I am attempting to make a very good quality +/-17.5 v power supply.
Please help me with this.
1. I have (does not mean I need to use it) an R core transf with two 18v secondaries. Model is RN-20.
2. Also, I have a rectifier board based around LM317 and LM337 regulators with AC,Gnd,AC on inputs and V-,Gnd,V+ on outputs.
3. And finally I have two Jung Superregulator boards.
Can I use the above to make what I am looking for? If not, what do I need to change?
thank you,
Herman
Please help me with this.
1. I have (does not mean I need to use it) an R core transf with two 18v secondaries. Model is RN-20.
2. Also, I have a rectifier board based around LM317 and LM337 regulators with AC,Gnd,AC on inputs and V-,Gnd,V+ on outputs.
3. And finally I have two Jung Superregulator boards.
Can I use the above to make what I am looking for? If not, what do I need to change?
thank you,
Herman
You have what you need. If you use the jung boards you will need to add rectifiers and caps before the board. But it will likely sound better than the 317/337 reg. What are you trying to power with this?
Your transformer will work with either reg. The 317/337 reg will be easier and cheaper to implement and is adjustable via a pot if that matters to you. The jung reg will require a little math to get the resistor values right.
Ive used both and prefer the jung reg.
Your transformer will work with either reg. The 317/337 reg will be easier and cheaper to implement and is adjustable via a pot if that matters to you. The jung reg will require a little math to get the resistor values right.
Ive used both and prefer the jung reg.
I don't get the idea that you are chasing perfection here, but want something that will perform well. 317/337 based regulated supplies are plenty good for analog audio applications. With the adjust pin bypassed and with input and output caps chosen correctly the 317/337 combination provides a relatively low noise and reliable option.
My idea was to power 317/337 board by transformer that I have. The 317/337 will power the Jung regulator for additional filtration.
has anyone tried this?
has anyone tried this?
Could work, you need at least a 2 volt drop on the 317 and a 5 volt drop on the super reg. Thats a 7 volt drop. Your transformer should give 24 v. That leaves you with 17 volts. But iam guessing you want to do this to use the smoothing caps and rectifiers of the 317 board with the super reg. You could just bypass the regs in the 317 board instead.
BTW...the choice of ic in the super reg is important at higher votages. Ad817 should work. Iam not an expert though.
Salas shunt is nice too but you may need a higher voltage transformer.
BTW...the choice of ic in the super reg is important at higher votages. Ad817 should work. Iam not an expert though.
Salas shunt is nice too but you may need a higher voltage transformer.
More questions.
JMFahey, do you believe it not necessary to regulate further the "basic" regulation of 317 and 337 because it will not improve the sound quality coming out of the opamp based pre-amp that I use? Please clarify, as I thought (without actually hearing the result) that cleaner power will improve the sound. Maybe not but please explain your reason to doubt this idea.
Hikari1, thanks for the clear answer about voltage requirement in my application.
I would like to ask for general advice on getting good sound out of the opamp based pre-amp through the use of a proper power supply. How far do I need to go? I am open to recommendations.
regards,
Herman
JMFahey, do you believe it not necessary to regulate further the "basic" regulation of 317 and 337 because it will not improve the sound quality coming out of the opamp based pre-amp that I use? Please clarify, as I thought (without actually hearing the result) that cleaner power will improve the sound. Maybe not but please explain your reason to doubt this idea.
Hikari1, thanks for the clear answer about voltage requirement in my application.
I would like to ask for general advice on getting good sound out of the opamp based pre-amp through the use of a proper power supply. How far do I need to go? I am open to recommendations.
regards,
Herman
The op amp used, layout, component selection, proper bypassing at the op amp supply pins, good grounding, etc. are all more important than "super regulating" your power supply. A poorly designed circuit can not really be improved with a better power supply. Take a look at the PSRR for your op amp - the op-amp's circuitry is already pretty immune to the power supply.
There are good implementations of the 317/337 and not so good ones. But implemented properly, these regulators are more than fine for analog audio power supplies.
Im new to the forum and hobby. I have blown a regulated board on a 2050 Class T amp. It worked perfectly well with my JLH 1969. What is the difference in power need?
Just curious why +/-17.5Vdc. If you are planning on using that for an op-amp with a datasheet "absolute maximum voltage" rating of +/-18Vdc (=36Vdc, or even 38Vdc), it probably isn't the best way to go. There is usually a disclaimer burried in the datasheet fine print that says something to the effect of "running at or near the absolute maximum values will reduce the life of the product". Plus what they don't say is several of the datasheet parameter listings may not be in spec, either. At the very least consider backing it down to +/-17Vdc since the voltage regulators are often +/-0.25V or +/-0.5V on load regulation. +/-16.5Vdc or +/-16Vdc should be "safe".
If you are using an op-amp with an absolute maximum rating of +/-23Vdc (=46Vdc) though, like the LME49860, then no problem. But in that case might as well round it off to +/-18V which is one of the datasheet table conditions, or bump it up to something like +/-20Vdc. The datasheet on that one is spec'ed at +/-22Vdc too, although I probably wouldn't do it if it were me.
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Why +/-17.5Vdc?
Because my pre-amp is stock with a switch mode PS. I measured with no load -- +/-17.5v.
This is the PS I want to replace with proper linear one, to see if it improves the sound. Not saying it will but need to try. I figure the PS is a good start.
regards,
Herman
Because my pre-amp is stock with a switch mode PS. I measured with no load -- +/-17.5v.
This is the PS I want to replace with proper linear one, to see if it improves the sound. Not saying it will but need to try. I figure the PS is a good start.
regards,
Herman
A regulated supply does not change voltage substantially when conditions change.
A linear supply changes voltage when the mains changes and when the load changes.
Simply swapping from regulated to linear could damage your circuit.
You need to find out the maximum recommended supply voltage for your circuit and you need the absolute maximum supply voltage.
You then need to DESIGN your linear supply to NEVER exceed the absolute maximum voltage for all worst case conditions.
An example.
an opamp could be specified for +-15Vdc and usable at upto +-17Vdc (starts to run a bit hot and may need attention to cooling/ventilation). The datasheet may specify absolute maximum as +-18Vdc (same as 36Vdc)
A linear supply changes voltage when the mains changes and when the load changes.
Simply swapping from regulated to linear could damage your circuit.
You need to find out the maximum recommended supply voltage for your circuit and you need the absolute maximum supply voltage.
You then need to DESIGN your linear supply to NEVER exceed the absolute maximum voltage for all worst case conditions.
An example.
an opamp could be specified for +-15Vdc and usable at upto +-17Vdc (starts to run a bit hot and may need attention to cooling/ventilation). The datasheet may specify absolute maximum as +-18Vdc (same as 36Vdc)
AndrewT,
I understand your point. Clarification: I plan to make a linear, regulated PS to replace the stock switch mode PS. The question is, when I am making a regulated linear supply, does it make sense to add a superregulator on top. From what i have read the superregulator will improve the basic regulated supply.
Is this a good idea or to bluntly state a waste of time?
Herman
I understand your point. Clarification: I plan to make a linear, regulated PS to replace the stock switch mode PS. The question is, when I am making a regulated linear supply, does it make sense to add a superregulator on top. From what i have read the superregulator will improve the basic regulated supply.
Is this a good idea or to bluntly state a waste of time?
Herman
Herman,
I think it is likely a waste of time. Walt Jung and Didden know what they are doing...and might even perform better by itself since it will be dropping more voltage.
That being said, if you have all the parts why not try the lm317 as a prereg. I would bet the difference is not big if even audible.
I think it is likely a waste of time. Walt Jung and Didden know what they are doing...and might even perform better by itself since it will be dropping more voltage.
That being said, if you have all the parts why not try the lm317 as a prereg. I would bet the difference is not big if even audible.
Personal opinion, others may differ, is that the LM317/337 output already shows microvolts ripple and noise; to be more precise, and quoting direct from the datasheet:
http://www.ti.com/lit/ds/symlink/lm317.pdf
and
And a typical Op Amp, let's say the humble TL072 , already has supply rejection of:
http://www.ti.com/lit/ds/symlink/tl072.pdf
So in practice possible hum and supply noise will be (considering worst case) 132dB below supply voltage which actually means it will be buried in the Op Amp own noise.
Which is excellent.😀
So in my personal view, adding extra 40 or 60dB attenuation ... below noise ... won't be noticed.
But that's not the main point.
What worries me a little is that if the purported objective were: "reduce ripple and noise by using XXXX" , that's a clear goal, and measurements or even calculation (if all data is available) can prove or disprove success, but when the dreaded words " it will sound better" are used, everything becomes subjective, some will say "I like it better than before" , others will say "no difference" and no conclusion is achieved.
Hope I made myself clear 🙂
EDIT: FWIW I think that the switching supply you are trying to substitute is noisier than anything an LM317 can offer ... and yet your preamp has worked very well 🙂
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The jung super regulator boards I built already had a preregulator in the circuit, eliminating the need to add another 317 in front of the jung.
I used the ALW boards.
Randy
I used the ALW boards.
Randy
When I first bought them, they were the only jung reg you could buy. And at some point he had a group buy here for a pretty reasonable cost.
And now there are other options.
Randy
If your equipment double insulation is the protection from electrocution and you will be replacing that with a transformer based supply you will need to consider the legal requirements about an electrical earth.
A possible way around that would be to house the transformer and rectification in a separately earthed chassis. That would give you scope to use a larger transformer, and larger smoothing caps. Feed would be by an umbilical cord with suitable male connector at the output end and matching female on the chassis.
Some advantages of that approach is that you can build a much more substantial power supply. If you select say 25-0-25 volt a.c. windings you can fit a pre-regulator in the separate chassis to bring the voltage to whatever levels you need for the regulators inside the main equipment.
This is an approach I have used to remove sources from radiated fields and vibration away from the proximity of signal inputs.
In building in a modular way like this you will have something you can re-use if you upgrade your present equipment or build your own project.
As far as IC regulators go I have used 317's and 337's mainly on the basis they don't require a lot of board space and they should be good enough as pre-regulators.
A possible way around that would be to house the transformer and rectification in a separately earthed chassis. That would give you scope to use a larger transformer, and larger smoothing caps. Feed would be by an umbilical cord with suitable male connector at the output end and matching female on the chassis.
Some advantages of that approach is that you can build a much more substantial power supply. If you select say 25-0-25 volt a.c. windings you can fit a pre-regulator in the separate chassis to bring the voltage to whatever levels you need for the regulators inside the main equipment.
This is an approach I have used to remove sources from radiated fields and vibration away from the proximity of signal inputs.
In building in a modular way like this you will have something you can re-use if you upgrade your present equipment or build your own project.
As far as IC regulators go I have used 317's and 337's mainly on the basis they don't require a lot of board space and they should be good enough as pre-regulators.
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