[MD1032]

Hey guys, my dad and I are trying to get our vinyl system up and running so we can record our LP's onto CD via his computer's line in.

We are using a Pioneer PL516 turntable and a Pioneer SX3700 reciever. Both are very old and worn out. the turntable is using the amp as a ground, power source, and preamp to go to the computer (so the comp is actually plugged into the amp). Our problem lies in a nasty hum we are getting when the cartridge is on the vinyl.

We first suspected the cartridge was bad, and Todd agreed with us, so we ordered a Grado Black off his site to replace the very old and worn-out stock Audio Technica one. The new Grado picks up more pops, ticks, and hum if anything (it also sounds amazing in comparison).

It turns out the hum is being caused my the motor itself. We took the plate, belt, and cover thing off the TT and looked inside. The otor is isolated from the base of the turntable by rubber grommets. They are very old and hard and are undoubtedly not doing their isolating job nearly as well as they used to. These will need to be replaced, but we don't know where we could get such a thing. The belt also needs to be replaced. It is extremely worn to the point where I can hear the "eeee" of it slipping when the TT starts up.

I suspected the motor was bad for a long time, but it seems that maybe it's just the turntable. We took the plate and belt off and the spindle was squeaking, so we put a little oil in it and it immediately stopped. The hum persisted. I think the problem lies in the fact that we need to isolate the motor from the cartridge and center spoke more, where I'm sure the vibrations are coming in. Someone suggested sheilding the motor because the Grado might be picking up some interference. Other than that, we need to get some grommets and a new belt, but I don't know where to find those.

We also desperately need to clean our LP's, as they are very dusty. We need to purchase some vinyl zyme from Todd and use some kind of manual system to clean it out, since we obviously don't have $500 or more to throw away on a fancy vacuum system.

Here are the sound files. turntable_hum a and g are the same sound file played with the old AT cartridge and the new Grado one repectively.

http://www.geocities.com/lawncutta/turntable_hum.zip

Now: I need to make it very clear that this is not a grounding problem. Every connection we have quadruple checked at least, and every ground wire is properly connected and grounding. I have tried the TT without the earth ground and it produces a buzz that is horrific. The hum we are talking about here is a hum that is caused by the motor. The vibrations are transferred via those rubber grommets to the base, and then into the center spoke to the vinyl itself. This explains why the hum only happens when the cartridge is on the vinyl.

Thanks for any help. If you have any information about where I could get new belts and those grommets, please post it.

 

[bln]

According to NeedleDoctor.com, this is the belt you need for a Pioneer PL-516.

http://www.needledoctor.com/app/site...t.A/id.1014/.f

Thankfully, it's cheap. Good luck.

 

[bln]

As for the grommets, here's a manual for the PL-516 that may have information helpful to you.

http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WD1V

Are you doing basic Google searches to find these items? It didn't take me more than 5 minutes or so to turn up these links.

 

[MD1032]

Yes, I tried googling. I can find the belts everywhere. The grommets are another story.

We might have a manual, I don't know. I know we have the original boxes for all of this stuff! I will check. Good idea, maybe they have ordering info in there.

 

[joelongwood]

Here's a suggestion for the belt, while you await a new one. Take the belt off and wash it in some mild soap and water, rinse well, let dry thoroughly and then roll it in some talcum powder. Shake off the excess and put it back on the TT. The "eee" you hear should be gone. These are the instructions that my Thorens and Empire TT's come with.
As for your hum, I listened to the sound files, and call me crazy, but that hum sure sounds electrical, not mechanical. Now, I know you're grounded, but there could be something going on with the wiring in the arm to the cartridge. I know you stated that the hum only appears when the stylus is placed on the record, but this stuff can be mysterious as hell. Just for the heck of it, have you attempted to reverse the leads to the cartridge to see if that changes anything? Also, have you inspected the wires that attach to the cartridge for any breaks in the shielding?
I had one turntable where I taped each individual wire clip that attached to the cartridge in order to get rid of a nasty hum.....much worse than yours....and it worked.
Another thought: Are the RCA cables permanently attached to the TT.....or, are they easily replaceable? If you can, try another set of cables.
And as for the grommets, I would take them off and visit a local hardware store. It won't be an exact replacement, but they may have something that will fit the bill.
Good luck with your restoration......it'll be worth it in the end.

BTW, you may also want to check out what people have to say about hum in the Vinyl Asylum (I searched for the word "hum" and read a few posts....man, hum can be caused by a LOT of things. Here ya go:
http://db.audioasylum.com/cgi/search...searchtext=hum

 

[drminky]

If you are just using the turntable to record lp's to digital, there may be another solution to your problem if you can't sort out your hum...

I mean, ideally just borrow a working turntable off a friend for the weekend, but failing that, and failing a cheap fix for the hum, this is a 'last resort' option that, while not ideal, I have actually seen work quite well.

Record a long stretch of the hum (alone) onto the computer. Invert the waveform using a sound editing program of your choice. If you don't have a good one, here's one for free which should hopefully do the job:

http://www.digidesign.com/ptfree/

Then record a bit of music, put it on one track and put the inverted hum track on another. You may need to slip the hum file around a few notches to get the phase right - do this against a 'silent' part of the song (ie the lead-in of the song) so you can visually line up the waveforms. You are trying to achieve a 'waveform cancellation' - cancelling out the hum and leaving the pure music behind.

If this all sounds too complicated, there are plugins that will be a bit more user friendly, but you will have to pay for them, and it's not that hard to do without it.

Its not guaranteed to work, but worth a try!

 

[MD1032]

Quote:

Originally Posted by joelongwood Here's a suggestion for the belt, while you await a new one. Take the belt off and wash it in some mild soap and water, rinse well, let dry thoroughly and then roll it in some talcum powder. Shake off the excess and put it back on the TT. The "eee" you hear should be gone. These are the instructions that my Thorens and Empire TT's come with. As for your hum, I listened to the sound files, and call me crazy, but that hum sure sounds electrical, not mechanical. Now, I know you're grounded, but there could be something going on with the wiring in the arm to the cartridge. I know you stated that the hum only appears when the stylus is placed on the record, but this stuff can be mysterious as hell. Just for the heck of it, have you attempted to reverse the leads to the cartridge to see if that changes anything? Also, have you inspected the wires that attach to the cartridge for any breaks in the shielding? I had one turntable where I taped each individual wire clip that attached to the cartridge in order to get rid of a nasty hum.....much worse than yours....and it worked. Another thought: Are the RCA cables permanently attached to the TT.....or, are they easily replaceable? If you can, try another set of cables. And as for the grommets, I would take them off and visit a local hardware store. It won't be an exact replacement, but they may have something that will fit the bill. Good luck with your restoration......it'll be worth it in the end. BTW, you may also want to check out what people have to say about hum in the Vinyl Asylum (I searched for the word "hum" and read a few posts....man, hum can be caused by a LOT of things. Here ya go: http://db.audioasylum.com/cgi/search...searchtext=hum

Hmmm, it's possible, but the hum from the motor sounds identical to the hum we're picking up in the cartridge. Good point, though. I'm sure there are a lot of things that need to be sheilded. We connected the cartridge as per the Grado instructions for wiring the colors right. Would inverting them ruin the cartridge? I'm guessing it might.

As for the wires to the cartridge, they're completely unsheilded, just open to the air hanging below the little clip thing the cartridge is mounted on.

Can I use aluminum for all of my sheilding? It would be easy and cheap to determine whether this is a sheilding issue.

Will try the belt thing, if we have talcum powder. We have baby powder, would that do it?

 

[joelongwood]

Baby powder should be fine.....I believe it lists talc as the primary ingredient. I've used it with no problems, although some vinyl addicts say only pure talc is acceptable.
As far as switching the cartridge leads from left to right and vice versa, it shouldn't be a problem. But, thinking about your problem bit more, that would probably be a waste of time and effort.
If you could change the rca cables, that would at least eliminate them as the source of your hum. I know what you're saying about the motor humming, but it sounds electrical to me. Did you try plugging it into a different outlet in a different room?
I'm pretty much out of ideas........
Did you check out the vinyl asylum? Those guys live and breath turntables. There are many, many posts on the topic of hum.....I guess it's a major plague of vinyl.One of the first I read dealt with RF interference from tuners and flouescent lights. There's a lot more. You could also pose your question there.....it can't hurt. Just make sure you tell them it's definitely grounded.

Keep us posted.

 

[MD1032]

Baby Powder's main ingredient is corn starch. I'm assuming that's no good for the belt.

The turntable is plugged into the amp and actually produces a buzz when it isn't, so I'm guessing that's OK, but I'll try plugging the amp into a different outlet. I don't think the RCA cables are detachable.

So is aluminum foil a good idea? I'm ready to just cover the motor and cartridge in it to eliminate any chance of RF interference.

I'm sure the cartridge is hooked up right, switching the wires will be one of the last things I do.

I'm really kind of waiting for a second to open in my life so that I can play with this thing! Dangit. When I open it up, I'll take a load of pictures to show you guys what we're dealing with.

 

[joelongwood]

Well, Baby Powder used to be mainly Talc......I guess they discovered it's unsafe....just like everything else on this planet. Yeah, I wouldn't use cornstarch.....the drugstore does carry talcum powder, though.
The aluminum foil would probably work for the motor, but I wouldn't use it around the cartridge. I don't think your cartridge is the problem, since you had a hum with your old cartridge. I'm really at a loss here......sorry.

 

[merc82]

My TT hums due to wore RCA cables. They're actually RCA at one end and connect under the TT chassis with four crimps (signal and ground for left and right).