Help me resolve humming noise problem

gobble

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Hello HiFivers

I am currently auditioning Viren's Lync preamp. Unfortunately the new addition in my setup is creating the infamous problem of Hum. It is audible when listening to music during the quieter passages and also interferes in late night low level listening. It is a very smooth Brrrr kind of mid to low freq noise when playing. With nothing playing it is better described as a buzz. Let me detail the things I tried to fix it.

1. Connect a thin single core wire from metal contact on preamp to the Amp - No change
2. Connect the wire from metal chassis of pre or amp to window grill - No change
3. Disconnect preamp and CDP from mains leaving only the amp powered on - no change
4. Remove preamp<>amp RCA cable. Hum gone but obviously this is not a solution
5. Use 3 pin socket without earthing pin on Pre (since amp and CDP have no earthing ground pin) - No change


Until yesterday morning there was only the faint buzzing hum from the speakers. Since last night when I first switch on the preamp, the hum triples in volume then fades away to the original level by 15 secs. Likewise when I switch off the preamp, the hum disappears completely (yipee!) - but the buzz returns after 15secs.

6. On day one, switching on CDP resulted in the loud initial hum as above, but it is not affecting since yesterday night.

I tried lifting the CDP away at a distance from the pre and the noise varies with distance. I've now placed the preamp one empty rack below the CDP. There was in improvement in imaging and SQ. Varying the distance from preamp and amp (within reasonable limits) had no effect on buzz or SQ.

Edit: The distance between top of bottom shelf and bottom of upper shelf is 7 inches. The MDF is 16mm.

Request your suggestions on fixing this vexing problem.

TIA
Regards
 
Last edited:

Kamal

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Cosidering pts 4 & 2nd para of pt 6,suggest give Viren a call- 011-41401143,
he prob wld have experience in matters where his pre is involved in the audio chain.
 

suri

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Hello HiFivers

I am currently auditioning Viren's Lync preamp. Unfortunately the new addition in my setup is creating the infamous problem of Hum. It is audible when listening to music during the quieter passages and also interferes in late night low level listening. It is a very smooth Brrrr kind of mid to low freq noise when playing. With nothing playing it is better described as a buzz. Let me detail the things I tried to fix it.

1. Connect a thin single core wire from metal contact on preamp to the Amp - No change
2. Connect the wire from metal chassis of pre or amp to window grill - No change
3. Disconnect preamp and CDP from mains leaving only the amp powered on - no change
4. Remove preamp<>amp RCA cable. Hum gone but obviously this is not a solution
5. Use 3 pin socket without earthing pin on Pre (since amp and CDP have no earthing ground pin) - No change


Until yesterday morning there was only the faint buzzing hum from the speakers. Since last night when I first switch on the preamp, the hum triples in volume then fades away to the original level by 15 secs. Likewise when I switch off the preamp, the hum disappears completely (yipee!) - but the buzz returns after 15secs.

6. On day one, switching on CDP resulted in the loud initial hum as above, but it is not affecting since yesterday night.

I tried lifting the CDP away at a distance from the pre and the noise varies with distance. I've now placed the preamp one empty rack below the CDP. There was in improvement in imaging and SQ. Varying the distance from preamp and amp (within reasonable limits) had no effect on buzz or SQ.

Edit: The distance between top of bottom shelf and bottom of upper shelf is 7 inches. The MDF is 16mm.

Request your suggestions on fixing this vexing problem.

TIA
Regards

gobble,

use shielded interconnects - do this experiment -

power on preamp, amp and cdp but remove the interconnects between preamp and amp - if the hum is gone, you know what to do

suri

edit - you have already done that - i just see, and if the preamp and amp were powered on, then the cause of the hum is the use of non-shielded IC's
 
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gobble

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gobble,

use shielded interconnects - do this experiment -

power on preamp, amp and cdp but remove the interconnects between preamp and amp - if the hum is gone, you know what to do

suri

edit - you have already done that - i just see, and if the preamp and amp were powered on, then the cause of the hum is the use of non-shielded IC's

Thanks. Which ones do you suggest?
Edit: I use DIY cables, one is the Calrad you donated which is between pre<>Power , the other is solid silver made by Mr. Murthy between CDP<>Pre. Can shielding be applied to these?
Changing to Profigold pg4201 budget cable at either link did not resolve the problem.

TIA
regards
 
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gobble

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Cosidering pts 4 & 2nd para of pt 6,suggest give Viren a call- 011-41401143,
he prob wld have experience in matters where his pre is involved in the audio chain.

Yeha he is looking into potential reasons the issue as well. If you google you will find this is a very common problem when seperates are involved esp tube pre's. Usually it is a ground loop...

Regards
 

mahiruha

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Hello gobble,
are you getting the hum from speakers or from the prem amp itself. when I turn on my amplifier there is a slight noise from the tubes as if they are being heated. I do get some humming noise from the speakers when listening to TT but that is not very significant.
thanks.
 

gobble

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Hello gobble,
are you getting the hum from speakers or from the prem amp itself. when I turn on my amplifier there is a slight noise from the tubes as if they are being heated. I do get some humming noise from the speakers when listening to TT but that is not very significant.
thanks.

The buzz and hum is from speakers not the tubes. with pre switched off there is only faint buzz, then when switched on it is a hum like someone doing prolonged OM chanting (not too loud but audible in quite passages and low volumes) . Trouble is I feel my stress levels build up after a while of listening just like with the whining of a PC fan, and I suspect the steady background hum to be the cause.

Regards
 
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dinyaar

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Yeha he is looking into potential reasons the issue as well. If you google you will find this is a very common problem when seperates are involved esp tube pre's. Usually it is a ground loop...

Regards

Yes very true so Viren will be the best person to solve this issue.

Gobble u have introduced a Lyrita Pre with your Nad integrated (removed the jumpers & using the power section) with your Wharfies?? The above problems are with these components in the chain?

Are u using any power strip? Or powering directly from walls outlets.

The Nad does not have a third pin(ground) on the IEC Male at the rear? I thought it did. The other end may have a schuko which does not mean that the unit does not require ground.
I can understand a cdp/tuner/deck etc not needing ground.

Point 3 states u disconencted the cdp & Pre and the hum still remains!!!

Ground loops can be a real pain in the neck.
Shielded/screened Ics are an option to try. Are ur ICS running alongwith the power cables? I presume u are using the power cords that came alongwith the gear.

PS :Just a clarification for all : Suri mentioned removing the IC between the Pre and power section to check. If anyone is doing this PLEASE ENSURE THAT THE UNITS ARE NOT POWERED ON as the regular RCA breaks ground first and u hear a loud noise potentially blowing a tweeter or the crossover. A Balanced(XLR) or a Neutrik Profigold make ground first and break ground last for this very reason. Best thing is to SHUT THE POWER AMP and save potential damage.
 
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dinyaar

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Hi dinyaar, what is the danger?

A few years ago a friend of mine was doing an A/B/C between preamps for a Rotel 200 W power amp + Dyna speakers.
All preamps were put in front of the Rack and the ICS ran to the power amp on the rack.
His dog suddenly jumped over the set up and knocked the left channel IC while the music was playing. There was a loud sound from the speaker and the tweeter blew!!!!
U mentioned powering on all the gear and then removing the IC and hence i cautioned anyone attempting it.
Rgds
 

gobble

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Yes very true so Viren will be the best person to solve this issue.

Gobble u have introduced a Lyrita Pre with your Nad integrated (removed the jumpers & using the power section) with your Wharfies?? The above problems are with these components in the chain?

Are u using any power strip? Or powering directly from walls outlets.

The Nad does not have a third pin(ground) on the IEC Male at the rear? I thought it did. The other end may have a schuko which does not mean that the unit does not require ground.
I can understand a cdp/tuner/deck etc not needing ground.

Point 3 states u disconencted the cdp & Pre and the hum still remains!!!

Ground loops can be a real pain in the neck.
Shielded/screened Ics are an option to try. Are ur ICS running alongwith the power cables? I presume u are using the power cords that came alongwith the gear.

PS :Just a clarification for all : Suri mentioned removing the IC between the Pre and power section to check. If anyone is doing this PLEASE ENSURE THAT THE UNITS ARE NOT POWERED ON as the regular RCA breaks ground first and u hear a loud noise potentially blowing a tweeter or the crossover. A Balanced(XLR) or a Neutrik Profigold make ground first and break ground last for this very reason.

Hello Dinyaar

I've been using Fostex 166E with sensitivity 94db (Audire Callisto) since months now. I believe sensitive speakers will sound some mild buzz and I do not find that initial buzz bothersome as much as the hum after I switch on the preamp.

In point 3 I meant I disconnected the power cord of pre and CDP, not the RCA cables which were still daisy-chained from CDP to AMP. The NAD is fine as a standalone. Its the chain that is creating the issue.

I use a multiplug socket with all 3 power plugs drawing power from it. The NAD and CDP is 2 pin. No Schuko's here. The NAD plug is styled like a schuko without the ground clips.

TIA
Regards
 

dinyaar

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Sorry Gobble but i still am not clear.I guess the problems when we interact on the net!!!
Are u using a multiplug and plugging all your components into this 3 way muliplug into A SINGLE MAINS SOCKET? This is the reason u are making a power strip for which u are seeking suggestions on another thread?
Am not saying the hum is caused by this, though cheap multiplugs can be dangerous.

Sorry one last question as its been a while since i really examined a Nad 320. It has only 2 metal pins at the rear where u attach ur power cord? Or does it have a captive power cord?

Yes naturally a sensitive speaker will show up a more pronounced hum/buzz. That is a given.
Rgds
 
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gobble

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Sorry Gobble but i still am not clear.I guess the problems when we interact on the net!!!
Are u using a multiplug and plugging all your components into this 3 way muliplug into A SINGLE MAINS SOCKET? This is the reason u are making a power strip for which u are seeking suggestions on another thread?
Am not saying the hum is caused by this, though cheap multiplugs can be dangerous.

Sorry one last question as its been a while since i really examined a Nad 320. It has only 2 metal pins at the rear where u attach ur power cord? Or does it have a captive power cord?

Yes naturally a sensitive speaker will show up a more pronounced hum/buzz. That is a given.
Rgds

Correct, I dont want to crowd them all into one 3 way socket hence building an extension box. I am using a new anchor brand 3 way, als o tried the MX one.

The NAD 325 has a captive cord. No scope for changing that.

Regards
 

gobble

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Correct me if I am wrong - I can only use unbalanced ICs in my system correct? Because my equipment does not support balanced connectors ... ?

Was reading this interesting article and trying to make sense ... http://www.rane.com/note110.html
TIA
Regards
 

dinyaar

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Gobble u cannot use XLRs (balanced) as that provision is not there. U can only use single ended/RCA.
Balanced is two conductors carrying signal (hot/cold i.e pins 2&3) and the third is ground (pin 1)
If using a balanced cable with an RCA common practice is to join the two conductors and solder as signal and solder shield to body of the RCA.
Example is a VDH D102 which has two coductors inside. This cable can be used as a balanced or as an unbalanced cable where as say A BAY can only be used as a single ended IC

I use balanced as both components support it. (One has pin 2 as hot while the other has pin 3 as hot so i had to make a cable accordingly)

U should try reversing the two pin plugs into the mains. There is a remote chance that it may remove hum. If cables are unscreened/unshielded even moving them a bit can increase/decrease hum. Does this happen?
Rgds
 
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Sumit

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Hi Gobble!!

Try This:

Buy aluminium foil- used for wrap food -from the market. Wrap foil all around the interconnects. This is nothing but shielding albeit 'desi one'. Use more than one layer if required.

This might work...might, not sure.

Cheers!!
 

Hiten

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Hi :)
Sorry to advice with little knowledge but are any audio cables/interconnects (specially preamp's) in very close proximity with AC power line or power transformers of equipments ?
Regards
 
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