Turntable Issue

andycc72

Active Member
I’ve just got a new Technics SL1500c turntable after 20 odd years without one.

minor hassle setting it up but after a few hiccups we go there in the end and it sounded excellent. Though truth be told I probably prefer the sound of high res streaming but I was enjoying playing records again and can definitely see the attraction. Then out of the blue every time I put a record in the cone starts vibrating really aggressively, literally flapping and the sound becomes massively distorted and it feels like it will damage/blow the speakers.

does anyone know what this is and what causing it? I played one record it was fine I then played another and this happened. I didn’t touch anything in between. Then every record I put on from then on it happened. I’m afraid it might damage the speakers so don’t want to keep trying it.

all advise greatly received. I tried to post a video but it appears you can’t on this site.
 
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andycc72

Active Member
Here’s a link to the video that shows what I’m talking about

 

job

Standard Member
Looks like very low frequencies, are you on a wooden suspended floor ?
The turntable might need more isolation from vibration caused by the speakers or even footsteps. Good isolation will improve every aspect of a turntable.
 

andycc72

Active Member
Looks like very low frequencies, are you on a wooden suspended floor ?
The turntable might need more isolation from vibration caused by the speakers or even footsteps. Good isolation will improve every aspect of a turntable.
I am on a wooden floor but it's not suspended.

It doesn't happen when I stream music or play CD's and I've had the turntable a week now and played lots of records, none of which up until today had this effect.

The system is on a Norstone Hifi rack, the speakers are on speaker stands with spikes on granite chopping boards and the 2 subs are on Acoufoam stands. I don't think that is the issue otherwise it wouldn't it be the same when streaming or playing CD's???
 

Ugg10

Distinguished Member
does it do the same if you use the opposite phono preamp (iirc you have preamps in the turntable and the amp ? )
 

andycc72

Active Member
should I start
does it do the same if you use the opposite phono preamp (iirc you have preamps in the turntable and the amp ? )
I haven't tried that. I'll go and do that now and report back.
 

andycc72

Active Member
does it do the same if you use the opposite phono preamp (iirc you have preamps in the turntable and the amp ? )
It still does it, if anything it seems worse through the Cyrus One phono stage.

Someone on another forum suggested it might be the needle, but I can't see anything wrong with-it and there was no trauma to it between it working fine and then this happening.
 
It looks like a very low frequency rumble. If it is only happening on your turntable then the culprit is almost certainly here. Have a look at your cartridge while the problem is there and see if it looks like it is vibrating. If so I would suggest a set up issue. Are there transit screws which need to be removed?
 

oscroft

Member
Possibly silly suggestions, but is your stylus pushed in firmly, and are the cartridge nuts and bolts tightened properly?
 

wine man

Active Member
Turntables are much more prone to feedback problems than CD or streaming. Your stylus should, in a perfect world, read what's in the groove without outside interference. That's why suspended subchassis decks were invented - it was an attempt to isolate the platter, arm and cartridge playing operation from external vibration. This could be airborne, reflective surfaces, through a floor, footfall etc. You can exaggerate this by placing a deck on the same shelf as a pair of speakers. The sound is received by the speakers, the drivers vibrate to reproduce the sound, this feeds back along the shelf into the deck. The stylus picks up the feedback and sends it out again along with the music signal.
Try putting the stylus into the groove of a stationary record. Turn the volume up slightly and tap the turntable plinth a few times. Can you hear the sound through the speakers? If I do this with my suspended design it is completely silent.
The only other possibility I can think of is a damaged stylus (unlikely) or the tracking weight has changed due to you accidentally catching the counterweight (I'm not suggesting you are clumsy!).
Keep reporting your findings and we will try to help.
 

andycc72

Active Member
It looks like a very low frequency rumble. If it is only happening on your turntable then the culprit is almost certainly here. Have a look at your cartridge while the problem is there and see if it looks like it is vibrating. If so I would suggest a set up issue. Are there transit screws which need to be removed?
There are no transit screws o the SL1500c.

It was playing fine for about probably about 20 hours with the same set up before this started to happen. It's much more pronounced when playing above halfway but you can see the woofer pumping abnormally even at lower levels
 

oscroft

Member
There are no transit screws o the SL1500c.

It was playing fine for about probably about 20 hours with the same set up before this started to happen. It's much more pronounced when playing above halfway but you can see the woofer pumping abnormally even at lower levels
That's what makes me suspect something, somewhere, has come loose.
 

andycc72

Active Member
Possibly silly suggestions, but is your stylus pushed in firmly, and are the cartridge nuts and bolts tightened properly?
Just checked and it's all pushed in properly.
 

andycc72

Active Member
Turntables are much more prone to feedback problems than CD or streaming. Your stylus should, in a perfect world, read what's in the groove without outside interference. That's why suspended subchassis decks were invented - it was an attempt to isolate the platter, arm and cartridge playing operation from external vibration. This could be airborne, reflective surfaces, through a floor, footfall etc. You can exaggerate this by placing a deck on the same shelf as a pair of speakers. The sound is received by the speakers, the drivers vibrate to reproduce the sound, this feeds back along the shelf into the deck. The stylus picks up the feedback and sends it out again along with the music signal.
Try putting the stylus into the groove of a stationary record. Turn the volume up slightly and tap the turntable plinth a few times. Can you hear the sound through the speakers? If I do this with my suspended design it is completely silent.
The only other possibility I can think of is a damaged stylus (unlikely) or the tracking weight has changed due to you accidentally catching the counterweight (I'm not suggesting you are clumsy!).
Keep reporting your findings and we will try to help.
Just did that and you can definitely hear a loud noise when I tap the plinth.

Do you think I should set the tone arm up again up from scratch?
 

Ugg10

Distinguished Member
Do you have a vertical force scale to check the VTF with, may be the VTF is set too light or the weight slipped/moved. 2M red needs 1.6-2.0g, I would start with 2.0g and go from there. But it is odd that it just started doing it, almost as if the sub frequency filter in the phono stage (if it has one) has inverted.
 

andycc72

Active Member
Do you have a vertical force scale to check the VTF with, may be the VTF is set too light or the weight slipped/moved. 2M red needs 1.6-2.0g, I would start with 2.0g and go from there. But it is odd that it just started doing it, almost as if the sub frequency filter in the phono stage (if it has one) has inverted.
I've got it set at 1.8 as per the instructions. I'm going to set it up again from scratch again and try the different weights between 1.6 and 2g...see if that helps.

It is telling that when the volume is turned u0p load the pumping of the woofer even starts when it's on the outer part of the record (with no music, not sure f the actual name of that area)?
 
Hmmm, I suspect there is something happening with the motor. Can you try the following:
Lift the arm with the Arm support and move it to the middle of a record. Set the speed to 33/3 and start the TT but do not lower the arm. Place your fingertips on the plinth and see if you can feel a vibration. If you can, switch the TT to 45 RPM, has the vibration changed?
 

andycc72

Active Member
Hmmm, I suspect there is something happening with the motor. Can you try the following:
Lift the arm with the Arm support and move it to the middle of a record. Set the speed to 33/3 and start the TT but do not lower the arm. Place your fingertips on the plinth and see if you can feel a vibration. If you can, switch the TT to 45 RPM, has the vibration changed?
I tried that and couldn’t feel a vibration at either speed.

could it be the fact that turntable is located close to a sub and one speaker ??

57034BBB-4468-4687-AC05-73B775C9785D.jpeg
 

andycc72

Active Member
I don't have the grounding wires running from amp to TT. Could that be a factor?
 

oscroft

Member
I don't have the grounding wires running from amp to TT. Could that be a factor?
Don't think so - I'd expect a mains frequency hum at worst if it needed grounding. But I'd defintely try moving the sub and see if that changes it.

I'm thinking there could be some sort of feedback going on - a low frequency excites the turntable, which then transmits it through to the speakers, which play it and excite the turntable some more...
 
My experiment was to eliminate a rumble within the Turntable, which it has. My next suggestion was what Oscroft has suggested, a low frequency feedback. A way of confirming this is to try using headphones, if the problem goes away then that is it. Oh, I'd definitely move the Sub!
 

andycc72

Active Member
Chaps really appreciate all your advice.

tried with headphones, no issue at all.

so what do I do know? I can’t move the sub but I can move the System across couple of feet away.

should I also realign the tone arm from scratch ??
 

oscroft

Member
Moving the system away from the sub is worth trying, and if that doesn't help just try it with the sub switched off. (I wouldn't realign the tonearm yet - work out if it's a sub/low frequency feedback first)
 
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Chaps really appreciate all your advice.

tried with headphones, no issue at all.

so what do I do know? I can’t move the sub but I can move the System across couple of feet away.

should I also realign the tone arm from scratch ??
So it is a feedback issue. As suggested, try it without the Sub. If all is well then there is an issue with vibration coming from the Sub and getting into the TT which is radiating out of the speakers into the TT etc etc etc. From your photo, can you get the Sub onto that carpet, that may help.
 

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