Hi fi Hum

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terrybooth
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Hi fi Hum

Unread post by terrybooth » Sun Apr 15, 2018 10:29 am

This keeps popping up in threads, so I thought I'd start a specific thread.

Unwanted hum is omething I guess we've all experienced over time and some tolerate more than others.

Its probably something we've all experienced, whether it's the noise of a guitar amp on a recording, the unearthed phono input or all the other things that might cause it.

Something that's present in my system. Only noticeable when not playing music.

I think - and I put this up as a straw man - there are three causes:

Broken circuit (including earths)
Induced - ie radio frequency/magnetic fields interfering
Mains borne

Yesterday, I was in front of my system and my wife was moving things around in the room. No music playing. I notices that, when she moved to a certain position, the hum changed, she moved away and it stopped. However, I then got her to move back to the same position and there was no change. So what was that all about - a temporary change in mains; she didn't move back to exactly the same position but was somehow changing the fields around the equipment; something else that I wasn't aware of?
Pioneer PL71/DL103/ Phono2/HiFiPi/P90SA/TIS/CubixPro two-up

Alfi
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Re: Hi fi Hum

Unread post by Alfi » Sun Apr 15, 2018 10:40 am

I get hum through the speakers if my systems cables are like a rat's nest. Carefully re-routing and keeping signal cables from power cables help to eradicate it.

I also get serious RF noise from our DECT phone when my wife is on a call.

Finally I get transformer buzzing which varies throughout the day and seems worse in the evenings. The BMU helped a bit with this as do ferrites clamped around the power lead where they enter the Phono2 power supplies/ power amps.

Alfi.
Heavily modified LP12, Sole VIII sub-chassis, "In Sole" advanced polymer suspension, Ai bearing, PU7, DV20X2, Norton Airpower clone. Technics SL110A, AT 1005, Denon DL301A. NVA Phono 2 MC (2 power supplies), NVA P50 SA, NVA A40 Mk1 power amps, custom birch ply Allison 6/NVA Cube 1 clones, NVA TIS mk2 , SSC, LS6.

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zebbo
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Re: Hi fi Hum

Unread post by zebbo » Sun Apr 15, 2018 11:15 am

I do have a degree of transformer hum even though my system is entirely fed from a mains regenerator then through a BMU, but it's not too bad considering I have six massive power supplies idling away. I might try some graphite rings close to the supplies to see if that quietens them a bit more.
Audio Grail "Sable" Garrard 401 with constrained layer plinth / SME V / Benz Gullwing SLR, Phono 3 + 2X BBPSU - MEGA!, NVA P90sa, NVA Cubix-Pro, (top & mid sections). (Oh and a Pioneer BDP LX70A when I just want some background music!)

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Dr Bunsen Honeydew
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Re: Hi fi Hum

Unread post by Dr Bunsen Honeydew » Sun Apr 15, 2018 12:22 pm

You need to define if acoustic hum from equipment or through the speakers or everyone gets confused as to what you are referring to.

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zebbo
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Re: Hi fi Hum

Unread post by zebbo » Sun Apr 15, 2018 12:50 pm

For me, on this thread, I'm talking about mechanical noise from transformers.
Audio Grail "Sable" Garrard 401 with constrained layer plinth / SME V / Benz Gullwing SLR, Phono 3 + 2X BBPSU - MEGA!, NVA P90sa, NVA Cubix-Pro, (top & mid sections). (Oh and a Pioneer BDP LX70A when I just want some background music!)

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Dr Bunsen Honeydew
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Re: Hi fi Hum

Unread post by Dr Bunsen Honeydew » Sun Apr 15, 2018 4:01 pm

The bigger the transformers and the more of them the bigger the hum, it is a trade off that has always been there. You will never find an A20 with transformer hum.

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alfafan123
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Re: Hi fi Hum

Unread post by alfafan123 » Mon Apr 16, 2018 7:55 am

I can vouch for that. My A20 is silent. No acoustical or electrical hum I can hear and I am sitting within 2 feet of it and the speakers on my desktop system.

Stemcor1990
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Re: Hi fi Hum

Unread post by Stemcor1990 » Mon Apr 16, 2018 8:23 am

I’ll second Alfa’s comment on the A20. My TSS varies from near silence to being a busy bee.

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Dr Bunsen Honeydew
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Re: Hi fi Hum

Unread post by Dr Bunsen Honeydew » Mon Apr 16, 2018 11:25 am

My wife use the hair dryer and everything hums and buzzes. Other things have same effect, it looks like if you want big amps Stemcor then it is BMU. The other choice for removing hum but IMO at the expense of some music is a DC blocker. The best one is done by Lurcher (nick) of this forum.

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Classicrock
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Re: Hi fi Hum

Unread post by Classicrock » Mon Apr 16, 2018 11:29 am

Most hum in my experience is due to some type of earth loop or lack of earthing. Even issues between certain components that use a different internal earthing arrangement. Obviously using a passive pre helps in this situation. Also mains problems that affect certain component transformers. I have a component that hummed moderately in my last house and dead silent here, but tying the NVA BMU actually brought the transformer hum back with a vengeance.

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