toroid for car amp smps

[B.I.G]

jackinnj so you are saying that even in a grounded case the RF can still get out

My smps is in a computer PSU case

[Eva]

A grounded metal case provides decent attenuation to electric fields [capacitive propagation of quick voltage changes] but attenuation to magnetic fields [inductive propagation of quick current changes] may pass through the case with 20dB or less attenuation

Also, the case does nothing against EMI radiated through the input and output wires acting as antennas

[B.I.G]

i can hear it with the radio at LW ... it is not loud but it exists ..... i`ve lost the top cover from the PC psu so i can not test it in the case (((

[sss]

imho if u can hear it then there is something wrong allready

[Sheriff]

Hi,

What in your experience makes a good SMPS for audio use.

Looking at an off line converter -

Active PFC with more than enough 'C' to cover low line worst case?

Good LF gain?

tightest regualtion at the output?

loop response that covers the audio bandwidth?

Transient response?

Low output noise?

etc.

Just looking form some parameters and what benefots they offer over a traditional linear PSU for use in a domestic amplfiier

Cheers

Sheriff

Sheriff

[subwo1]

Originally posted by jackinnj
... what will mystify you even with a spice model is the compensation for the comparator/error amplifier --

I have simulated my design of a SMPS because it is a very simple circuit theoretically. I know it is not perfect, but I have not found an approach I like more, even in real life. That circuit definitely shows the benefits of phase compensation in the feedback loop. I think that concept is what you mean.

[subwo1]

Originally posted by Sheriff
Hi,

Active PFC with more than enough 'C' to cover low line worst case?

0f

I feel that for DIY passive is more than sufficient, and much simpler, with no added interference.

[Sheriff]

Hi Subwo1,

How about the pros / cons compared to a linear PSU powering a class D amp for example.

I know you have much experience on this topic also.

I guess that with a bit of messing around you could sync an active PFC stage to the downconverter to a multiple of the Class D amps switching frequency in an atempt to avoid beat frequencies.

The trouble is developing a good amplifier with a fixed carrier frequency....., and then filtering the sync'd noise...

Cheers

Sheriff

[jackinnj]

Originally posted by sss
yeah but when u put the sub circuit into the whole smps circuit the computer barely moves and the whole thing makes stupid software errors

then you need better software -- GIGO

[subwo1]

Hi Sheriff,
Reality turns out to be not much more than a bunch of trade-offs. I try not speak on the issue of the best approach for any one individual, unless they already have a set course I can give advice I am comfortable with.

I did tinker with an unregulated SMPS which also was the source of the constant switching frequency of an amp. But other projects needed attention and I did not return to experimenting with the circuit.