Not that crazy at all compared to yours, mate. No match.
A total of 480.000 µF, 240.000 µF per channel. Ungregulated CLC with 2.7 mH inductors.
Trannies are shielded 500 VA per channel. Lytics are Epcos Sikorel, Krummer, Mundorf HC,
Panasonic and a few Kendeils, most of them 100 V 105° LL, some are 125° LL.
Keep in mind it's just an Aleph J (25 W). 😉
I'll have to make some pics of the finished PSU soon.
Andy, doesn't a Class A amp draw a constant current? 😕
There's some much to read about general PSU design, but so few about designing a
Class A PSU in particular.
I'd highly appreciate any useful and detailed information about Class A PSU design. 🙂
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Ummm... this flies in the face of virtually everything ever written about using regulators.
Using series current limiting resistors then allows the caps to "float" freely, mostly down in voltage, but they're not under control. Yeah you can draw extra current with big caps, but then why do you need a regulator at all?
The argument that the regulator makes "perfect" the DC I suppose has some merit, but in practice I'd prefer a choke in that hole over the poor regulator. I'd guess that the output impedance of the supply would be lower with a choke in the hole over the regulator + series current limtiing resistor.
Keep in mind that my Symphony No.1 amplifier first designed and built ~1990 uses about 1/2 Farad in PS capacitance and >4kVA of iron, this for a high bias class AB mosfet amp rated at 180wrms per channel. So, I'm not in disagreement with the idea of big capacitance by any means.
Anyhow, I'd prefer it if the designer answered the questions...
_-_-
very confused.
The vast majority of ClassA amplifiers do not draw constant current.
There are a few ClassA topologies that draw constant current but they are rarely adopted.
F5x is one of these.
Looks very nice and neat build. Where is the main transformer ? None of the transformers shown seem big enough to handle 600W.
A proper full-on Class A will draw constant current. My Pass Aleph4 draws over 200W/Channel even at idle.
Are you getting confused with so called Class A amps that switch to Class B above a certain threshold ?
No, I am not getting confused.
The rail currents modulate with the the output current.
Change the output current by 1A and the rail current will change in sympathy by that amount.
As I said and I really meant it, only a few ClassA topologies draw constant current.
The rail currents modulate with the the output current.
Change the output current by 1A and the rail current will change in sympathy by that amount.
As I said and I really meant it, only a few ClassA topologies draw constant current.
Andrew, what do you mean when you say "change the output current by 1A"?
Are you talking instantaneous current per rail or averaged current per output stage/amplifier??
So ur making the case that bridged Class A causes constant draw? Yeah, but only if you use a common power supply for both sides of the bridge,eh?
Wonder when ur going to present one of your builds here in DiyAudio?
Would love to see your expertise put into a real world implementation.
_-_-
Are you talking instantaneous current per rail or averaged current per output stage/amplifier??
So ur making the case that bridged Class A causes constant draw? Yeah, but only if you use a common power supply for both sides of the bridge,eh?
Wonder when ur going to present one of your builds here in DiyAudio?
Would love to see your expertise put into a real world implementation.
_-_-
Exactly - Proper Class A will draw a constant current as the output devices are always ON.
My Alephs draw no more current at Full Power than they do at idle. The only difference is the amount of wasted heat. At idle it goes into the heatsinks at full power it goes into the load.
My Alephs draw no more current at Full Power than they do at idle. The only difference is the amount of wasted heat. At idle it goes into the heatsinks at full power it goes into the load.
Not that crazy at all compared to yours, mate. No match.
Keep in mind it's just an Aleph J (25 W). 😉
Amplifiers development of Nelson Pass is very popular in Russia, but I never tried to build its design.
Consider what one transistor does in a P-P class A amp?
It is baised "on" but as signal is applied to one side's transistors that transistor is caused to draw more or less current. So considering that rail alone the current drawn varies. Overall the amp draws nearly constant current assuming the bias is set appropriately for the load.
Your amps must produce the same heat regardless of load, or signal, unless the bias is insufficient for the amp to remain in class A for a given load impedance. The power does not "go to the load" somehow bypassing or eliminating the current draw of the bias in the quiescent state.
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