For sometime, I have been following conventional widom and replacing 78 and 79 regulators with LT 1085/6, LT323 and LM320/340 types. How wrong!!
I wanted to use lower noise units for a dac ; and so made some measurements on 5V units with 50mA current and 10uf tantalum output cap with an ac volmeter capable of up to 1 Meg with 0.5 uV or better resolution.
Result?
JRC 7805 - 40 uV - to spec
LT1086 - 150 uV - to spec
LT323 - 50 uV
LM340 - 60 uV
Why is the LT range so touted??
Does anyone know who makes the M5F7805L range of reulators; I want to check on spec as I have a whole bunch of them in my dac?
Has anyone designed/sell a pin compatible replacement on a pcb that costs less than £40 with say 10 uV or less noise wideband?
I wanted to use lower noise units for a dac ; and so made some measurements on 5V units with 50mA current and 10uf tantalum output cap with an ac volmeter capable of up to 1 Meg with 0.5 uV or better resolution.
Result?
JRC 7805 - 40 uV - to spec
LT1086 - 150 uV - to spec
LT323 - 50 uV
LM340 - 60 uV
Why is the LT range so touted??
Does anyone know who makes the M5F7805L range of reulators; I want to check on spec as I have a whole bunch of them in my dac?
Has anyone designed/sell a pin compatible replacement on a pcb that costs less than £40 with say 10 uV or less noise wideband?
Conventional wisdom is using 78xx regulators. As I found out too they are not as bad as people think they are. Some exceptions are 78Lxx ( 100 mA version, tends to oscillate easily ) and 78Sxx ( 2 Amp version, for some reason screws up sound when used as a replacement for 78xx ).
Could it be that the internals of the newer 78xx series differs from the old ones ? I can remember that I had to match 7818's because some gave 17.2 and some even 19 Volt. Newer 78xx regulators are very precise and noise is lower too. Negative 79xx series were famous for oscillation when used without cap at the output and without load. Nowadays they don't have a problem with that
Could it be that the internals of the newer 78xx series differs from the old ones ? I can remember that I had to match 7818's because some gave 17.2 and some even 19 Volt. Newer 78xx regulators are very precise and noise is lower too. Negative 79xx series were famous for oscillation when used without cap at the output and without load. Nowadays they don't have a problem with that
Re: Re: Re: Voltagr Reugulator NOISE
Go back and make sure you don't have a bad part. Also, adjustable regulators allow you to bypass the adjustment terminal to lower the noise below fixed voltage regulators. I have found the LT 1086 to be a measurable and sonic improvement over fixed voltage three terminal regulators. I think you guys just what to save money with 78XX types. They are much cheaper. Why not build your own discreet transistor regulators?
fmak said:
Go back and make sure you don't have a bad part. Also, adjustable regulators allow you to bypass the adjustment terminal to lower the noise below fixed voltage regulators. I have found the LT 1086 to be a measurable and sonic improvement over fixed voltage three terminal regulators. I think you guys just what to save money with 78XX types. They are much cheaper. Why not build your own discreet transistor regulators?
My two cents worth!
You should listen to Fred. The difference between a good discreet regulator and a chip are usually huge. Much more than the difference between chip types.
I have replaced chip regulators in some rather expensive equipment with discreet regulators and always have had excellent results.
Not meaning to advertise for Fred but he has posted an exellent design in the forum, you owe it to yourselves to try.
Regards,
Jam
You should listen to Fred. The difference between a good discreet regulator and a chip are usually huge. Much more than the difference between chip types.
I have replaced chip regulators in some rather expensive equipment with discreet regulators and always have had excellent results.
Not meaning to advertise for Fred but he has posted an exellent design in the forum, you owe it to yourselves to try.
Regards,
Jam
Re: Re: Re: Re: Voltagr Reugulator NOISE
Don't need to. Whatever people hear, go to the LT1086 data sheet; the noise voltage is 0.003% of output voltage which is 150 uV for 5V out. For a 7805, the noise voltage is 40 uV. Now the output impedances and other factors may differ, but that is another issue.
What have you measured about the 1086 which is better?
I agree that discrete regulators are better. Twenty, thirty years ago, we were building Japanese designs with current sources etc. which sounded much better. The problem now is that these and other designs are TOO big for stuffing into existing digital systems which may need 9-12 regulators. The only design I know off is the Audiocom regulator which can be plugged into a 78x or 79x designed board but they want £40 for one which to me is too much. Hence my post.
----------------------------------------------Fred Dieckmann said:
Don't need to. Whatever people hear, go to the LT1086 data sheet; the noise voltage is 0.003% of output voltage which is 150 uV for 5V out. For a 7805, the noise voltage is 40 uV. Now the output impedances and other factors may differ, but that is another issue.
What have you measured about the 1086 which is better?
I agree that discrete regulators are better. Twenty, thirty years ago, we were building Japanese designs with current sources etc. which sounded much better. The problem now is that these and other designs are TOO big for stuffing into existing digital systems which may need 9-12 regulators. The only design I know off is the Audiocom regulator which can be plugged into a 78x or 79x designed board but they want £40 for one which to me is too much. Hence my post.
So, does anybody have a printed wiring board for either of those discrete regulators?
I too, am looking for a good regulator for a preamp project, and if its small enough, would consider replacing some 78XX regulators in my CDP.
Audioexpress sells the jung superregulator board for $25 plus shipping, but that seems kind of expensive for just a board.
Been searching here and at headwize, and I find threads on regulators, but never found where anybody acutally offered a PWB.
Randy
I too, am looking for a good regulator for a preamp project, and if its small enough, would consider replacing some 78XX regulators in my CDP.
Audioexpress sells the jung superregulator board for $25 plus shipping, but that seems kind of expensive for just a board.
Been searching here and at headwize, and I find threads on regulators, but never found where anybody acutally offered a PWB.
Randy
PCB for discrete regulators
Go here and you will find the Sulzer regulator:
http://hitechnetworks.net/bwaldron/audioelectronics/sb1_regulator.htm
That sophisticated regulator is also very good, still measured quite well on Walt Jung's test and it's easier to build, because it uses a one-sided board.
W.Jung did a revision on his superregulator, which was published in in Audio Electronics, to solve some problems the first design had. Do find out if the pcb Audioxpress sells now is modified for those revision changes. If it is go for it, if it's not you would have to do further wirings and modifications to do those changes. Certainly not worth the money you paid.
Carlos
randytsuch said:
Go here and you will find the Sulzer regulator:
http://hitechnetworks.net/bwaldron/audioelectronics/sb1_regulator.htm
That sophisticated regulator is also very good, still measured quite well on Walt Jung's test and it's easier to build, because it uses a one-sided board.
W.Jung did a revision on his superregulator, which was published in in Audio Electronics, to solve some problems the first design had. Do find out if the pcb Audioxpress sells now is modified for those revision changes. If it is go for it, if it's not you would have to do further wirings and modifications to do those changes. Certainly not worth the money you paid.
Carlos
PCB for discrete regulators
Go here and you will find the Sulzer regulator:
http://hitechnetworks.net/bwaldron/audioelectronics/sb1_regulator.htm
That sophisticated regulator is also very good, still measured quite well on Walt Jung's test and it's easier to build, because it uses a one-sided board.
W.Jung did a revision on his superregulator, which was published in in Audio Electronics, to solve some problems the first design had. Do find out if the pcb Audioxpress sells now is modified for those revision changes. If it is go for it, if it's not you would have to do further wirings and modifications to do those changes. Certainly not worth the money you pay.
Warning: none of these regulators (or any discrete one) is "small enough". Certainly not to replace a chip regulator. But they are worth finding the space to put them in.
Carlos
randytsuch said:
Go here and you will find the Sulzer regulator:
http://hitechnetworks.net/bwaldron/audioelectronics/sb1_regulator.htm
That sophisticated regulator is also very good, still measured quite well on Walt Jung's test and it's easier to build, because it uses a one-sided board.
W.Jung did a revision on his superregulator, which was published in in Audio Electronics, to solve some problems the first design had. Do find out if the pcb Audioxpress sells now is modified for those revision changes. If it is go for it, if it's not you would have to do further wirings and modifications to do those changes. Certainly not worth the money you pay.
Warning: none of these regulators (or any discrete one) is "small enough". Certainly not to replace a chip regulator. But they are worth finding the space to put them in.
Carlos
binatang said:
My guess is they are probably W.Jung supply clones, which were also a variation of the Sulzer supply.
The main thing Jung brought to the Sulzer design, besides using modern chips like the AD797, was a direct feedback from the point where the supply went into the powered device.
The Audiocom regulator uses an AD797, but I don't think they provide that feedback.
ALW and others reported very good results using the AD825, which is a bit less tricky than the AD797 to implement.
Carlos
carlmart said:
Just for the record: the Jung regulator article series was a joint effort of Walt Jung, Gary Galo and myself. The introduction of the feedback from the load point (known as remote sensing) to these regulators was from the undersigned.
If you look for an updated pcb, ALW has an excellent implementation, which I have tested and found to be superior to the original ones.
Jan Didden
Other improvements
Also the later revision added a bootstrapped supply ot the op-amp, improving line rejection greatly.
The AD825 versions are superb, cheap and very stable. The variant Jan measured used the newer AD8065, for even wider bandwidth.
It limits voltage a bit though, as the AD8065 is a +/-12V part
It's worth noting and pondering that the AD825 gives better SONIC performance than the lower noise AD797.
Andy.
Also the later revision added a bootstrapped supply ot the op-amp, improving line rejection greatly.
The AD825 versions are superb, cheap and very stable. The variant Jan measured used the newer AD8065, for even wider bandwidth.
It limits voltage a bit though, as the AD8065 is a +/-12V part
It's worth noting and pondering that the AD825 gives better SONIC performance than the lower noise AD797.
Andy.
Noise
You should also be aware that the noise specs for many reg's (e.g. LM317 / LT1086) is the same, but the LT1086 parts measure considerably quieter.
The data sheets are often cautious - there's no substitute for actual experience here.
For a simple discrete design, try the POOGE reg - a few transistors and better than 3-terminal performance. Search here, you'll find the schematics (just noticed JAM posted it already!).
Andy.
You should also be aware that the noise specs for many reg's (e.g. LM317 / LT1086) is the same, but the LT1086 parts measure considerably quieter.
The data sheets are often cautious - there's no substitute for actual experience here.
For a simple discrete design, try the POOGE reg - a few transistors and better than 3-terminal performance. Search here, you'll find the schematics (just noticed JAM posted it already!).
Andy.
An externally hosted image should be here but it was not working when we last tested it.
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