hum and buzz from turntable.....

[cptslow]

Hello,

My TT is connected to the amp via a phono preamp.the output of the phono preamp is connected
to one of the line level inputs of the amp. When i have the volume turned up to the half way
mark and above i hear a constant buzz/hum from the speakers. It progressively gets louder when i increase the volume level.
When i select other sources like my cd player the hum/buzz is not there. so its the TT+phono preamp thats the source of the buzz. I barely go past 25% on the volume pot for my normal listening, so this buzz might have been there all along and i never noticed it. The buzz is very audible upto 10-15 ft from the speakers. I have checked all connections,cables, TT ground everything seem to be fine.
My question is , is this normal or do i need a new phono preamp. any thoughts comments ?

 

[slipperybidness]

What TT, amp, and phono pre are we talking about here?

How long are your RCA cables? Most importantly, how long is the cable from the TT to the pre? Are these cables shielded?

 

[cptslow]

TT is a project debut carbon with the AC motor,
Amp : NAD C370
phono : its one of these

http://www.amazon.com/TC-750-BLACK-Audiophile-Phono-Preamplifier/dp/B000A36LQ4/ref=sr_1_fkmr2_3?ie=UTF8&qid=1441312140&sr=8-3-fkmr2&keywords=teac+phono+preamp

from the phono pre to the amp is a 3ft rca cable i got from monoprice.

from the tt to the phono pre, not sure how long it is (may be ~2ft), it came with the TT in the box.

 

[cpd]

TT is a project debut carbon with the AC motor,
Amp : NAD C370
phono : its one of these

http://www.amazon.com/TC-750-BLACK-Audiophile-Phono-Preamplifier/dp/B000A36LQ4/ref=sr_1_fkmr2_3?ie=UTF8&qid=1441312140&sr=8-3-fkmr2&keywords=teac+phono+preamp

from the phono pre to the amp is a 3ft rca cable i got from monoprice.

from the tt to the phono pre, not sure how long it is (may be ~2ft), it came with the TT in the box.

Dollars to donuts this is the problem. The stock RCA with the Pro-ject TT is not good at all -- at least mine wasn't. I had a terrible hum, replaced that cable with a well shielded cable from BJC and viola - no more hum.

Try a different cable between the tt and phono-amp and see if that helps.

 

[cpd]

If you don't have another RCA cable handy, at least try running the monoprice cable from the tt to the phono-amp and the Pro-ject cable from the pre-amp to the amp. The un-amplified signal coming from the tt is more susceptible to interference, so if you put the better shielded cable there it should help.

It may not solve the issue but will at least help you diagnose the problem. If the hum decreases, order a well-shielded cable, to run from the tt (the monoprice cable should be fine from the pre-amp to the amp -- i have a 50ft of monoprice cable running from my pre-amp).

 

[TLS Guy]

Most turntables need to have a grounding wire connected to the amp. Your turntable does have a grounding wire which does need to be connected form your turntable to your NAD.

Do you hear the hum if the turntable is not connected to the phono preamp? If so that phono pre amp is no good.

 

[cptslow]

If you don't have another RCA cable handy, at least try running the monoprice cable from the tt to the phono-amp and the Pro-ject cable from the pre-amp to the amp. The un-amplified signal coming from the tt is more susceptible to interference, so if you put the better shielded cable there it should help.

It may not solve the issue but will at least help you diagnose the problem. If the hum decreases, order a well-shielded cable, to run from the tt (the monoprice cable should be fine from the pre-amp to the amp -- i have a 50ft of monoprice cable running from my pre-amp).

I tried swapping the cables the noise has not reduced.

 

[cptslow]

Most turntables need to have a grounding wire connected to the amp. Your turntable does have a grounding wire which does need to be connected form your turntable to your NAD.

Do you hear the hum if the turntable is not connected to the phono preamp? If so that phono pre amp is no good.

When the turntable is not connected to the preamp i dont hear the buzz. so i guess the preamp might be ok.
I think it might be the ground connection thats the problem, i just simply touched the ground terminal on the TT and the noise reduces a lot. even though the ground from TT is connected to the ground in the preamp. If the grounding is the problem how do i solve it. ?

 

[TLS Guy]

When the turntable is not connected to the preamp i dont hear the buzz. so i guess the preamp might be ok.
I think it might be the ground connection thats the problem, i just simply touched the ground terminal on the TT and the noise reduces a lot. even though the ground from TT is connected to the ground in the preamp. If the grounding is the problem how do i solve it. ?

Without being there it is hard to say. My hunch is that the phono preamp is creating a resistance to ground through its internal circuitry. I note your preamp has a ground post and the manufacturer recommends connecting the turntable ground to the preamp ground and not your amp ground.

So I would change the ground from the NAD to the preamp.

If that does not work connect the turntable to the preamp ground and make another wire to also connect the preamp ground to the NAD so all three grounds are bonded. I suspect this latter will actually give the lowest hum.

I do note that other customers have had hum issues with this unit they could not solve and that the manufacturer will not accept returns. These customers say the manufacturer says hum is normal, which it is not. My turntables are dead quiet.

If neither of the above solutions work you need a different preamp.

 

[cptslow]

Without being there it is hard to say. My hunch is that the phono preamp is creating a resistance to ground through its internal circuitry. I note your preamp has a ground post and the manufacturer recommends connecting the turntable ground to the preamp ground and not your amp ground.

So I would change the ground from the NAD to the preamp.

If that does not work connect the turntable to the preamp ground and make another wire to also connect the preamp ground to the NAD so all three grounds are bonded. I suspect this latter will actually give the lowest hum.

I do note that other customers have had hum issues with this unit they could not solve and that the manufacturer will not accept returns. These customers say the manufacturer says hum is normal, which it is not. My turntables are dead quiet.

If neither of the above solutions work you need a different preamp.

I thank you all for all the input, I will try to ground the all three together.
in the meanwhile i need suggestions for a good preamp .I want to spend NO more than 300 bucks unless spending more makes a real difference in the sound.

Thanks......

 

[TLS Guy]

I thank you all for all the input, I will try to ground the all three together.
in the meanwhile i need suggestions for a good preamp .I want to spend NO more than 300 bucks unless spending more makes a real difference in the sound.

Thanks......

Please follow my instructions step by step. Start by moving the ground from the NAD to the preamp. If that fails then link the preamp to the the TT and NAD. The reason for this is that quite often you get rid of hum by reducing the number of grounds!

Lets talk about another preamp if this one can not be made to work. An RIAA Eq circuit is a very simple low tech affair and does not have to cost a fortune.

If it does, I would use the expression unit basically made for that TT.

 

[cptslow]

Please follow my instructions step by step. Start by moving the ground from the NAD to the preamp. If that fails then link the preamp to the the TT and NAD. The reason for this is that quite often you get rid of hum by reducing the number of grounds!

Lets talk about another preamp if this one can not be made to work. An RIAA Eq circuit is a very simple low tech affair and does not have to cost a fortune.

If it does, I would use the expression unit basically made for that TT.

I am kinda lost here, the ground on the TT is already connected to the ground on the preamp. I still hear the buzz . I dont understand the part on how to move the ground from the NAD amp to the phono preamp.

 

[TLS Guy]

I am kinda lost here, the ground on the TT is already connected to the ground on the preamp. I still hear the buzz . I dont understand the part on how to move the ground from the NAD amp to the phono preamp.

The first step is to follow the preamp manufacturer's instructions. They recommend that the ground wire from the TT go straight to the ground terminal on their preamp, with NO ground wire going to the amp. So first take the ground wire from the TT off the NAD and put it on the ground terminal on the preamp. If you still have buzz, then make a wire to go from the preamp ground to the NAD terminal ground. There will then be two ground wires on the preamp, one form the TT and one going from the preamp ground to the NAD ground.

If none of those work, toss the premap over the wall.

 

[cpd]

Another important question - when exactly does the hum occur? When the stylus is on a spinning record, when the tt is on regardless of whether the stylus is on a record, or even when the tt is off?

My hum was there regardless of whether the tt was off or on. If that's the case, I still believe the stock RCA cable may be your problem. My recommended experiment may not have been a helpful diagnostic tool however, as switching the cables would have removed the ground from the tt to the phono amp. It helped me diagnose my issue because my hum decreased.

If the hum exists with the motor off, there is a chance it is caused by interference from outside sources penetrating that stock RCA cable (that was my issue) and that a good cable run between the tt and the phono amp may solve the issue. I won't guarantee it, but I would at least try it before spending a few hundred on a new preamp. My 6' BJC LC-1 cable with ground wire was $60 - if you only need 2 feet it should be substantially less. And if it doesn't work, at least you have a decent cable.

If the hum exists only with the motor on/needle in the groove it could be a motor hum. There are people that have reported motor hums with the Pro-ject tt, and some solutions you can find online for fixing that as well.

As for preamps I have the Pro-ject Phono Box S and it works great.

 

[cptslow]

Another important question - when exactly does the hum occur? When the stylus is on a spinning record, when the tt is on regardless of whether the stylus is on a record, or even when the tt is off?

My hum was there regardless of whether the tt was off or on. If that's the case, I still believe the stock RCA cable may be your problem. My recommended experiment may not have been a helpful diagnostic tool however, as switching the cables would have removed the ground from the tt to the phono amp. It helped me diagnose my issue because my hum decreased.

If the hum exists with the motor off, there is a chance it is caused by interference from outside sources penetrating that stock RCA cable (that was my issue) and that a good cable run between the tt and the phono amp may solve the issue. I won't guarantee it, but I would at least try it before spending a few hundred on a new preamp. My 6' BJC LC-1 cable with ground wire was $60 - if you only need 2 feet it should be substantially less. And if it doesn't work, at least you have a decent cable.

If the hum exists only with the motor on/needle in the groove it could be a motor hum. There are people that have reported motor hums with the Pro-ject tt, and some solutions you can find online for fixing that as well.

As for preamps I have the Pro-ject Phono Box S and it works great.

I hear the hum when i select the input to which my TT is connected. The TT doesnt even have to be ON, as long as the preamp in ON , and the TT input is selected i get a hum. Hence i am thinking the preamp grounding could be the problem.

Sent from my SM-G920V using Tapatalk

 

[TLS Guy]

I hear the hum when i select the input to which my TT is connected. The TT doesnt even have to be ON, as long as the preamp in ON , and the TT input is selected i get a hum. Hence i am thinking the preamp grounding could be the problem.

Sent from my SM-G920V using Tapatalk

You can guarantee your issue is grounding. It should be solvable unless the designers completely screwed up the ground plain of the circuit board.

 

[cptslow]

You can guarantee your issue is grounding. It should be solvable unless the designers completely screwed up the ground plain of the circuit board.

I ordered a new Emotiva phono pre-amp, and I plugged it in and I still hear the buzz pretty loud and clear,so it definitely not the pre-amp thats creating the noise. I have tired swapping out RCA cables.
I get the hum even when the turntable is not "ON". I unplugged the turntable powersupply, i still hear the hum. there is something wrong with the turntable it think. I am just all out of ideas now, and it is getting kinda frustrating that i cant fix it. Any would really appreciate any last thoughts before i give up. Thanks for all the help guys.

 

[TLS Guy]

I ordered a new Emotiva phono pre-amp, and I plugged it in and I still hear the buzz pretty loud and clear,so it definitely not the pre-amp thats creating the noise. I have tired swapping out RCA cables.
I get the hum even when the turntable is not "ON". I unplugged the turntable powersupply, i still hear the hum. there is something wrong with the turntable it think. I am just all out of ideas now, and it is getting kinda frustrating that i cant fix it. Any would really appreciate any last thoughts before i give up. Thanks for all the help guys.

Sorry to hear of your continuing difficulties.

Grounding issues can often be very difficult to solve.

Now it is time to start disconnecting grounds to sort this out.

Disconnect the turntable grounds from the preamp and NAD. Do you hear hum? If so then use a cheater plugs to disconnect all grounds in your system.

Do you now hear hum from the turntable? If yes then connect grounds back from the turntable to the preamp and then the NAD and then both together.

If none of these options stops the hum then there is something wrong with the grounding inside your turntable or you have induced hum. (See Below)

If the hum stops when you break all the grounds and you have your turntable connected correctly, then remove the cheater plugs one at a time to see which one is creating the ground loop.

If you do this carefully you will find out where your ground loop comes from.

One last thing, it is possible you have induced hum and not a ground loop. So make sure the turntable is not right next to a source of a magnetic field. This means keeping the turntable some distance from units like your NAD that has a power transformer.

Hum like this is always a ground loop or electromagnetically induced hum, with ground loops being the most common.

 

[slipperybidness]

OP, do you have a cable box and coax cable hooked to your system? Those are notorious for poor grounding and introducing hum!

 

[cptslow]

Sorry to hear of your continuing difficulties.

Grounding issues can often be very difficult to solve.

Now it is time to start disconnecting grounds to sort this out.

Disconnect the turntable grounds from the preamp and NAD. Do you hear hum? If so then use a cheater plugs to disconnect all grounds in your system.

Do you now hear hum from the turntable? If yes then connect grounds back from the turntable to the preamp and then the NAD and then both together.

If none of these options stops the hum then there is something wrong with the grounding inside your turntable or you have induced hum. (See Below)

If the hum stops when you break all the grounds and you have your turntable connected correctly, then remove the cheater plugs one at a time to see which one is creating the ground loop.

If you do this carefully you will find out where your ground loop comes from.

One last thing, it is possible you have induced hum and not a ground loop. So make sure the turntable is not right next to a source of a magnetic field. This means keeping the turntable some distance from units like your NAD that has a power transformer.

Hum like this is always a ground loop or electromagnetically induced hum, with ground loops being the most common.

I have the turntable sitting on a table thats not very tall and right next to it is my sub. the powersupply from the plate amp might be creating a hum. i will try to move it as far from power source as possible.