Different toroid trans mounting produce different sonic?

cent88 · 11th January 2011, 02:08 PM

Naim and some other amps toroids are filled with black thingy(epoxy?) in the center core. is it better than the standard mounting(cover on top).

I felt there is some sonic difference between cover top mounting and without mounting(lye on table). without mounting sound more airy.

AndrewT · 11th January 2011, 03:00 PM

Must be the Helmholtz resonator affecting the airy sound !

cent88 · 11th January 2011, 04:03 PM

or may be I need thicker silicon/rubber pad to isolate it?
I can feel the vibration when touching both left/right side of top cover.

bobodioulasso · 11th January 2011, 04:15 PM

Looks like you have a noisy transformer, or Dc is present at your mains.
Search for DC blocker.

cent88 · 11th January 2011, 04:35 PM

@bobo
I'm using nuvotem talema toroid(non-isolated).
Theres a lot of noises in my mains, electrical/electronic stuff's trans will buzz especially the water heater is on.
I wonder that my neighbour grounded her neutral(illegal) will affected my mains or not.

bobodioulasso · 11th January 2011, 05:03 PM

I have many transformers but no Nuvotem, so i can't say.
Some are more or less noisy and some are silent.
If Dc is present on your mains it can make a transformer hum.
Look at:
DC Blocking Filter for Mains
Also search into DIYAudio using "DC blocking" between brackets.

cent88 · 12th January 2011, 03:33 PM

wow.. there are a lots of DC filter but which one is safe to use and effective?

can I simplify it by using X2 caps in series with both live and neutral?

AndrewT · 12th January 2011, 03:56 PM

Quote:

Originally Posted by cent88

can I simplify it by using X2 caps in series with both live and neutral?

No.
The 50Hz AC impedance of the caps must be very low in comparison to the effective impedance of the transformer.
This usually requires 5mF to 60mF of capacitance in the power line.
AND some form of diode protection to stop you blowing up the caps during high pulse start ups and/or system failure and/or shorting out the speaker terminals.

11th January 2011, 02:08 PM	#1
cent88 diyAudio Member Join Date: Dec 2010 Location: Pearl of Orient	Different toroid trans mounting produce different sonic? Naim and some other amps toroids are filled with black thingy(epoxy?) in the center core. is it better than the standard mounting(cover on top). I felt there is some sonic difference between cover top mounting and without mounting(lye on table). without mounting sound more airy.

11th January 2011, 03:00 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Must be the Helmholtz resonator affecting the airy sound ! __________________ regards Andrew T.

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11th January 2011, 04:03 PM	#3
cent88 diyAudio Member Join Date: Dec 2010 Location: Pearl of Orient	or may be I need thicker silicon/rubber pad to isolate it? I can feel the vibration when touching both left/right side of top cover.

11th January 2011, 04:15 PM	#4
bobodioulasso diyAudio Member Join Date: May 2008	Looks like you have a noisy transformer, or Dc is present at your mains. Search for DC blocker.

11th January 2011, 04:35 PM	#5
cent88 diyAudio Member Join Date: Dec 2010 Location: Pearl of Orient	@bobo I'm using nuvotem talema toroid(non-isolated). Theres a lot of noises in my mains, electrical/electronic stuff's trans will buzz especially the water heater is on. I wonder that my neighbour grounded her neutral(illegal) will affected my mains or not.

11th January 2011, 05:03 PM	#6
bobodioulasso diyAudio Member Join Date: May 2008	I have many transformers but no Nuvotem, so i can't say. Some are more or less noisy and some are silent. If Dc is present on your mains it can make a transformer hum. Look at: DC Blocking Filter for Mains Also search into DIYAudio using "DC blocking" between brackets.

12th January 2011, 03:33 PM	#7
cent88 diyAudio Member Join Date: Dec 2010 Location: Pearl of Orient	wow.. there are a lots of DC filter but which one is safe to use and effective? can I simplify it by using X2 caps in series with both live and neutral?

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