This regulator gives a clean, detailed and neutral sound. Impressive is that you chose RF parts yet I can't hear any oscillation so I hope it does not have any.
If you are into a bit of warmth, tone, slam, musicality, etc, you may stick with Salas v1 or v1.1, as it is very good in that department. This v1.5 may not be the one for you as those may be lost. Of course, when we talk about these subjective terms, it is highly system dependant.
If you look for details, transparency, accuracy, then this v1.5 is superb. As those characteristics are what I am looking for, in my personal opinion, it is the best I have had and I am finally settled on this one.
Thanks, Iko. Well done.
I may not have a lot of time these days checking into the forum. I usually stay in the Multi-way forum these days and don't check other forums. If your circuit further evolves in the future please DO send me an updated schematic to my personal email address (please keep it!).
I guess there may be a chance that the performance can be improved by using all FETs. You may also select the parts to make it more temporature stable.
If you are into a bit of warmth, tone, slam, musicality, etc, you may stick with Salas v1 or v1.1, as it is very good in that department. This v1.5 may not be the one for you as those may be lost. Of course, when we talk about these subjective terms, it is highly system dependant.
If you look for details, transparency, accuracy, then this v1.5 is superb. As those characteristics are what I am looking for, in my personal opinion, it is the best I have had and I am finally settled on this one.
Thanks, Iko. Well done.
I may not have a lot of time these days checking into the forum. I usually stay in the Multi-way forum these days and don't check other forums. If your circuit further evolves in the future please DO send me an updated schematic to my personal email address (please keep it!).
I guess there may be a chance that the performance can be improved by using all FETs. You may also select the parts to make it more temporature stable.
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Thanks for the report! BTW, the RF parts are chosen with the sole purpose of avoiding oscillation.
At the moment I don't think that using fets everywhere would improve anything. The circuit will stay like this for a while because I'm super busy with the pcb and moving forward to offer it to people who aren't as brave as you
You well done!
At the moment I don't think that using fets everywhere would improve anything. The circuit will stay like this for a while because I'm super busy with the pcb and moving forward to offer it to people who aren't as brave as you
You well done!
There is nothing to tweak other than the output capacitor. In my case, the "input" capacitor is already the best I have, i.e. a quite transparent Vishay Blue Box MKP 1.1uF.
Surprisingly, the output capacitor still has a strong sonic signature.
I know your reference is to make the uF as small as possible.
Initially I had a 10uF Nichison Gold. An old capacitor taken from a NAD CD player which may have been played for a while. The reason I used it was because that was the lowest value I could find in my parts bin.
The sound was generally good but dry. I have done this sort of listening (output caps on regulators) a lot so I guess I am fairly experienced with it. I guessed that either the ESR was too high or the uF was not large enough.
I then replaced it with a Rubycon ZL 22uF/50V 0.34R ESR. The music was a lot more fuller, smoother and more live. However, just like every other Rubycon ZLs, the treble became a bit thick / exaggerated, a touch of brightness.
I was shocked by the fact that the output capacitor can influence the sound so much, given that you said the output capacitor only serves for stablity, not for the close loop. No matter how low the impedance of the capacitor, the regulator still has far lower impedance so in theory the capacitor should not influence the sound much. But reality is different from our theory.
Surprisingly, the output capacitor still has a strong sonic signature.
I know your reference is to make the uF as small as possible.
Initially I had a 10uF Nichison Gold. An old capacitor taken from a NAD CD player which may have been played for a while. The reason I used it was because that was the lowest value I could find in my parts bin.
The sound was generally good but dry. I have done this sort of listening (output caps on regulators) a lot so I guess I am fairly experienced with it. I guessed that either the ESR was too high or the uF was not large enough.
I then replaced it with a Rubycon ZL 22uF/50V 0.34R ESR. The music was a lot more fuller, smoother and more live. However, just like every other Rubycon ZLs, the treble became a bit thick / exaggerated, a touch of brightness.
I was shocked by the fact that the output capacitor can influence the sound so much, given that you said the output capacitor only serves for stablity, not for the close loop. No matter how low the impedance of the capacitor, the regulator still has far lower impedance so in theory the capacitor should not influence the sound much. But reality is different from our theory.
I found in my parts bin Rubycon ZL 15uF/100V ESR=0.54, which may be better than the 22uF/50V ESR=0.34.
But before I try that, I have been thinking about that if the output indeed needs only small uF to be stable, as indicated in the schematic of 5uF only, then I may use film capacitor as well.
I don't want to consume my 1.1uF Vishay though, as they are too valuable to me and too many are needed to be consumed in this case. They should be used as input/output caps and in filter circuits. But if they do give a better sound then I may have to use them.
I have a plenty of ICW SA Clarity caps. I don't mind using them in modelling XOs. I don't like them in line level circuit. Solen is a lot worse. In fact, I am not sure if any large bulky MKP made for XOs sound better than ordinary MKP made for lower voltage use.
An alternative is to use 2.2uF Polyester MKT capacitors, I have at least two dozens of them on hands. They are very small so I can even parallel 5 of them to make up to 11uF. However, in my previous experiments using them in critical locations, I found that the Vishy blue box sounds better, and I prefer MKP to MKT.
In whichever case, I guess I need to pad some resistence to the film capacitors to prevent oscillation. Perhaps 0.5R? 1R?
It would be good if you could provide us an answer with your LTSpice modelling, not just "you have to experiment yourself".
But before I try that, I have been thinking about that if the output indeed needs only small uF to be stable, as indicated in the schematic of 5uF only, then I may use film capacitor as well.
I don't want to consume my 1.1uF Vishay though, as they are too valuable to me and too many are needed to be consumed in this case. They should be used as input/output caps and in filter circuits. But if they do give a better sound then I may have to use them.
I have a plenty of ICW SA Clarity caps. I don't mind using them in modelling XOs. I don't like them in line level circuit. Solen is a lot worse. In fact, I am not sure if any large bulky MKP made for XOs sound better than ordinary MKP made for lower voltage use.
An alternative is to use 2.2uF Polyester MKT capacitors, I have at least two dozens of them on hands. They are very small so I can even parallel 5 of them to make up to 11uF. However, in my previous experiments using them in critical locations, I found that the Vishy blue box sounds better, and I prefer MKP to MKT.
In whichever case, I guess I need to pad some resistence to the film capacitors to prevent oscillation. Perhaps 0.5R? 1R?
It would be good if you could provide us an answer with your LTSpice modelling, not just "you have to experiment yourself".
Would you please explain more? What resistor value with which JFET gives the best stability?
I was thinking about whether the lowish current level was related to temporature instability.
Each jfet has a zero TC point. It's closer to Vgs(off) than to Vgs = 0 (G and S pins tied together). There is no exact resistor value that will work for all jfets.
About your other points. Simulation is too far from reality to give us answers to subtle things. You know yourself how subjective the sound of a capacitor is. Sorry, I wish I had a better answer for you.
While you mentioned that you prefer to use a low value uF capacitor at the output, I am referencing the LM317/337 datasheets, in which says that a 1uF - 25uF output capacitor would make it stable, while values up to 1000uF would improve transient response. The datasheet also gives the transient response graphs of some output capacitor values.
I know each regulator is different. Would the transient response of your regulator depend on the output capacitor in any degree? The dry / thinner sound when I used the low value high esr at the output initially may suggest a larger cap helps with transient response?
I know each regulator is different. Would the transient response of your regulator depend on the output capacitor in any degree? The dry / thinner sound when I used the low value high esr at the output initially may suggest a larger cap helps with transient response?
Does that mean the higher resistor value has better temporature stability than lower resistor value, if we don't know that value and put in a guess?
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I am not looking for the subtle sonic difference between capacitors, which can't be modelled anyway.
I guess the output capacitor is part of the close loop. So from simulation you would be able to work out the optimal value.
It is also important to work out the lowest permissible ESR before the regulator starts to oscillate. I guess this could be modelled as well. I am not referring to the interaction between this cap and the circuits, which can't be modelled. I am referring to the output capacitor interacting with the regulator itself.
Hard to tell without an oscilloscope tracing Vout and the shunt current. I suspect that there wasn't enough shunt current. This is an example where simulation and reality obviously differ. There are other factors which will influence Zout, as I said before, the layout, the length of wire from the regulator to the circuit, etc.
In my opinion the best regulator will probably be set back to the level of an average one by these subtle effects of layout and connection to the next circuit in the chain. Ideally it'd probably be best to go with surface mount devices. I've entertained this idea for some time. That may be the next thing I do after the through hole pcb is tested and out.
In my opinion the best regulator will probably be set back to the level of an average one by these subtle effects of layout and connection to the next circuit in the chain. Ideally it'd probably be best to go with surface mount devices. I've entertained this idea for some time. That may be the next thing I do after the through hole pcb is tested and out.
Not really. Each jfet has a pinch-off voltage, which can be measured. To do it correctly you'd need to then trace Idss at different temperatures while varying the resistor between G and S, and see where they intersect. Then you'd select a resistor value that correspond to the intersection. But it's time consuming. So you can just choose a resistor that gives you a Vgs of about 80% of Vgs(off), the pinch-off value.
The ESR and ESL of the capacitor is easy enough to simulate. In fact all my simulation include values for the parasitic parameters. It's the rest of your regulator parasitic values that we don't know, because it's dependent on your particular implementation. That's where the problem lies. If we had a reference PCB, all measured and such, then we could optimize for the best output capacitor. But that's far off in the distance still. Lots of work to do.
Hi, Ikoflexer, Salas and experts,
I understand the importance of the short path between the reg output and the load.
I am planning on using two regulators on my 4 way active line level XO/EQ.
One regulator is built on the actual board of the tweeter circuit (2kHz and above) which consists of only 4 ICs/opamps for both channels, so that the PSU can be as close to the supply pins of the ICs as possible.
The other regulator can be on its own, with wires going to the boards for the midrange (2kHz and below), bass and sub. Wires can be of 10-15A rated.
What do you think of this plan?
The question is, does the longer path between the PSU and the ICs pins only affects higher frequencies due to wire resistance and inductance? Would it affect lower frequency at all?
I thought the answer is that short path is only critical for high frequencies. But I post this question for verification and to be sure.
I understand the importance of the short path between the reg output and the load.
I am planning on using two regulators on my 4 way active line level XO/EQ.
One regulator is built on the actual board of the tweeter circuit (2kHz and above) which consists of only 4 ICs/opamps for both channels, so that the PSU can be as close to the supply pins of the ICs as possible.
The other regulator can be on its own, with wires going to the boards for the midrange (2kHz and below), bass and sub. Wires can be of 10-15A rated.
What do you think of this plan?
The question is, does the longer path between the PSU and the ICs pins only affects higher frequencies due to wire resistance and inductance? Would it affect lower frequency at all?
I thought the answer is that short path is only critical for high frequencies. But I post this question for verification and to be sure.
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Salas,
I am planning to use very thick (60A?) cables between the reg out and the star ground of the load, and from the star ground to the psu pins of ICS I would use 10A cables.
I know long wires (which translates to higher resistance) would affect the bass. But in my case, the resistance is very very low.
What I can't change is the inductance because thick wires do not reduce inductance.
So I understand your answer was correct.
But if I rephrase my question: provided that resistance is extremely low, is inductance, say 200nH, would affect the bass performance of ICs, provided that RF does not get into the circuit somehow.
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