Re: Re: poweramp regulated supply
... but it is still YOUR experience, and as such has exactly the same value (if any) as Elso's. Let's keep this straight.
Jan Didden
carlosfm said:
Elso, that is your experience with your amps and PSUs.
In my experience with regulated PSU and these chips, it's the most impressive bass slam I have heard out of them.
But notice that I use 2,200uf caps after the regs, and the PSU is not so conventional.
It is fully snubberized, which makes a whole of a difference.
... but it is still YOUR experience, and as such has exactly the same value (if any) as Elso's. Let's keep this straight.
Jan Didden
Upupa Epops said:Look at 338 datasheet, there is parallel connection of three regulators, which give 15 A. Or use power transistor. All is easy, you must read datasheets and not only ask friends here.
Data sheet applications contain suggestions for possible use with the general aim to sell as many as possible. Where the hell does this 15A requirement come from?? Don't tell me you guys spec you power supply according to the max current the chip can deliver before selfdestruct? What nonsense is that?
Jan Didden
Re: Re: Re: poweramp regulated supply
Jan,
I suppose we are talking about chip amps here.
And this PSU.
One member has tried this complete PSU as I recommend and he is very impressed.
If that's worth something for you, of course.
http://www.diyaudio.com/forums/showthread.php?postid=631625#post631625
PS: good to see you back on form.
janneman said:
Jan,
I suppose we are talking about chip amps here.
And this PSU.
One member has tried this complete PSU as I recommend and he is very impressed.
If that's worth something for you, of course.
http://www.diyaudio.com/forums/showthread.php?postid=631625#post631625
PS: good to see you back on form.
Attachments
Re: Re: Re: Re: poweramp regulated supply
No it isn't. But you knew that already, no?
Edit: Carlos, I'm not poking at you, honestly. But you say one thing, Elso another. Just give me one reason why I should believe you instead of Elso. Or maybe believe Elso instaed of you. Ok, you come up with someone who agrees with you. Is that it? 2 to 1, so you're right? There must be something more!
Jan Didden
carlosfm said:
No it isn't. But you knew that already, no?
Edit: Carlos, I'm not poking at you, honestly. But you say one thing, Elso another. Just give me one reason why I should believe you instead of Elso. Or maybe believe Elso instaed of you. Ok, you come up with someone who agrees with you. Is that it? 2 to 1, so you're right? There must be something more!
Jan Didden
janneman:
Unless I'm totally out of it, two LM4780's per amp on a 4ohm nominal speaker could deliver over 100W. Theoretically, I think over 200W? Though not probable all said and done. Again, thats not saying I'm ever going to actually demand that much, but it could come close depending on the configuration I end up with speaker-wise. We're talking a somewhat high sensitivity dipole, and there can be a lot of power demands by the woofers in this case. Higher sensitivity should mitigate power needs, but I may end up having to give up on that particular design goal to keep the size of the final project within the realm of what will fit in my house reasonably! This is a pair of LM4780's being used in the SyperSymmetry layout proposed by Nelson Pass. 4780's because low impedance is entirely probable, and a simple pair of 3886's may run into trouble.
oh yeah - on "who to believe" - if it's a simple circuit, why not try it?
Upupa:
If you read my initial post, you'll note that I *have* read the datasheet - many times. The layouts they propose use obsolete chips OR are suggesting a max voltage a bit less than I would like (though not so much so that I couldn't go that route if I felt it was the best choice). Besides that, datasheets tend to give you circuits that work, not circuits that are ideal or the best. The conversation generated here has been quite clear (for the most part) on discussing the merits of regulation, and whether I should bother trying it.
At any rate, thank you all for the help and comments so far!
C
Unless I'm totally out of it, two LM4780's per amp on a 4ohm nominal speaker could deliver over 100W.
Theoretically, I think over 200W? Though not probable all said and done. Again, thats not saying I'm ever going to actually demand that much, but it could come close depending on the configuration I end up with speaker-wise. We're talking a somewhat high sensitivity dipole, and there can be a lot of power demands by the woofers in this case. Higher sensitivity should mitigate power needs, but I may end up having to give up on that particular design goal to keep the size of the final project within the realm of what will fit in my house reasonably! This is a pair of LM4780's being used in the SyperSymmetry layout proposed by Nelson Pass. 4780's because low impedance is entirely probable, and a simple pair of 3886's may run into trouble.oh yeah - on "who to believe" - if it's a simple circuit, why not try it?
Upupa:
If you read my initial post, you'll note that I *have* read the datasheet - many times. The layouts they propose use obsolete chips OR are suggesting a max voltage a bit less than I would like (though not so much so that I couldn't go that route if I felt it was the best choice). Besides that, datasheets tend to give you circuits that work, not circuits that are ideal or the best. The conversation generated here has been quite clear (for the most part) on discussing the merits of regulation, and whether I should bother trying it.
At any rate, thank you all for the help and comments so far!
C
cjd,
I can follow your post and I am sure you are well aware of all the issues; in the end you have to make the decision. My numbers were just examples and it may well be that your numbers change the picture as far as max current requirements. Maybe 15A IS required for 2 channels low impedance bridge etc. But continuously, DC, at 100% duty cycle?? Even in that case, you probably are comfortable with just a few amps capability (DC) plus a couple of capacitors. That was my point, as you know.
Good luck wading through all this and to get to some decision!
Jan Didden
I can follow your post and I am sure you are well aware of all the issues; in the end you have to make the decision. My numbers were just examples and it may well be that your numbers change the picture as far as max current requirements. Maybe 15A IS required for 2 channels low impedance bridge etc. But continuously, DC, at 100% duty cycle?? Even in that case, you probably are comfortable with just a few amps capability (DC) plus a couple of capacitors. That was my point, as you know.
Good luck wading through all this and to get to some decision!
Jan Didden
janneman said:
Something more you can ask everybody on this forum.
Seriously, Elso has good intentions and I understand his point of view.
But as I said millions of times here, high capacitance doesn't sound good with these amps, unless it's snubberized.
So, Elso´s choke recommendation will not work well. He also refuses to snubberize, and doesn't have experience with these amps, so who to believe is everyone's choice.
If there's a will to go regulated again, I'm guilty and I'm the one to shoot.
So shoot me.
I've been guilty of plenty of things happening here in the last years, so hang me.
PS: ask those (too many to count now) who tried the snubberized PSU if I'm crazy, or if that is a REAL improvement.
I don't play with gold-plated resistors and their polarity.
Upupa Epops said:15 A regulator : NS LM 138 , page 14
up,
That isn't the point. You pay me enough money, I'll design a 50 amps +/- 50V supply for you. The point is that your music system needs this only 1 sec in a forthnight. All the other time it is idling at less than an amp. So my point was, take a standard 5 amps supply and hang a couple of caps on it, and be done with it.
Jan Didden
cjd said:
So, it's one LM4780 per channel, right?
Then a complete LM338 PSU per channel will do.
http://www.diyaudio.com/forums/showthread.php?postid=636970#post636970
No need to parallel regs, no need for pass transistors.
Just independent rectifiers/caps/regs per channel.
janneman said:
Forget it, Jan.
I don't need to say anything.
Just hundreds (thousands?) of people around the globe to testify.
And I don't make one penny out of this.
So why bother?
This has already gave me too much work just trying to explain, and it's not worth it.
While you guys talk, I DO, and there's a time gap between us.
We are alrealdy discussing a PSU that, to my knowledge, only one person besides me have tried it.
But there's too many people lurking here, so you never know.
To Jan : I agree with you, one regulator + batery of caps can make the same result. But probably better result will be with discrete regulator without feedback, LM ... can oscilate in this case. This oscilations probably are suppresed by " Carlos's snubber " ( it is the same case as " Boucherot " at output of PA, not the same case as " Carlos's snubber " connected beside rectifier ).
ue,
There are many ways to skin a cat, but the disadvantage of a discrete reg without feedback for me is that it really isn't a regulator, it's a stabilizer or super-power-zener or whatever. So, you put in all those power parts, but stop at the regulation. It is surely better than just bridge & caps, but I would just close the regulation loop. Stability can be done by the means you say or any other accepted compensation method. This is not different from the compensation of the amp itself.
Much also depends on the amp, its PSRR and other things. It is difficult to give a standard solution without knowing where it will be used.
But one thing is sure: amps are designed with the assumption that the supply is stable and for AC is the same as ground. If that is not the case (and it never is), the supply will influence the sound, in principle.
Jan Didden
There are many ways to skin a cat, but the disadvantage of a discrete reg without feedback for me is that it really isn't a regulator, it's a stabilizer or super-power-zener or whatever. So, you put in all those power parts, but stop at the regulation. It is surely better than just bridge & caps, but I would just close the regulation loop. Stability can be done by the means you say or any other accepted compensation method. This is not different from the compensation of the amp itself.
Much also depends on the amp, its PSRR and other things. It is difficult to give a standard solution without knowing where it will be used.
But one thing is sure: amps are designed with the assumption that the supply is stable and for AC is the same as ground. If that is not the case (and it never is), the supply will influence the sound, in principle.
Jan Didden
carlos: Two LM4780's per channel. Four for a two-channel amp. Hence my desire to have a little more juice available than a single LM338 provides. I can always just go high-cap snubbered or whatever.
Upupa: I'm aware of that one. In fact, it's the one I was alluding to when I stated in my first post I haven't figured out where they get their listed voltage range (4.5V-25V) to know if my target 30V was do-able or not. 25V would not be a problem regardless. It's on the table.
C
Upupa: I'm aware of that one.
In fact, it's the one I was alluding to when I stated in my first post I haven't figured out where they get their listed voltage range (4.5V-25V) to know if my target 30V was do-able or not. 25V would not be a problem regardless. It's on the table.C
The audio sector is the only ( in electronics ) when select technical are bound by the "opinions".
Here is am touched 3 diverge problems: The power supply dimensioning, the correct value of accumulated energy for audio amplifiers and the differences among a stabilized and non stabilizeded PSU.
How to in all the projects, be necessary tackles a problem for time;
The power supply dimensioning: if not is regulated, is chosen the proper diodes bridge and a battery of capacitors of "levelling". The diodes bridge has to be able to manage the " charge current peaks" of the capacitors and this is the only reason for which are used very strong seas. The middle current (on a diodes) of management of an amplifier in "real"conditions are too low of that theory ( after 2 to 30 % to second of the musical son-in-laws ).
Accumulated energy: Is diffused opinion that a widens has to dispose of a good energetic reserve (joule) from "Discharge" on the load when maids. Affair remembers that the capacitors of levelling works of continue to 100Hz with proportional current goes the instant discharges on the load, and not all the "theory" energy is in hand. To resolve this technical problem are used as the LC circuits and the stabilization. When are used active circuits of stabilization is has to hold account that to work has to be a voltage loss ( 10-30 % ) and that the regulator, for his nature, doesn't dispose of the speed necessary to current "follower" with the load in "real time", and a "cache" energetics reserves is that relative to the capacitors on output.
P.S. Using the protection diodes on LM338 and the slow start-up circuit, are able use cap. in exit => 10.000 UF without problems
Mauro
Here is am touched 3 diverge problems: The power supply dimensioning, the correct value of accumulated energy for audio amplifiers and the differences among a stabilized and non stabilizeded PSU.
How to in all the projects, be necessary tackles a problem for time;
The power supply dimensioning: if not is regulated, is chosen the proper diodes bridge and a battery of capacitors of "levelling". The diodes bridge has to be able to manage the " charge current peaks" of the capacitors and this is the only reason for which are used very strong seas. The middle current (on a diodes) of management of an amplifier in "real"conditions are too low of that theory ( after 2 to 30 % to second of the musical son-in-laws ).
Accumulated energy: Is diffused opinion that a widens has to dispose of a good energetic reserve (joule) from "Discharge" on the load when maids. Affair remembers that the capacitors of levelling works of continue to 100Hz with proportional current goes the instant discharges on the load, and not all the "theory" energy is in hand. To resolve this technical problem are used as the LC circuits and the stabilization. When are used active circuits of stabilization is has to hold account that to work has to be a voltage loss ( 10-30 % ) and that the regulator, for his nature, doesn't dispose of the speed necessary to current "follower" with the load in "real time", and a "cache" energetics reserves is that relative to the capacitors on output.
P.S. Using the protection diodes on LM338 and the slow start-up circuit, are able use cap. in exit => 10.000 UF without problems
Mauro
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