the margins are also calculated incorrectly.
Of course it is right. This amplifier have low open loop gain (micron). This is the open loop gain using Bob Cordell method (insert 1GH inductor in feedback).
You make an assumption, please run the simulator
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This is what I see, looking at the global loop
You're right, the loop gain is low. The margins are good, mainly because of that reason - although they are slightly lower than the ones presented earlier. But ULGF at 140 KHz shows the amp is heavily compensated (mainly with the cap between the VAS output and (-) input - influencing overall speed of the circuit and THD at the higher end of the audio frequency range, as well as phase response (around 8.5 degrees phase shift @ 20 KHz with the loop closed).
Nevertheless, it's an interesting, working low loop gain design with rather low THD (for such a low loop gain).
Cheers,
Valery
You're right, the loop gain is low. The margins are good, mainly because of that reason - although they are slightly lower than the ones presented earlier. But ULGF at 140 KHz shows the amp is heavily compensated (mainly with the cap between the VAS output and (-) input - influencing overall speed of the circuit and THD at the higher end of the audio frequency range, as well as phase response (around 8.5 degrees phase shift @ 20 KHz with the loop closed).
Nevertheless, it's an interesting, working low loop gain design with rather low THD (for such a low loop gain).
Cheers,
Valery
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This is what I see, looking at the global loop
You're right, the loop gain is low. The margins are good, mainly because of that reason - although they are slightly lower than the ones presented earlier. But ULGF at 140 KHz shows the amp is heavily compensated (mainly with the cap between the VAS output and (-) input - influencing overall speed of the circuit and THD at the higher end of the audio frequency range, as well as phase response (around 8.5 degrees phase shift @ 20 KHz with the loop closed).
Nevertheless, it's an interesting, working low loop gain design with rather low THD (for such a low loop gain).
Cheers,
Valery
This circuit is simple, class B. If it make class AB, it can achieve high ULGF, like http://anistardi.wordpress.com/2014/04/19/aksa-55-dalam-simulasi/
By the way, tian probe is easier to measure phase margin and gain margin, but I know you don't like to use Ltspice.
The phase margin reported from post #73 is 88.9 deg and the gain margin 24.6dB, which are different from those figures in post #49.
I tend to believe post #73 is correct, with simple Miller compensation, in theory the phase margin cannot exceed 90 degree.
The Tian probe plot in post 54 indicates an OLG of 6dB @1kHz, which is very suspicious when the CLG is much higher.
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It is OK.
But my favorite is Blameless 150. I sell the PCB. It is mini Honey Badger (like Honey Badger but without input cascade and PSU is +-45V DC). It you want to try it, just PM your email, I will send the schematic and the gerber file. I do not want publish the schematic
https://anistardi.wordpress.com/2014/06/25/blameless-150/
First time I design this amp, conservatively. I was afraid to make fast amp (high slew rate). But with slew rate about 90V/uS, it better than 4 OEM amp which more expensive. But my friend said the bass is not deep. Then I tweak to get more deep bass and more fast.
The trannies that I use on Blameless 150 are not easily to find in my country
Some of my friends want me to design powerful amp with "ordinary" components. The love powerful amp
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