Regulated valve buffer with lm317 and lm337.
I want to regulated a valve buffer of a gainclone.
I know i can do this with the lm317 and lm337.
Have them laying around.
The transformer i want to use is 30 volts.
So that would be 40 volts DC on each rail.
Thats the max input voltage of these regulators.
And i want a output of 35 volts.
I don't want to run them that high.
My question is can i lift the adjust pin with a zener diode?
Lets say i put in a 10 volt zener, so that the input to adjust pin on
the lm3xx would be 30 volts.
Is this possible?
I want to regulated a valve buffer of a gainclone.
I know i can do this with the lm317 and lm337.
Have them laying around.
The transformer i want to use is 30 volts.
So that would be 40 volts DC on each rail.
Thats the max input voltage of these regulators.
And i want a output of 35 volts.
I don't want to run them that high.
My question is can i lift the adjust pin with a zener diode?
Lets say i put in a 10 volt zener, so that the input to adjust pin on
the lm3xx would be 30 volts.
Is this possible?
I know there's a constant current.
I don't think i understand you Franz.
As i see it the voltage of the +- rails of about 35 volts can drop or rise when the mains is not stable.
So with regulation this will be stable.
So my question was how to let the lm317 and the lm 337 work with an input voltage of 40 volt.
I don't want to run them on there maximum input voltage.
I don't think i understand you Franz.
As i see it the voltage of the +- rails of about 35 volts can drop or rise when the mains is not stable.
So with regulation this will be stable.
So my question was how to let the lm317 and the lm 337 work with an input voltage of 40 volt.
I don't want to run them on there maximum input voltage.
Hi,Franz G said:
Regulators are used to suppress ripple from bridge stage. Tube buffer has poor PSRR and needs very clean rails. But, regulators can insert HF noise in rails also, etc. CLC network is the best solution, IMO. Or maybe using Didden's regulators.
Yes, You are wrong. Regulators are normally used in constant current applications. Three pin regulators are usually poor performers in power amps applications.
Regards
Milan
This might be a crazy idea to try....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=26097&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=26097&highlight=
Lm317/Lm337 don't have a max. input.
To Ebijma
The Lm317T/Lm337T don't have a max. input voltage, but it does have a max. input-output difference of 37 V. This means that the regulator is "floating" and you could have 200 V at the input and 180 V at the output if you get my point, so your 40 V at the input and 35 V at the output is not a problem.
Have fun
Thomas
To Ebijma
The Lm317T/Lm337T don't have a max. input voltage, but it does have a max. input-output difference of 37 V. This means that the regulator is "floating" and you could have 200 V at the input and 180 V at the output if you get my point, so your 40 V at the input and 35 V at the output is not a problem.
Have fun
Thomas
Hi,
If you want to improve the performance of the tube buffer, use a CCS as a current sink on the cathode of the tube.
Moamps probably designed one already IIRC....
You can still regulate the B+ and B- voltagewise if you must but I'm no big fan of the LM317 series of regs to do that.
Besides, series regs are basically high NFB class B amps but this shouldn't be an issue here.
In fact the best results_soundwise_ can be obtained using a common mode choke CLC type filter/regulator IMO provided you run the stage in Class A1, which I think is what you guys do anyway.
Cheers,
If you want to improve the performance of the tube buffer, use a CCS as a current sink on the cathode of the tube.
Moamps probably designed one already IIRC....
You can still regulate the B+ and B- voltagewise if you must but I'm no big fan of the LM317 series of regs to do that.
Besides, series regs are basically high NFB class B amps but this shouldn't be an issue here.
In fact the best results_soundwise_ can be obtained using a common mode choke CLC type filter/regulator IMO provided you run the stage in Class A1, which I think is what you guys do anyway.
Cheers,
Upupa Epops said:CLC network is not regulator ( stabiliser ). " ... constant current application.. " - realy ? " ... three pin... " - realy ? Why ? Summary : Franz, do all like in year '26, 'cos all past this year is wrong
What's your problem UpupaEpops? First, fix your broken English and explain in full sentences what it is exactly that bothers you about what I wrote in my last post. Then I'll explain everything you want to know in the simplest of terms, free of charge this time. Next time I will ask you for a proof that you have made a payment of US$20 minimum for diyAudio server maintenance.
Milan
moamps, I'll give it a try (I've spent way too much time in Prague- I'm starting to understand them!):
"A CLC network is not a regulator. It is a filter, but has progressively worse performance at low frequencies and DC. I do not believe this to be a constant current application, so the lack of regulation could end up being a problem. The audio design art reached its apogee in 1926; everything since then has been retrograde. Do things the way a 1926 engineer would when you're working with 1926 technology."
Personally, for the buffers in my electronic crossover, I'm pretty happy with a 317K floated by a high-voltage MOSFET at the input, with its gate tied to 15 volts above the regulated output via a resistor and a zener. With proper bypassing at the output and the appropriate protection diodes, it's a regulator that's stable, quiet, and reliable, if not the last word in low source Z. But for a tube circuit, the source Z is low enough.
"A CLC network is not a regulator. It is a filter, but has progressively worse performance at low frequencies and DC. I do not believe this to be a constant current application, so the lack of regulation could end up being a problem. The audio design art reached its apogee in 1926; everything since then has been retrograde. Do things the way a 1926 engineer would when you're working with 1926 technology."
Personally, for the buffers in my electronic crossover, I'm pretty happy with a 317K floated by a high-voltage MOSFET at the input, with its gate tied to 15 volts above the regulated output via a resistor and a zener. With proper bypassing at the output and the appropriate protection diodes, it's a regulator that's stable, quiet, and reliable, if not the last word in low source Z. But for a tube circuit, the source Z is low enough.
SY said:
You've obviously never been to Croatia...I bet we can top both the wine and the girls hands down.
http://www.bluedanubewine.com/croatia.html
My European sales manager is Czech, so it was just like reading one of his trip reports.
Anyway, with regards to regulation, Joe Curcio claims that if you do the 317 plus stand-off transistor trick, you should use a bipolar, not a FET. I used a FET because I happened to have a bunch and I'm not too worried about the slightly higher channel resistance. It seems to work just fine. But does anyone else have any experience comparing performance in a circuit like this?
Anyway, with regards to regulation, Joe Curcio claims that if you do the 317 plus stand-off transistor trick, you should use a bipolar, not a FET. I used a FET because I happened to have a bunch and I'm not too worried about the slightly higher channel resistance. It seems to work just fine. But does anyone else have any experience comparing performance in a circuit like this?
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