Why is this external noise from my Turntable when put on at high volume?

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philipmorris
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#1 erstellt: 18. Jul 2006, 08:05

Dear Friends,
I am facing a typical problem & I do need some views or suggestions from you all.

I have 2 turntables - 1)Pioneer Direct Drive old model & 2)Project Debut III new belt drive model.

The typical problem that I am facing is when I am increasing the volume levl of my Yamaha Stereo Amp(496) to almost full level the sound of earthing do comes in the backdrop if the Project is connected.Mind you this I am talking when I am not playing any music but just the TT is connected to the amp.Same is happening with Pioneer but in case of Pioneer the earthing sound is much much less.Its a bit hummmmmmm sound that is coming.

I do convert my LPs using Sound Forge software to my pc.But when I hv recorded this sound using sound forge I have not seen any change in the straight line graph of both the channels.Generally with any external noise or sound the graph do show some changes in its course.

My querry is Is this very normal that such a humm sound or earthing noise is heard when one puts his amplifier to top volume which in general doesn't affect the LP that you will be playing.Or is it that whatever level the volume is put there shouldn't be any such noise.

Please suggest.

rgds,
phil

Amp_Nut
Inventar

#2 erstellt: 18. Jul 2006, 08:46

Hi Philip,

Try this :

With your Amp connected to the TT, and the Amp volume fully up, TAP ( with yr fingernail ) the WIRE between the TT and the amplifier ?

Surprise ?

philipmorris
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#3 erstellt: 18. Jul 2006, 08:58

Hi,
Do you mean to say the rc jack that connects the TT to the amp I should tap that?Or is it the earthing wire supplied along with the RC connected to the GND in TT?

Also tapping means should I just gently touch it or hit it moderately?

May I know what difference will I get?Just curious.

ani
Stammgast

#4 erstellt: 18. Jul 2006, 09:26

Hi Philip,

It is normal to hear slight noise and hum if you turn the volume way up, some of the hum can be picked up by the cartridge, tone arm wires etc part of it may be from the preamp. If there is no hum at the highest listening level, ie max volume you can sit and listen to forget about it

you are not going to hear it while playing your LP's. if you want to bring further down isolate the hum check the tone arm earthing and cartridge connections. BWT are you using the same model type of cartridge on both the TT? some cartridges are more susceptible to hum and noise pick up and nothing can be done except change them when they are worn out.

Amp_Nut
Inventar

#5 erstellt: 18. Jul 2006, 09:26

Moderately tap the shielded wire that connect the signal from the tt to the amplifier.

You should hear a LOUD Tap in the Speakers !

philipmorris
Ist häufiger hier

#6 erstellt: 18. Jul 2006, 09:48

ani schrieb:

Hi Ani,
Yes you are correct that you tend to hear slight noise when the volume is turned up.
But are you sure that this slight noise or hum will not affect the LP sound.I mean suppose when I am transferring the LP to my computer this ound will not get recorded?

How do I check the tone arm earthing?Yes you are correct maximum earthing sound happens from tone arm and cartridges.
No I am suing a SHURE Cartridge in Pioneer & Ortofon catridge in Project.But the humming sound of Project is more.

philipmorris
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#7 erstellt: 18. Jul 2006, 09:49

Amp_Nut schrieb:

Moderately tap the shielded wire that connect the signal from the tt to the amplifier.

You should hear a LOUD Tap in the Speakers ! :D

How does it help?
Man I am trying seriously here to solve my problem.So why are you doing this?

ani
Stammgast

#8 erstellt: 18. Jul 2006, 10:03

Hi Philip,

If you cannot hear it at the max listening level you are not going to hear it in your CD's. Try swapping the interconnects to check if the hum is caused by them.

Tone arm earth wire is the 5th lead that is screwed to the tone arm near to the head shell other end is earthed at the RCA terminal box. Check the connections are ptoper at both ends.

Amp nut was trying to show you how microphonic high amplification is and you need not worry about what you hear when you turn up volume all the way round.

Amp_Nut
Inventar

#9 erstellt: 18. Jul 2006, 10:21

Amp nut was trying to show you how microphonic high amplification is and you need not worry about what you hear when you turn up volume all the way round.

Thanks !

philipmorris
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#10 erstellt: 18. Jul 2006, 10:41

ani schrieb:

Hi Ani,
So it means that if slight humming sound is there with volume up also it will not affect on the LP output.So the songs while transferred into a CD also will be glitch free.Am I correct?

Try swapping the interconnects to check if the hum is caused by them.------> Can you please clarify what you meant by this?

Tone arm earth wire is the 5th lead that is screwed to the tone arm near to the head shell other end is earthed at the RCA terminal box. Check the connections are ptoper at both ends.---------?But how do I check this?If I open the head shell also is this 5th lead visible which will help me in checking them?Same with the RCA Box.

Amp nut was trying to show you how microphonic high amplification is and you need not worry about what you hear when you turn up volume all the way round------> Cldn't understand as how does it help?By tapping on the wire what effect will I get that might help me to resolve my doubts.

I am sorry for bothering you guys.Please bear with me.

ani
Stammgast

#11 erstellt: 18. Jul 2006, 11:01

If you are using different cables to connect the tt to preamp try swapping them if the hum is now more on Pioneer, the cable is the culprit.

You must be able to see the earth lead screwed on to the metal tone arm from underneath, make sure that it is making good contact.

I am not familiar with both your cartridges, there may be difference in them.

philipmorris
Ist häufiger hier

#12 erstellt: 18. Jul 2006, 11:08

ani schrieb:

Cables that are used to connect the amp are directly inbuilt which comes with the TT.One side of the cable goes inside the TT.

Yes one more observation which I have noticed is that when I am connecting the Project TT drectly with my Amp the hum is less in comparision to when the same TT is connected to the PreAmp which in turn gets connected to the Amp.Also when I touch the preamp there is a slight drop in the humming noise.

Do you mean to say when i lift the tone arm after removing the headshell I should be able to see the naked lead touching the tone arm?But in high end TTs like Project and all can it be viewed just like that?Also Project TT tonearms are not metal ones.

You didn't come back to me on the tapping issue on the cable.

philipmorris
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#13 erstellt: 18. Jul 2006, 12:07

philipmorris schrieb:

Amp_Nut schrieb:

Moderately tap the shielded wire that connect the signal from the tt to the amplifier.

You should hear a LOUD Tap in the Speakers ! :D

How does it help?
Man I am trying seriously here to solve my problem.So why are you doing this?

Please suggest as how does it help?

Amp_Nut
Inventar

#14 erstellt: 18. Jul 2006, 12:32

How does it help?
Man I am trying seriously here to solve my problem.

Sorry, I am NOT trying to be a tease.... but

Ani's response said it all :

Amp nut was trying to show you how microphonic high amplification is and you need not worry about what you hear when you turn up volume all the way round------> Cldn't understand as how does it help?By tapping on the wire what effect will I get that might help me to resolve my doubts.

philipmorris
Ist häufiger hier

#15 erstellt: 19. Jul 2006, 05:05

Amp_Nut schrieb:

I am nt able to understand as by tapping on the wire what conclusions I can infer.Can somebody please help me?

ani
Stammgast

#16 erstellt: 19. Jul 2006, 05:22

"you need not worry about what you hear when you turn up volume all the way round-"

it just demonstrates how microphonic some cables can be, you can hear the slightest tap on a TT through your speakers when you turn your volume to FULL.

I had a DIY phono stage that worked as an excellent AM tuner when the shields removed and volume turned well above the normal listening level

SO the point is if you cannot hear suprious noise, hum etc at your highest listening level of volume dont bother to correct it. At very high amplification such as in a phono pre amp it is difficult to eliminate it, in Moving coil pre amp the noise can be even more. You get lower noise level as you go up the ladder price vise and quality wise, but remember that the quietest phono pre amp may not be the best there are other factors too.

philipmorris
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#17 erstellt: 19. Jul 2006, 05:35

ani schrieb:

Ok.Now I hv understood.Actually you guys were trying to demonstrate that how sensitive TT is tht a slightest tap on the cable can make a good sound in the speakers.But suppose when the vinyl is getting played & recorded in the comp will this sound also gets recorded if suppose I tap on the cable & a thud comes out of the speaker?

Yes phono preamp is definitely a sensitive product.Always low humm noise doesn't mean that the other qualities are the best in it.

philipmorris
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#18 erstellt: 19. Jul 2006, 05:37

ani schrieb:

in Moving coil pre amp the noise can be even more.

Can you please explain what you meant by this?What is a moving coil pre amp?

Amp_Nut
Inventar

#19 erstellt: 20. Jul 2006, 05:01

First a primer on Cartridges.

1. Basic Physics : An electrical current is produced in a wire, if the wire is moved relative to a magnet ( ie inside a magnetic field )

Hence a Cartridge can generate a signal, by moving :

1. CASE 1: A Magnet and keeping the coil of wire fixed

or

2. CASE 2: Moving the coil of wire and keeping the magnet fixed.

In CASE 1: The coil of wire is fixed, so it can be made larger ie more turns of wire in the coil. More turns yields more voltage ie a stronger signal that needs less amplification. This is a Moving Magnet (MM) cartridge, and its the most common type around. All Shure cartridges, are MM.

In CASE 2: The coil has to be small and light, so that it does not weigh down the free movement of the stylus.

Also the wires need to connect a moving coil to the fixed cartridge body.

Fewer turns - lower output voltage, and you need about 10 Times more amplification for the Moving Coil cartridge than a moving magnet cartridge.

More amplification may mean more noise, but MC buffs find the delicacy in sound from these cartridges, well worth the noise ( and cost ) penalty.

A good MC cartridge can cost well opver US $ 500.