I think you need a photo of his total thing to replicate in case you wanna do checks on the HP anyway. 
Guys, don't worry about that LTSpice thing. It is not related to your regulators. I was giving a generic example to argue the case why Overm found the Rubycon ZA sounded a whole lot better than a film cap and to answer for Telstar anf fff0's curiosities.
Errm.. in conclusion , is the below statement correct?
All film cap only local decoupling is no good and its ok to have electrolytic cap + film cap (so the impedance is not too low that affects the DF)
All film cap only local decoupling is no good and its ok to have electrolytic cap + film cap (so the impedance is not too low that affects the DF)
Film caps have much better DF / DA figures therefore should have lower distortions. MKP is better than MKT in this regard, which again betters electrolytic.
However, my discussions with the LTSpice model did not consider any other factors of capacitors other than capacitance, ESR and ESL.
Generally, bypassing electrolytic capaicitors with film capacitors is for the reason that the ESL of an electrolytic capacitor is high at higher frequencies, making it ineffective, while a film capacitor has much lower ESL so it works well at high frequencies.
When inductance (L), capacitance (C) and resistance (R) are met they form a resonant circuit and will ALWAYS resonate unless there is sufficent R there to damp it. The problem with bypassing is this: the output of a regulator may be inductive, wires have inductance, they interact with the capacitors and resonate, unless you have sufficient resistance to damp it.
The reason film capacitors can easily cause resonance is because their ESR is very low. On the other hand, non-low-ESR type of electrolytic capacitors usually have enough ESR to damp the resonance.
But then if your PSU has extremely low inductance and you use ground plain, etc, the circuit may have low enough inductance that a film cap alone may work very well.
With regards to "All film cap only local decoupling is no good and its ok to have electrolytic cap + film cap ", whether the statement is correct or not really depends. Under unusual conditions when the electrolytic capacitor is VERY VERY LARGE comparing to the film cap and it has the right amount of ESR then it can damp the circuit. You need to use some formulae to calculate it or model it with Spice. It is usually not practical.
However, my discussions with the LTSpice model did not consider any other factors of capacitors other than capacitance, ESR and ESL.
Generally, bypassing electrolytic capaicitors with film capacitors is for the reason that the ESL of an electrolytic capacitor is high at higher frequencies, making it ineffective, while a film capacitor has much lower ESL so it works well at high frequencies.
When inductance (L), capacitance (C) and resistance (R) are met they form a resonant circuit and will ALWAYS resonate unless there is sufficent R there to damp it. The problem with bypassing is this: the output of a regulator may be inductive, wires have inductance, they interact with the capacitors and resonate, unless you have sufficient resistance to damp it.
The reason film capacitors can easily cause resonance is because their ESR is very low. On the other hand, non-low-ESR type of electrolytic capacitors usually have enough ESR to damp the resonance.
But then if your PSU has extremely low inductance and you use ground plain, etc, the circuit may have low enough inductance that a film cap alone may work very well.
With regards to "All film cap only local decoupling is no good and its ok to have electrolytic cap + film cap ", whether the statement is correct or not really depends. Under unusual conditions when the electrolytic capacitor is VERY VERY LARGE comparing to the film cap and it has the right amount of ESR then it can damp the circuit. You need to use some formulae to calculate it or model it with Spice. It is usually not practical.
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surely 5cm-7.5mm max (shorter in many cases) with remote sensing, 4.7uf PPS and local 100pf/10pf PPS or PET bypassing of the load should have me sorted?
I tried it long time ago. At the time I had no equipment to measure it. So unfortunately I can't give you an answer.
Added Rubycon ZL 47uF / 25V to the Vref this morning.
Negative rail was found not regulating. The 17V/5A protection Zener ran HOT!!!
I got -18.6V on the negative rail, exceeding the maximum rating of the opa627 ($50) of -18V.
Spent some time debugging it. Suspected that the J201 on the negative has gone to heaven. Took it out, measured it and confirmed the case. Replaced it with a new one. The negative rail was regulated again. As expected, the opa627 survived. I remember for once I had 23V on the pos rail for half a minute or so and the opa627 survived. I think I will get a 15V zener instead of the 17V. Even with 5A rating, I touched it and almost got my finger tip burnt! The max current should not exceed the CCS current of 150mA and dissipation should be (26-18)V x 0.15A = 1.2W. Theoretically the zener should be fine. In reality, I don't know if the zener can survive continuously with such temporature.
I found no reason that the J201 could be burnt, even if the 47uF was dead short. So I guess it might be that when I soldered the sense wire I over heated the J201.
Anyway, adding the 47uF to the Vref does not upset the sound for sure. It is not run-in yet. I also changed the reg output electrolytic cap from 100uF ZA to 47uF ZL. Waiting for them to run-in before making any subjective accessment.
Negative rail was found not regulating. The 17V/5A protection Zener ran HOT!!!
I got -18.6V on the negative rail, exceeding the maximum rating of the opa627 ($50) of -18V.Spent some time debugging it. Suspected that the J201 on the negative has gone to heaven. Took it out, measured it and confirmed the case. Replaced it with a new one. The negative rail was regulated again. As expected, the opa627 survived. I remember for once I had 23V on the pos rail for half a minute or so and the opa627 survived. I think I will get a 15V zener instead of the 17V. Even with 5A rating, I touched it and almost got my finger tip burnt! The max current should not exceed the CCS current of 150mA and dissipation should be (26-18)V x 0.15A = 1.2W. Theoretically the zener should be fine. In reality, I don't know if the zener can survive continuously with such temporature.
I found no reason that the J201 could be burnt, even if the 47uF was dead short. So I guess it might be that when I soldered the sense wire I over heated the J201.
Anyway, adding the 47uF to the Vref does not upset the sound for sure. It is not run-in yet. I also changed the reg output electrolytic cap from 100uF ZA to 47uF ZL. Waiting for them to run-in before making any subjective accessment.
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47uF on Vref it took very little time to reach the voltage. Next time I may try 100uF.
The caps may have been run-in. They were used a few months ago.
The sound seems to be even a little more cleaner. Note that it was already very clean.
The caps may have been run-in. They were used a few months ago.
The sound seems to be even a little more cleaner. Note that it was already very clean.
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I've had that experience with J201 as well. Usually some mishap with the probes in the running circuit or with the soldering iron. Sensitive little ones.
Yes, most of us can only dream of having a system half, no a quarter, as good as yours. 😀
Greg,
I am flattered! You have to come and listen to my new system, which shall be ready in the next 4 weeks, it should be much better than the one you listened to before. Bring your amps and stuff too.
Regards,
Bill
I am flattered! You have to come and listen to my new system, which shall be ready in the next 4 weeks, it should be much better than the one you listened to before. Bring your amps and stuff too.
Regards,
Bill
For yet another test I've just finished another sample of revision 5k, this time air sculpture, which is my favorite way to prototype. This one worked out of the box, so to say, no artifacts of any kind. Used a 33uF electrolytic at the output, a 220uF to bypass R9 and R11 (27k, got 11.1V output). Took a bit long to get to 11.1V, perhaps 90s or so. I think a 47uF to 100uF should be better there. Once it gets to the output voltage the current is stable, the voltage is stable, good stuff!
No listening tests yet as far as I'm concerned, so I thank Bill for all the input in that department so far. It's good to have someone with nice equipment and a good ear test it.
Incidentally today I also put a couple of solid hours into the positive 5k pcb design, which is now finished, but I want to go over it with a clear mind another couple of times just to make sure there's no funny stuff. We're getting there...
No listening tests yet as far as I'm concerned, so I thank Bill for all the input in that department so far. It's good to have someone with nice equipment and a good ear test it.
Incidentally today I also put a couple of solid hours into the positive 5k pcb design, which is now finished, but I want to go over it with a clear mind another couple of times just to make sure there's no funny stuff. We're getting there...
will do when the PCBs arrive, too far gone on other projects currently to do any more prototyping. I actually meant 100NF/10NF rather than pf
This one, posted a few months ago, should be finished in a few weeks for sure. Upgraded all 3 power amps a couple of weeks ago. Everything is ready, just need to put the XO/EQ/preamp together with a few shunt regs each driving the tweeter, midrange, woofer and subwoofer. Still need one additional amp to drive the subwoofers not in site of the photo.
http://www.diyaudio.com/forums/powe...-voltage-shunt-regulator-137.html#post1953990
Nice system!
Bill, what other regulators have you tried so far? How would the sound compare?
Bill, what other regulators have you tried so far? How would the sound compare?
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J201 was the cause of 2 blown Mosfets when I did the 5d beta too. Mine just gave up the ghost when at work under 220uF. With 47uF it lives on.
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