What's the difference

[Crash006]

Hi,

I finally had a chance to get to my local Long and McQuade to see about renting a power conditioner.

I got there and they only offered one product to rent. I was hesitant to rent it as it is more of a fancy power bar then a power conditioner and when i questioned he refenced that the one they rented offered EMI & RFI filtering.

I want to rent a power conditioner as our building is old and we know it has dirty power throughout. When the dimmable lights (throughout the main level and lower level) are turned on the existing buzz gets louder. I was hoping to rent one to test before purchasing one. This buzz only lives in our Headsets or in ears. We are running from our TF3 mixer to a Behringer Headphone Amp via an analog snake. Our active mains and our active monitors do not exhibit this issue.

What i rented:
https://www.long-mcquade.com/91803/Pro- ... System.htm

What i wanted (or something similar):
https://www.long-mcquade.com/93694/Pro- ... utlets.htm

Is there a big difference between the two? or should i be looking into something completely different hardware wise.

Thanks.

[Wonks]

Because we generally have nice clean power here in the UK, power conditioners are rarely needed. We have the occasional brown-outs and even rarer black-outs, but generally bad quality mains, no.

In my experience, dimmers generally cause RFI issues, so it's air-borne rather than mains-born noise that causes the problems.

That type of power conditioner is pretty basic and is trying to filter out higher harmonics resent on the mains and send them back to ground. It will also help protect against a mains spike, but normally if the spike is worth protecting against, the protective device is destroyed and may then cause its own problems.

The more complex (and expensive) Furman units are rather like a mini-online UPS (but without the batteries) in that they convert 'rough' AC to DC and then back to a smooth AC output. If you want a good quiet mains supply, then that's the type I'd go for (though I'd probably opt for a UPS that did the same thing to avoid problems with power cuts).

The dimmer switches you have may well be older ones. These days they should be ones which only switch at the zero crossing point i.e. when the sinusoidal waveform is at an 0v point, rather than switching off at anytime in the cycle, which can cause huge harmonic issues. At least they should be here in the UK/Europe where it's been legally required for new dimmers for a long time.

Obviously I don't know what lighting controls you've got fitted, but it might be worth having the dimmers checked out and replaced if necessary. Much better to cure (or at least improve the situation) at source.

I'd consider getting in someone to check the mains power supply to see if it is particularly noisy. Over here, the power supply needs to conform to set standards, otherwise the power supply company has to fix it. The checker could also see if the power conditioner unit is doing much to improve the quality of the AC power.

[Crash006]

Because we generally have nice clean power here in the UK, power conditioners are rarely needed. We have the occasional brown-outs and even rarer black-outs, but generally bad quality mains, no.

In my experience, dimmers generally cause RFI issues, so it's air-borne rather than mains-born noise that causes the problems.

That type of power conditioner is pretty basic and is trying to filter out higher harmonics resent on the mains and send them back to ground. It will also help protect against a mains spike, but normally if the spike is worth protecting against, the protective device is destroyed and may then cause its own problems.

The more complex (and expensive) Furman units are rather like a mini-online UPS (but without the batteries) in that they convert 'rough' AC to DC and then back to a smooth AC output. If you want a good quiet mains supply, then that's the type I'd go for (though I'd probably opt for a UPS that did the same thing to avoid problems with power cuts).

The dimmer switches you have may well be older ones. These days they should be ones which only switch at the zero crossing point i.e. when the sinusoidal waveform is at an 0v point, rather than switching off at anytime in the cycle, which can cause huge harmonic issues. At least they should be here in the UK/Europe where it's been legally required for new dimmers for a long time.

Obviously I don't know what lighting controls you've got fitted, but it might be worth having the dimmers checked out and replaced if necessary. Much better to cure (or at least improve the situation) at source.

I'd consider getting in someone to check the mains power supply to see if it is particularly noisy. Over here, the power supply needs to conform to set standards, otherwise the power supply company has to fix it. The checker could also see if the power conditioner unit is doing much to improve the quality of the AC power.

Hey Wonks,

The issue only lives in the Behringer headphone amp, the mains and the monitors are perfectly clear regardless of lights.

This could be an issue with other items as well like cables or connectors, or the headphone amp itself. I have tried moving it to another sanctuary and got the same thing however it was the same building so same wiring. I have tried using different cables and connectors and from time to time I have gotten rid of it only for it to come back for no reason.

[James Perrett]

I guess this is a continuation of the problem in

https://www.soundonsound.com/forum/view ... hp?t=87747

In which case, I would say you are wasting your time with mains filters. You may need to change the headphone amp - or you may just need to change the audio cable. We went through it all with you in the previous thread.

[Crash006]

I guess this is a continuation of the problem in

https://www.soundonsound.com/forum/view ... hp?t=87747

In which case, I would say you are wasting your time with mains filters. You may need to change the headphone amp - or you may just need to change the audio cable. We went through it all with you in the previous thread.

You would be correct in this.

However since then I have tried new cables, new connectors, new headphones, new outlets, and even switched back to the old headphone amp. Same issue.

Nothing has worked. I have not tried the cable thing as of yet but renting a power conditioner was easy to do as I was in the store picking up something else.

I can try the cable if I can get one ordered. That is next. I was asking about this as I found it odd that they suggested it.

[The Red Bladder]

The basic steps are -

1. Proper grounding/earthing of everything.
2. Balanced cables throughout.
3. Quality equipment (i.e. not Behringer!)
4. No domestic dimmers.

[James Perrett]

However since then I have tried new cables, new connectors, new headphones, new outlets, and even switched back to the old headphone amp. Same issue.

Nothing has worked.

So what haven't you changed? Is there any fixed wiring involved? What happens if you wire the headphone amp directly to the mixing desk with just a short cable?

[Crash006]

However since then I have tried new cables, new connectors, new headphones, new outlets, and even switched back to the old headphone amp. Same issue.

Nothing has worked.

So what haven't you changed? Is there any fixed wiring involved? What happens if you wire the headphone amp directly to the mixing desk with just a short cable?

Fixed wiring would be the snake from the mixer to the headphone amp. When i had the rolls installed i attempted to move it to the mixer. Tried all ports with different wires (all new within the last year) and same issue. I have not tried this with the Behringer.

[Crash006]

The basic steps are -

1. Proper grounding/earthing of everything.
2. Balanced cables throughout.
3. Quality equipment (i.e. not Behringer!)
4. No domestic dimmers.

1. Proper grounding/earthing of everything. - not possible to old of a building. Hence the reason i was looking at renting a power conditioner. Is there a better option then that?
2. Balanced cables throughout. - All new XLR to TRS cables within the last year.
3. Quality equipment (i.e. not Behringer!) - We were sold a Rolls Headphone amp and the issue was worse. It got a little better with the Behringer. Why do you not like Behringer?
4. No domestic dimmers. - Domestic Dimmer? Not sure what you mean by that.

In the previous thread mentioned by James Perrett it was suggested to build my own wires or buy TRS - XLR cables that were soldered in a certain fashion. That has not been done either, but the cables that i bought last year for this were PIN 1 = Sleeve, PIN 2 = TIP, PIN 3 = Ring.. here is the link https://www.amazon.ca/gp/product/B07J64 ... =UTF8&th=1.

[Hugh Robjohns]

I'm a bit lost in following this and the other thread as so much has/hasn't been tried.... but fundamentally your problem is interference.

Most interference gets in as RFI through poor/inappropriate cables or poor equipment construction. Some can get in via the mains supply, but it's rare as most equipment has adequate RF protection in the power supply to stop it.

In my experience, mains filters are rarely effective and can even make the issues worse. If you genuinely believe the mains is the problem, get a good UPS, use that to power the gear, and disconnect it's mains input to it's running on battery. If the unwanted noises go away you known they were getting in via the mains. If not, it's RFI and nothing to do with the mains.

Interference problems are always made worse if the mains supply is not properly grounded, and/or if the equipment powered via the mains is not connected correctly to that ground.

Unbalanced cabling will always pickup more interference than balanced cabling.

Lighting dimmers are a well known source of radiated RFI.

The only way to resolve an issue like yours is to correctly identify where the unwanted interference is getting in, which means stripping the system down to its simplest elements and checking as each device is connected.

As your problem seems to revolve around the headphone amp, the very first thing to check is whether the headphone amp produces the buzz on its own with no input cables connected at all.

If it does, the headphone amp is the problem. Get one that's better designed.

If the headphone amp is quiet on its own, then connect one input. Quiet or noisy? If quiet, add the next input etc.

If noisy, then explore the source and wiring to that input. Is the source noisy itself? If so, then explore and cure that problem. If it is quiet, then explore the cabling between source and headphone amp. Is it balanced? Is it routed near something noisy? etc etc...

[AlecSp]

In the case of the Behringer HA8000 I referred to in the other thread (if only this had continued there, rather than in this annoyingly uselessly titled thread...) it was clear that all the hum we experienced, especially on higher numbered channels, was from the transformer. Detaching the transformer and moving it around had a clear effect on the induced hum on nearby channels.

Rubbish design and cheap components. Livable with after a bit of internal tweaking.

No amount of external kit change would make a blind bit of improvement.

[Crash006]

In the case of the Behringer HA8000 I referred to in the other thread (if only this had continued there, rather than in this annoyingly uselessly titled thread...) it was clear that all the hum we experienced, especially on higher numbered channels, was from the transformer. Detaching the transformer and moving it around had a clear effect on the induced hum on nearby channels.

Rubbish design and cheap components. Livable with after a bit of internal tweaking.

No amount of external kit change would make a blind bit of improvement.

Alec,
Are you saying to open up the Behringer and move the internal cabling around so its not close to a transformer? If i do this should i add shieling, if so what should i add.

[Crash006]

I'm a bit lost in following this and the other thread as so much has/hasn't been tried.... but fundamentally your problem is interference.

Most interference gets in as RFI through poor/inappropriate cables or poor equipment construction. Some can get in via the mains supply, but it's rare as most equipment has adequate RF protection in the power supply to stop it.

In my experience, mains filters are rarely effective and can even make the issues worse. If you genuinely believe the mains is the problem, get a good UPS, use that to power the gear, and disconnect it's mains input to it's running on battery. If the unwanted noises go away you known they were getting in via the mains. If not, it's RFI and nothing to do with the mains.

Interference problems are always made worse if the mains supply is not properly grounded, and/or if the equipment powered via the mains is not connected correctly to that ground.

Unbalanced cabling will always pickup more interference than balanced cabling.

Lighting dimmers are a well known source of radiated RFI.

The only way to resolve an issue like yours is to correctly identify where the unwanted interference is getting in, which means stripping the system down to its simplest elements and checking as each device is connected.

As your problem seems to revolve around the headphone amp, the very first thing to check is whether the headphone amp produces the buzz on its own with no input cables connected at all.

If it does, the headphone amp is the problem. Get one that's better designed.

If the headphone amp is quiet on its own, then connect one input. Quiet or noisy? If quiet, add the next input etc.

If noisy, then explore the source and wiring to that input. Is the source noisy itself? If so, then explore and cure that problem. If it is quiet, then explore the cabling between source and headphone amp. Is it balanced? Is it routed near something noisy? etc etc...

Hey Hugh,

So i am going there tonight and hopefully will have a chance to check into this. I will remove all inputs and outputs and test each channel by itself and there should be no humm.

[Wonks]

In the case of the Behringer HA8000 I referred to in the other thread (if only this had continued there, rather than in this annoyingly uselessly titled thread...) it was clear that all the hum we experienced, especially on higher numbered channels, was from the transformer. Detaching the transformer and moving it around had a clear effect on the induced hum on nearby channels.

Rubbish design and cheap components. Livable with after a bit of internal tweaking.

No amount of external kit change would make a blind bit of improvement.

Alec,
Are you saying to open up the Behringer and move the internal cabling around so its not close to a transformer? If i do this should i add shieling, if so what should i add.

No. It is what it is. Alec moved the transformer away from the PCBs and wires for testing purposes, but you can't do that as there is nowhere else for it to go.

From pictures on this website http://dhvan-assistenciatecnica.blogspo ... a8000.html it looks like they've used a toroidal transformer, so no major improvements could be made there.

The later pictures show there's no room to move cables either.

But the channels furthest from the transformer (i.e. the lowest numbered channels) should be least affected.

So you might have some transformer hum, but if the real noise comes on when the dimmers are on, then it won't be the transformer, it will be RFI.

I forget what we've checked so far, but you need an outlet tester to check whether the power outlet used has a ground. If not, that is almost certainly the cause. If it has, then less than ideal cable connections are probably allowing the RFI in.

It's very hard to say more without being there in person. Just run through Hugh's testing list and see where you get to.

[Crash006]

In the case of the Behringer HA8000 I referred to in the other thread (if only this had continued there, rather than in this annoyingly uselessly titled thread...) it was clear that all the hum we experienced, especially on higher numbered channels, was from the transformer. Detaching the transformer and moving it around had a clear effect on the induced hum on nearby channels.

Rubbish design and cheap components. Livable with after a bit of internal tweaking.

No amount of external kit change would make a blind bit of improvement.

Alec,
Are you saying to open up the Behringer and move the internal cabling around so its not close to a transformer? If i do this should i add shieling, if so what should i add.

No. It is what it is. Alec moved the transformer away from the PCBs and wires for testing purposes, but you can't do that as there is nowhere else for it to go.

From pictures on this website http://dhvan-assistenciatecnica.blogspo ... a8000.html it looks like they've used a toroidal transformer, so no major improvements could be made there.

The later pictures show there's no room to move cables either.

But the channels furthest from the transformer (i.e. the lowest numbered channels) should be least affected.

So you might have some transformer hum, but if the real noise comes on when the dimmers are on, then it won't be the transformer, it will be RFI.

I forget what we've checked so far, but you need an outlet tester to check whether the power outlet used has a ground. If not, that is almost certainly the cause. If it has, then less than ideal cable connections are probably allowing the RFI in.

It's very hard to say more without being there in person. Just run through Hugh's testing list and see where you get to.

Is this what you were referring or is there a better option.
https://www.canadiantire.ca/en/pdp/mast ... s#store=35

[Wonks]

Yes, that sort of thing. Anything you plug into a power outlet and can tell if there’s no ground or live and neutral are swapped.

[AlecSp]

Are you saying to open up the Behringer and move the internal cabling around so its not close to a transformer? If i do this should i add shieling, if so what should i add.

In addition to what the others have productively said about there being little you can do, given the internal construction of this unit, I'd also point out that I suspect from all I've read that you're probably not equipped with the skills/experience to go playing around safely with a mains power supply.

[James Perrett]

Are you saying to open up the Behringer and move the internal cabling around so its not close to a transformer? If i do this should i add shieling, if so what should i add.

In addition to what the others have productively said about there being little you can do, given the internal construction of this unit, I'd also point out that I suspect from all I've read that you're probably not equipped with the skills/experience to go playing around safely with a mains power supply.

From looking at the pictures in the link, there are a few things that an experienced technician could try to reduce the likelihood of hum but I'd agree with Alec that this isn't the sort of thing that someone with little experience should attempt.

[Wonks]

Once you’ve checked the outlet, if it fails, then it needs to be fixed before it’s used again. Do not use it if it is faulty as it is very dangerous. Run an extension cable from an outlet that does check out OK.

if the outlet tests out OK, then instead of your current connection method of individual mix feeds to each channel’s aux input, you could try running just a left and right mix into one set of the main inputs on the HA8000 with balanced TRS feeds from the desk.

This keeps it simple and you know the connections are balanced and will give maximum noise rejection. Hopefully this should give a hum-free headphones signal.

If not, you should try lifting the sleeve ground connections at one end of the cables to see if this stops the hum as it might be a ground loop. Unfortunately there’s no ground lift switch on the HA8000 to make this easy.

Assuming you can then get a hum-free (or a much reduced level of hum that can be lived with), then you probably need to think about how you do the headphones.

The HA8000 has two main inputs and those can be selected as the source by a switch on each headphone output channel. Using just the left channel of each main input gives a mono headphone feed. So for two separate headphone mixes, one output uses the mono main input 1 feed, and the other used the mono input 2 feed.

For more mixes you could then get more HA8000s, so that each one does two of your required monitor mixes. So for 4 mixes there are two HA8000s, for 5 or 6 mixes there are three HA8000s. Or you get different headphone amps, one per monitor mix, that can accept a single balanced connection and convert it into a dual mono headphone output.

[Arpangel]

You all know my situation, and the dodgy wiring scenarios of the past, and my use of cheaper gear like Behringer.
I also had issues with mains noise, intermittent hum, grounding issues, and zipper noise from lighting dimmers.
I did a number of things,

Had the basement rewired with a new ring-main, we wired the new ring right back to the board with its own separate consumer unit.

We went through the house removing every single dimmer, replacing them with normal switches.

I rewired as much equipment as I could with balanced foil screen cable, and connected all mains leads via a star system of distribution boards.
Also made sure all audio and mains cables are kept as separate as possible.

Now it’s very quiet. OK, I'm not in the heart of a big city, a hostile environment, but the difference now, and what it was like before is amazing.
Also, very often I found the older vintage gear, especially synths, was very prone to RF interference, taxis etc, more so than modern gear.

[Wonks]

The Behringer Miniamp AMP800 headphone amp might be worth trying. Like the HA8000 it can accept two different mixes and each channel can select between the two mixes. If you use it for just two headphone outputs then you arent being as wasteful. Plus it is externally powered with 9v AC with no ground connected to the 9v, so there's no risk of a ground loop and balanced cables can be used without lifting the ground.

From the specs the output levels seem to be the same. I have no idea if the sound quality is comparable, but they are less than half the price of the HA8000 (in the UK £55 vs £138 in Andertons).

[Crash006]

Going to get an outlet tester tomorrow and start there. I will post a follow up then.

[Wonks]

[Crash006]

Got an outlet tester.

Did a quick test and there it was came back “correct”. This test was with zero lights on in the building not sure if that matters.

Next step?

[The Red Bladder]

The first thing I do in such cases is to make sure that every bit of kit is 100% earthed. If that means having to run a cable to the Mother Earth outside and then driving a metal spike into the ground, then so be it! That is an old PA trick BTW. In an old house, that could be the heating system, the pipes and/or the walls. The pipes leading to the house will almost certainly be plastic, but if they are metal, they will touch enough stuff to be an earth via the building.

Remember that every piece of kit is linked via the sleeve to the earth of every other piece of kit, so earth loops on unearthed equipement are perfectly possible - indeed all the more likely!

Also, somewhere in all that, a piece of kit may be missing an earth. A customer once had a buzzing problem with some 19" converter that was not internally earthed. It was just a case of adding a bit of wire from the internal board to the casing and the earth-loop and therefore the buzz was gone.