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TheWretchedWorld

Buzzing toroidal transformer

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Posted (edited)

So my Parasound 2250 power amplifier has buzzing from the transformer which is audible in my listening position. I did some research and found that DC offset could be the cause of it. I understand I can purchase a DC blocker from holton audio but I want to be 100% sure that this will fix the problem. Is there a way of knowing that DC offset is the cause of the buzzing or if its just the transformer thats developed it through age. Also if it isn't caused by DC offset is there any solution to this problem or would I be better of saving my coin for an Emotiva XPA 2 gen 3? I love this amp sounds great with my LS50s its just that the buzz from the transformer is driving me nuts.

Edited by TheWretchedWorld

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It doesn't take a lot to get a toroidal to buzz.  DC on the mains is always suspected. You need to experiment by trial and error process elimination.  Tranformers buzzing can be cause by numerous issues and I've read many posts here that using a DC blocker "did not fixed the issue"   And the initial response is always DC on the mains.  Every case is unique.  I've read marketing materials that claim that the DC is caused by a very distorted mains,  I've got to say yes that's true but have you seen a 240V supply on a scope?  Let's just say it's far from perfect.  I've always have said this because I was exposed to DC getting injected onto the mains, and that's not good becuase the customer was complaining about smelling smoke in the room.  If  DC was on the mains your toroidal transformer will heat up very quickly so will every other piece of equipment that uses a step down transformer. 

So let me asked the question is it a mechanical buzz from the amp with the speakers disconnected or is via the speakers?

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Its purely from the amp itself. The speakers are dead silent. A testament to the amps low noisefloor.

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Hmm this is quite strange. It seems to be a lot quieter now than it was earlier in the day... Might be worth investing in that dc blocker.

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Be patient.

 

Lets hope someone will chime in and be able to to lend you an isolation transformer or a DC blocker to try 1st b4 we go jumping the gun.   Or even if you're in the west of Melb you can bring it to my place and see if the amp still buzzes.

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Good idea. I'll probably take it down to my folks place tomorrow just to suss it out. That being said whats there to say there isn't dc offset in their grid aswell.

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Better get a reasonable digital multimeter or an electrician with an oscilloscope to measure the DC offset on your AC lines.

 

DC offset is something you not only want to prevent with your audio equipment, but everything else in the home too, so best to isolate the source and remove rather than just filtering it out before the amp.

 

DC offset. The presence of a dc voltage or current in an ac power system is termed dc offset. This can occur as the result of a geomagnetic disturbance or asymmetry of electronic power converters. Incandescent light bulb life extenders, for example, may consist of diodes that reduce the RMS voltage supplied to the light bulb by half-wave rectification.
 
Direct current in ac networks can have a detrimental effect by biasing transformer cores so they saturate in normal operation. This causes additional heating and loss of transformer life. Direct current may also cause the electrolytic erosion of grounding electrodes and other connectors.
 

 

JSmith :ninja:

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9 hours ago, TheWretchedWorld said:

So my Parasound 2250 power amplifier has buzzing from the transformer which is audible in my listening position. I did some research and found that DC offset could be the cause of it. I understand I can purchase a DC blocker from holton audio but I want to be 100% sure that this will fix the problem.

 

Hi Louis,

 

Holton is not the only one who makes DC blockers.  @guru does ... and so do I.

 

I have one in stock and could lend it to you for the weekend, if you want to try it out (I always recommend trying it before you buy it - as Atm suggested).

 

PM me if you're interested.

 

 

Regards,

Andy

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This is a Quote from the Holton Precision Audio Site

Sound familliar ?

 

 

Holton DC Blocker One AC mains conditioner.

If your amplifier has ever suffered from a noisey buzzing power transformer that seems to come and go depending on the time of day.

Your sound system is most likely suffering from DC on the AC mains.

DC on the mains is generated from a lot of modern appliances like air conditioners, laser printers, switchmode power supplies etc.

its causes clipping of the AC mains waveform and this generates direct current to be formed which is piggy backed on the AC mains.

The result is it saturates power transformers primary winding creating a very loud acoustic buzz which can more often than not be heard across your listening room.

It also robs the power transformer of power and dynamics, which in turn rob the amplifier of sound quality.

The Holton DC blocker is a very high power AC mains conditioner which not only removes the DC from the mains but also filters high frequency noise from the mains as well.

The Holton DC blocker is capable of power devices as high as 2400 watts from your standard Australian GPO without any drop off in power delivery.

The DC blocker also comes with high quality AC volt and AC current meters so you can see exactly what is happening with what you are powering.

The result of using the Holton DC Blocker is restored dynamics and resolution in your sound system and no noisy power transformers.

 

Unquote

I would go for something like this, game over.

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Pardon my ignorance but if there is DC on the mains wouldn't all the trannys buzz ?

or just random ones?

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1 hour ago, joz said:

Pardon my ignorance but if there is DC on the mains wouldn't all the trannys buzz ?

or just random ones?

depends what your amps have built in, all mine  plugged straight in the wall :)

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24 minutes ago, :) al said:

depends what your amps have built in, all mine  plugged straight in the wall :)

Yep mine too, never ever had an issue.

So just makes me wonder what could be causing it?

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The major cause of DC on the mains are solar panel inverters hooked up to the mains supply, mostly inexpensive units belonging to neighbours.

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4 minutes ago, guru said:

The major cause of DC on the mains are solar panel inverters hooked up to the mains supply, mostly inexpensive units belonging to neighbours.

i have solar and so do some of my neighbours and no issue :) maybe its not inexpensive :) my solar does cost more than one of my amps ! :D 

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Posted (edited)

I had/have a similar experience, I bought a used pre amp and it has had a hum since purchase.

I got my electricity supplier to check voltage and it was ok, I thought it might be a DC issue, so I bought a PS Audio P10 regenerator, not just for the hum but I thought I would get other benefits, which it did.

Unfortunately the hum still exists, probably lower with the P10 but still exists, inaudible from the listening chair, but audible near the equipment.

I think my issue is a faulty transformer, need to get it investigated.

So it might not be a DC issue.

Edited by awayward

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Most blockers I sell go to people using them for their visual displays, nothing to do with hifi .

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16 minutes ago, guru said:

Most blockers I sell go to people using them for their visual displays, nothing to do with hifi .

indeed my pio kuro buzzes... 

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4 minutes ago, :) al said:

indeed my pio kuro buzzes... 

That's the plasma panel, not the transformer buzzing from DC offset on the mains.

 

Plasma's have always buzzed, some more than others... usually when bright images are up. It's to do with the electrical charges that are used to create the images on the screen. The higher in altitude a plasma panel is, the more it will buzz too. It's normal for a plasma panel, it can often increase with age and can be exacerbated by wall mounting in a noise controlled room.

 

JSmith :ninja:

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Posted (edited)
8 minutes ago, JSmith said:

That's the plasma panel, not the transformer buzzing from DC offset on the mains.

 

Plasma's have always buzzed, some more than others... usually when bright images are up. It's to do with the electrical charges that are used to create the images on the screen. The higher in altitude a plasma panel is, the more it will buzz too. It's normal for a plasma panel, it can often increase with age and can be exacerbated by wall mounting in a noise controlled room.

 

JSmith :ninja:

 

CRT are even worst.  Everytime I switch old CRT on my Daughter screams at me to switch it off.   They come with high pitch squeal.

 

Edited by Addicted to music

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2 hours ago, joz said:

Pardon my ignorance but if there is DC on the mains wouldn't all the trannys buzz ?

or just random ones?

It doesn't take a lot to make a toroidal to buzz,  only a few hundred millivolts of DC especially for  any toroidal over 300W.   

Like I posted earlier in the peace the mains waveform isn't perfect, far from it!  Any non symmetrical cycle will become DC on the line.

Like I posted earlier if there was real DC injected in the lines every device that has a step down transformer will be effected and that will be heat related as well.

my experience with real DC on the mains was back in my Kodak days.  A SSR(solid state relay) normally have 4 pins,  2 are for a 24V optocoupler to control 240vac was the cause because it was powering a normal laminated transformer. Because the 24 leaked into the 240V the transformer was smoking hot!   The client was complaining of electrical burn odour in the room.  Like I posted earlier if there was Real DC injected on the lines every device using a step down transformer will get extremely hot!   Anything with a coil driven by DC like solenoids and speaker coils will heat up very quickly even the ones with 12-24VDC.  That's why most solenoids are operated temporarily.

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Posted (edited)
2 hours ago, :) al said:

depends what your amps have built in, all mine  plugged straight in the wall :)

 

Not quite sure what you're inferring there, al ... are you saying your amps already have DC blockers built in?

 

The power traffos in all my amps don't buzz either - and they are all plugged straight into the wall ... and they don't have a DC-blocking mechanism built in.  All I can surmise from this is that:

  1. they are good quality power transformers - Aus-made ... no Jaycar/Chinese sh*t here! :lol:
  2. I'm possibly lucky enough not to have DC on my mains.

 

Andy

 

Edited by andyr

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6 minutes ago, andyr said:

 

Not quite sure what you're inferring there, al ... are you saying your amps already have DC blockers built in?

 

The power traffos in all my amps don't buzz either - and they are all plugged straight into the wall ... and they don't have a DC-blocking mechanism built in.  All I can surmise from this is that:

  1. they are good quality power transformers - Aus-made ... no Jaycar/Chinese sh*t here! :lol:
  2. I'm possibly lucky enough not to have DC on my mains.

 

Andy

 

yes you are probably quite right to surmise :D prob hit nails on head...

 

 

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