IEC Inlet with or without line filter for CD transport? - diyAudio
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Old 21st August 2009, 12:41 PM   #1
pooya is offline pooya  Germany
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Default IEC Inlet with or without line filter for CD transport?

I have read here a lot of about players/transports mods. Now, I am going to do a full grade up of my CD transport: clock, caps, power supply, connectors, ect. I have to choose between IEC Inlet with or without Line Filter. What do you suggest? If with filter, which one, which values of L, C?
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Old 22nd August 2009, 06:29 AM   #2
Mooly is online now Mooly  United Kingdom
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You need to be clear on just what you are trying to filter. If the AC inlet is 2 core (L/N) then you need a filter that operates as such. This would consist of a cap across L/N followed by inductive filtering in each line, possibly on a common toroidal core and a further cap on the "output side.
A filter that includes an earth line will do this and also filter noise on each line to earth, by including caps from L/N to earth.
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Old 22nd August 2009, 06:58 AM   #3
pooya is offline pooya  Germany
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Quote:
Originally Posted by Mooly View Post
You need to be clear on just what you are trying to filter. If the AC inlet is 2 core (L/N) then you need a filter that operates as such. This would consist of a cap across L/N followed by inductive filtering in each line, possibly on a common toroidal core and a further cap on the "output side.
A filter that includes an earth line will do this and also filter noise on each line to earth, by including caps from L/N to earth.
Thanks for your replay!

A filter that includes an earth line should be better, am I right? I know the basic schematic of both types. But which values have to have the filter LC components, how can I chose the right one? There are so many

Are the line filters they any good for CD transports/players? Can they make the sound worse in some way? My CD transport is Audiomeca Mephisto
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Old 22nd August 2009, 11:14 AM   #4
Mooly is online now Mooly  United Kingdom
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If your CD/Transport has a 3 core mains lead with the earth connection in use i.e. it is connected to some point within the equipment (case, PSU ground etc) then use a filter intended for use with an earth line.
The PSU in the transport may well have it's own filter anyway on the incoming mains side... have you looked or have you a circuit.
It all depends on what is originally fitted and how the player is wired.

First page here shows circuit of some different filter types.
http://www.schaffner.com/mediapool/files/mediaPool7.pdf
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Old 22nd August 2009, 11:41 AM   #5
infinia is offline infinia  United States
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Hi
If the player is 2 wire, then please don't introduce a earth connection inside the player. If so you can still use a filter> be sure to select the medical grade (no capacitor connections to E) If you start adding a ground to one that does not exist before, it now becomes a complicated system design issue and trouble awaits the novice. The higher rated current within a given series has more filtering in general.

The newer CD/DVD players have SMPS and can benefit more from common mode IEC filtering keeping the noise from exiting thus entering other devices in your system.
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Old 22nd August 2009, 11:47 AM   #6
pooya is offline pooya  Germany
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Quote:
Originally Posted by Mooly View Post
If your CD/Transport has a 3 core mains lead with the earth connection in use i.e. it is connected to some point within the equipment (case, PSU ground etc) then use a filter intended for use with an earth line.
The PSU in the transport may well have it's own filter anyway on the incoming mains side... have you looked or have you a circuit.
It all depends on what is originally fitted and how the player is wired.

First page here shows circuit of some different filter types.
http://www.schaffner.com/mediapool/files/mediaPool7.pdf
No, there is no filter, please look at the picture. I have already looked at www.schaffner.com and found this one . It should be the best one from schaffner. What do you think?
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Old 22nd August 2009, 12:04 PM   #7
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to introduce filter, you need to know what is the noise frequency you want to attenuate
different filter have different characteristics, attenuate different frequencies
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Old 23rd August 2009, 06:58 AM   #8
pooya is offline pooya  Germany
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Originally Posted by infinia View Post
Hi
If the player is 2 wire, then please don't introduce a earth connection inside the player. If so you can still use a filter> be sure to select the medical grade (no capacitor connections to E) If you start adding a ground to one that does not exist before, it now becomes a complicated system design issue and trouble awaits the novice. The higher rated current within a given series has more filtering in general.

The newer CD/DVD players have SMPS and can benefit more from common mode IEC filtering keeping the noise from exiting thus entering other devices in your system.
As you can see on the picture above the player has 3 wire power supplies (with earth connection) so I do not need to add a ground. The power supply is not SMPS but with LM317/337, L7805 and L7815. I will make a completely new power supply with 3-4 transformers.
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