Can anyone tell me why inductors should or should not be used in an Aleph PSU? Someone told me once (I read it here I think) that only resistors should be used to drop voltage for the rails and that inductors were a no no. Why is this? I can't find the link anywhere.
Don't inductors posses a lot of great qualities for dropping voltage, quietly without affecting current.
Or give me a link to the post and I'll be happy.
C🙂
Don't inductors posses a lot of great qualities for dropping voltage, quietly without affecting current.
Or give me a link to the post and I'll be happy.
C🙂
Yes but an inductor can have a much lower DC resistance than high frequency impedance - they can be usefully used to filter out HF noise without dropping too much DC potential.
But great care has to be taken with the design otherwise you can get 2 x Vcc voltgae at turn on which could well destroy your amp.
I would recomend modelling in spice before you build.
The basic principal I have fould is that if you want to avoid this initial overshoot is to have for instance 10kuF L 20kuF L 40kuF and the resistance of the coils should not be to low perhaps 0.1 - 0.2 ohms minimum.
PLEASE NOTE THAT I AM NOT GIVING YOU A DESIGN HERE JUST SOME IDEAS TO START WITH AND TEST VERY CAREFULLY.
good luck - I find that choke supplies sound great
mike
But great care has to be taken with the design otherwise you can get 2 x Vcc voltgae at turn on which could well destroy your amp.
I would recomend modelling in spice before you build.
The basic principal I have fould is that if you want to avoid this initial overshoot is to have for instance 10kuF L 20kuF L 40kuF and the resistance of the coils should not be to low perhaps 0.1 - 0.2 ohms minimum.
PLEASE NOTE THAT I AM NOT GIVING YOU A DESIGN HERE JUST SOME IDEAS TO START WITH AND TEST VERY CAREFULLY.
good luck - I find that choke supplies sound great
mike
Hi Clarkcr,
I just happened to reading about this today so I'll quote you a few points from the text. Please be aware that I have no personal experiences with these filters.
Generally speaking L-C filters are preferred.
L-C filter
======
"The choke input filter allows a continuous current from the rectifier diodes, rather than the pulsating current demand by the capacitor input filter, and because of the, it has better voltage regulation. Maximum current is available to the load with this type of operatoin, so this filter is more suited to higher load-current demand.
On the debit side, the output voltage of the filter is equal to the average of the AC voltage delivered to the rectifier, rather than the peak value. It is also very costly, because a physically large, low resitsance inductance is required."
C-L-C filter
========
"The pi filter is more efficient.....is used on medium-current equipment, it does produce a higher output voltage then the L-C filter, but the regulation is not as good."
C-R filter
======
"this type of filter is less expensive. The filtering action is not as good, and here is some loss of DC voltage at the output because of the voltage drop across ther resistor. It is limited to low-current equipment..."
Reference
=======
Understanding DC Power Supplies - barry Davis
As I said earlier I am only quoting from a text and can't confirm the information is correct, but I hope it is useful.
I just happened to reading about this today so I'll quote you a few points from the text. Please be aware that I have no personal experiences with these filters.
Generally speaking L-C filters are preferred.
L-C filter
======
"The choke input filter allows a continuous current from the rectifier diodes, rather than the pulsating current demand by the capacitor input filter, and because of the, it has better voltage regulation. Maximum current is available to the load with this type of operatoin, so this filter is more suited to higher load-current demand.
On the debit side, the output voltage of the filter is equal to the average of the AC voltage delivered to the rectifier, rather than the peak value. It is also very costly, because a physically large, low resitsance inductance is required."
C-L-C filter
========
"The pi filter is more efficient.....is used on medium-current equipment, it does produce a higher output voltage then the L-C filter, but the regulation is not as good."
C-R filter
======
"this type of filter is less expensive. The filtering action is not as good, and here is some loss of DC voltage at the output because of the voltage drop across ther resistor. It is limited to low-current equipment..."
Reference
=======
Understanding DC Power Supplies - barry Davis
As I said earlier I am only quoting from a text and can't confirm the information is correct, but I hope it is useful.
Thanks you guys, that's a great start. I hav a copy of SPICE that I havn't installed yet....maybe now is the time. I was told by a neighbor of mine that the toroidial inductor will will also bring the capacitors up slowly so as to limit the in rish of current that plays havok with my house circuit breaker.
It seems from Greg's text that the LC is preferred....Why not an LCLCC or even an LCLCLC. I'm using 6 72,000 uF capacitors in my filter supply per amp. I'm also using a 1500va Piltron toroid. I don't mind the heat of the CR filter but, am very intrigued by the other advantages of the choke.
Chris
It seems from Greg's text that the LC is preferred....Why not an LCLCC or even an LCLCLC. I'm using 6 72,000 uF capacitors in my filter supply per amp. I'm also using a 1500va Piltron toroid. I don't mind the heat of the CR filter but, am very intrigued by the other advantages of the choke.
Chris
analog_sa said:
I meant with less heat, slower in rush of current. Greg's text book quote even talks of the differences in current loads. It also adds to the ultimate goal of lowering the ripple current.
Will somebody please speak up for the lowly reisitor in a CR???????
Chris
This is probably a forum no no, but I posted the same thread on the solid state board to see what response I'd get there as well.
here is a response I got. Very interesting...does Single Ended Class A make this situation any better or any worse?
Quote:
A LC cell provides 12dB/oct filtering but the L and C values have to ve carefully selected to create a damped non-resonant system, depending on inductor Rdc and capacitor ESR
The LC filter design goes more and more complex as more LC cells are added in series, it will definitely require custom-wound inductors with custom inductance and Rdc values and some minimum load resistance on the output to avoid resonance
In the other hand, a RC cell provides only 6dB/oct filtering but it will never resonate, even in case of crazy R and C values, and you can easily place several in series
Thanks to you all again.
Chris
here is a response I got. Very interesting...does Single Ended Class A make this situation any better or any worse?
Quote:
A LC cell provides 12dB/oct filtering but the L and C values have to ve carefully selected to create a damped non-resonant system, depending on inductor Rdc and capacitor ESR
The LC filter design goes more and more complex as more LC cells are added in series, it will definitely require custom-wound inductors with custom inductance and Rdc values and some minimum load resistance on the output to avoid resonance
In the other hand, a RC cell provides only 6dB/oct filtering but it will never resonate, even in case of crazy R and C values, and you can easily place several in series
Thanks to you all again.
Chris
the first LC section of an LCLC... behaves completely differently from subsequent stages. It means that your amp will create less havoc with the mains supply. It is quite an elegant design that requires very careful design and is only really suitable for amps that runs in class A. The more the bias current he easier it is to make this design work properly. ( Properly means that there is always current flowing in the transformer coils )
have fun with the spice
mike
have fun with the spice
mike
Clarkcr said:
Depends on who you want an answer from. 😎
Clarkcr said:
All quite true, but easily covered as long as you use big enough
capacitors - which is what you want to do anyway. Resistors
across inductors also help damp out such systems - values
like 10 ohms or less.
And you know what I mean when I say big. I mean porno BIG.
😎
/pass/: gets lots of amplifier ideas from porn movies 😉
Member
Joined 2002
jleaman said:
I mean making porn. 😉
leadbelly said:
No air cores here. Steel fist in velvet glove, dipped in
Velveeta (tm) 😉
Ever seen the porno with the 72,000 uF capacitor? So there's the toroid right....all nice and pretty, got her black wrap plastic cover on. Wires all differnt colors. Then come walk in 6 tall dressed in Mallory Blue capacitors 72,000 uF tall. 😀
Are custom wound inductors excessively expensive? Should I use SPICE to (trust SPICE) to run my calculations?
Thanks for the laugh Nelson. That was s good one.
Chris
Are custom wound inductors excessively expensive? Should I use SPICE to (trust SPICE) to run my calculations?
Thanks for the laugh Nelson. That was s good one.
Chris
By the way Nelson, wait until you see the faceplate I have designed for this baby. You're gonna turn green!!!!
C
C
I think I made a mistake....Nelson help!!!
I was under the impression that the Aleph 1.2 was produced origianlly with a 1200 VA tranni. I thought at the time produdent to round up to 1500va so that's what I bought from Piltron.
Just so happens I settled in on the couch this morning with a cup of coffee to read Anthony H. Cordesman's review of the 1.2 in Audio magazine from July 1997. He indicates that it takes a 2000va trannie not a 1200va. I pulled out the specification manual and it indicated "10 times the rated power". Oops, that would be 200 watts times 10.....2000 watts (VA)!!!!
Did I really screw myself here? Should I save up for another set of 1500 from Piltron and have 3000VA total, or maybe the Master can calm me down and tell me everything will be alright. Have another cup of coffee and not worry about the puny toroid.
I was under the impression that the Aleph 1.2 was produced origianlly with a 1200 VA tranni. I thought at the time produdent to round up to 1500va so that's what I bought from Piltron.
Just so happens I settled in on the couch this morning with a cup of coffee to read Anthony H. Cordesman's review of the 1.2 in Audio magazine from July 1997. He indicates that it takes a 2000va trannie not a 1200va. I pulled out the specification manual and it indicated "10 times the rated power". Oops, that would be 200 watts times 10.....2000 watts (VA)!!!!
Did I really screw myself here? Should I save up for another set of 1500 from Piltron and have 3000VA total, or maybe the Master can calm me down and tell me everything will be alright. Have another cup of coffee and not worry about the puny toroid.
After building an Aleph 4 and wanting to get a quieter PSU began trying CRC filters but wasn’t much of a help. Next tested an CLC following that made an LCRC which robed too much voltage and finally settled to an LC filter which gave a very nice and quiet supply eliminating much of the roughness from the diode bridge and giving a surprising regulation to the PSU.
The only drawback to this setup, for me, is that I have lo live with a lower rail voltage. So for the next time I will factor in the voltage drop on the secondary. I wouldn’t do another class A without an LC filter.
In this case L is about 18 mH mounted on a gapped EI–100 iron, home built, good for some 3-4 Amps, plus 130K uf per rail.
Also on my Zen I followed Nelson’s suggestion of a Pi filter CLC with an air core inductor with some 2 mH with good results. But for my liking this should be at least 5 mh to get most of the advantage for this setup, but for an air core this would be large.
The only drawback to this setup, for me, is that I have lo live with a lower rail voltage. So for the next time I will factor in the voltage drop on the secondary. I wouldn’t do another class A without an LC filter.
In this case L is about 18 mH mounted on a gapped EI–100 iron, home built, good for some 3-4 Amps, plus 130K uf per rail.
Also on my Zen I followed Nelson’s suggestion of a Pi filter CLC with an air core inductor with some 2 mH with good results. But for my liking this should be at least 5 mh to get most of the advantage for this setup, but for an air core this would be large.
Attachments
Clarkcr
Nelson Pass uses resistance instead of inductance in the XA160 and XA200 power supply filters and he still quotes them as 3uV quiet at the outputs. The ripple produced in these supplies looks to be around 50mV by my calculations so if you can get the ripple in your supply down around 50mV you should be okay.
Nelson Pass uses resistance instead of inductance in the XA160 and XA200 power supply filters and he still quotes them as 3uV quiet at the outputs. The ripple produced in these supplies looks to be around 50mV by my calculations so if you can get the ripple in your supply down around 50mV you should be okay.
Not quite.
see
http://www.stereoplay.de/d/52576
http://www.stereoplay.de/sixcms/media.php/188/stp0704PassXA160.pdf
Leeuwarden provided us these links.
Regards
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