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Vincent PHO preamp transformer hum?


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Hi All, bit of a noob here. Just took my nice shiny Vincent PHO-300 out of the box and hooked it up. Looks and feels great quality, and a massive upgrade for my Behringer.

After hooking it up, I have noticed the power supply unit has a small but slightly audable 'hum' when you put your ear next to it. I'm not talking about hearing it through the stereo, I mean you can hear it with your ear up to the unit itself. Only subtle but that slightly annoying electric hum nonetheless. 

Is this completely normal? If so I will ignore and enjoy the records. Thanks

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Maybe don't stick your ear next to it?  :)   

 

Seriously I don't see it as a problem.  Let's hear from someone who has one and can try the same trick.

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7 minutes ago, aussievintage said:

Seriously I don't see it as a problem.  

Thanks, I tend to agree.

I only ask because Vincent make a big deal out of the whole separate power supply box thing to reduce noise and interference etc.  Cheers

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I would return it for exchange if it were me. Regardless of audibility in the music ,this sort of thing shouldn't happen.

 

Just IMO.

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53 minutes ago, horatiojb said:

I have noticed the power supply unit has a small but slightly audable 'hum' when you put your ear next to it. I'm not talking about hearing it through the stereo, I mean you can hear it with your ear up to the unit itself.  

 

Is this completely normal? If so I will ignore and enjoy the records. Thanks

 

It's not desirable - but it may be DC on your mains which is causing the power transformer in the PHO-300 power supply to vibrate?

 

If so - you might need a 'DC blocker' between the PHO-300 PS and the wall socket (to stop the DC which is on your mains from passing into the PHO-300).

 

2 minutes ago, thathifiguy said:

Is it placed nearby to other power supplies or products that have large transformers?

 

That's a good question - although as the hum is not coming through the spkrs ... there's no 'induced hum' happening.  It's a mechanical thing.

 

42 minutes ago, rantan said:

I would return it for exchange if it were me. Regardless of audibility in the music, this sort of thing shouldn't happen.

 

Agreed, rantan - but it's possible that every PHO-300 the OP installs will have the same problem (if DC on the mains is the culprit!)  :(

 

51 minutes ago, horatiojb said:

Thanks, I tend to agree.

I only ask because Vincent make a big deal out of the whole separate power supply box thing to reduce noise and interference etc.  Cheers

 

Vincent's 'selling point' of having the power transformer in a separate box is good practice and will tend to stop noise coming through the spkrs!  But DC will annoy some (many?) mains transformers - whichever box they are in.

 

1 hour ago, aussievintage said:

Let's hear from someone who has one and can try the same trick.

 

So Queensland's electricity supply is so good there is no such thing as 'DC on the mains'?  :lol:

 

 @horatiojb, as you are in Melbourne, it would be simple (now we're out of lockdown!) for me to bring over one of my DC blockers and test it out on your PHO-300.  PM me if you are interested.

 

Andy

 

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2 minutes ago, andyr said:

So Queensland's electricity supply is so good there is no such thing as 'DC on the mains'?  :lol:

 

Where the heck did you see me ever say that??  Huh???

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1 minute ago, aussievintage said:

Where the heck did you see me ever say that??  Huh???

 

You said "Let's hear from someone who has one and can try the same trick ".  My point was basically that "someone who has one " will be in a different location and might not experience the same hum because they have no (or less) DC on their mains.  Even in Qld!  :)

 

Andy

 

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55 minutes ago, andyr said:

 

You said "Let's hear from someone who has one and can try the same trick ".  My point was basically that "someone who has one " will be in a different location and might not experience the same hum because they have no (or less) DC on their mains.  Even in Qld!  :)

 

Andy

 

Wow.  You certainly didn't communicate any of those steps you took in between.  L0L! 

Just FYI, I have never needed to employ a DC blocker in all my years in hifi. Lucky me😀

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1 minute ago, aussievintage said:

Wow.  You certainly didn't communicate any of those steps you took in between.  L0L! 

 

No I didn't - sorry.  :(
 

1 minute ago, aussievintage said:

Just FYI, I have never needed to employ a DC blocker in all my years in hifi. Lucky me😀

 

Well, you live in Qld, right!  :lol:

 

Andy

 

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Seriously you lot. A guy puts his ear next to a power supply, hears a VERY minor hum (which has nothing to do with the sound)and you are having a debate. Donald, Help me!!

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1 minute ago, Wimbo said:

Seriously you lot. A guy puts his ear next to a power supply, hears a VERY minor hum (which has nothing to do with the sound)and you are having a debate. Donald, Help me!!

Such is the nature of first world pursuits and their attendant problems.:lol:

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1 hour ago, andyr said:

So Queensland's electricity supply is so good there is no such thing as 'DC on the mains'?

Definitely no different in Queensland, I had a buzzing double C core transformer in my old phono stage and a DC Blocker silenced it stone cold :D

 

Edit: I should put that in my CD Player just because I have it still.

Edited by muon*
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40 minutes ago, Wimbo said:

Seriously you lot. A guy puts his ear next to a power supply, hears a VERY minor hum (which has nothing to do with the sound)and you are having a debate. Donald, Help me!!

 

heh, well I did start out by saying I didn't think it was a biggie :) 

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Thanks for all your responses. I will try plugging it in other parts of the house and see if the hum continues. Not aware of any nearby electrical transformers that might be interferring...

 

I agree it's a first world 'problem', but at the same time it did cost a bit so you'd expect it to work well. My el cheapo Behringer phono preamp doesn't hum lol

 

 

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26 minutes ago, horatiojb said:

Thanks for all your responses. I will try plugging it in other parts of the house and see if the hum continues. Not aware of any nearby electrical transformers that might be interferring...

 

I agree it's a first world 'problem', but at the same time it did cost a bit so you'd expect it to work well. My el cheapo Behringer phono preamp doesn't hum lol

 

 

Doesnt have the same size tranni most prob and this should not be recognized as an undesirable fault IMO. 

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6 minutes ago, Wimbo said:

Doesnt have the same size tranni most prob and this should not be recognized as an undesirable fault IMO. 

Okay interesting, would you mind expanding on this- as a noob I would like to learn. Are you suggesting the hum actually indicates a desirable trait? Thanks

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45 minutes ago, horatiojb said:

Okay interesting, would you mind expanding on this- as a noob I would like to learn. Are you suggesting the hum actually indicates a desirable trait? Thanks

 

"There are more things, Horatio ..."!  :)

 

Small power transformers tend not to be as affected by DC on the mains as larger power traffos.  But, in my experience, small power traffos - say 60 VA - whilst they might theoretically be perfectly suitable for a phono stage (when you just consider the current draw) ... do not give as good a bass as a larger power traffo - say 160VA.  But the larger power traffo will be affected to a greater degree by DC.  :(

 

So whilst the hum is not desirable ... the fact that Vincent would seem to have used a larger traffo - which unfortunately is susceptible to hum from DC on the mains - is a good thing!  :thumb:

 

Andy

 

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My 2 cents worth: try 220v in with a variac to see if that lessens the hum on the power traffo.

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Just borrow a DC Blocker off another member and see if that stops the transformer from buzzing.

Edited by muon*
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8 hours ago, muon* said:

Just borrow a CD Blocker off another member and see if that stops the transformer from buzzing.

 

Which I offered to do.  :)

 

Andy

 

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12 hours ago, horatiojb said:

Okay interesting, would you mind expanding on this- as a noob I would like to learn. Are you suggesting the hum actually indicates a desirable trait? Thanks

Do you have the phono pre sitting on the power supply? If so, move it away from the power cord input side.

Some trannys are bigger and (depending on design) can make a little noise ,Laminations for a start. As I said before, I think its a mountain out of a mole hill.

Phono preamp placement is more important because of noise floor problems.

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  • 2 weeks later...

As a follow up on this thread, I took the power supply back to the good folk at Selby and we compared it with another unit in the store... guess what, they both have a hum lol! So not much to be done with this model it would seem.

 

Next step was to compare the next model up- PHO-500, and this was noticeably quieter, although did have some very minor hum too. 

 

And then the PHO-701 was totally quiet.

 

I'm planning to return the 300 and upgrade to the 701

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47 minutes ago, horatiojb said:

 

I'm planning to return the 300 and upgrade to the 701

 

 

Yes - probably cheaper than adding a DC blocker to your PHO-300.  :)

 

Andy

 

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15 hours ago, andyr said:

 

Yes - probably cheaper than adding a DC blocker to your PHO-300.  :)

 

Andy

 

Yes indeed...

 

So what is the lesson here? It is the, ahem, Chinese transformer quality? Don't buy low end?

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15 hours ago, andyr said:

Yes - probably cheaper than adding a DC blocker to your PHO-300. 

 

 

Why do you still think it is being caused by DC when it happens, just the same amount, at the dealers.  Also, it doesn't happen to the more expensive model.  All points to a quality issue - not DC.

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35 minutes ago, aussievintage said:

 

Why do you still think it is being caused by DC when it happens, just the same amount, at the dealers.

 

 

Because this is Vic, av - not Queensland.  :lol:  We have DC in many suburbs - not just the OP's.

 

35 minutes ago, aussievintage said:

 

Also, it doesn't happen to the more expensive model.

 

 

I agree that is interesting - as I would suspect the 'more expensive' model would:

  • be in a bigger case
  • have more circuitry inside
  • and use a bigger VA power traffo (which would be more likely to suffer when there is DC on the mains than a smaller one).

 

35 minutes ago, aussievintage said:

 

All points to a quality issue - not DC.

 

 

Do you think they build the more expensive model with more care (to get better 'quality') ... or with more expensive (ie. presumably better quality) parts?

 

Andy

 

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1 hour ago, andyr said:

Do you think they build the more expensive model with more care (to get better 'quality') ... or with more expensive (ie. presumably better quality) parts?

 

Depends.  All or none of the above.    The point is , it would/should not be worse in any respect  - at least I would hope not.

 

1 hour ago, andyr said:
  • and use a bigger VA power traffo (which would be more likely to suffer when there is DC on the mains than a smaller one).

 

uhuh, and yet it was quieter

 

 

1 hour ago, Wimbo said:

I rekon you should all give it away and go play Zep 2.

 

At least you wouldn't hear the humm when played at the appropriate volume  :)  

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  • 3 weeks later...

The PHO-701 has been working great, perfectly quiet, and looks the part with the illuminated valve display. The whole valve thing is not really my thing, but it sounds great. Valve upgrade next hehe

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