Turntable and Vinyl Queries -

[greenhorn]

I saw an ad on quickr some time back, which showed a turntable and some 60 LP's up for sale at hyderabad. Wasted no time, and by evening, it was mine, all mine for a 5 digit price tag!
But to bring it to Chennai was the longer story, and eventually a friend of a friend endured a long ordeal to bring it to chennai.

It's an entry level JVC turntable - Model JVC AL-A1.

Initially there was a LOT of feedback, but I moved my speakers to the floor, and found that it was missing one of its feet, so replaced it with a sock. Now for ordinary listening levels, it works fine.

Currently my setup is

Turntable -> Pioneer SA 606 amp acting as phono pre-> tape out-> RCA Splitter-> Active Bookshelves (Circle Arko 80W Aka Microlab Solo 5C) and a 2.1 (logitech Z 2300) acting as a sub.

If i turn the Z2300 up too much, or the bass on the bookshelves up at full volume, there is this low frequency hum (much like on PA systems). This does not occur if I turn the speakers off and listen from the Amp's headphone out.

A lot of the records that I got are the disco era, and would really come alive with some full bodied bass, which is currently turned down to keep the feedback to bearable levels

While I did get a whole bunch of records, a lot of them are not in good shape, with what looks as some crud that was spilled onto the surface of some of them, and some of them crackling a lot.


So to summarize:What can I do to take care of the following

1) feedback - Currently thinking about using cut tennis ball halves to mount the TT
2) Crackling records - Hopefully the washing threads here on HFV ( water, IPA, drop of liquid soap + cotton cloth) should help
3.) crud on the records - this is a bit more stubborn to go. Seems like insect droppings - not really sure. Would the fevicol method take care of this?

Thanks for your help

 

[gopib]

First the cleaning - get the disc's cleaned by the IPA method, see how much of the crud goes. I also let my records soak for some five minutes in the solution. Though I have been warned that the label may get messed up soaking, it is yet to happen to me. I have managed to get a lot off badly handled/stored disc's by this method.

I am not sure what you mean by "feedback" - is it hum, vibration or some sort of noise?? Generally feedback is a term used when speaker sounds goes back to source, like being picked up by a microphone. I would suggest you check and connect grounding points of the turntable, amp are all connected to the same point. I am sure there must be something like that in your equipment...

 

[Saket]

So to summarize:What can I do to take care of the following

1) feedback - Currently thinking about using cut tennis ball halves to mount the TT
2) Crackling records - Hopefully the washing threads here on HFV ( water, IPA, drop of liquid soap + cotton cloth) should help
3.) crud on the records - this is a bit more stubborn to go. Seems like insect droppings - not really sure. Would the fevicol method take care of this?

Thanks for your help

1. Feedback, hmmm...that can be nasty specially with placement limitations. However, make sure that the speakers are as far from the TT as possible. What kind of table are you using for the TT? Is it a normal table or like a cabinet top with some storage space inside the cabinets? If its the latter, try opening the door of the cabinets, this will help NOT TRAP the vibrations and echo of the speakers. Also, make sure that the TT is well earthed. Try keeping the TT on small pieces of thermocol. It just might help absorbing the vibrations. I am sure that these will help to some good extent, let us know the end result.

2. About record cleaning, you have to give it some patience and time. There are a lot of methods discussed on the forum which are both cheap & effective.

Regards,
Saket

 

[greenhorn]

When I meant feedback, I meant the same sort of sound that happens in PA systems if you turn up the gain too much or put the mics near the speakers. I'm having the problem only if I turn up the speaker volume/bass and even then, it grows gradually until it becomes unbearable.

Ground points - all the equipment have only 2 pin power plugs, and I'm not sure if my apartment has good grounding, but hey, it's worth a shot, and I've had hum issues with my tape decks too ( i get mild shocks when I touch their cases!)

Yes, the TT is kept on an office table made from particle board (or whatever cheap computer tables are made of) , and there is a drawer and a cabinet right underneath. Let me try opening them and see

 

[omishra]

Keep in mind some records are clean after 2 or more washing. Till that time you have to scrub-wash-dry-play and again scrub-wash-dry-play...may be repeat one more time.

 

[Record Player]

Hey Greenhorn - There are quite a few methods tried and tested which have been discussed in detail here on the forum. A couple of additions to this process I've done for real dirty records is use a extreme smooth brush to clean the record with the cleaning solution. 2-3 attempts should get the record clean. Also, some Records are born with that pop and click which you just have to live with. Also ensure to calibrate the Anti-Skate on the TT to get optimum performance on your records.

 

[Thad E Ginathom]

<Moving conversation from the other thread > <And crossposted with several>

Hum from turntables can be an earthing issue, although this would be more likely if it happened at any volume and even when not playing music. Does your TT have an earth wire, and is it connected to your acting-phono-pre? It is important to connect this wire.

Earth loops is a rather more esoteric subject, but I believe they can be avoided by having all the equipment connected to the same earth, which, in household electrics practical terms means plugged in to the same socket [I think].

It is essential that your turntable is level and rock-solid stable. Not by-eye level, but really level. If you do not have one, then go to a good builders/hardware shop and buy a spirit level at once. There are even phone apps that are amazingly accurate. You need to replace that missing foot with something firm and exactly the right hight.

The cable from your cartridge to your pre-amp carries very small signals. Make sure that you keep it away from, eg, mains cables.

Stick to the basics, and eschew the esoteric. Basic turntables do not need anything esoteric to make them work: they are what we all, up to a couple of decades ago, used to just plug in and play.

<crossposted>

You might need to do something about that earthing. I cannot understand an apartment not having any earth (no: I can... my house was cabled 3-pin, but there was no actual earth connection !) as it is dangerous. You might need to work something out.

Even in one of my UK houses I had to run a think wire from the hifi to ground, to get rid of the the voltage I could feel on metal cases.

 

[greenhorn]

Thad, I'm not really sure if its just hum - I mean if it was hum it should not grow When the volume levels are steady, and be disproportionately higher at some volume levels?

Planning to download a frequency analyzer app on my phone and check if this hum is 50hz or something else

 

[Saket]

Thad, I'm not really sure if its just hum - I mean if it was hum it should not grow When the volume levels are steady, and be disproportionately higher at some volume levels?

Planning to download a frequency analyzer app on my phone and check if this hum is 50hz or something else

Yup, as per your description, that's not hum. Its acoustic feedback which will keep growing as its forms an infinite loop by the vibrations coming out fro mthe speakers getting transferred to the stylus/ tonearm and then again amplifying it and speakers re-transmitting it and the process goes on forever. However, after a second or tow, it becomes unbearable and you switch off the system. Give the TT rubber/ spring feet, in case you find along with other remedies that we just discussed. Should help reduce it, if not eliminate it completely.

Regards,
Saket

 

[jls001]

Its acoustic feedback which will keep growing as its forms an infinite loop by the vibrations coming out fro mthe speakers getting transferred to the stylus/ tonearm and then again amplifying it and speakers re-transmitting it and the process goes on forever.

Is this happening because the sound energy coming from the speakers are somehow causing the stylus to vibrate/modulate in unwanted ways? Assuming it is, does that mean the turntable is kept in the direct path of the sound coming out from the speakers? Or perhaps too close to the speakers? I am curious to know what all things can go wrong - and usually does - with a turntable setup:lol:

 

[reubensm]

Why dont you post a pic of your listening space. The earlier pic of your turntable suggests that you've placed it on some kind of a work-bench. From my experience, a good way to isolate feedback would be to dampen the plinth and tone arm. However you can move things around in your room till you get the best results. Try swinging the balance control to the left and then to the right to ascertain which particular speaker is causing the feedback. There is a great chance that your turntable is picking up vibrations from the surroundings through contact. Lift the arm off the record, increase the volume, do you hear feedback or is it only when you play music? You've not mentioned the volume levels at which you normally listen to music. Is your tt's plinth an empty box or is it dampned? Lots of possibilities, you'll have to go by the elimination method starting with your cabling (position of cables) and earthing. Make a start by putting you speakers in a different room and then check for feedback.

Here is some interesting reading:

http://www.lencoheaven.net/forum/index.php?topic=2955.0

 

[greenhorn]

some more stuff to add -
The TT's plinth is a plastic enclosure. I don't think it's damped - it seemed rather light to pick up. If I tap it with my fingers, I can hear the sound through the speakers. The platter is aluminum and rather light.

The feedback issue is there only when the needle is resting on the record. When the cueing switch is up, or the arm is resting on the support, there is no feedback.

I had routed the RCA's going in to the Pre and coming out to reduce any chance of interference.

 

[Record Player]

Have you tried re-balancing the tonearm?

 

[greenhorn]

I went through the service manual, the only settings seemed to be for speed, stylus height and tonearm auto return position. What looked like the counterweight seemed to be fixed, and I couldn't see anything for anti skate either.

 

[Thad E Ginathom]

...Make a start by putting you speakers in a different room and then check for feedback.

Or turn the speakers off and plug in a pair of headphones! hyeah:

(assuming a headphone socket, of course!)

 

[greenhorn]

Or turn the speakers off and plug in a pair of headphones! hyeah:

(assuming a headphone socket, of course!)

whoops, thats what i meant when I said

This does not occur if I turn the speakers off and listen from the Amp's headphone out.

this issue isn't there when listening via headphones

 

[Thad E Ginathom]

Whoops... I did read that at the time, and then forgot. Sorry

 

[greenhorn]

update. here's what the feedback sounds like frequency wise.


Uploaded with ImageShack.us
Important thing is that the peak is not 50 hz.

so hum is ruled out. Still not sure what to do.

EDIT: planning to play around with subwoofer, and then TT placement. Maybe standing waves in the room?

Further EDIT: moving the sub by a foot seems to have cured it for now. Will have to check in the morning. Cant turn it up too much at 12 midnight

 

[reubensm]

The feedback issue is there only when the needle is resting on the record. When the cueing switch is up, or the arm is resting on the support, there is no feedback.

So that's it. Its confirmed. Your cart is not picking up feedback like a microphone. Its indeed your TT's enclosure. Its acting as one big resonating diaphragm. Its picking up external vibrations and transferring the same to your stylus.

Honestly, IMO there's very little you can do to solve this problem unless you dampen the cabinet (likely to be a hollow plastic cabinet).

 

[greenhorn]

Honestly, IMO there's very little you can do to solve this problem unless you dampen the cabinet (likely to be a hollow plastic cabinet).

Can do. Nothing I love more than taking equipment apart

Anway I'll have to open is up for having a look at why the auto return Isn't working.

People seem to have tried dynamat and plasticine. Leaning towards dynamat since I can use some for my platter as well.

Any alternatives/Recommendations?