TT noise - wiring diagram

[Lace'd Taste]

Hi all,

So I'm getting a fair bit of noise (i can actually see the mid woofer vibrating when the volume is in the 9 o'clock position) from my Pioneer PL-12D. It's currently plugged into a A&R A60 via the MAG P.U. input. I've tried it through the AUX input and there is still a noise (not as loud though) - the AUX input from my laptop/DAC has no noise so i know it's coming from the TT. I re-wired the TT signal so that they terminate to RCA output sockets on the back plate of the TT - the amp ground wire and power cord go through this plate too but have no contact with it. I rewired using "Canare L-4E6S Star Quad" 4 core pure copper shield wire.

It might be my soldering but I've never had problems with my soldering in the past and I've made cables/ rewiring audio equipment. I've enclosed a diagram of the wiring, I'm assuming it's a grounding issue.

http://farm8.staticflickr.com/7344/11210841986_fe03e52345_b.jpg (http://www.flickr.com/photos/49376303@N03/11210841986/)

Cheers

Jayson

[PaulStewart]

Hi Jayson,

Is this while the TT is playing and the stylus is in contact with the record, or all the time?

[Lace'd Taste]

All the time - even with the TT off.

[walpurgis]

Are you talking about hum or is it some other kind of noise?

[PaulStewart]

Is it a constant hum 50Hz? If so looking at the diagram there could be an earth loop try disconnecting the the earth wire to the amp. If this is not it try lifting the earth to the baseplate.

[Lace'd Taste]

Yeh noise, rather loud to

[PaulStewart]

Sorry still need clarification, noise as in hiss or hum?

[Lace'd Taste]

I'll try removing the grounds tomorrow morning and post my results. May take a recording of the sound too.

[PaulStewart]

Lifting the grounds will only work if it is hum, noise could just be the fact that pick up inputs are more sensitive and can produce more noise. What percentage of the available gain is nine o'clock on your amp. Where are you measuring from, are you starting from knob fully at minimum being seven o'clock?

[PaulStewart]

Also, looking at your diagram, it may be worth trying a connection between signal earth and the earth terminal on the contact strip first.

Best of luck

[Lace'd Taste]

Yeh starting at 7 so not much at all - say 20-25%

[walpurgis]

Might be a dud cap or dry joint if it's not hum, it happens on older amps.

[Lace'd Taste]

I'll hook up the TT to the Denon downstairs and see if I get the same noise.

[YNWaN]

Yes, as previously asked, what kind of noise? Describe it in character specifically. If it is a hum, like a bee, or lower in frequency it is an earth loop issue (which it probably is).

[walpurgis]

I very much doubt the PL-12D is at fault (unless you left the transit screws in). They tend to run pretty quiet.

[Lace'd Taste]

24 hours of investigation...

So i wired up the TT to the Denon amp last night, had to turn it up well past what i considered too much before we could hear the same noise but I realise the TT has a weak output signal (that's right isn't it?) Anyways i decided to get the opinions of my flatmate on whether what i was hearing was indeed a group/earth loop hum - they're re both in various bands and construct their own pedals/ amps/ oscillators etc

Mate 1: "Doesn't sound like a ground loop, doesn't have that hum to it"

Mate 2: "It's ground hum"

We then proceeded to make a ground loop on the TT as a reference and we got that "Hum" a few of you mentioned - the noise I'm hearing is constant like that yet is a bit higher and doesn't have the "Hum" - mate 2 described it as a "lower quality ground loop".

Anyways i realised last night that i hadn't installed the RCA sockets on the back properly so the Signal grounds for the left and right channels were both connected through the back mounting plate - didn't know if this would be the cause but thought I sort it out in the morning.

Today i re-drilled the holes for the RCA output so that the plastic spacers were creating a decent sized gap and that the signal ground wouldn't touch the back plate, I then desoldered and re-soldered all the points leading from the tone arm cables to the RCA output. I wired it back up to the amp and tried again and yet I'm getting the same noise. Again I'm using the MAG P.U. input on the amp and realise this has a high gain than the others - would this make it more interceptable to interference, for example if I'm using the cheapest cable known to man? I do notice that when i grab the cable in one hand and hold the tone arm in the other the noise dramatically decreases - like a lot! The same effect happens when i wrap the cable around the tone arm (a lot of trial and error to find that one).

I think my next step is to make my own 5pin DIN > RCA cable - i have some decent quality shield 4 core shield cable which i can use. Whilst writing this i just found in the service manual which further convinces me it's the cable:

http://farm6.staticflickr.com/5512/11224037986_8abbaaf289_b.jpg (http://www.flickr.com/photos/49376303@N03/11224037986/)

Lastly does anyone know the Pinout for the older A60 Mag P.U. input? All i could find on the net was the newer disc model which had RCA input (see below)

http://farm6.staticflickr.com/5471/11224027694_bc6630154b_b.jpg (http://www.flickr.com/photos/49376303@N03/11224027694/)

Anymore suggestions other than just a cable upgrade? Originally I wanted decent cables just couldn't go through with it due to the amount of money I've already spent on the project.

Thanks again :)

[Oldpinkman]

Deep breath

From the illustrations, and my memory of the amp, the DIN plugs are for line inputs. Disc (turntable, Mag PU, whatever you call it) is RCA only.

I have the option for Din or RCA on the PIP - cos Owen was a DIN junkie. Use RCA'a

You CANNOT plug the record player into the other inputs. It needs RIAA equalisation ( tone adjustment built into phono amps to boost the bass and cut the treble) and more gain (which is why the noise is louder on that input than the other ones)

It is VERY unlikely to be the cable per se.

If it makes a noise just plugging it in, and it doesn't make a noise on that input selection when nothing is plugged in, then hum has to be the number one candidate. It would help if you could describe the noise to us

("You hum it, we'll play it son")

Hum is always based around a 50hz note. (In the UK) Thats a note a bit lower than the lowest note on an acoustic guitar. Its just about the 1st fret 1st string on a bass guitar (edit - only its not, that's an octave to high!! its 4th fret 4th "E" string!!! Easier just to grab the bass guitar jack with your hand before plugging into the guitar! its the 3rd G to the left of middle C on a piano)

It can sound different , louder , or buzzier, or with added whistle, but its main sound is going to be g sharp on a bass guitar!

It probably is hum. If it is hum it will be an earth loop. F****ng nightmare sometimes, but probably easy with your record player. Tidy up the wiring so that the arm cable rca's are just connected to the signal and return pins on the cartridge (via however many joints, but not to ground earth). Make sure the metal of the arm is connected to the turntable earth cable
Connect tt earth to amplifier chassis (there should be a ground connector, but a screw on a metal casing will do)
Don't for the minute have anything else connected apart from the speakers.
If you still have a hum, try disconnecting the earth on the turntable at the plug. Make sure you have a good earth from the TT to the amp, and that the amp is earthed (test with a meter)

report back. :cool:

[PaulStewart]

Looking at your diagram again and as you point out that the hum disappears when you hold the arm, it would seem there is no earthing of the signal earth. I would repeat what I said in post 10, link the signal earth to the centre ground soldering post and see if that works. BTW I assume you have you attached the earth lead to the post on the back of the amp.

Also, DIN plugs are electrically way better than RCAs and have the advantage of earthing through the screen before the signal lead makes, preventing thumps.

Let us know how you get on.

[Dominic Harper]

You have tonearm grounded to both amp and turntable chassis. Remove the turntable ground and just ground arm to amp. That should sort the issue. You may need to ground turntable to mains earth seperately. Do not have common ground between mains and phono input.
Additionally, use a sheilded output cable between arm and phono input.

[PaulStewart]

Dominic I already suggested that, and understood it had been tried. Also, surely the fact that touching the arm stops the noise, suggests a lack of earth to the arm.

[Dominic Harper]

Sorry, me skipping through posts. If thats true then it must be bad wiring or joints assuming input on amp has been tested with another deck.

[Lace'd Taste]

It probably is hum. If it is hum it will be an earth loop. F****ng nightmare sometimes, but probably easy with your record player. Tidy up the wiring so that the arm cable rca's are just connected to the signal and return pins on the cartridge (via however many joints, but not to ground earth). Make sure the metal of the arm is connected to the turntable earth cable
Connect tt earth to amplifier chassis (there should be a ground connector, but a screw on a metal casing will do)
Don't for the minute have anything else connected apart from the speakers.
If you still have a hum, try disconnecting the earth on the turntable at the plug. Make sure you have a good earth from the TT to the amp, and that the amp is earthed (test with a meter)

report back. :cool:

Cheers for the input Richard - yeh from what everyone has been saying I'm 100% sure it's some grounding issue now. As you can see I've enclosed various photos which may point out some errors that the diagram hasn't. I will try what you suggested in the morning and report back. When you say "make sure you have a good earth from the TT to amp...test with meter" what part am i testing, at the plug or the earth point at the back of the amp?




From the illustrations, and my memory of the amp, the DIN plugs are for line inputs. Disc (turntable, Mag PU, whatever you call it) is RCA only.

All my inputs on the back of the amp are 5 pin DIN - see photo:

http://farm4.staticflickr.com/3667/11227071476_8ec9d05fc9_b.jpg (http://www.flickr.com/photos/49376303@N03/11227071476/)


Looking at your diagram again and as you point out that the hum disappears when you hold the arm, it would seem there is no earthing of the signal earth. I would repeat what I said in post 10, link the signal earth to the centre ground soldering post and see if that works. BTW I assume you have you attached the earth lead to the post on the back of the amp.

Hi Paul - yeh earth is attached on the back of the amp, again i will try this in the morning - too much solder fumes for one day! :eek:


You have tonearm grounded to both amp and turntable chassis. Remove the turntable ground and just ground arm to amp. That should sort the issue. You may need to ground turntable to mains earth seperately. Do not have common ground between mains and phono input.
Additionally, use a sheilded output cable between arm and phono input.

Cheers for the input Dom, yeh the table is ground via mains earth too. I will try your suggestion although feel i may have tired disconnecting the turntable ground yesterday and testing - if by "TT ground" you mean the one connected to the bottom TT panel.


Right here's some photos so you guys can see what's going on:

1. Here's the PL-12D when i received it - for closer inspection click on the photo. I haven't changed any of the wiring confirmations since i received it - just removed the amp

http://farm4.staticflickr.com/3806/11106848125_b7c8010a2e_b.jpg (http://www.flickr.com/photos/49376303@N03/11106848125/)


2. New RCA outputs on the back plate - small wire > ground to amp, big wire > mains.

http://farm3.staticflickr.com/2836/11227068996_eb1f44da57_b.jpg (http://www.flickr.com/photos/49376303@N03/11227068996/)


3. Close up on RCA outputs to the solder tags, - White is signal - Blue signal ground, 4 wires on the ground post (I'm guessing this is ground to the TT here as it's screwed - maybe unscrewing this - is this what you mean Dom?) - the one running towards the bottom of the photo goes to TT bottom panel

http://farm6.staticflickr.com/5539/11227066004_ae8b21e1c9_b.jpg (http://www.flickr.com/photos/49376303@N03/11227066004/)

4. General internal photo

http://farm6.staticflickr.com/5520/11227070874_580c35e4dc_b.jpg (http://www.flickr.com/photos/49376303@N03/11227070874/)


Right i think that's it, hopefully that might clear up some errors - I'm starting to question whether i should have bothered terminating to the new sockets on the back or just soldered new cables to the solder tags.

Thanks again

[Lace'd Taste]

Dominic I already suggested that, and understood it had been tried. Also, surely the fact that touching the arm stops the noise, suggests a lack of earth to the arm.

Yeh i think i may have thought I'd done that by removing the ground lead to the bottom panel of the TT but forget it is actually grounded at the solder tag post - i will be trying that tomorrow. If it does work can i just epoxy resin the solder tag post to the turntable?

[walpurgis]

Just a thought. Your RCA phono sockets and signal leads are quite close to the mains lead. Might a screened mains lead help?

[Lace'd Taste]

Yeh that did pass my mind a few times - but then again if i change the signal lead so it's one continuous shielded cable right form the solder tags to the amp (like how the PL-12D is originally) that should have the same shielding effect?

I just removed the TT ground (the one holding the soldering tags to the TT) results as follows:

Ground to amp connected/ ground to TT disconnected - no change
Ground to amp disconnected/ ground to TT disconnected - Louder noise

So i know how to make it louder :) - going back to the tone arm, the one thing i haven't been able to check is the ground to the arm itself via the 2 small black wires - I haven't found anything online of someone dismantling the arm and ideally i wouldn't want to do this due the delicate wires. Does anyone know what part of the arm would be grounded? Is it near the base where the pivots are or does it run down the length of the arm?

[Dominic Harper]

Is that an in built phono stage I see? If so is it being used? If it is do not connect to the mag input, it must be connected to line level only.

[Dominic Harper]

Looking at the second pic with simpler layout, make sure the tag board for the arm wiring is not connected to the chassis, ie the ground from arm not going to turntable chassis because you already have this grounded to earth via the mains.

[walpurgis]

if i change the signal lead so it's one continuous shielded cable right form the solder tags to the amp (like how the PL-12D is originally) that should have the same shielding effect?

It's difficult to screen the signal leads and sockets and tag strip properly. Fitting a screened mains lead is easy. It can't hurt anyway, as long as you don't earth both screen ends.

[Lace'd Taste]

Is that an in built phono stage I see? If so is it being used? If it is do not connect to the mag input, it must be connected to line level only.

That was a pre-amp that was in there when i received it - that has been removed, i just posted it up to show original wiring. I've disconnected the tag board and it makes no difference to the noise, should i leave it disconnected anyways?

[Lace'd Taste]

It's difficult to screen the signal leads and sockets and tag strip properly. Fitting a screened mains lead is easy. It can't hurt anyway, as long as you don't earth both screen ends.

I see what your saying. I'm thinking about taking the tonearm apart to find these grounds on it - i know there's two grounds on there and the noise gets a lot lower when i touch the arm and RCA leads leading from the TT to the amp so i wonder if the arm isn't grounded properly. If i do take the arm apart i may just recable the arm all the way from the headshell to the RCA posts with a shielded cable - I'm assuming this would be fine if the gauge was small enough.

[walpurgis]

I doubt that the internal arm earths are faulty, due to the limited amount of movement an arm travels through, the internal wiring does not undergo massive amounts of flexure which could cause failure. Best only to use dedicated fine arm wiring in arms, otherwise you'll find wire stiffness causing problems. The arm is largely self screening anyway due to its metal construction. I think your problems are elsewhere.

Another thought, are your mains plug earths secure?

[Lace'd Taste]

Yeh I replace the mains cable the other day, new 3a fuse and plug - both earths are solid.

[walpurgis]

It's years since I had a serious hum problem and I always managed to sort them out.

If I were in your shoes I'd disconnect all earths apart from the mains to the TT chassis, then start reconnecting in logical sequence, keeping the arm/signal earths separate and grounded to the amp via the signal lead, at least to start with. Testing at each stage to see what effect there is.

[Lace'd Taste]

Cheers Geoff, I'll have a day of it tomorrow and give it ago along with some other suggestions - hopefully I'll be back on here in 24 hours with a success story! :)

[Oldpinkman]

Lots of stuff on this thread, so I'll try not to add confusion until you have had a chance to try and report back

To answer your question about my point about a meter, I meant check continuity between the earth pin on the plug and the amp and deck (Not Ant and Deck) chassis. This is a nerdy health and safety point from a boy who is hopelessly naughty in this regard and generally lifts earths with gay abandon. Just covering my arse in case you electrocute someone with a faulty appliance

I think we have established it is hum, in spite of the fuddled error in my previous post about what hum sounds like (I will edit it next for the benefit of future generations reading this thread). It might be from more than one source, so you will need to be prepared to eliminate one cause and improve but not fix the problem, and then turn to the next (smaller) cause. I have suffered this more than once. In that regard, it would be helpful to have another cartridge to try at some stage.

I think the main problem, as Paul Stewart has noted, for the reasons he states, is grounding of the tonearm itself. Fairly easy to test. Attach a bit of wire to a good ground on the chassis and touch the other end to the tonearm and listen to the effect. If the hum reduces that is a problem which needs fixing. If it disappears, its the only problem. If it reduces but doesn't disappear it still needs fixing but so do other things which you can then move onto.

I don't think shielded mains is going to solve anything. Leaving aside what I have been told about shielded mains generally, pragmatically this turntable sold in its thousands, and if shielded mains had been needed to make it work without humming, it would have been fitted, and it wasn't.

Finally, as a knot in my hanky, cos I can't scroll up to the picture while I write this - Din v RCA. The choice is simple on this occasion - the only socket available is Din NOT RCA as I thought, and so its pretty much of a no-brainer. You need a Din plug. Paul is again right about the theoretical advantage of Din over RCA as Owen repeats ad-nauseum. However, even Owen wouldn't suggest those reasons mean they sound any different, and was happy to use RCA's on Pip 2 (with some mutterings about how much harder it was to get the boards in and out as a consequence). My objections to Din plugs are

1) I am ham-fisted and attempting to solder them leads to piles of rejects and the stench of burning flesh
2) They are a king-size pain in the arse if you are swapping equipment about. Most use RCA's. Having to rewire cables is no fun (you have RCA sockets on your TT which makes it easier - a normal arm cable doesnt)
3) Folk choose the pin configurations in a non-standard fashion. Not sure the text on the back of the amp provides an unambiguous guide to pin configuration. Find out, and make sure you have it right.

Hoping to hear some positive news in your next post. Fingers (what remain of them, after attempting to solder Din plugs) crossed :)

[Lace'd Taste]

I am ham-fisted and attempting to solder them leads to piles of rejects and the stench of burning flesh haha what a lovely image! :lol:

Right just a quick update whilst I'm on me lunch break. So i had a little play this morning with a lot of sucess - probably not in the way you might imagine. So I got a loose cable and started playing a kinda reverse operation game with the TT. I started disconnecting grounds and reconnecting them, trying different combinations to see what had the best effects. Anyways by chance i touch my laptop with my hand and could hear the noise get louder through the speakers, i ripped that one out of the multi plug and the noise got quieter. I then proceeded to unplugged all the other devices around my work area including a florescent desk lamp I'd been working under and all pretty much all noise has gone leaving me with a nice clear low hum! This is a massive result now because with the amp at the 9o'clock position (a resonable listening level) the hum is actually bareable now . After discovering all this i decided to setup base camp in the longue - have the TT and amp using serpate wall sockets from opposing sides of the room.

Now that I've done this the hum has quietened more, i notice it gets louder if the mains cable is running alongside the signal so I'm going to contruct a quick RCA - DIN tonight and see what happens. I got the pinout now - 3 left signal, 5 right signal, 2 ground. I quick question on shielded cables (was gonna start a new thread for this but I'm sure it's a pretty straight forward answer. I use Canare Star Quad Microphone Cable (L-4E6S) for constructing interconnecters - it is a tightly twisted quad cable (not 2 twisted pairs) with a braided copper shield (more info here: http://www.canare.com/ProductItemDisplay.aspx?productItemID=53) Anyways i use the diagonally opposite wires as pairs, in this example the blue wires are one pair and the white is another.... you know what I'm not great with words here's a diagram:

http://farm8.staticflickr.com/7329/11238452863_3c8da8b4db_b.jpg (http://www.flickr.com/photos/49376303@N03/11238452863/)

Or do i not even need to connect the shield due to the twisting, actually maybe solder to the circle ring around the din plug? Anyways when i get back I'm going to keep trying with the Hum thing and post my findings again. Cheers for all the suggestions, I'm getting somewhere! :)

[Lace'd Taste]

11:46pm - mission accomplished!! Right so i made the cable - soldered the shield to the DIN "ring" and soldered the other wires to their relevant pins, i also used some spare shielding from a previous project to carry the shields right up to the RCA plugs and soldered them to the main shield at the "Y" split. Anyways went to test the cable to see if my laptop/ desk lamp was still interfering on the signal and to my surprise the Hum has practically gone! I have to turn it up to the 1-2 O'clock position before i can start to hear it and even then it is mask by the noise (i'm assuming this noise is just because of the high gain channel). Anyways i can't see it being turned past 12o'clock anyways so i will call it a day. Learnt my lesson not to skimp out on interconnectors ever again - may have to make another one tomorrow to run my laptop from the amp. ;)

Thanks for everyone who inputed - wish there was a more dramatic conclusion to this whole ordeal but I'm afraid that's your lot.

Beer time! :cool:

[Oldpinkman]

11:46pm - mission accomplished!! Right so i made the cable - soldered the shield to the DIN "ring" and soldered the other wires to their relevant pins, i also used some spare shielding from a previous project to carry the shields right up to the RCA plugs and soldered them to the main shield at the "Y" split. Anyways went to test the cable to see if my laptop/ desk lamp was still interfering on the signal and to my surprise the Hum has practically gone! I have to turn it up to the 1-2 O'clock position before i can start to hear it and even then it is mask by the noise (i'm assuming this noise is just because of the high gain channel). Anyways i can't see it being turned past 12o'clock anyways so i will call it a day. Learnt my lesson not to skimp out on interconnectors ever again - may have to make another one tomorrow to run my laptop from the amp. ;)

Thanks for everyone who inputed - wish there was a more dramatic conclusion to this whole ordeal but I'm afraid that's your lot.

Beer time! :cool:

Result :D

[walpurgis]

Nice result Jayson!