ZenV4 PSU noise

[Roberto Amato]

Originally posted by aaronpiet
It seems, that it's not only the ripple current of the caps but also the capacity itself that has big influence on the sound on these special class-A Amps, perhaps also the speed of the caps.
Thanks for helping finding these results.

The more capacitance you add, more filtering (and less ripple) you get, so the sound changes for shure... when to say "stop, it's enough" it's another matter. Inductors do anyway a great job in filtering high frequency garbage (noticeable in smoother highs and increased listening easiness and ambience) much more than caps alone do... I couldn't do whithout.

I forgot to add an observation about Sikorel (but I think appliable to any other cap, especially big ones): they need a lot to "burn in". The sound "relax" a lot after many 10s hours. At first I thought was mosfet that needed so much time, but after having substituted the "burned in" ones (~400hrs) with a mint couple, the sound was very very close to what I was used to. That surprised me, without that try I would have never known.

ciao,
Roberto Amato

[PsykoK]

Originally posted by Roberto Amato

The more capacitance you add, more filtering (and less ripple) you get, so the sound changes for shure... when to say "stop, it's enough" it's another matter. Inductors do anyway a great job in filtering high frequency garbage (noticeable in smoother highs and increased listening easiness and ambience) much more than caps alone do... I couldn't do whithout.

I forgot to add an observation about Sikorel (but I think appliable to any other cap, especially big ones): they need a lot to "burn in". The sound "relax" a lot after many 10s hours. At first I thought was mosfet that needed so much time, but after having substituted the "burned in" ones (~400hrs) with a mint couple, the sound was very very close to what I was used to. That surprised me, without that try I would have never known.

ciao,
Roberto Amato

Yes you're right a Pi filter is the better solution to have a good PS.

[aaronpiet]

Is there no disadvantage using coils in the ps?
As far as i have seen, Nelson Pass doesn't need them in his amps.
In his x-models he has NTCs in a CRC-combination.

[janneman]

Originally posted by Roberto Amato

The more capacitance you add, more filtering (and less ripple) you get, so the sound changes for shure... [snip]ciao,
Roberto Amato

Roberto,

don't forget that the more cap you add, the more the ripple spectrum shifts to higher frequencies, where the rejection of the amp get worse. Indeed, it will for sure change the sound, but not necessarily for the better.
If you are interested, his has been discussed in other threads
ad nauseam

Jan Didden

[Roberto Amato]

Originally posted by janneman

Roberto,

don't forget that the more cap you add, the more the ripple spectrum shifts to higher frequencies, where the rejection of the amp get worse. Indeed, it will for sure change the sound, but not necessarily for the better.
If you are interested, his has been discussed in other threads
ad nauseam

Jan Didden

Exactly right. That's why I stress the importance of inductors in a power supply.

ciao,
Roberto Amato

[Roberto Amato]

Originally posted by aaronpiet
Is there no disadvantage using coils in the ps?
As far as i have seen, Nelson Pass doesn't need them in his amps.
In his x-models he has NTCs in a CRC-combination.

Well... cost for sure. Bulkiness. They put a resistance in series with the supply, so you have to calculate the voltage drop and act accordingly... but so do NTCs. I've never used them but if Nelson does I'm sure they work very very good. If I recall well, Nelson does a CRCRCRC... filtering, don't remember how many CRC cells. Seems to me they have many advantages in terms of cost and space they free... but until I try them out I don't have a personal opinion about performance differences.

ciao,
Roberto Amato

[stadams]

I am sure that we have all seen the pictures in the Aleph-X thread, but for those that haven't, here is a link to the pictures of the XA-200 and brief descriptions of each by Mr. Pass.

XA-200 pictures from Aleph-X thread.

He has implemented RC filtering before, just look at the BOZ. Of course it is much easier to realize an RC filter when the current demands of a system are in the milliamp range. Speculating what the demands from the XA-200 power supply are, I can understand the use of the thermistors as part of the filter network for the power supply.

Also, as Jan has said, filtration capacity, its impact on diode conduction angle, and its effects on noise spectra have been throughly explored, albeit don't let that stop a thoughtful and lucid discussion from continuing.

Later,