At this point, I would suggest listening to Nelson's suggestion regarding "cheater" plugs:
http://www.diyaudio.com/forums/pass-labs/252734-xa30-5-noise.html#post3852522
This is what a cheater plug in the USA looks like:
Cheater plug - Wikipedia, the free encyclopedia
Notice that the round ground lead is disconnected when using the adapter. Often this will help eliminate ground loop issues. I know Norway uses the two round prong plugs that are common in the UK. Aren't similar adapters sold there for the same purpose? (only in this case isolating the top and bottom grounding tabs?)
The other suggestion would be to check the bonding in your mains box to be sure it's properly grounded. I don't know the electrical code in the UK, but here in the US the box must be bonded (connected) to a earthen ground rod and the plumbing of the house. If your grounding rod has become disconnected, or the lead is loose, it might be that the entire house is not properly grounded and could be the source of the noise.
I found the following thread and thought it contained good advice. Have you tried unplugging every component in the room except for the amps? The gentleman discovered his projector was causing a ground loop even though he had special mains circuits run to his media room. While I realize all of the audio interconnects are unplugged, perhaps one of the other components is injecting noise into the mains:
Cheater plug is a godsend for reducing hum | Steve Hoffman Music Forums
Lastly, are you using fluorescent light bulbs in your home? You mentioned that you turned off all outlets in the house when checking, but were the lights still on????
I would unplug everything in the room, disconnect all inputs from the amp, short the rca plugs, install cheater plugs on the mains to lift the grounds and see what you get.
Hopefully, it will be nice and quiet!
That buzz would irritate me; there is no reason to have to live with that.
Kind regards,
Steve
http://www.diyaudio.com/forums/pass-labs/252734-xa30-5-noise.html#post3852522
This is what a cheater plug in the USA looks like:
Cheater plug - Wikipedia, the free encyclopedia
Notice that the round ground lead is disconnected when using the adapter. Often this will help eliminate ground loop issues. I know Norway uses the two round prong plugs that are common in the UK. Aren't similar adapters sold there for the same purpose? (only in this case isolating the top and bottom grounding tabs?)
The other suggestion would be to check the bonding in your mains box to be sure it's properly grounded. I don't know the electrical code in the UK, but here in the US the box must be bonded (connected) to a earthen ground rod and the plumbing of the house. If your grounding rod has become disconnected, or the lead is loose, it might be that the entire house is not properly grounded and could be the source of the noise.
I found the following thread and thought it contained good advice. Have you tried unplugging every component in the room except for the amps? The gentleman discovered his projector was causing a ground loop even though he had special mains circuits run to his media room. While I realize all of the audio interconnects are unplugged, perhaps one of the other components is injecting noise into the mains:
Cheater plug is a godsend for reducing hum | Steve Hoffman Music Forums
Lastly, are you using fluorescent light bulbs in your home? You mentioned that you turned off all outlets in the house when checking, but were the lights still on????
I would unplug everything in the room, disconnect all inputs from the amp, short the rca plugs, install cheater plugs on the mains to lift the grounds and see what you get.
Hopefully, it will be nice and quiet!
That buzz would irritate me; there is no reason to have to live with that.
Kind regards,
Steve
Last edited:
Before you go and plug other stuff in and try cheaters and so forth, my subconscious suggested the following to me in my sleep:
With the stand-alone amp + full passive XO setup,
1. Are you shorting the inputs? If not, does shorting them change the buzz?
2. If you momentarily touch the outer rings of the two RCA jacks together with a piece of wire or jumper of some kind, does the buzz change?
3. If you momentarily touch the outer ring of an RCA jack to some metal on the chassis (or perhaps a screw) does the buzz change in that channel?
4. Don't forget to check out the white paper on this topic at www.passlabs.com if you haven't seen it yet.
The possibility has occurred to me that we are all in a Philip K. Dick novel.
With the stand-alone amp + full passive XO setup,
1. Are you shorting the inputs? If not, does shorting them change the buzz?
2. If you momentarily touch the outer rings of the two RCA jacks together with a piece of wire or jumper of some kind, does the buzz change?
3. If you momentarily touch the outer ring of an RCA jack to some metal on the chassis (or perhaps a screw) does the buzz change in that channel?
4. Don't forget to check out the white paper on this topic at www.passlabs.com if you haven't seen it yet.
The possibility has occurred to me that we are all in a Philip K. Dick novel.
Last edited:
PRELIMINARY CONCLUSIONS
A very experienced HiFi friend listened today and the basic noise from a single XA30.5 without any connected than the speakers is not audible from the listening position. From 0,5 meter we can hear a small hizz from the tweeter and a hizz/buzz from the midrange. This is only a small problem and mostly HiFi paranoia
With XP10 connected in mute position both with XLR and RCA cables the basic noise doesnt increase BEFORE i turn the volume knob from 0 to 1, then noise doubles. This must be a small groundloop.
I will test your suggestions sometime next week.
I will also bring the amp with some Fostex fullrange drivers to another building without error in the mains system.
Another thing i will test is to connect one component after another with measuring equipment and turning of the plugs 180 degrees in the sockets in order to minimize groundloops.
Last edited:
So, the buzz isn't "louder than a whisper" at your listening position? Now it's inaudible?
I think someone owes me a pizza. I just spent the last hour studying the Norwegian power grid and the IT earthing system.
Well, in a quiet house the noise is slightly audible. My friend think it could be either mains or the noise a standard XA30 noise, or both. It is still annoying and compared to his 300B 110dB horn system it is worse.
@superlian
I hope you know I'm only teasing. I never know if my humor translates.
I think this is not entirely true. Power standards should be quite equal in Sweden and Norway - or at least the phase/gnd/zero should have the same name.
L is Phase, N is Zero.
In Sweden the Zero and Ground have same potential in the power central of the house - but they are separated in the central and have a Residual Current Breaker (Ground current breaker), if something goes wrong outside in the house - so that current cannot travel from Phase to Ground - then it kills power.
But i guess that if you don't have any ground all the way from the power central to your wall outlet then you can float the ground between the Zero and Phase, which would put the "virtual" or floating ground exactly between your phase and Zero.
If this is true - then i guess this maybe could be a problem, depending on how everything connected is grounded...
Norway is special in this case - it is not like Sweden and Denmark. They do not have "neutral" or "zero", but have two "live" instead. However, I don't think this is the cause of noise, because then most audio equipment would have such noise in Norway.
Superlian, do you have something interesting on your power grid - solar panels, private windmill?
Looking forward to hear the final conclusion.
Before you go and plug other stuff in and try cheaters and so forth, my subconscious suggested the following to me in my sleep:
With the stand-alone amp + full passive XO setup,
1. Are you shorting the inputs? If not, does shorting them change the buzz?
2. If you momentarily touch the outer rings of the two RCA jacks together with a piece of wire or jumper of some kind, does the buzz change?
3. If you momentarily touch the outer ring of an RCA jack to some metal on the chassis (or perhaps a screw) does the buzz change in that channel?
4. Don't forget to check out the white paper on this topic at www.passlabs.com if you haven't seen it yet.
The possibility has occurred to me that we are all in a Philip K. Dick novel.
Today i tested a cheat plug and nothing changes.
I will later do the 1-3 steps.
Which white paper?
That's interesting. Out of curiosity, what equipment did you cheat?
https://passlabs.com/articles/ground-loops
https://passlabs.com/articles/ground-loops
Last edited:
AC Mains Noise
I’ve dealt with similar problems before on a few systems I had to trouble shoot. I also think you have an issue with the AC mains in your house. There are two main causes for this type of noise in equipment that I have worked on:
1.) Somewhere on the AC mains line there is a device that is commutating the AC line with high DI/DT spikes. The current spike can be superimposed on all outlets in the house. If the lines are soft (high impedance) then the effect is worse. Devices that can do this are TRIAC (found in light dimmers, washing machines, light fixtures and even some TV’s and audio equipment. The device that is causing the problem could be outside of your home before it enters the house.
2.) Your AC main has DC content which is saturating the amplifier’s transformer. Toroid transformers are very susceptible to this. If the DC content is high enough the transformer will saturate and cause mechanical buzzing from the transformer and possible buzzing from the speakers. Many amplifier manufactures do place a diode/capacitor bridge devices to help prevent this. I’m not sure if your amplifier has this.
Reading all the posts, my guess is that you have either or both of these issues. I recommend that when you run your test with the amps, not only disconnect everything except the AC main and the speaker wire, but turn off all electronics and electrical appliances that are connected to the mains in your house. If you have dimmer lights in your house, turn them all off. This may expose if the problem is #1 that I listed. If the spikes are coming from outside the house than there is not much you can do.
The best way of knowing if you do have a noisy or DC offset mains line is with a Digital Scope and high voltage probe (THE SCOPE MUST BE FLOATING AND NOT GROUNDED WHEN YOU DO THIS !! The best option is a battery power scope since.). I’m not sure if you have one and making such a measurement must be done very carefully as the voltages are high. If you do not have a high voltage probe ( that can measure 500V+) than you could build a voltage divider using the right wattage resistors and values to get the voltage. A good electrician could help you find out if you have a mains problem, but he would need a hand held FLUKE scope or similar test equipment to do the test.
Another quick test, not not so easy on the back is to take your speakers and amps to a friend’s house and try it there. This would eliminate many variables about your house.
xsipower
I’ve dealt with similar problems before on a few systems I had to trouble shoot. I also think you have an issue with the AC mains in your house. There are two main causes for this type of noise in equipment that I have worked on:
1.) Somewhere on the AC mains line there is a device that is commutating the AC line with high DI/DT spikes. The current spike can be superimposed on all outlets in the house. If the lines are soft (high impedance) then the effect is worse. Devices that can do this are TRIAC (found in light dimmers, washing machines, light fixtures and even some TV’s and audio equipment. The device that is causing the problem could be outside of your home before it enters the house.
2.) Your AC main has DC content which is saturating the amplifier’s transformer. Toroid transformers are very susceptible to this. If the DC content is high enough the transformer will saturate and cause mechanical buzzing from the transformer and possible buzzing from the speakers. Many amplifier manufactures do place a diode/capacitor bridge devices to help prevent this. I’m not sure if your amplifier has this.
Reading all the posts, my guess is that you have either or both of these issues. I recommend that when you run your test with the amps, not only disconnect everything except the AC main and the speaker wire, but turn off all electronics and electrical appliances that are connected to the mains in your house. If you have dimmer lights in your house, turn them all off. This may expose if the problem is #1 that I listed. If the spikes are coming from outside the house than there is not much you can do.
The best way of knowing if you do have a noisy or DC offset mains line is with a Digital Scope and high voltage probe (THE SCOPE MUST BE FLOATING AND NOT GROUNDED WHEN YOU DO THIS !! The best option is a battery power scope since.). I’m not sure if you have one and making such a measurement must be done very carefully as the voltages are high. If you do not have a high voltage probe ( that can measure 500V+) than you could build a voltage divider using the right wattage resistors and values to get the voltage. A good electrician could help you find out if you have a mains problem, but he would need a hand held FLUKE scope or similar test equipment to do the test.
Another quick test, not not so easy on the back is to take your speakers and amps to a friend’s house and try it there. This would eliminate many variables about your house.
xsipower
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.