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Post by Gary Cook on Sept 13, 2014 17:35:04 GMT -5
Where do you have the Sensitivity set at? Have you tried turning it down?
Next I'd try taking one to another room and check if the hiss changes, loudness or frequency. If either then they are getting EMI, EMF and or RFI from something in that room or closer to it.
Cheers
Gary
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Post by mgoldshteyn on Sept 13, 2014 19:01:51 GMT -5
Where do you have the Sensitivity set at? Have you tried turning it down? Next I'd try taking one to another room and check if the hiss changes, loudness or frequency. If either then they are getting EMI, EMF and or RFI from something in that room or closer to it. Cheers Gary The sensitivity is set all the way down. The hiss is independent of the sensitivity. It is independent of placement, since both monitors have the same level of hiss. It's somewhat independent of the power source, since whether the power is going through two power conditioners or is direct from the outlet, the hiss level is the same. It is independent of the input, since it is constant whether a source is plugged in or not. The only thing I haven't tried is plugging one of the speakers into an outlet on a different 15 amp circuit in my house and/or taking it to someone else's house. The former will probably do nothing, since all circuits are wired to the same 200 amp main, the later is not really a solution. That's where I'm holding at the moment. |
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Post by mgoldshteyn on Sept 13, 2014 21:31:57 GMT -5
Some additional info:
Using a calibrated Dayton Audio EMM-6 Measurement Microphone connected to a Behringer DEQ2496 EQ/RTA mastering processor, I have been able to determine that the buzz coming out of the woofers is centered at 100 Hz (+/- 6 Hz) and is about 5-10 dB above the ambient level in my room.
The noise coming out of the tweeters is less intrusive and is spread across a wide spectrum making it difficult to isolate.
However, it is the raspy woofer buzz at 100 Hz that is most annoying.
Update: I just stepped away from the speakers for about half an hour and the buzz from the woofers has greatly diminished. It is still audible if I place my ear near the drivers, but is no longer audible at 3-4 feet distance. Could this be due to a change in the power line quality, since it is 10:15 PM on Saturday night here? There is certainly no change with regard to the equipment that is currently running on the same circuit as the monitors.
Could this be due to some sort of settling/burn-in of the electronics? But if it is, how could it affect both monitors at the same time? They have been both on the same amount of time, but still this is way to coincidental.
I remeasured the buzz coming out of the woofers using the Dayton microphone just to make sure that I am not going nuts and it is also showing very little noise at 100 Hz that is above ambient (maybe 2-3 dB one inch from the driver). The ambient level has not changed since my last measurement.
Well, one way to know for sure if this is due to settling of the amplifier, power noise or EM interference is to try again tomorrow. If the noise never comes back, it's almost certainly due to some sort of internal settling/burn-in.
Interestingly, the amplitude of the hiss coming out of the tweeters has not changed as far as I can tell, but since the woofer noise was the annoying part I am quite happy where things stand at the moment. The big question is, will the 100 Hz noise come back tomorrow or Monday. I will report then...
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Post by knucklehead on Sept 13, 2014 22:18:28 GMT -5
I'd try them at a friends house. Someone that doesn't live too close. I suspect it might be RF interference which could be very difficult to trace down as to the cause.
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Post by mgoldshteyn on Sept 13, 2014 22:39:48 GMT -5
I have found a correlation. If I set the halogen lights in my house to 50% brightness using the Lutron dimmers that control them, the buzz comes back although it is milder. If all lights are off or at 100%, the buzz is almost non-existent. Now, is this power or EM interference related, that is the question. Could the neighbors use of dimmers also be a factor? I will try to do more research. The thing that has changed this evening is that most of the lights are out.
The tweeter hiss is most likely either amplifier thermal noise or noise at the amplifiers inputs coming from some of the monitors' circuitry, since it has not been affected by any of this. Fortunately, it is mild, non-bothersome and for all practical purposes inaudible at a reasonable distance of 3 feet or more.
I am happier now that the source of the buzz problem appears to be external to the monitors. Now I just need to figure out if its power related (which may be possible to fix) or EM interference related (which would be nearly impossible to fix). My dimmed lighting is pretty far away from the monitors, so my bet is on this being related to the power. I can also try to bring a monitor into the room with the lighting and see if the buzz increases (which it will if this is EM related). More testing for tomorrow.
I am sure that the fact that the buzz is at 100 Hz is a big clue, but a big clue to what mode of interference?
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Post by knucklehead on Sept 13, 2014 22:56:51 GMT -5
I agree - since the problem is in both speakers the odds of both being defective are pretty slim. If you were having problems with one then the odds of a defect go way up IMO. Dimmers are a frequent source of problems. Probably from feedback into the electrical system and can affect the entire house. I don't know that a neighbors dimmer would have such an effect.
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hemster
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Post by hemster on Sept 13, 2014 23:42:18 GMT -5
@op, it appears to be electrical in nature. However as you say, it's not really an issue beyond about 3 feet so I'm not sure I'd worry about it too much.
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Post by jevans64 on Sept 14, 2014 1:59:40 GMT -5
I plugged my Stealth 6 into my CyberPower UPS. No change in the hiss, which is pretty-much inaudible more than 4" away. Since mgoldshteyn mentioned halogen lights on a dimmer, I tried that as well. My 13 60w halogen cans on a Lutron MIR600 dimmer have no impact on the Stealth speakers but they are on entirely different circuits since I made a point to keep those luminaries off of any circuits that have receptacles. IF your dimmer happens to be on the same circuit as the receptacles feeding the speakers, then this would definitely mess with them.
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Post by Gary Cook on Sept 14, 2014 5:46:46 GMT -5
Dimmers (one of the worst sources of noise) can not only transmit EMI and RFI via the power supply they also radiate it it.
Cheers
Gary
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Post by Davecski65 on Sept 14, 2014 6:24:49 GMT -5
This could be why I don't hear any hiss out of my stealths,as my dimmer is on its own circuit,and the outlets have there own breaker.
So I am isolated from my dimmer.Well at least you were able to figure it out.
Glad it wasn't the speaker.
I had one of my stealths go bad.
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Post by mgoldshteyn on Sept 14, 2014 7:49:58 GMT -5
Just as a point of information, my dimmers are all on circuits different than the ones that the Stealths are plugged into as well. But, like in any house, all of the individual 15 Amp circuits meet up at the same main 200 Amp panel in the basement.
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edrummereasye
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Post by edrummereasye on Sept 14, 2014 10:24:27 GMT -5
Some additional info: Using a calibrated Dayton Audio EMM-6 Measurement Microphone connected to a Behringer DEQ2496 EQ/RTA mastering processor, I have been able to determine that the buzz coming out of the woofers is centered at 100 Hz (+/- 6 Hz) and is about 5-10 dB above the ambient level in my room. The noise coming out of the tweeters is less intrusive and is spread across a wide spectrum making it difficult to isolate. However, it is the raspy woofer buzz at 100 Hz that is most annoying. Update: I just stepped away from the speakers for about half an hour and the buzz from the woofers has greatly diminished. It is still audible if I place my ear near the drivers, but is no longer audible at 3-4 feet distance. Could this be due to a change in the power line quality, since it is 10:15 PM on Saturday night here? There is certainly no change with regard to the equipment that is currently running on the same circuit as the monitors. Could this be due to some sort of settling/burn-in of the electronics? But if it is, how could it affect both monitors at the same time? They have been both on the same amount of time, but still this is way to coincidental. I remeasured the buzz coming out of the woofers using the Dayton microphone just to make sure that I am not going nuts and it is also showing very little noise at 100 Hz that is above ambient (maybe 2-3 dB one inch from the driver). The ambient level has not changed since my last measurement. Well, one way to know for sure if this is due to settling of the amplifier, power noise or EM interference is to try again tomorrow. If the noise never comes back, it's almost certainly due to some sort of internal settling/burn-in. Interestingly, the amplitude of the hiss coming out of the tweeters has not changed as far as I can tell, but since the woofer noise was the annoying part I am quite happy where things stand at the moment. The big question is, will the 100 Hz noise come back tomorrow or Monday. I will report then... I think you were right when you said "...still too coincidental". Even if it never comes back, I'd bet on "the neighbors turned off their grow lights" :-\ |
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djreef
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Post by djreef on Sept 14, 2014 17:23:02 GMT -5
Hiss with active monitors is fairly common. A hack to minimize this is to back the volume down at the monitor and increase the gain coming in (if possible). It won't eliminate the hiss completely, but it will minimize it.
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Post by mgoldshteyn on Sept 14, 2014 18:50:29 GMT -5
Hiss with active monitors is fairly common. A hack to minimize this is to back the volume down at the monitor and increase the gain coming in (if possible). It won't eliminate the hiss completely, but it will minimize it. We are talking about noise coming from the active monitor itself. It is independent of any control on the back that I can possibly turn or press. It is present when the XLR input is not connected to anything. In other words it is coming from either EMI/RMI influencing the monitor itself or is caused by noise in the power that is powering it, leaving not too many options. |
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Post by mgoldshteyn on Sept 15, 2014 8:50:41 GMT -5
I did more research on the light dimmers. Lutron ($25-$45) dimmers are TRIAC based forward phased cut dimming devices ( Lutron Dimmer Info), so clearly those are out if you don't want noise. There is an FET option using a reverse phase cut dimmer and I am wondering if these generate less noise/interference. Is anyone using these? Here is Lutron's statement on RFI: RFI control |
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Post by mgoldshteyn on Sept 15, 2014 11:50:28 GMT -5
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Post by mgoldshteyn on Nov 29, 2014 19:34:18 GMT -5
I wanted to add an update. I have put a 1000 VA (medical grade w/filtering) isolation transformer between my outlet and the Stealth 6 speakers. This has reduced the buzz/hiss by about 50-75% when several of the dimmers in my house are activated. This lowers the noise floor to quite bearable levels. Of course isolation transformers with this kind of power cost hundreds of dollars, occupy quite a bit of floor space and depending on their construction can generate a hum of their own, so the solution is not very practical. Here is a link to a sample isolation transformer if you have not seen one before: Carebase medical isolation transformerThe one I am using uses a toroidal core (vs. an E-I core in the one in the link, above), so it is more efficient less noisy and more expensive than the one in the above link, but it's worth it not to have to listen to buzz during afternoon/evening hours. The measures one has to go to, because Emotiva didn't bother to add good power line filtering to their speakers (i.e., this is the only audio product in my house with such horrible line noise rejection). |
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