Hello all, thank you for any help. I have a question. Lately I have been having excessive high pitch. I'm not sure how to describe it. I guess it would be like scratching your nails on a chalkboard sound in the background of music and movies. It just started about 2 weeks ago. And a lot of people are complaining at our movie theater about a very uncomfortable sound. I'm not sure if it's coming from a receiver, the amps or the speakers. I've never heard of anything like this. It almost sounds like a high-pitched squeal or like a ringing in your ears. I'm just curious if anybody has any experience with this with a full-blown system. I have two marantzs receivers and bunch of four channel amps and a bunch of speakers. This is a movie theater/ event location for children. I don't want to be damaging or causing discomfort to the children. I'm not sure how to track this down. I've turned off multiple amps to see if it went away and it's still there. If I pull the marantz receivers then I have no sound so I'm not sure how to test for it or to find out what's causing it. Any ideas? Thank you for any help.
Isolate the channel / speaker and shut off the amp. If it is in all channels check the decoder.
If you have a music PA that is on before the movie check that too.
If you have a music PA that is on before the movie check that too.
It sounds to me like you are using an unfiltered class D amplifier. Common in HTIB systems and cheap car amps. The ultrasonics they put out interact with my tinnitus and it literally drives me out of the room. Properly output filtered class D does not do this.
Marantz SR8015 x2
Sound Town 4-channel NIX-6000X4 x6
This is what I have. Not sure what the amps are just know how too hook them up. Everything was donated. We use to have two SR6011 but got upgraded. I will try isolating the channel it just hard with the amount of speakers and I can't always hear the sound. Is there any device that can help me isolate the sound that doesn't cost a ton of money. This is a non profit.
Sound Town 4-channel NIX-6000X4 x6
This is what I have. Not sure what the amps are just know how too hook them up. Everything was donated. We use to have two SR6011 but got upgraded. I will try isolating the channel it just hard with the amount of speakers and I can't always hear the sound. Is there any device that can help me isolate the sound that doesn't cost a ton of money. This is a non profit.
For tools: You could try an SPL meter app on your phone and walk around the room near each speaker and piece of electronics and see where it gets loudest. Preferably one of the apps that shows the audio spectrum real time, like Decibel X. This may or may not help, depending on the phone microphone. Another option is the Dayton Audio IMM-6S. This could plug into a laptop and be used with REW, into an iPhone via Apple adapter with a good iPhone app, or into an Android with appropriate adapter if your phone does n9t have a headphone jack (adapter must have TRRS 3.5mm connection rather than typical headphone TRS connection). The Parts Express page also links good apps for each phone type.
To get sound to the amps and bypass the Marantz units involved, plug RCA cable from PC or phone or DVD player directly to an amp. Test one amp at a time to start. You would need a 3.5mm to RCA adapter from phone or PC. Anything you find at Amazon, Best Buy, thrift store, etc will work. If the problematic sound only accompanies loud content (you say you can't always hear it), make sure to use loud content while testing. You could try by ear at first, and later try with SPL meter, but it will be more difficult to see on the meter the more other sounds are involved. You could pump in a loud low frequency tone if using an app with frequency graphs.
If the tests mentioned so far in the thread don't help pinpoint the sound, a more detailed description or diagram of the equipment hookups would help further troubleshooting. And to double check, is the sound gone with Marantz receivers on and all amps off? And have you tested turning one Marantz off and leaving the other on?
If the tests mentioned so far in the thread don't help pinpoint the sound, a more detailed description or diagram of the equipment hookups would help further troubleshooting. And to double check, is the sound gone with Marantz receivers on and all amps off? And have you tested turning one Marantz off and leaving the other on?
So far I have tested it by turning one amp off and then checking to see if I can hear it. And then going to the next then the next. I tried turning one marantz receiver off at a time and honestly I cannot tell. That's why I was trying to find a device that may be able to find out. My hearing is not as good as some other people's. I have a lot of damage from when I was in military. So high-pitched noises I don't hear is clearly. My thoughts is it's coming from one of the receivers possibly. If I turn everything off yes there is no noise so it has to be coming from something. I've tried even disconnecting speaker by speaker. I just cannot tell. Scratches on the chalkboard when I was kid did not bother me so maybe I'm less sensitive than some other people. I'm thinking it's a high frequency that you necessarily can't hear with a lot of noise or at least I can't. But I'll try one of those devices. And I do have an RCA to 3.5 so I can try that too. Thank you!
As far as the hookups, I have heights connected to the receivers. The heights are connected via banana plugs and 16 gauge wire. I have all the other speakers connected to the amps, the fronts, center, the sides and the rears. They go RCA pre-outs from receiver to the 1/4 connector. I ran it like that to keep the heat down from the receivers. Somebody recommended it.
What is the incoming program material?
I have been experiencing something that is certainly not in any amp that is just above my hearing by a small margin. It just gives a feeling of ear wax building up.
I will not say anything else yet until I know where your low level audio is coming from.
My advice is not to blame the amps yet as I suspect that they are just doing what they say on there cans.
The one thing I have done it to eliminate amps from my problem.
I have been experiencing something that is certainly not in any amp that is just above my hearing by a small margin. It just gives a feeling of ear wax building up.
I will not say anything else yet until I know where your low level audio is coming from.
My advice is not to blame the amps yet as I suspect that they are just doing what they say on there cans.
The one thing I have done it to eliminate amps from my problem.
The sound is not there with everything off. As far as material it's everything from music to movies. I have tried different things. It can be prime, netflix, or apple tv programs. Music can be Prime music or YouTube music. Just different stuff whatever the kids want to watch really. I'm trying to narrow it down but I don't think it's the content because it's so many different types and it's all doing it.
One weird thing is if I turn on the tone control and turn the treble all the way down and the bass all the way up it'll eliminates it to a certain degree so that's why I was thinking it was hardware. It just start doing this. The same people who let me know when it first started are the same that keep saying it's giving them a headache. 6 different kids and 4 adults have said the same thing. It's like a high pitch squeak hurting their ears. I asked one person to help track it down. And set both receivers to a tone test. They could not narrow it down.
My amp elimination process ran as far as pulling in the audio from a mono FM radio.
It was there through the little amp in a small mono FM radio.
There is something that makes listening tiring on the signal from the studio.
It is on promotional baggage for future programs and on jingles as well as programs from some but not all production companies.
I have at this stage put it down to lousy DAC syndrome.
There is a dodgy batch of digital keyboards and jingle machines out there manufacturing ear was on an industrial scale.
It is just cheap stuff with DAC clocks that may be as low as half that of a DAC clock in a first generation CD player.
The first clue was when memories of those 1980s spelling practice gadgets people bought for young children popped up each time I blinked my eyes while it was happening.
Don't blame the amps.
The fact that it is coming in on an analogue radio has eliminated any DACs local to the amps here in UK.
If you can make or get a low pass filter to try at the input to your amps it will prove it.
It was there through the little amp in a small mono FM radio.
There is something that makes listening tiring on the signal from the studio.
It is on promotional baggage for future programs and on jingles as well as programs from some but not all production companies.
I have at this stage put it down to lousy DAC syndrome.
There is a dodgy batch of digital keyboards and jingle machines out there manufacturing ear was on an industrial scale.
It is just cheap stuff with DAC clocks that may be as low as half that of a DAC clock in a first generation CD player.
The first clue was when memories of those 1980s spelling practice gadgets people bought for young children popped up each time I blinked my eyes while it was happening.
Don't blame the amps.
The fact that it is coming in on an analogue radio has eliminated any DACs local to the amps here in UK.
If you can make or get a low pass filter to try at the input to your amps it will prove it.
Mostly reinforcing what's been said already:
If it's loud enough to bother people, it should show up on a spectrum analyzer app on a smartphone/tablet (probably with the internal mic - especially with an Apple product - so I'd start there). Chasing it down with measurements/hardware should be easier than trying to get people to reliably tell you what they hear. Also, some high frequency sounds are hard to localize and can have vastly different perceived loudness depending on head position/angle to the source.
Turning the treble down is just decreasing the volume level of the squeal comparatively. That doesn't really tell you a lot at this point.
As others pointed out, you could try a DVD player/CD player/whatever as the source and see if the problem resolves. Or just unplug your current source and see if the problem goes away. It's not clear to me whether the tone is always there when the system is powered up and connected normally or only when a song/video is playing. If it's always there when powered, it will be easier to see on the spectrum analyzer with nothing playing.
Your description up to now sounds like the source was always a computer/streaming. Has that hardware been constant?
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Use the mic on your phone with an fft app
The mic gets to 20k. It can sense the filtered 19khz pilot tone on FM
The mic gets to 20k. It can sense the filtered 19khz pilot tone on FM
A graphic equalizer at the amp input. One with as many channels as you can beg or borrow.
Start with it cut right down above 5khz and work your way up.
Mobile phone mics will just pick up confusing snippets.
Start with it cut right down above 5khz and work your way up.
Mobile phone mics will just pick up confusing snippets.
If the amps are self-oscillating Class-D (they do not have a fixed switching frequency), then having too many of them physically close together can generate beat frequencies within the audio range. However, turning some of them off would not make this sound, making it hard to pinpoint the source.
That reminds me that the local radio station here, where I am a volunteer, had weird tones twice:
The first time was when they still had an analogue mixing console with 7815/7915 voltage regulators on each module. The manufacturer had used 10 uF instead of the recommended 22 uF aluminium electrolytic decoupling capacitors at their inputs. It worked fine for many years, then the electrolytics lost some capacitance and the voltage regulators started oscillating at ultrasonic frequencies. When two of them oscillated, something somewhere produced an audible beat frequency.
The second time was when a computer sound card with a sigma-delta DAC with a bit of clock residue was connected to a cheap sigma-delta ADC without a decent analogue anti-aliasing filter, while their clocks were not synchronized. The clock residue just aliased to an audio frequency that depended on the difference between their clock frequencies, I could clearly hear the pitch of the tone change when I touched a pin of the crystal of the ADC.
That is it.
Signals going through more than one bit of digital gear causing a build up of clock residue.
It used to be known as tape hiss in the analogue days.
Studios need to be a single bit of equipment as a desktop computer is. It does not happen when you record stuff at home on a desktop unit with one ADC and one DAC on the same crystal for record and playback.
If you make a mix for in car use you just paste over the digital recordings from CD to an SD card without conversion so there is no problem.
Taking the output of something digital to headphones for monitoring and back through an ADC in a transmitter will cause the problem we have got.
It has taken a few years for the clock residue to build up but it does look like that is what we have got.
It is indeed getting bad enough to bring up images of 1980s spelling practice gadgets in my mind but at least I know why and can stop it with the off button on the player.
I guess that most modern studios are just a rack of bits of gear from a wide area of the far east with no parallel digital transfer when material is listened to on headphones between units.
I think the broadcasters have got complacent over digital being free of tape hiss over the years and the signal quality is coming back to bight them.
Signals going through more than one bit of digital gear causing a build up of clock residue.
It used to be known as tape hiss in the analogue days.
Studios need to be a single bit of equipment as a desktop computer is. It does not happen when you record stuff at home on a desktop unit with one ADC and one DAC on the same crystal for record and playback.
If you make a mix for in car use you just paste over the digital recordings from CD to an SD card without conversion so there is no problem.
Taking the output of something digital to headphones for monitoring and back through an ADC in a transmitter will cause the problem we have got.
It has taken a few years for the clock residue to build up but it does look like that is what we have got.
It is indeed getting bad enough to bring up images of 1980s spelling practice gadgets in my mind but at least I know why and can stop it with the off button on the player.
I guess that most modern studios are just a rack of bits of gear from a wide area of the far east with no parallel digital transfer when material is listened to on headphones between units.
I think the broadcasters have got complacent over digital being free of tape hiss over the years and the signal quality is coming back to bight them.
So just a quick question, if I use that app and find out all the speakers are producing this sound would that drop it back to the marantz receivers maybe having an internal dac problem or bad capacitors? Yes, you are correct. The sources have not changed it just started out of the blue. All the equipment has been working fine for the past year. I haven't had any problems. It just started. I hope it's a marantz receiver cuz they're still under warranty.