Re: Re: Given up on the AD811...
Thanks for the offer Bernhard, but I think I might leave this one for a while and build something that might work!😉
I used the basic schema of Netlist, as shown below, and I tried many permutations of feedback resistors, put in some dominant poles, ( even down to 20K), coupled this, decoupled that, and just created a huge mess, destroying 3 of my 4 811s and one OPA 548 in the process. But it was fun, (I think), and I certainly don't regret it one bit, and I learnt a lot of stuff in the process.
I think when I come back to this I might be tempted to try and use Self's class G outputs (dual high and low power rail) to try and make a high power version.
Bernhard said:
Could you post your schematic ?
You know I had oszillation problems like hell too, but I fixed it
May be I can help.
Thanks for the offer Bernhard, but I think I might leave this one for a while and build something that might work!😉
I used the basic schema of Netlist, as shown below, and I tried many permutations of feedback resistors, put in some dominant poles, ( even down to 20K), coupled this, decoupled that, and just created a huge mess, destroying 3 of my 4 811s and one OPA 548 in the process. But it was fun, (I think), and I certainly don't regret it one bit, and I learnt a lot of stuff in the process.
I think when I come back to this I might be tempted to try and use Self's class G outputs (dual high and low power rail) to try and make a high power version.
Attachments
I'm not sure what you mean by this?Bernhard said:There is a way to make my high power version work rail to rail
/Hugo
Netlist said:
Now still there is a clipping barrier of 6V below rails,
maximum Vop output is 2 x ( rails - 6V ),
and I believe it is possible to shift this barrier very close to the rails.
Netlist said:
I understand now. Too bad I can't get you 'engineering' advice.
/Hugo
I'm not sure what you mean by this?
Instead of the BC550/60 + 2 resistors I could try low drop 78/7912 voltage regulators. 
With 12V rails for the OPs instead of 15 V the clipping starts 5 V below rails instead of 6 V.
Not what I dreamed of.
What about TO3 Voltage regulators instead of mosfet/bipolar transistors ?
I heard a fixed voltage regulator can be made variable by connecting the pin in the middle to a voltage instead to ground.
With 12V rails for the OPs instead of 15 V the clipping starts 5 V below rails instead of 6 V.
Not what I dreamed of.
What about TO3 Voltage regulators instead of mosfet/bipolar transistors ?
I heard a fixed voltage regulator can be made variable by connecting the pin in the middle to a voltage instead to ground.
I re-adjusted R15 and R16 back to 7.5k.
This final version gives me the best performance technically and musically unless any further adjustment and improvement is made by masters like Nelson Pass (without introducing additional components).
JH
Building two more ships to complete 6 channels. 🙂
This final version gives me the best performance technically and musically unless any further adjustment and improvement is made by masters like Nelson Pass (without introducing additional components).
JH
Building two more ships to complete 6 channels. 🙂
Attachments
As the high power version is stable now and I won another 16 lateral MosFets @ ebay, I will start building the 8 channels soon, if not...
...if not the idea of dynamic idle current will melt my brain
Also I am thinking about a real dynamic current source for single ended operation, with real low idle current
and I won another 16 lateral MosFets @ ebay, I will start building the 8 channels soon, if not......if not the idea of dynamic idle current will melt my brain
Also I am thinking about a real dynamic current source for single ended operation, with real low idle current
Having great pleasure in hearing from you, I must say, ¡°Indeed thanks to you, Nelson Pass, I¡¯ve got this project.¡± When I have first seen your sketch, I have seen a great value from it because it has been made by a man having really shining know-how and long experience.
By the way, most appreciation is that this project has motivated me to read and study the basic of electronics: voltage, current, resistor, capacitor, inductor, physics, math, op amp, transistor, oscillation, loop gain, phase shift, stability and...
Meanwhile, a bad news is that, nevertheless, I am still confused with them.
I have wanted to complete this project nice way as professionals do. My limited capability however does not allow it. If some one could do, I would really like to leave it to him (or her) and appreciate much.
Thanks again, Mr Nelson Pass.
JH
PS
Eeeeeeeng... I might have to be away from diyAudio for a while. I would have a business trip to Shanghai, where I might move to for years.
Hoping no more SARS...
By the way, most appreciation is that this project has motivated me to read and study the basic of electronics: voltage, current, resistor, capacitor, inductor, physics, math, op amp, transistor, oscillation, loop gain, phase shift, stability and...
Meanwhile, a bad news is that, nevertheless, I am still confused with them.
I have wanted to complete this project nice way as professionals do. My limited capability however does not allow it. If some one could do, I would really like to leave it to him (or her) and appreciate much.
Thanks again, Mr Nelson Pass.
JH
PS
Eeeeeeeng... I might have to be away from diyAudio for a while. I would have a business trip to Shanghai, where I might move to for years.
Hoping no more SARS...
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