I Need Help !!

[AVNoob2014]

I have my Thorens turntable sitting directly on top of my amp.

When I play a record and I wish to crank up the volume, I get this really loud hum come over my speakers...

what am I doing wrong ? Is it down to the position of my deck ? Are my speakers too close ?

Any advice appreciated

Thanks !

 

[Gonepostal]

Have you tried putting your record deck in a different position. I’m no expert, far from it, but surely putting your deck on top of the amp is a bad idea.

 

[ifor]

... is the turntable to the speakers?

 

[nopiano]

The cartridge in your turntable is very sensitive, because it is highly amplified. It will therefore pick up hum from the mains transformer in any amplifier.

It is easy to check. Without a record playing, and with the arm carefully secured, select a high volume on the phono input until you hear hum. Lift the turntable away, bearing in mind the finite length of the connecting cables. If it reduces or stops you need to rearrange. It’s no surprise that turntables are usually shown alongside and not above an amplifier.

 

[Al ears]

The cartridge in your turntable is very sensitive, because it is highly amplified. It will therefore pick up hum from the mains transformer in any amplifier.

It is easy to check. Without a record playing, and with the arm carefully secured, select a high volume on the phono input until you hear hum. Lift the turntable away, bearing in mind the finite length of the connecting cables. If it reduces or stops you need to rearrange. It’s no surprise that turntables are usually shown alongside and not above an amplifier.

Nopiano is quite correct. The turntable, moreso the cartridge, is going to be affected more by the proximity of the amplifier rather than the speakers so your first move should be to reposition that deck. Even if it means buying longer phono cables you should attempt to position it to the side or somewhere away from that amp.

Can you fit a wall-shelf above the rest of your kit?

 

[MajorFubar]

You can't stick a turntable on top of an amp with some thunking great unshielded power transformer in it without getting hum through the magnetic cartridge. What did you expect?

 

[Al ears]

You can't stick a turntable on top of an amp with some thunking great unshielded power transformer in it without getting hum through the magnetic cartridge. What did you expect?

Calm down Major... 🙂

Make you wonder how some of those old all-in-one stack systems worked eh?

 

[MajorFubar]

Make you wonder how some of those old all-in-one stack systems worked eh?

With ceramic cartridges, usually, which are of course immune. Some that did have a magnetic cartridge had their one solitary pea-sized transformer screwed miles away at the bottom of those Amstrad-style cases that look like they're separate components but aren't. On the slightly better ones with true separate components, the amp and turntable were commonly at least separated by a tuner.

Mostly though, they just assumed their buying demographic couldn't care less and wouldn't know what mains-induced hum was if you nailed their ear to the transformer.

 

[brownz]

I have my Thorens turntable sitting directly on top of my amp.

When I play a record and I wish to crank up the volume, I get this really loud hum come over my speakers...

what am I doing wrong ? Is it down to the position of my deck ? Are my speakers too close ?

Any advice appreciated

Thanks !

On top of the amp is far from ideal without a good air gap and isolation.

It's more likely to be feedback from the speakers.

Does the hum increase to a loud moan as you increase the volume, then go away as you decrease the volume ?

If so then yes, you need to isolate the speakers and move them away from the TT.

If it's all a bit tight then you can try just isolating the speakers - half a squash ball under each corner works quite well. Other expensive isolation gizmos are available online or through your favourite HiFi shop.

 

[Al ears]

I have my Thorens turntable sitting directly on top of my amp.

When I play a record and I wish to crank up the volume, I get this really loud hum come over my speakers...

what am I doing wrong ? Is it down to the position of my deck ? Are my speakers too close ?

Any advice appreciated

Thanks !

On top of the amp is far from ideal without a good air gap and isolation.

It's more likely to be feedback from the speakers.

Does the hum increase to a loud moan as you increase the volume, then go away as you decrease the volume ?

If so then yes, you need to isolate the speakers and move them away from the TT.

If it's all a bit tight then you can try just isolating the speakers - half a squash ball under each corner works quite well. Other expensive isolation gizmos are available online or through your favourite HiFi shop.

I guess it might help if the OP actually said how close his speakers actually are......

I agree with your first sentence though.

Might it possibly be an earth loop?

 

[davedotco]

If you are serious about trying to get decent performance from your player, then there are a number of issues that need to be addressed.

Firstly, there is the issue of wiring and earthing, each component of the player, turntable, arm, cartridge needs to be earthed once and once only, if it is bought as an 'integrated' package this is usually taken care of. Just make sure that the connectors are firmly connected as is the earth lead if the player has one.

Secondly, the signal from the cartridge is at a very low level, any interference from other components will seem quite large in comparison, resulting in noise, usually a hum or buzz. This can easily be checked by moving the player away from the amplifier.

The most likely culprit is likely to be acoustic feedback, the music will cause vibrations in the room, in the furniture, whatever the equipment is sitting on, this is picked up by the cartridge, amplified by the system and causes a feed back loop.

Best practice is always to place the player away from the amp, often just to the side or a few inches above the amplifier is sufficient. It is also best that the player is supported correctly, ideally on a separate table or shelf. In either case the support should be as light and rigid as possible, avoid placing the player on heavy furniture, however solid you think it is.

Try setting up your system again using the advice in the thread however do not try and extend the signal leads from the turntable, this is not a good idea and rarely necessary.

 

[brownz]

"I guess it might help if the OP actually said how close his speakers actually are......"

Agreed.... and re-visited this thread to let us know how hes getting on ! ;-)

Ground hum tends to be constant and not overly loud - unless really cranked up, from what he's describing it sounds more like feedback, but until the OP replies we are left in limbo hanging on all our suggestions with tentative trepedation.

 

[Al ears]

"I guess it might help if the OP actually said how close his speakers actually are......"

Agreed.... and re-visited this thread to let us know how hes getting on ! ;-)

Ground hum tends to be constant and not overly loud - unless really cranked up, from what he's describing it sounds more like feedback, but until the OP replies we are left in limbo hanging on all our suggestions with tentative trepedation.

Indeed we are ;-)

Let's hope he returns soonest.