Gilmore amp
Jayel,
s'ppose that question was addressed to me.
No, I did not build the Gilmore amp. I just happened to have a lot of OPA548 from times when BB/TI sent out up to 10 samples per item
... I use them as power amps actually, in a bi-amped system with active x-o. I will use those as headphone drivers soon as well, I am now at a stage where I finally start to have a halfways decent understanding of op-amps so I'll stick with chips for the time being... I am very happy with OPA548, they have similar specs to LM3886 which is highly regarded in some circles; for some reason the OPA548 does not get attention.
Anyway, it can be used as low noise regulator as well and I needed that for my op-amp based DIY preamp. Gilmore uses it as second stage after a 317 and with a precision external voltage reference, me I used the built-in voltage reference as per datasheet, the rest of the circuit is similar to Gilmore's. I just wanted to know if one can improve on that.
MBK
Jayel,
s'ppose that question was addressed to me.
No, I did not build the Gilmore amp. I just happened to have a lot of OPA548 from times when BB/TI sent out up to 10 samples per item
... I use them as power amps actually, in a bi-amped system with active x-o. I will use those as headphone drivers soon as well, I am now at a stage where I finally start to have a halfways decent understanding of op-amps so I'll stick with chips for the time being... I am very happy with OPA548, they have similar specs to LM3886 which is highly regarded in some circles; for some reason the OPA548 does not get attention. Anyway, it can be used as low noise regulator as well and I needed that for my op-amp based DIY preamp. Gilmore uses it as second stage after a 317 and with a precision external voltage reference, me I used the built-in voltage reference as per datasheet, the rest of the circuit is similar to Gilmore's. I just wanted to know if one can improve on that.
MBK
Some clarification
Are Term3/6/20/10/17 connected to +ground? Are Term11/13/19/18/15 connected to -ground?
Is -ground connected to + ground? or There are 2 circuit grounds?
What's the purpose or +/-load and +/- sense? In the schematics, these are Term2/9 for positive voltage and Term14/17 for negative voltage. Where are these terms connected to in the circuit?
Thanks
Jayel
Are Term3/6/20/10/17 connected to +ground? Are Term11/13/19/18/15 connected to -ground?
Is -ground connected to + ground? or There are 2 circuit grounds?
What's the purpose or +/-load and +/- sense? In the schematics, these are Term2/9 for positive voltage and Term14/17 for negative voltage. Where are these terms connected to in the circuit?
Thanks
Jayel
Jayel
These reg's have remote sensing options, i.e. the ability to regulate at the load.
In order to do this Term 9 is connected to the +ve rail at the load and Term 10 is connected to 0V at the load. If using this option though the 10R / 0.01u shown in my diagram may need to be implemented.
If this option is wanted connect Term9 to Term2 and Term 10 to Term3.
Term 2 is the +ve feed to the load, Term 3 is the 0V feed to the load.
Additionally Term6 needs returning to the raw supply 0V (e.g. smoothing caps).
Term 7 connects the -ve sense point to a ground plane on the PCB.
P.S. change the values in the tracking pre-reg options to R101=R102=R103=R104=249R.
A.
These reg's have remote sensing options, i.e. the ability to regulate at the load.
In order to do this Term 9 is connected to the +ve rail at the load and Term 10 is connected to 0V at the load. If using this option though the 10R / 0.01u shown in my diagram may need to be implemented.
If this option is wanted connect Term9 to Term2 and Term 10 to Term3.
Term 2 is the +ve feed to the load, Term 3 is the 0V feed to the load.
Additionally Term6 needs returning to the raw supply 0V (e.g. smoothing caps).
Term 7 connects the -ve sense point to a ground plane on the PCB.
P.S. change the values in the tracking pre-reg options to R101=R102=R103=R104=249R.
A.
Jung Didden circuit questions
Well, I think the best person to answer or comment those questions would be Jan himself.
You should also read the original articles, as all aspects are commented on and explained on them.
Grounds (+ and -) are all separated and joined only on one point on each board. There's also a ground plane.
The sense points serve to include the feedback from the powered chip entering point, that is there will be a resistor connected just at the pin point. And you should only power one chip with each +/- pair.
It is a very tricky circuit, and I'm not sure it's very DIY.
Carlos
Well, I think the best person to answer or comment those questions would be Jan himself.
You should also read the original articles, as all aspects are commented on and explained on them.
Grounds (+ and -) are all separated and joined only on one point on each board. There's also a ground plane.
The sense points serve to include the feedback from the powered chip entering point, that is there will be a resistor connected just at the pin point. And you should only power one chip with each +/- pair.
It is a very tricky circuit, and I'm not sure it's very DIY.
Carlos
improved 317
Ref ALW's circuit above: you can implement the CRD by deleting everything around the Q2 (I think it's Q2, can't read it very well) current source: delete the LED, the 10k, R7, the transistor. Connect the CRD between Vraw and the junction of the zener and Base of Q1 (the output transistor).
Note: I have NOT discussed this with Walt Jung. Since ALW's circuit is basically Walt's further development of our common baseline article, he may or may not agree to this mod. I only can tell you that it works for me with a Vraw to Vout reserve of at least 6 volts at max load.
On the question of the physical implementation of the AA articles, on the board basically everything is returned to the star ground. This is quite important. The star point is the only zero volts point on the board, because when I laid out the board I decided that it should be the zero voltage point. (See what you make of that!). The consequence is that everything has to be referred, and thus returned, to it to make it work. Ideally, no two component leads should join a track or wire, because there will be interaction. Read the original article for more info.
Cheers, Jan Didden
Ref ALW's circuit above: you can implement the CRD by deleting everything around the Q2 (I think it's Q2, can't read it very well) current source: delete the LED, the 10k, R7, the transistor. Connect the CRD between Vraw and the junction of the zener and Base of Q1 (the output transistor).
Note: I have NOT discussed this with Walt Jung. Since ALW's circuit is basically Walt's further development of our common baseline article, he may or may not agree to this mod. I only can tell you that it works for me with a Vraw to Vout reserve of at least 6 volts at max load.
On the question of the physical implementation of the AA articles, on the board basically everything is returned to the star ground. This is quite important. The star point is the only zero volts point on the board, because when I laid out the board I decided that it should be the zero voltage point. (See what you make of that!). The consequence is that everything has to be referred, and thus returned, to it to make it work. Ideally, no two component leads should join a track or wire, because there will be interaction. Read the original article for more info.
Cheers, Jan Didden
Kevin
The circuit shown can work with noise levels of the order of 3nV/rt Hz @ 1k.
Basically the noise of the opamp (1.2nV / rt Hz peak) + the filtered reference.
In order to acheive this careful layout is needed, as Jan's post implies. My own PCB also incorporates star earthing and star- supply for all connections.
Of more importance than the noise is the output impedance, which starts at 40 uOhms at LF rising to only 1mOhm or so at several 100 kHz.
Line rejection is awesome too.
Jan's update is not something Walt would implement, since he wanted low dropout for the super-reg's and the bipolar current source is much better than a FET in this instance.
A better solution to the dynamic stability and slightly worse performance of the bipolar source is to use a pre-reg. This is Walt's latest incarnation and it uses a tracking LM317 pre-regulator, set to maintain the dropout votage of the super-reg, referenced to the super reg output.
See carlmart's post above - these reg's are totally bloody awesome!
A.
The circuit shown can work with noise levels of the order of 3nV/rt Hz @ 1k.
Basically the noise of the opamp (1.2nV / rt Hz peak) + the filtered reference.
In order to acheive this careful layout is needed, as Jan's post implies. My own PCB also incorporates star earthing and star- supply for all connections.
Of more importance than the noise is the output impedance, which starts at 40 uOhms at LF rising to only 1mOhm or so at several 100 kHz.
Line rejection is awesome too.
Jan's update is not something Walt would implement, since he wanted low dropout for the super-reg's and the bipolar current source is much better than a FET in this instance.
A better solution to the dynamic stability and slightly worse performance of the bipolar source is to use a pre-reg. This is Walt's latest incarnation and it uses a tracking LM317 pre-regulator, set to maintain the dropout votage of the super-reg, referenced to the super reg output.
See carlmart's post above - these reg's are totally bloody awesome!
A.
Two main advantages
1. The floating pre-reg needs no adjustment on a case-by-case basis, it's o/p V is fixed for every o/p voltage. Saves a bit of aggro when setting o/p V as there's only one adjustment to be done.
2. It improves regulation quality. 317's et al produce an o/p voltage w.r.t. to their -ve Kelvin sense point (i.e. the bottom of the lower divider resistor). If this is connected conventionally it prodces an o/p V w.r.t. ground (0V).
By conencting this to the super-reg o/p, it produces an o/p w.r.t. a very quiet sensed point, the i/p / o/p differential of the super reg is then being maintained very accurately, with much reduced noise input.
If you don't believe this is important look at this post here Kelvin sensing at the bottom of page3 / top p.4 for the easily measurable effect of connecting things up 'wrong'.
By using the tracking pre-reg there's a much better chance to get it right.
A.
1. The floating pre-reg needs no adjustment on a case-by-case basis, it's o/p V is fixed for every o/p voltage. Saves a bit of aggro when setting o/p V as there's only one adjustment to be done.
2. It improves regulation quality. 317's et al produce an o/p voltage w.r.t. to their -ve Kelvin sense point (i.e. the bottom of the lower divider resistor). If this is connected conventionally it prodces an o/p V w.r.t. ground (0V).
By conencting this to the super-reg o/p, it produces an o/p w.r.t. a very quiet sensed point, the i/p / o/p differential of the super reg is then being maintained very accurately, with much reduced noise input.
If you don't believe this is important look at this post here Kelvin sensing at the bottom of page3 / top p.4 for the easily measurable effect of connecting things up 'wrong'.
By using the tracking pre-reg there's a much better chance to get it right.
A.
What is important?
Perhaps you may remember my off-hand comments about this project not being too DIY. The main reason for this was the use of a double-sided pcb, not an easy one to DIY, which was rather expensive as sold by Old Colony.
The other reason were the problems (oscillation, lock-up, etc.) that were already commented on the first article (particularly when using the AD797), that made W. Jung revisit the design and make some further changes. The version I put on this Forum is the latest.
One idea came into my mind since the beginning. The original Jung/Didden regulator was a development of Sulzer's regulator. Which used an NE5534 as main chip. If you have a look at Jung's measurement graphs, Sulzer's turns out excelent specs when compared with this new version.
The Sulzer regulator was used and built by many DIYers, even by Didden himself on an excellent DAC project on The Audio Amateur, where he made extensive use of star-tracing each part on the pcb, both for ground and +/- supplies. Erno Borbely also used it on several TAA preamps from then on. It was an easy to achieve DIY project and no one complained on anything.
The improvements Jung brought to Sulzer's supply turned out into slightly better specs, but with an important trade-off (in my opinion): construction problems, parts inflexibility, higher price.
One thing I thought might de done is including the improvements (when feasible) in the more DIY Sulzer project, particularly adding star tracing and load sense.
The AD797 seems to be tricky to implement, and as you see one new choice is the more stable AD817. DIY also asks for DIP instead of SOIC.
Soon I should be carrying some tests using different supplies (and batteries) to see what changes in the preamp sound.
Opinions, please!
Carlos
Perhaps you may remember my off-hand comments about this project not being too DIY. The main reason for this was the use of a double-sided pcb, not an easy one to DIY, which was rather expensive as sold by Old Colony.
The other reason were the problems (oscillation, lock-up, etc.) that were already commented on the first article (particularly when using the AD797), that made W. Jung revisit the design and make some further changes. The version I put on this Forum is the latest.
One idea came into my mind since the beginning. The original Jung/Didden regulator was a development of Sulzer's regulator. Which used an NE5534 as main chip. If you have a look at Jung's measurement graphs, Sulzer's turns out excelent specs when compared with this new version.
The Sulzer regulator was used and built by many DIYers, even by Didden himself on an excellent DAC project on The Audio Amateur, where he made extensive use of star-tracing each part on the pcb, both for ground and +/- supplies. Erno Borbely also used it on several TAA preamps from then on. It was an easy to achieve DIY project and no one complained on anything.
The improvements Jung brought to Sulzer's supply turned out into slightly better specs, but with an important trade-off (in my opinion): construction problems, parts inflexibility, higher price.
One thing I thought might de done is including the improvements (when feasible) in the more DIY Sulzer project, particularly adding star tracing and load sense.
The AD797 seems to be tricky to implement, and as you see one new choice is the more stable AD817. DIY also asks for DIP instead of SOIC.
Soon I should be carrying some tests using different supplies (and batteries) to see what changes in the preamp sound.
Opinions, please!
Carlos
IMHO
D/S sided PCB's aren't really a problem - one does not need to etch the ground plane side, just counterbore where connections are not required.
They can be prone to oscillation, but all of the other start-up problems with the original units seem primarily related to constructional problems. One particular correspondant who'd claimed to have soldered thousands of connections had still made assembly errors!
The level-shift zener eradicates all these problems AFAICT. All 4 of the home made prototypes (my own PCB design) have worked perfectly without any problems whatsoever.
Trust me when I say I've built both Sulzer and Jung reg's. The Sulzer's have experienced more problems than the Jung ones I've built, and the difference in performance is substantial and well worth the effort. They seem expensive at first glance (the primary reason I'd put off trying them myself) but when one realises the improvements they bring and realise that one would need to spends thousands acheiving improvements by other means they look fantastically cheap to me now.
The sulzers are good - they are what made me try the Jung reg's, but I'd never go back now.
I disagree with almost all the above. The construction should present no problems to anyone who can solder competently, the specs are significantly better, particularly the line rejection and o/p impedance - more important than ultimate noise level IMO.
The only parts inflexibility is in the op-amp choice, caps, transistors etc. are all open to user selection if so desired.
The only components I've really kept the same are the o/p device, and op-amp, although I've used a BD135 as an o/p device with excellent results. Again it's not that critical.
As for price, see comment above, and also note the AD817 / AD825 is quite cheap incomparison. I've only used AD797 so far.
It think you then end up with Jung-type circuits
I shall be interested in your results, but bear in mind the Jung reg provides lower noise than any battery source I've tried (I've actually measured this), along with much lower o/p impedance across a wider bandwidth.
Batteries suck, IMVHO, for audio supplies. Narrow bandwidth and non-load correlated o/p noise are bad things in an audio supply.
You did ask
Regards,
A.
D/S sided PCB's aren't really a problem - one does not need to etch the ground plane side, just counterbore where connections are not required.
They can be prone to oscillation, but all of the other start-up problems with the original units seem primarily related to constructional problems. One particular correspondant who'd claimed to have soldered thousands of connections had still made assembly errors!
The level-shift zener eradicates all these problems AFAICT. All 4 of the home made prototypes (my own PCB design) have worked perfectly without any problems whatsoever.
Trust me when I say I've built both Sulzer and Jung reg's. The Sulzer's have experienced more problems than the Jung ones I've built, and the difference in performance is substantial and well worth the effort. They seem expensive at first glance (the primary reason I'd put off trying them myself) but when one realises the improvements they bring and realise that one would need to spends thousands acheiving improvements by other means they look fantastically cheap to me now.
The sulzers are good - they are what made me try the Jung reg's, but I'd never go back now.
I disagree with almost all the above. The construction should present no problems to anyone who can solder competently, the specs are significantly better, particularly the line rejection and o/p impedance - more important than ultimate noise level IMO.
The only parts inflexibility is in the op-amp choice, caps, transistors etc. are all open to user selection if so desired.
The only components I've really kept the same are the o/p device, and op-amp, although I've used a BD135 as an o/p device with excellent results. Again it's not that critical.
As for price, see comment above, and also note the AD817 / AD825 is quite cheap incomparison. I've only used AD797 so far.
It think you then end up with Jung-type circuits
I shall be interested in your results, but bear in mind the Jung reg provides lower noise than any battery source I've tried (I've actually measured this), along with much lower o/p impedance across a wider bandwidth.
Batteries suck, IMVHO, for audio supplies. Narrow bandwidth and non-load correlated o/p noise are bad things in an audio supply.
You did ask
Regards,
A.
Low Noise Regulators
Hi All,
Some time ago I had a interesting discussion/thread with Carlos on the AudioAsylum about Jung/Schulzer like regulators and the need for pregulation:
http://www.audioasylum.com/audio/tweaks/messages/32609.html
Rather than repeating myself please follow the link!
Hi All,
Some time ago I had a interesting discussion/thread with Carlos on the AudioAsylum about Jung/Schulzer like regulators and the need for pregulation:
http://www.audioasylum.com/audio/tweaks/messages/32609.html
Rather than repeating myself please follow the link!
Opinions on regulator
Thanks ALW for your comments!
You're the first person that I know that had problems with Sulzer's circuit. Can you tell us why?
In fact I did have some talks with Elso some time ago at the Audio Asylum. One interesting thing for me, back then, was that there was not too much interest on that subject, important as I think it was, from other people.
Elso's comments seem quite similar to ALW's, preferring the super regulators to batteries.
About the construction issues, just allow me to disagree on easily making a double sided pcb at home. It's far from simple, except if you use a machine or tool to etch the ground plane away on non-connected pads. Though I'm open to simpler ways to achieve better pcbs.
It's good to know your supplies worked well. And also good that they proved better in audio results, which should really be the issue.
The construction problems I mentioned have to do with the pcb difficulties. And I did etch them for a friend.
Choice of parts are quite inflexible though. It was adviced not to change the transistors, not to increase the capacitor values, to use only the Old Colony pcb, not using other chips, etc. And I believe you when you say it's not critical, as it shouldn't be.
When I mention implementing some of the new ways in Sulzer's design, I do guess it should be half way into Jung's territory. And it's fine with me as long as I get some DIY flexibility back.
Carlos
Thanks ALW for your comments!
You're the first person that I know that had problems with Sulzer's circuit. Can you tell us why?
In fact I did have some talks with Elso some time ago at the Audio Asylum. One interesting thing for me, back then, was that there was not too much interest on that subject, important as I think it was, from other people.
Elso's comments seem quite similar to ALW's, preferring the super regulators to batteries.
About the construction issues, just allow me to disagree on easily making a double sided pcb at home. It's far from simple, except if you use a machine or tool to etch the ground plane away on non-connected pads. Though I'm open to simpler ways to achieve better pcbs.
It's good to know your supplies worked well. And also good that they proved better in audio results, which should really be the issue.
The construction problems I mentioned have to do with the pcb difficulties. And I did etch them for a friend.
Choice of parts are quite inflexible though. It was adviced not to change the transistors, not to increase the capacitor values, to use only the Old Colony pcb, not using other chips, etc. And I believe you when you say it's not critical, as it shouldn't be.
When I mention implementing some of the new ways in Sulzer's design, I do guess it should be half way into Jung's territory. And it's fine with me as long as I get some DIY flexibility back.
Carlos
Carlos
I believe it is important to be careful when using alternative parts, but through careful choice, and an examination of the specs of the original components can lead to suitable, even better alternatives.
The difficulty is knowing what is important in the original spec's.
Additionally SPICE simulation can allow very accurate experimentation, without lifting a soldering iron.
I suspect layout is the primary key, and I put a LOT of time into my PCB layout, in order to optimize the design as far as is practicable. Possibly overkill, but I only have to do the PCB layout once, so it's worth some time devoted to it. Since I also implemented some of the updates, the OCSL PCB's weren't suitable as I hate bodged add-ons.
My primary reason though was I wanted to make a drop-in replacement for the reg. board in an old Naim Audio SNAPS PSU, as I have several of these kicking around and wanted to prove that intelligence and design effort wins over brute force (if you've seen a Naim PSU you'll understand).
I can safely report that it does, by a truly massive margin.
Hence each regulator board I build saves me a minumum of 800ukp for each genuine PSU I'd otherwise need!
Now you see why I'm so keen
A.
P.S. the Sulzer problems I had were startup / oscillation related - go figure, maybe it's just me
P.P.S. for D/S ground plane PCB, just etch one side, drill and then counterbore the groundplane using a spot face cutter or drill bit. Tracks on both sides is addmittedly more fun, but not too difficult if using a light box. Press'n'peel may be more of a challenge though.
I believe it is important to be careful when using alternative parts, but through careful choice, and an examination of the specs of the original components can lead to suitable, even better alternatives.
The difficulty is knowing what is important in the original spec's.
Additionally SPICE simulation can allow very accurate experimentation, without lifting a soldering iron.
I suspect layout is the primary key, and I put a LOT of time into my PCB layout, in order to optimize the design as far as is practicable. Possibly overkill, but I only have to do the PCB layout once, so it's worth some time devoted to it. Since I also implemented some of the updates, the OCSL PCB's weren't suitable as I hate bodged add-ons.
My primary reason though was I wanted to make a drop-in replacement for the reg. board in an old Naim Audio SNAPS PSU, as I have several of these kicking around and wanted to prove that intelligence and design effort wins over brute force (if you've seen a Naim PSU you'll understand).
I can safely report that it does, by a truly massive margin.
Hence each regulator board I build saves me a minumum of 800ukp for each genuine PSU I'd otherwise need!
Now you see why I'm so keen
A.
P.S. the Sulzer problems I had were startup / oscillation related - go figure, maybe it's just me
P.P.S. for D/S ground plane PCB, just etch one side, drill and then counterbore the groundplane using a spot face cutter or drill bit. Tracks on both sides is addmittedly more fun, but not too difficult if using a light box. Press'n'peel may be more of a challenge though.
Low Noise Regulators
Hi, See also
http://www.audioasylum.com/audio/tweaks/messages/36827.html
and http://www.audioasylum.com/audio/tweaks/messages/48064.html
Hi, See also
http://www.audioasylum.com/audio/tweaks/messages/36827.html
and http://www.audioasylum.com/audio/tweaks/messages/48064.html
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