Hi, guys
You just don't read all threads it seems to me... The 2N4401/03 similar improved parts from Hitachi were pointed in my post 391 ...
The Rbb' is only 2 Ohms for the 2SB737, and, sorry for the small mistake, its 2SD786 compliment (instead of 2SD756) is only 4 Ohms...
Great parts for MC cartridges preamplifiers but, sadly enough, no more in production now l
Jbaudiophile
You just don't read all threads it seems to me... The 2N4401/03 similar improved parts from Hitachi were pointed in my post 391 ...
The Rbb' is only 2 Ohms for the 2SB737, and, sorry for the small mistake, its 2SD786 compliment (instead of 2SD756) is only 4 Ohms...
Great parts for MC cartridges preamplifiers but, sadly enough, no more in production now l
Jbaudiophile
Hi,
For the power supply of its Blowtorch Preamplifier, we know all that John Curl uses, a shunt regulation with MosFets as second regulator.
Few designers use this principle. We can to built a shunt regulation, for a same polarity, with channel P Mosfet or channel N Mosfet.
But in the Post 164, Mr. Curl says:
"" the second regulator is an open loop shunt regulator ""
It is not a disposition very frequent.
Also, today, I propose you, for opinion, a new design, that I think to be an open loop regulator.
LM317 and R0 = CCS
Voltage regulator = TL431
R2 and C1 = noise filter of the TL431
Darry
For the power supply of its Blowtorch Preamplifier, we know all that John Curl uses, a shunt regulation with MosFets as second regulator.
Few designers use this principle. We can to built a shunt regulation, for a same polarity, with channel P Mosfet or channel N Mosfet.
But in the Post 164, Mr. Curl says:
"" the second regulator is an open loop shunt regulator ""
It is not a disposition very frequent.
Also, today, I propose you, for opinion, a new design, that I think to be an open loop regulator.
LM317 and R0 = CCS
Voltage regulator = TL431
R2 and C1 = noise filter of the TL431
Darry
Nice reg
I do not know if it is open loop, but looks like it should get the output noise way down there. Have you looked at the other rail supply yet?
Planning on building another supply for my current linestage. It is not class A. The supply used now is a sledgehammer type approach. High impedance, lots of passive filtering and energy storage after a 317/337 combo.
I may try copying some like the regs in my Borbely 419 phono. These are widebandwidth and all active. Should be better with changing current demands.
This thread is very interesting. Lots of ideas bounced around. Sorry for the OT posts.
And I am glad that the fets are better for the actual circuitry. I hate to waste time chasing unobtainium and then not liking the results when it is all said and done.
George
I do not know if it is open loop, but looks like it should get the output noise way down there. Have you looked at the other rail supply yet?
Planning on building another supply for my current linestage. It is not class A. The supply used now is a sledgehammer type approach. High impedance, lots of passive filtering and energy storage after a 317/337 combo.
I may try copying some like the regs in my Borbely 419 phono. These are widebandwidth and all active. Should be better with changing current demands.
This thread is very interesting. Lots of ideas bounced around. Sorry for the OT posts.
And I am glad that the fets are better for the actual circuitry. I hate to waste time chasing unobtainium and then not liking the results when it is all said and done.
George
Darry said:
Looks very nice Darry...
Which is the advantage of connecting the LM317 as a current reg?
Does this mean that the reg works both ways? current and voltage? I'm sure this will sound a very silly question but I seldom see a current reg except for coils that seem to work on a diferent way though.
It would be nice to see a shematic for the negative rail as a complement
Typical active regulators have many problems. However, they are cheap and can give a reasonably accurate output voltage.
These problems include:
They are noisy, because the reference is unbypassed.
They respond to changes in current with transient overshoot.
They are virtually out of the circuit at low RF or CD clock frequencies.
They can easily pass fast line transients.
This is OK?
These problems include:
They are noisy, because the reference is unbypassed.
They respond to changes in current with transient overshoot.
They are virtually out of the circuit at low RF or CD clock frequencies.
They can easily pass fast line transients.
This is OK?
Hi, John, and others,
Yes, the internal voltage reference can't indeed be bypassed... Sadly... And the integrated opamp just put lots of current toward the output, with a very low impedance (say, 0.2 ohms)... Not easy fo filter any noise then...
You had a previous thread just explaining us that a better way to use them would be to use not too good a capacitor then, or to put a low value resistor in series with the output in order to have the impedance higher, and degrade LM317 performance...
But Darry's idea is quite different, as I can see it. It is to use the LM317 as a SERIES preregulator ahead a SHUNT regulator, as I can see it. Running open loop, yes.... And perhaps too class A, a concept too rarely seen (only ONE exception IMO....).
With this arrangement, the LM317 can't do any harm, as the charge will see a very low impedance supply source... With the Mosfet that helps, the output impedance can be pretty low, perhaps 30 milliohms or lower... That's is a fairly good improvment on the LM317 alone... Ands the Mosfet can be large enough to run large currents without too much problems, and no heat sink for preamplifiers supplies . Interesting concept... from a mine native ! Panelhead and Darry, just drop me a line !!!
I will just drop soap operas at my TV set to suit that thread... LOL ! My own calculator is now on !
But still happy to have your own coimments on, John, as most students here... In fact, the biggest university on Earth !
Jbaudiophile
Yes, the internal voltage reference can't indeed be bypassed... Sadly... And the integrated opamp just put lots of current toward the output, with a very low impedance (say, 0.2 ohms)... Not easy fo filter any noise then...
You had a previous thread just explaining us that a better way to use them would be to use not too good a capacitor then, or to put a low value resistor in series with the output in order to have the impedance higher, and degrade LM317 performance...
But Darry's idea is quite different, as I can see it. It is to use the LM317 as a SERIES preregulator ahead a SHUNT regulator, as I can see it. Running open loop, yes.... And perhaps too class A, a concept too rarely seen (only ONE exception IMO....).
With this arrangement, the LM317 can't do any harm, as the charge will see a very low impedance supply source... With the Mosfet that helps, the output impedance can be pretty low, perhaps 30 milliohms or lower... That's is a fairly good improvment on the LM317 alone... Ands the Mosfet can be large enough to run large currents without too much problems, and no heat sink for preamplifiers supplies . Interesting concept... from a mine native ! Panelhead and Darry, just drop me a line !!!
I will just drop soap operas at my TV set to suit that thread... LOL ! My own calculator is now on !
But still happy to have your own coimments on, John, as most students here... In fact, the biggest university on Earth !
Jbaudiophile
Really nice regulator Darry, but you must pay attention to the mosfet Vgs value to keep enough power supply margin for the op amp, or supply it before the current source and maybe you should add a resistor between the op amp output and the mosfet gate to avoid oscillation with complex loads, I like the RC filter after the TL431 reference in “open loop” configuration.
My question also.
The complex active regs look very good. My main question is if they work better on most circuits than a simple 317/337 with an LC filter on the output?
I have that one already, guess I need to sort out a suitable circuit and try the discrete widebandwidth, low feedback approach to see if I can hear any improvements.
The lower output impedance has to pay some benefits, plus the lack of large storage caps decoupling the circuits. In theory anyway.
Anyone know modern subs for 2SJ313, 2SJ148, 2SK982, and 2SK2013? Going seaching now to see.
George
The complex active regs look very good. My main question is if they work better on most circuits than a simple 317/337 with an LC filter on the output?
I have that one already, guess I need to sort out a suitable circuit and try the discrete widebandwidth, low feedback approach to see if I can hear any improvements.
The lower output impedance has to pay some benefits, plus the lack of large storage caps decoupling the circuits. In theory anyway.
Anyone know modern subs for 2SJ313, 2SJ148, 2SK982, and 2SK2013? Going seaching now to see.
George
It probably depends on what type of circuit you are using as a preamp. Some are more sensitive to power supply than others. I KNOW that my Vendetta input stage is very sensitive to power supply regulators. I have done A-B comparisons. For a simple IC based line amp, the power supply is probably less important.
Typical active regulators have many problems. However, they are cheap and can give a reasonably accurate output voltage.
These problems include:
They are noisy, because the reference is unbypassed.
They respond to changes in current with transient overshoot.
They are virtually out of the circuit at low RF or CD clock frequencies.
They can easily pass fast line transients.
This is OK?
These problems include:
They are noisy, because the reference is unbypassed.
They respond to changes in current with transient overshoot.
They are virtually out of the circuit at low RF or CD clock frequencies.
They can easily pass fast line transients.
This is OK?
Hi, Upupa,
John used lots of capacitor mutipliers in early works, then switched to Jfet or Mosfet based filters.
But he never departed from LM317 use, so it must be OK for our own PSUs...
And I just don' fully agree with your point of view : John said a couple times that the rubbish on mains supply lines has grown those 10 last years at a tremendous rate. I could verify that it is no more "clean" as it used to be, and from my own data, very fast transients on mains just enter your own audio stuff very easily indeed.. RFI, industrial ngenerated noise, airwaves,... All of that IS on the mains now...
It is not possible to have mains clean again, so the best we can do is to PREVENT, or at least ATTENUATE the noise rubbish on mains.... I plan to run a close cousin of the Blowtorch supply, as John was kind enough to tell us the key concept : several progressive acting trap, all doing their job in different frequency domains. IMO, the Blowtorch supply is NOT a PSU, but rather a full multi level trap !!!
Split-bobbin Xformer, CMC filtering, series regulators, shunt regulators perhaps as per Darry's idea...
Interesing idea, at least for me !!!!
Jbaudiophile
John used lots of capacitor mutipliers in early works, then switched to Jfet or Mosfet based filters.
But he never departed from LM317 use, so it must be OK for our own PSUs...
And I just don' fully agree with your point of view : John said a couple times that the rubbish on mains supply lines has grown those 10 last years at a tremendous rate. I could verify that it is no more "clean" as it used to be, and from my own data, very fast transients on mains just enter your own audio stuff very easily indeed.. RFI, industrial ngenerated noise, airwaves,... All of that IS on the mains now...
It is not possible to have mains clean again, so the best we can do is to PREVENT, or at least ATTENUATE the noise rubbish on mains.... I plan to run a close cousin of the Blowtorch supply, as John was kind enough to tell us the key concept : several progressive acting trap, all doing their job in different frequency domains. IMO, the Blowtorch supply is NOT a PSU, but rather a full multi level trap !!!
Split-bobbin Xformer, CMC filtering, series regulators, shunt regulators perhaps as per Darry's idea...
Interesing idea, at least for me !!!!
Jbaudiophile
Dear Sirs,
I went through all this thread but I could not find any post hinting about the topology of the circuit.
I seem to remember some rumors about a single amplification stage made out of more fets in parallel, no feedback.
Something like the Conrad Johnson ART preamp but made instead with fets.
Any info about this.
Kind regards,
beppe
I went through all this thread but I could not find any post hinting about the topology of the circuit.
I seem to remember some rumors about a single amplification stage made out of more fets in parallel, no feedback.
Something like the Conrad Johnson ART preamp but made instead with fets.
Any info about this.
Kind regards,
beppe
- Status
- Not open for further replies.