Hey guys. Thats to all that helped me in my last thread of buzzing background noise. I finally isolated that down to my Juno 6.

Since then I have added 2 x Behringer ADA8000s. Thing is these are supposed to be balanced. So I bought balanced cables to go with. An now this buzzing is back. I was under the impression if you used balanced cables this couldn't happen.

http://www.thomann.de/gb/behringer_ultragain_pro8_digital_ada8000.htm
http://www.thomann.de/gb/the_sssnake_fxp_8030.htm

I have followed advice from last time plugging in and out. I think there now is a few causes but the above items are certainly contributing to the problem.

Just unplugged everything and back in one at a time. My unbalanced studio quad causes a slight buzz but its so slight I wouldn't care.

These behringers though. Buzz city. Im not saying its the behringer brand by the way. I have a few other Behringer pieces and they seem to work absolutely fine. Im no gear snob.

Im just wondering whats left to do. I plug one of the 8 outs from the ADA8000 into my mixer and the buzzing starts. The most big however is if I plug the other ADA8000 into my mixer with the other cable the same level of buzz occurs. These are independent units on independent cables.

http://www.gyraf.dk/schematics/Behringer_ada8000_analouge.PDF

The Bellringer outs are indeed balanced ^ but balanced operation is not a universal panacea to earth loops.
You might need break the shield wire, pin 1, to each of the output XLRs. Best to link shield to pin1 with a cap of about 1nf but you will probably get away with it.

NEVER! Bloody ends does it?

Dave.

Hi Dave,

haha, no never ends mate.

Ah bollox. Im really not wanting to break out soldering irons at all. Not my thing at all. I was hoping by buying balanced cables this problem just wouldn't happen.

Quote Kolakube:

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I was under the impression if you used balanced cables this couldn't happen.

---

No, I'm afraid not. Shouldn't happen, not couldn't happen! There have been reams of technical papers written about this in the learned audio journals, and is known as the 'pin 1 problem.'

If the equipment is designed properly, the audio circuitry ground reference is kept well away from the chassis safety earth and you won't hear any ground loop hums regardless of whether current is flowing or not.

Sadly, though, a lot of manufacturers still stupidly wire the XLR pin 1 shield connection straight to the audio ground right next to the input circuitry ground reference, instead of directly to the equipment chassis.

As a result, any ground loop current that might be flowing through the cable screen will cause the audio circuitry ground reference to move about, and you will hear hum. It's entirely down to crap design... and I'll say no more about it.

The solution -- assuming you have minimised ground loop area by plugging your new toys into the same power outlets in the star-distribution pattern we talked about before -- is as Dave says, to start snipping those pin 1 connections.

Before you do, just make sure that the cable manufacturer hasn't wired the XLR shell directly to the pin 1 connection inside the plug -- some do and although it should be fine with properly designed gear, it can make the problem worse in some cases.

If you have to resort to snipping the pin 1 connection, do so at the destination end, not the source end. If you feel brave, soldering in a small capacitor to link the cable screen and the pin 1 terminal will maintain the RF interference protection, while defeating the ground loop currents. It's a nice to have, but not essential in most cases.

if you don't want to do any soldering, or want to prove the solution before wrecking your cables, invest in a couple of HOSA GLT-255 ground lift adapters. These are XLRf-XLRm barrels with pin 1 left disconnected internally. About £2.80 from GAK -- other suppliers are available.

http://www.gak.co.uk/en/hosa-male-xlr-to-female-xlr-mic-ground-lifter-adap ter-glt-225/33559

Hugh

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Technical Editor, Sound On Sound

Hi Hugh,

Thanks for the reply. I know this all must sound easy to you electric pro lifer type guys like yourself and Dave but im way out of my league with this.

I try to listen to what you all say but its like listening to Hawkins take a PHD class for a presentation on wormhole physics.

I dunno, I have a mate who can do anything with cars. He once took an engine out of one and put it in another (legally before I get a load of banter about Geordie car thieves haha). You know how much training he'd had. None. He just gets cars, and such.

Me, I don't get much when it comes to electrics. Cutting pin one to me is like cutting the red wire on a nuclear bomb.

I know there's nothing you can do for me as this is a problem with myself. Just an observation on myself. Im just not mr DIY.

Quote:

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if you don't want to do any soldering, or want to prove the solution before wrecking your cables, invest in a couple of HOSA GLT-255 ground lift adapters. These are XLRf-XLRm barrels with pin 1 left disconnected internally. About £2.80 from GAK -- other suppliers are available.

---

Just saw your last paragraph Hugh. How do these work? Do I just plug the XLR end of my cable into this then into my Behringer ADA8000? Will work out expensive (as ever) as I have 16 of these XLRs to plug in. Still, better than soldering for me anyhow.


EDIT - Ok got it mate. Dyslexia. It becomes clearer on readin it a few million times haha.


OUCH - Thats 45 quids worth of these I need. One lot of money after another.



Edited by Kolakube (16/04/12 04:08 PM)

Quote Kolakube:

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Hi Dave,

haha, no never ends mate.

Ah bollox. Im really not wanting to break out soldering irons at all. Not my thing at all. I was hoping by buying balanced cables this problem just wouldn't happen.

---

No soldering needed, probably. Just open up each XLR plug, one end and snip off the screen to pin 1, tape it up so it can't short anything. Leave enough shield so that you CAN fit the caps later if you have any RFI problems.

Dave.

"Just an observation on myself. Im just not mr DIY."

No but you WILL be! If you want to carry on in sound recording there is a basic level of electrical knowledge and skill that you really cannot do without well, not unless you are very, very rich.

It is not for nothing that guys like Hugh and Dan Mills (and y'all else know who you are!) are called Recording/Sound ENGINEERS. Back in the days of tape you needed to be a mechanical engineer (Master) and Phd physics to keep things working. Nowadays, 99.9% of the time "off the shelf" kit works faultlessly but once in a 1000 times, it don't!

Dave.

Suppose Dave. Back in the 90s though I would hire a studio. (Remember them??) Was never my problem.

These days it is.

But then you could argue do you service your own car, paint your own house, unblock your own drains, service your washing machine, re point the side of your house, re wire your house etc.

Some things are best left to others. I do understand the money saving from learning each of these skills but then there would be no time left to spend it

Im just quite annoyed I shelled out for balanced audio interface, with balanced audio cables, and I still have to shell out another £50. But Id gladly pay that that snip pin 1. Honestly fella, I wouldn't have a clue what pin one looked like anyhow.

--------------------
(Sent via my iPhone and no doubt riddled with typos as a result)

Don't want to get too far OT here but for all those "domestic" matters you mentioned you could simply dip into yellow pages and easily find a dozen bods happy to come and do those tasks with varying degrees of skill and ripyouoffness.

But I task you to find a guy in YPs who can sort your hum loop problems! As Hugh says, this is not really a fault as much as poor design and sometimes you just have to work around it.

To pick the car analolgy from your list. You will be a heck of a lot more caring of your engine and gearbox if you have some knowledge of how they work. Then again, if you got your DAW and computer working faultlessy from day one, no crashes or glitches and a 64sample latency rate g'donya! Most of us have struggled. Fussywire and Chipsets (tho' not I), IRQ clashes, BSODS, the Ten Usb Bits scenario, the dreaded CODE 10! I am like you are with tronics when it comes to computers, well I was 6 years ago. Not A f in clue! But 'hI learn Mr Fawltey, 'hI learn!
Oh! And BTW, pin one is MARKED! You just need a good light and a glass!
Dave.

Edited by ef37a (16/04/12 05:59 PM)

Quote:

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get too far OT here but for all those "domestic" matters you mentioned you could simply dip into yellow pages and easily find a dozen bods happy to come and do those tasks with varying degrees of skill and ripyouoffness.

But I task you to find a guy in YPs who can sort your hum loop problems! As Hugh says, this is not really a fault as much as poor design and sometimes you just have to work around it.

---

haha - aye fair points mate. Don't I know it. Shame you didn't live closer, you could be that yellow pages man

Funnily enough I have found another ground loop but this time more slight. Again this is with balanced cables what is damned annoying. Yet again this is from Behringer kit. A 16 channel rack mixer I use for my FX returns.
http://www.behringer.com/EN/Products/RX1602.aspx

Would there be a magic plug to sort this out? This time its TRS jack to TRS jack. Not XLR.

Kola, I wasn't suggesting you buy 16 of those adapters, but one or two would only cost a few quid and would prove whether or not snipping the cable screens will cure the problem. you could then either modify your cables or get someone else t modify them for you.

I appreciate the frustration you are experiencing with this... But a steady logical approach and some basic engineering skills will sort this out.

Hugh

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Technical Editor, Sound On Sound

Hugh,

Im really thankful for Dave and your support. Its not too frustrating with people like yourselves to lean on. But im really not that soldering guy. Wish I was. Perhaps if I had someone to learn from in the same room.

Im more frustrated at the price of all these bits I need. Eliminating hum doesn't seem to come easy or cheap.

Do you have a suggestion for the hum coming from the Behringer 1602 mixer? Thats balanced out to balanced in and on TRS jack to TRS jack as opposed XLR

Silly thought, and it is NOT really a cure, but might get your noise level down to something you can live with:

Take a length of fairly heavy single core wire and use it to connect the cases of all your gear together (running the wire taped to the side of the relevant looms, connect at each bit of kit by stripping a few cm and trapping it under a case screw), 6mm green/yellow wire is usually available from the local DIY shed, or more cheaply from any electricians supply place.

This forms a "Parallel earth conductor" and may get the noise down far enough to be liveable with.

Further thought (Because while I don't like B kit, it is not usually this problematic), how are your power input arrangements set up? Do you for example have the system fed from multiple sockets on different sides of the room (Sure fire route to ground currents)? Can you try plugging everything into a chain of multi way trailing sockets and then feed the lot from one point?

BTW: Dave, I am out of the normal audio game these days, doing electronics for underwater acoustics now, fun stuff, with some remarkably familiar issues.

Regards, Dan.

--------------------
Audiophiles use phono leads because they are unbalanced people!

That rack mixer does have balanced inputs so the same pin one chop idea still holds.

But this time you could be lucky and find it is only when the two outputs are connected that the hum loop is completed. These outputs are not balanced but they are at a sensibly low 120Ohms source Z. You COULD try a pair of TS jack leads with shields lifted one end but in this case I think RFI is a more likley result.
If you can prove that it is just the outs that cause the hum then a transformer isolator from such as Orchid electronics would be a good solution.

Err? Just a thought. Do you have the mixer bolted into a rack with other gear? If so the joining of the chassis earths could be the problem. Try the mixer out of the rack.

Dave.

Dmills

Quote:

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This forms a "Parallel earth conductor" and may get the noise down far enough to be liveable with.

---

I think this is what Ill be aiming for ultimately fella. Its getting ridiculous trying to sort all these loops. I may take the plunge and just hire a bloody electrician or some other uber expensive pro to sort all this crap out. Honestly, there just isn't enough hours in the day for micro managing and farting about like this.

Dave

Yes the mixer is racked up. Ill try and take it out of the rack. How it works is my 4 FX units are connected to my main mixers aux send. (No hum here at all and I have some right old skool kit here id have thought would have been noisy as hell. ) Then these all plug into my FX mixer what in turn mixes all the FX returns to stereo. Its this stereo out from the rack mixer to my main mixer that introduces the light hum. Also it happens if one one of the stereo cables is plugged in or two.

Gonna buy a few of those thingys Hugh kindly linked me to. Maybe 4 or something. If this gits rid of the tape return buzz from the ADA8000s then I may just buy the bloody rest and pay the £50.

Honestly, Ive had my faith totally shattered in balanced kit. Its as bad as unbalanced from where im sitting. Ive just invested a few hundred quid too buying the shortest unbalanced cables I could and making anything balanced use a balanced cable and to be honest, my problems are worse than ever. Quite P'd off about this today. All as I can hear is this bloody buzzing.

If all was well before the introduction of the ADA8000s.
You know what I'm thinking, dont you?

--------------------
17ft here! Too deep for non divers.

There is a little truth to that, a big part of the reason pros have less of these problems is that they generally don't buy pony kit in the first place.

But seriously, none of this stuff is a big deal to solve with a careful, methodical, approach and a **little** knowledge of how things actually work.

BTW: Any professional engineer doing a call out to fix this will charge you way more then £50 for the visit, if those pin one lifts do the job they are actually very cost effective, if you are not prepared to go in and snip the screens yourself (Maybe a fiver for a cheap pair of dykes if you do it yourself and do not already have a set).

Regards, Dan.

--------------------
Audiophiles use phono leads because they are unbalanced people!

Quote:

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If all was well before the introduction of the ADA8000s.
You know what I'm thinking, dont you?

---

Yeah I certainly do mate. So much so I have removed the Behringer rack mixer and am just running my aux FX back to my main mixer direct.

Dan,

Yeah I know pony kit, but it was recommended by those on here that I trust as a cheap way to expand my not so pony fireface 800. Im sure they are not having such problems or they wouldn't have recommended.

I have never been a gear snob before but I think its time I got shot of Behringer. Only things making noise on my system is the supposedly balanced 1608 rack mixer (now gone) and these two supposedly balanced ADA8000. There is certainly a pattern forming here!

Not wanting to do work myself mate. Like I have repeatedly said to others, im just not confident enough to self tech or learn of the internet. Fine if there was someone in real life taking me through it. But there isnt so, non ta. I suffer from Dyslexia, reading and writing isn't my strongest ase4t. I am much more a inter-personal type monkey see monkey do type of learner as we used to say in the Army.

--------------------
(Sent via my iPhone and no doubt riddled with typos as a result)

K, ive ordered 16 of the buggers

http://www.gak.co.uk/en/hosa-male-xlr-to-female-xlr-mic-ground-lifter-adap ter-glt-225/33559


Ill report back in a few days with an update. Thanks to all that are taking the time to reply and try to help.

--------------------
(Sent via my iPhone and no doubt riddled with typos as a result)

To be frank Mickey I think you have been incredibly lucky to have amassed the kit you had before running into hum problems. As Dan says "pro" kit is generally better than stuff lower down the foodchain but not always, a 12month look at Hugh's reviews will reveal that susceptability to hum, even remnant hum itself is not confined to the Beringers of this world!

I can undertand your difficulties with "words" but I then wonder how you get your head around DAW software? Boggles me quite often(see my plea for help re Reaper!) and I like to think I am fairly literate?(shutup Will!). Learning any skill is hard and some things come to people easier than others. My son for example is a complete electronics numpty even tho' he could have had one on one instruction. He WAS interested but wasn't prepared to do the work on something he found "hard".On the other hand he is a brilliant guitarist and has a deep knowledge of musical theory and sight reads very well. But then from age about 13 he has put in 1000' and 1000s of hours of practice!

Dave.

Quote ef37a:

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To be frank Mickey I think you have been incredibly lucky to have amassed the kit you had before running into hum problems. As Dan says "pro" kit is generally better than stuff lower down the foodchain but not always, a 12month look at Hugh's reviews will reveal that susceptability to hum, even remnant hum itself is not confined to the Beringers of this world!

I can undertand your difficulties with "words" but I then wonder how you get your head around DAW software? Boggles me quite often(see my plea for help re Reaper!) and I like to think I am fairly literate?(shutup Will!). Learning any skill is hard and some things come to people easier than others. My son for example is a complete electronics numpty even tho' he could have had one on one instruction. He WAS interested but wasn't prepared to do the work on something he found "hard".On the other hand he is a brilliant guitarist and has a deep knowledge of musical theory and sight reads very well. But then from age about 13 he has put in 1000' and 1000s of hours of practice!

Dave.

---

Wa-what? Someone call?

Actually I've just been following along nodding my head wisely. I think all the options have been covered very well. The only thing I'd add is take breaks when trying to hunt something like this down. It can get very frustrating and you find your mind going round in loops rather than following a logical sequence - well that's what happens to me

--------------------
It wasn't me!
(Well, actually, it probably was)

Quote Kolakube:

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K, ive ordered 16 of the buggers

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Can't help thinking you're running at this like the proverbial bull in a china shop. As far as I can see, you have not yet proved that this latest hum really is a pin 1 problem... It was an educated guess and that's why I suggested buying just one or two to prove the point first, before spending another wad of cash or hacking a bunch of cables apart. I hope this latest expenditure solves the problem, but I wouldn't be surprised if it doesn't...

The thing is that I've never come across anyone else with ground loop problems when using Behringer ADA8000s, so I don't think it's a generic or common problem... which makes me think there are other issues in your system which seems to be very complex and changing in its equipment inventory almost daily.

Ground loops can be tricky buggers to find and resolve, but it is always solvable provided you approach the task calmly, methodically and logically and make absolutely sure of your assesments as you go along. I fear you're not taking that approach and may, as a result, actually be making things worse and spending money unnecessarily or in the wrong places!

hugh

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Technical Editor, Sound On Sound

My eyes glaze over when I read about ground loops and such, though I do try to follow the discussion.

If I may, 2 questions please:

1) Can someone point to an easy-to-read extremely basic discussion of the innards of cables, with LOTS of diagrams and pics? Even that very well written 2-part series in that mag a few years ago (Performing Musician? ... by our own Hugh??) assumed a basic level of knowledge I did not have. I've had similar problems with other things I've found on youtube. What is a "chassis" ...? etc.

2) Once I get to read the right paper, this question will probably sort itself out, but: I've read that it is extremely dangerous to clip the third prong (ground?) off the plug that goes into the wall socket. How is that different than clipping the #1 pin?

Thanks -

--------------------
Alexis -Cubase 6.5.0/SX3.1.1.944, XP SP2, 4GB RAM (1GB not accessible, but used just to balance the computer so it doesn't tip over); Delta 66 in Omni i/O Studio; Motif8; UAD-1

"2) Once I get to read the right paper, this question will probably sort itself out, but: I've read that it is extremely dangerous to clip the third prong (ground?) off the plug that goes into the wall socket. How is that different than clipping the #1 pin?"

Ooof! That ^ is pretty back to basics!
The danger comes because most home electrical supply outlets have one side of the supply connected to earth, the ground, terra firma, the ***t beneath your feet! So, if you are standing on the ground and somehow connect to the other, live, connection a current will flow via your body to earth and that could easily stop your heart and you would die PDQ if you did not get resus.
Now, a good deal of electrical kit is encased in a metal box. This box is connected to the ground via the third wire. Should a fault result in the live point inside the "box" touching the case (a very rare event these days it should be said) a very high current will flow banging out a fuse or breaker. Even better are Residual Current Breakers which work in a different way and offer vastly better protection. But you MUST still have that earth wire on those pieces of equipment that require it NO EXCEPTIONS.
The pin one XLR "earth" is just a screen and plays no part in safety.

I am sure links and better words will follow.....

Dave.

Quote alexis:

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1) Can someone point to an easy-to-read extremely basic discussion of the innards of cables, with LOTS of diagrams and pics?

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Try this: http://www.rane.com/note110.html

...and there's a lot more good stuff on the subject from Rane:

http://www.rane.com/library.html#apm1_2

Quote:

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What is a "chassis" ...?

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In this context the 'chassis' is normally a term used to refer to the outer (metal) case of the equipment which is normally grounded to the mains safety earth connection. Ideally, the screens of any connected audio cables will also be earthed to the chassis... but this isn't always the case.

Quote:

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I've read that it is extremely dangerous to clip the third prong (ground?) off the plug that goes into the wall socket. How is that different than clipping the #1 pin?

---

The safety earth ground in the mains lead is exactly that -- a safety earth. In the event of a serious fault the live conductor of the mains supply could potentially come into contact with the equipment's metalwork. This might be because the mains transformer fails, or the mains cable of IEC socket gets damage, or whatever.

If the equipment's metalwork was not connected to the mains safety ground it would become 'live' itself, and if you touched it you would risk electrocution.

However, if the equipment's exposed metalwork is connected to the mains safety earth, when that fault occurs there is a very low resistance circuit directly between the live conductor and ground. A large current will therefore flow and the protective fuse (or trip) in the equipment, the mains plug-top or the building's mains distribution unit will blow, (almost) instantly isolating the mains power supply and so protecting life and property!

If the mains safety earth connection in the mains lead or plug is cut or isolated in some way, that entire protective system is totally disabled, with serious risk of electrocution or fire in the event of a fault.

In contrast, the screen connection in the audio cables -- while nominally grounded to help 'screen out' external RF interference -- doesn't serve any safety function as far as the electricity supply is concerned. So it can be cut or isolated without affecting the equipment's intrinsic safety. The worst that can happen is some RF interference might get in and become audible.

The reason for wanting to cut the audio cable screen (and why cutting the mains safety earth appears to work) is to break the flow of current around the circular ground path that typically exists between two mains-powered and grounded devices.

Typically the loop runs from the mains safety earth of one device, through the audio cable screen to the other device and on to that unit's mains safety earth, and then through the mains earth cable in the building's mains supply wiring back to the first device.

The current flows because a small voltage often develops between different mains wall socket's earth terminals -- it is completely insigificant from the point of view of electrical safety, but it will cause a small current flow around the loop, and in badly designed equipment that current can find its way into the audio circuitry and become audible as a hum or buzz etc.

The solution is to break the loop in some way, but (hopefully) clearly, as I've explained above, cutting either of the mains safety earths -- while it would break the loop -- is intinsically unsafe. But cutting the audio cable screen would break the loop without affecting the equipment's safety grounding arrangements.

Using an audio isolation transformer in the audio connections will do the same thing because the input and output windings of the transformer are electrically isolated from each other, but pass the audio signal through magnetic coupling.

Does that make it clearer?

hugh

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Technical Editor, Sound On Sound

That Rane note is definitely an 'oldie but goodie' and it's what decided me to go 100% balanced on my gear. Anything I have which isn't balanced gets into the system via a DI as soon as possible; the only unbalanced bits I have are effects sends and returns, where I use top quality, short cables. I've always regarded unbalanced effects as God's way of telling you not to use them if you don't REALLY need to ...

Luckily, I haven't had any gear that's caused a problem, including the few Behringer items I own (Multi-way DI, 32 band EQ and a headphone amp that I've forgotten the location of as it's so long since I used it). However, I don't have a big rack of stuff which might make a difference, and in band situations I use a 'star' mains distribution unit so I KNOW exactly where the power is coming from and going to. Since all the intermediate connections are PowerCons and the final 'user sockets' are tailored to each performer or the PA system itself, the likelihood of ground loops is minimised. To date, the biggest problem I've had is non-humbucking guitars adding their unique signature to the sound, and this is usually controllable by forbidding the guitarist to take his hands off the strings (not that they do very often ...).

Also from band experience I'm continually surprised by the dodginess of cables people are using. Until a few years ago I made all my own, but I have bought some recently using the components I'd use anyway. Another benefit of going balanced is that most my cables are now XLR and of the ones that aren't, pretty well all of them are short, solid mono jack leads. I got rid of any unbalanced to balanced adapter cables as I got the balancing scheme in place and haven't looked back.

Not sure how this helps the OP, but my experience has been that 'all balanced' is good. I would add one to the item by item checking and careful mains configuration already suggested earlier in the thread. I get the feeling the Behringer ADA8000s aren't the problem on its own but they don't like something else that's already there. No logical basis for that, though.

Sometimes you can spend a lot of time looking for complicated solutions when the simple ones haven't been considered.

I've been called out to sort out noise problems when I've discovered something as simple as an output turned waaaaay down and the rest of the signal chain turned waaaaay up to compensate - result: loads of noise. In fact I see this all to often with everything from TV/Freeview boxes to sophisticated studio systems.

Heed the words of the wise above! You HAVE to be methodical and work through the problem - not just throw more gear and money at it! You have a lot of new gear arriving in a short space of time and that means a lot of variables to work through - and work through them you must.

When you choose the hardware route then you have to get used to this methodical analytical approach and you need patience to sort problems out - unfortunately it's going to happen from time to time.

--------------------
An Eagle for an Emperor, A Kestrel for a Knave.

Hugh

Quote:

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Can't help thinking you're running at this like the proverbial bull in a china shop. As far as I can see, you have not yet proved that this latest hum really is a pin 1 problem... It was an educated guess and that's why I suggested buying just one or two to prove the point first, before spending another wad of cash or hacking a bunch of cables apart. I hope this latest expenditure solves the problem, but I wouldn't be surprised if it doesn't...

---

The shop I bought from charger around £7 delivery if I buy a Korg Triton workstation or 1 of these XLR thingys.
So if your buying a big order like a workstation then your getting a good deal. However ordering one 3 quid XLR thingy your not.

With the returns law of England I can return the order in full if this doesnt fix my problem so nothing lost. Buying 1 and paying £7 delivery and then buying another 15 is another £7 delivery so there is method to my madness.

@ Everyone.

I really appreciate the help, and understand it frustrates you all that im not wanting to just whip out a knife and cut pin one or whatever. Sorry guys, its just not my thing. I wouldn't like to pee anyone off, but I am not prepared to start doing this. Unless someone can show me one on one what is obviously logistically impossible.

I remember someone saying I have been lucky to never have faced groundloops before. I have faced them before but never this bad. In honestly though I have only started getting this to this extent since I started using behringer kit. Maybe that's a coincidence, maybe not.

If these XLR thingys don't work im going to replace these Behringers ADA8000s with something of higher quality. It just seems odd how the Behringer balanced stuff give me more gyp than my ancient Alesis quadraverb 1.

Quote Kolakube:

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so there is method to my madness.

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Okay -- fair enough!

Quote:

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I wouldn't like to pee anyone off

---

I don't think that's an issue with anyone here. We're just concerned that maybe there's a bit of running around frantically, rather than calm logical evaluation.

Quote:

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If these XLR thingys don't work im going to replace these Behringers ADA8000s with something of higher quality.

---

And that's exactly the point. There is no fundamental reason why the ADA8000s should be the problem -- plenty of other people use them without any trouble at all. So the danger is you'd just be blowing more money and still have a problem.

Ground loops are usually 'systemic problems' -- you have to consider the system holistically as a whole entity, rather than blaming one bit of kit, or one cable or whatever. There is something about your system as a whole that is causing these problems and we need to calmly and logically work through it to resolve each ground loop issue in turn.

To be honest, I've completely lost track of what's going on. First it was all about an old Soundtracks console, then it was the synths, then some outboard, now the ADA8000s... and I think there was some talk of patchbays in there too at one time.

I'm sure I've said this before, but you have to start at the beginning and gradually connect more equipment bit by bit to test everything progresively, bit by bit, and cure the ground loops as they come up.

Step 1 is to get the mains distribution right and make sure that any external power supplies are kept well away from any audio cabling.

Step 2 is to connect the monitor speakers to the monitor controller (or console, or interface) and make sure that mot critical part of the chain is clean. Then you can connect each recording device in turn to the console and check those, then start connecting the console input sources one by one... and so on.

If you are using an interface rather than a console, do exactly the same, but read interface for console in the above.

Hugh

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Technical Editor, Sound On Sound

Quote Kolakube:

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I remember someone saying I have been lucky to never have faced groundloops before.

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I was wondering whether it was just me that rarely has these ground loop problems - I think I've only ever had 2 or 3 ground loop problems in my entire recording career. My ADA8000 seems to work fine and I'm mainly using it with unbalanced connections to a tape machine at the moment. The optical ADAT link probably helps to keep the computer isolated from the rest of the world.

Cheers

James.

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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

...and I'm running three pairs of ADA-8000s in three different studios with no ground problems at all. There's little point replacing them until you can narrow the problem down to them DEFINITELY being the cause.

In my own studio I've only encountered one ground problem - my Pro-One. Never had a problem before or since.

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An Eagle for an Emperor, A Kestrel for a Knave.

Hi Hugh.

Sorry if things are getting complex to follow. Summery below. In honesty I do think im moving forward a step at a time and methodically.



To refresh the situation as I appreciate it must ba hard to follow along as there is so much goin on.....



1 - Ground loop problem originally occurred as I changed my main mixer to a Soundtracs Solo. Until then id been mixing in the box and hating it via a MOTU 24 I/O.

I bought the Soundtracs fully serviced and then linked it up to a fireface 800. A ground loop existed that thanks to your help and others traced it back to my Juno 6.

STATUS = Going to try a Pseduo cable on it eventually but currently have an ITB project I need to mix down so Juno is jut left unplugged presently.

(Whilst addressing this step I rerouted all of my mains so one 6 way strip gets all the power from one socket. Then one single 8 way strip is plugged into one socket and another another socket and so on all on the main strip. No daisychaining is going on.)

2 - I bought 2 x ADA8000s to compliment my Fireface 800. This gives me the option to output 24 channels of ITB auido for mix down in the real world OTB via my Soundtracs tape ins.

However when I go anywhere near my Soundtracks inputs with the outputs from the ADA8000s a bad buzz occurs.

STATUS = I am awaiting delivery of the XLR thingys (lol an my tech naming) and will report back.


3 - Whilst I was on I noticed a slight buzz coming from my Behringer 1602 rack mixer that I used souly for Effects returns to I could get them all back to the same return channel on my Soundtracs mixer.
I have since rectified this by sodding that idea off and bypassing the mixer and simply plugging the FX into the returns direct.

STATUS - No need for further action. Way down the food chain of problems.


James and Elf

I fully trust it isnt the ADA8000s because you are both telling me and I trust you both after almost a decade of knowing each other on here. Im just frustrated and looking for a product to whip.

I too have hardly ever suffered ground loops before. Only one or two. Just seem to be getting all of them at once. Way it goes I guess.

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(Sent via my iPhone and no doubt riddled with typos as a result)

I would say that the common item is actually the mixer!

Just looking at the back panel on a solo pretty much tells me to expect pin one pain, and I would probably be expecting to telescope the shield on pretty much every cable I had connected between the thing and external mains powered kit (You don't telescope mic cables, but pretty much everything on jack would probably need it, as would line level signals coming in on XLR)......

Mixers of that vintage tended to more often then not have horrific pin one gotchas, the more modern stuff is usually much better in this respect.

You see the black binding post next to the DC power input connector? A good point to connect a parallel earth conductor that, and pretty much what it was made for (They called it a clean earth or sometimes a 'technical' earth, but parallel earth conductor is what it effectively was).

Regards, Dan.

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Audiophiles use phono leads because they are unbalanced people!

Quote Hugh Robjohns:

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Does that make it clearer?

hugh

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Yes, Hugh, almost infinitely - thank you.

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Just a few more questions, if I may please?

Quote Hugh Robjohns:

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Ideally, the screens of any connected audio cables will also be earthed to the chassis...

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Quote:

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tie the cable shield to the metal chassis (right where it enters the chassis) at both ends of the cable.

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Quote:

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with the shield bonded to the metal chassis at both ends.

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Each of these quotes (the latter two from the Rane note) directs that the cable shield be connected in some fashion: "earthed to the chassis ...", "tie ...", "bond ...". Though it's probably there in black and white, how is that physically accomplished - solder? ... some kind of alteration of the plug? ... ??

Rain article, Figure 4: Balanced equipment output connected via 1/4" to unbalanced equipment input (also 1/4" TRS). Do I interpret scenario #9 to say I should open up the TRS, and "snip" the Black/Ring wire?

Thank you, Hugh, and others!

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Alexis -Cubase 6.5.0/SX3.1.1.944, XP SP2, 4GB RAM (1GB not accessible, but used just to balance the computer so it doesn't tip over); Delta 66 in Omni i/O Studio; Motif8; UAD-1

Quote alexis:

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Each of these quotes (the latter two from the Rane note) directs that the cable shield be connected in some fashion: "earthed to the chassis ...", "tie ...", "bond ...". Though it's probably there in black and white, how is that physically accomplished - solder? ... some kind of alteration of the plug? ... ??

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Probably the most reliable way to do it is to drill a hole in the chassis, scratch away any paint around the hole and then put a bolt with a locking washer, solder tag and nut in the hole. Solder a short wire to the solder tag and then take that to whatever needs earthing. Some manufacturers may rely on metal spacers between a PCB and chassis giving a good connection while others may rely on the metal case of the connector having a good connection to the chassis.

Quote alexis:

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Rain article, Figure 4: Balanced equipment output connected via 1/4" to unbalanced equipment input (also 1/4" TRS). Do I interpret scenario #9 to say I should open up the TRS, and "snip" the Black/Ring wire?

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Only do this if you know that the balanced output requires this. There's no escaping from reading the manual if you want to connect a balanced bit of gear to an unbalanced bit of gear.

James.

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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

Quote alexis:

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Each of these quotes (the latter two from the Rane note) directs that the cable shield be connected in some fashion: "earthed to the chassis ...", "tie ...", "bond ...". Though it's probably there in black and white, how is that physically accomplished - solder? ... some kind of alteration of the plug? ... ??

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The cable screen is connected to pin 1 in the XLR or the sleeve of a TRS plug. In the corresponding socket in the device you're plugging in to, pin 1 or the sleeve connection should be wired directly to a terminal, contact or lug that is bolted to the chassis (often one of the socket mounting bolts) to make a good very low resistance ground connection.

Quote:

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Balanced equipment output connected via 1/4" to unbalanced equipment input (also 1/4" TRS). Do I interpret scenario #9 to say I should open up the TRS, and "snip" the Black/Ring wire?

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In a situation where the balanced output is happy to have the 'cold' side left playing no role, then you only connect the screen (to provide the ground reference/return) and the 'hot' signal.

In practice most outputs don't object to the cold side being grounded and you would be much better off using an ordinary unbalanced TS-TS jack cable for the purpose, rather than to start snipping cold wires in a balanced TRS-TRS cable.

hugh

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Technical Editor, Sound On Sound

Edited by Hugh Robjohns (19/04/12 02:15 PM)

Quote Kolakube:

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Summery below. In honesty I do think im moving forward a step at a time and methodically.

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Thanks for that Kola -- it was very helpful and, as Dan has said, your summary of events really does point the finger of doom very firmly at the mixer. I would say that the problem really isn't the Behringer ADA8000s at all, there is probably some old-school grounding nonsense in the Soundtracs mixer.

If you are connecting the ADA's to the mixer with XLR cables, then those ground isolating XLR adapters will almost certainly fix that problem.... but there'll probably be more grief if you connect other things and expect to have to do more pin-1 isolation / pseudo-balanced cables / transformer isolation!

Hugh

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Technical Editor, Sound On Sound

I was curious to see what you could buy off the shelf for pin 1 woes. This looks like the Rolls-Royce version!

http://www.canford.co.uk/Products/49-234_XLR-IN-LINE-EARTH-LIFT

Alternatively a little Googling found this for a tenth of the price.

http://www.gak.co.uk/en/hosa-male-xlr-to-female-xlr-mic-ground-lifter-adap ter-glt-225/33559

Of course a pair of tin-snips on the cable costs nothing. But if you might want the cable back in normal working order at some time, this may not be exactly what you want.