Rog
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Feb 13, 2021

Tonematch issues with HDMI projector and laptop

Bose L1 with a TS4 ToneMatch attached

USA

I was wanting to use this system at a retirement center for karaoke.  I was using a laptop to produce the sound for the video.  I ran the sound from the laptop out of the headphone out.  I used an 1/8 inch from the laptop to two 1/4 inch that I hooked into Channel 4 an 5 of the ToneMatch.  When I ran the sound this way, it sounded great.  The moment I hooked in the projector using an HDMI cable there came a very high pitched loud noise.  It actually blew the sound card on the laptop,  I tried a different laptop, it did the same.  I tried various combinations and nothing fixed this.  I tried different laptops, I tried different projectors, I tried all different cables, nothing worked, same loud sound.  I had disabled the sound going to the HDMI on the computer, and had it only coming from the headphone out and the same problem.  I took the system back to where I got it and they could not figure it out.  They even switched out a different ToneMatch and still the same high pitched sound.  I called Bose and they said I needed to disable the sound going to the HDMI, I told them I had done that and they had no help beyond that.  Any suggestions?  I need help.

5 REPLIES 5
Dylan_R
Moderator

Re: Tonematch issues with HDMI projector and laptop

Hi Rog,

Welcome to the Bose forum! Sorry to see you're having this problem.

The T4S ToneMatch mixer doesn't have any HDMI connections. Please could you provide some more details on how the projector is connected in this setup?

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Rog
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Re: Tonematch issues with HDMI projector and laptop

I am coming out of the laptop via HDMI to the projector for the video.  I then have tried it two ways to get the sound to work, but each way produces a horrible high pitched squeal.  Here are the two ways I have tried it:

1) Using an 1/8 inch to two 1/4 inch stereo cable, I have hooked the projector into the ToneMatch channel 4 and 5.  It gives that high pitched squeal.

2) Using an 1/8 inch to two 1/4 inch stereo cable, I came out of the headphone out on the laptop to channels 4 and 5, same crazy sound.

It only does this when an HDMI cable is hooked up to a laptop.  If there is no HDMI hooked in, and you use the cable out of the headphone jack of the laptop going into channels 4 and 5, it sounds great. 

We did make sure to change the sound settings on the computer to have the sound come through the laptop and not the HDMI port and the sound still is crazy as soon as you plug in the HDMI cable.  We tried it the other way (telling it to have the sound come out of the HDMI port) and it does teh same exact thing. 

I have tried it with different projectors, different laptops, and multiple cables, with the same horrible results.  I even took the system back to Guitar Center when I purchased it and they switched out the ToneMatch with another one that was on display, and it did the same exact thing. 

We then hooked the laptop up to an EV set of speakers and there was no problem when we had the HDMI cable in the laptop going to the projector.  We then hooked the set up (laptop, HDMI cable, projector) to a Bose L1 Pro 8 system and there was no problem.   Because we eliminated all other possibilities at the store, their audio pros agreed with me that the problem is the L1 with the ToneMatch system.  

Dylan_R
Moderator

Re: Tonematch issues with HDMI projector and laptop

Hello Rog,

From your description, it doesn't sound like the ToneMatch mixer is at fault, given the problem only occurs when the HDMI connection/projector is introduced.

Please could you confirm the model of the projector and laptop you are using?

As you mentioned you are using channels 4/5 for the audio input, please could you confirm whether your ToneMatch mixer is the T1 or T4S?

When you encounter the high-pitched feedback, does the signal indicator LED on the ToneMatch mixer indicate that the input signal is clipping/distorting, i.e. light up red?

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Rog
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Re: Tonematch issues with HDMI projector and laptop

The mixer is the T4S.

 

We tried it with different brands of projectors and three different brands of laptops. We deduced from that it was not a problem with the laptops or projectors (or chords - we changed those out as well.

The problem went away when we plugged it into another brand of speakers without the T4S.  It also went away when we used the new Bose Pro system.  

The problem is only there when we add the Tonematch T4 to the mix.

 

You asked:

"When you encounter the high-pitched feedback, does the signal indicator LED on the ToneMatch mixer indicate that the input signal is clipping/distorting, i.e. light up red?"

 

And yes, it does do just that.

Fish-54
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Re: Tonematch issues with HDMI projector and laptop

Hello Rog,

 

Whines and screeches are sometimes maddening to track down.  Here are some other ideas to consider.  (I'm not saying they will solve the problem, but may help diagnose the issue.)

 

Have you tried connecting the laptop to the T4S via USB cable instead of the 1/8" headphone output to Y-cable?  (If you do, make sure you have installed the latest T4S firmware, which enhances USB routing.)

 

Also, are you using your laptop on battery, or do you have its power supply plugged in?  I have had instances where I would get a high-pitched whine that stopped when I unplugged the power to the laptop.  Lots of these whines come from the switching power supplies used for lots of digital devices (in this case laptops and mixers.)  Does your projector also have an external power supply?  Are all three devices plugged into the same power strip with the same polarity?  There may be a grounding issue or noisy power supplies.

 

Do your projector and laptop have the older-style 15-pin SVGA video connectors?  If so, that may be worth a try instead of HDMI (not sure how the picture quality will be, though.)

 

Just some suggestions to try!