Rybo Posted October 25, 2021 Share Posted October 25, 2021 Hello all, I have created some musical sequences in S5, and sent them to an SD card to use on my Mini director. The sequences run perfectly in my show, but at startup and between sequences I get a loud hum through my powered speakers that is driving me nuts. Is there something I am missing, or is this just something I have to live with? I searched for this but came up with nothing, and I hope it's in the right place. Thanks Ya'll! Link to comment Share on other sites More sharing options...
k6ccc Posted October 25, 2021 Share Posted October 25, 2021 The hum is likely there all the time, you just don't notice it when the music is playing. It's most likely a ground loop. A couple things you can try. Some of these are really only for test as they are not practical for the show (but can help with troubleshooting). - If possible, turn around the power plug on the powered speakers (only practical if it is a non-polarized plug). - If possible, power the speakers from battery (not practical for show - only for testing). - Plug a pair of headphones into the Director output to see if you hear hum that way (likely that you wont). - Plug a different audio source into the powered speakers (such as your phone, an mp3 player, portable radio - in all cases something powered by battery). - A isolation transformer between the Director and powered speaker. Last question. How long of a cable are you using between the Director and the powered speakers? If it's long, as a test, try a short cable. Link to comment Share on other sites More sharing options...
PhilMassey Posted October 25, 2021 Share Posted October 25, 2021 If it is a 60 Hz hum it is a ground loop issue. Check the grounds on the equipment. This may help. https://www.amazon.com/Conext-Link-Channel-Isolator-Suppressor/dp/B082GV15Y1/ref=sr_1_19?dchild=1&keywords=ground+loop+isolator&qid=1635184400&s=electronics&sr=1-19 Link to comment Share on other sites More sharing options...
MattBrown Posted October 25, 2021 Share Posted October 25, 2021 Phil beat me to it, but I had hum between my Director and amplifier, and an audio isolation transformer took care of it. Link to comment Share on other sites More sharing options...
Rybo Posted October 25, 2021 Author Share Posted October 25, 2021 Awesome, thank you so much, these are things I can try. I am using a 100' 3.5 mm cable to a large 50 watt bluetooth type speaker, that is constantly connected to power via a USB wall wart. I think the combination of length and ground issue may be the culprit. I'll try these things today and see if it helps. Link to comment Share on other sites More sharing options...
TheDucks Posted October 25, 2021 Share Posted October 25, 2021 And don't run Audio cable close-parallel to power cords except for very short distances Link to comment Share on other sites More sharing options...
k6ccc Posted October 25, 2021 Share Posted October 25, 2021 2 minutes ago, Rybo said: I am using a 100' 3.5 mm cable That is the majority of your problem! Isolation transformer should help. If not, ask me how to do it right. As a part time broadcast engineer, I have some idea on how to get good quality audio more than a few feet. 1 Link to comment Share on other sites More sharing options...
Rybo Posted October 25, 2021 Author Share Posted October 25, 2021 1 minute ago, TheDucks said: And don't run Audio cable close-parallel to power cords except for very short distances This is a hard one. I'm using a Frightprops talking skull which has power and audio cables coming from the skull that I have to zip tie to the backbone to hide. I just purchased a 3.5mm ground loop filter as advised and will give that a shot. If anything I can test by removing the zip ties and holding the cable away from power though. Thanks! Link to comment Share on other sites More sharing options...
Vince4xmas Posted October 26, 2021 Share Posted October 26, 2021 I have always had some "hum" not really noticeable when running audio/shows. Link to comment Share on other sites More sharing options...
Rybo Posted October 26, 2021 Author Share Posted October 26, 2021 I did some troubleshooting last night. I bypassed everything and used a 1m audio cable directly from the mini director to the speaker without the speaker charging cable and still have the sound. The buzz is about 1 second long, and I can verify that it doesn't exist while the sequences are running, it's only right at startup and between each sequence. Almost as if it occurs any time the mini director is accessing the SD card to buffer. I have the ground loop interrupter arriving today, so as soon as I see the Amazon truck I'll give that a shot and update. Thanks all! Link to comment Share on other sites More sharing options...
TheDucks Posted October 26, 2021 Share Posted October 26, 2021 21 minutes ago, Rybo said: I did some troubleshooting last night. I bypassed everything and used a 1m audio cable directly from the mini director to the speaker without the speaker charging cable and still have the sound. The buzz is about 1 second long, and I can verify that it doesn't exist while the sequences are running, it's only right at startup and between each sequence. Almost as if it occurs any time the mini director is accessing the SD card to buffer. I have the ground loop interrupter arriving today, so as soon as I see the Amazon truck I'll give that a shot and update. Thanks all! Can you use a different power adapter for the mini director? That one might be marginal (filtering the DC) Link to comment Share on other sites More sharing options...
Rybo Posted October 26, 2021 Author Share Posted October 26, 2021 4 minutes ago, TheDucks said: Can you use a different power adapter for the mini director? That one might be marginal (filtering the DC) I probably have another power supply that will work for it, I'll see what I can dig up in the garage if the interrupter doesn't help. Link to comment Share on other sites More sharing options...
Rybo Posted October 26, 2021 Author Share Posted October 26, 2021 (edited) The plot thickens. The ground loop interrupter didn't work unfortunately. I removed the SD card and powered everything on so I could have continuous hum to test with. I unplugged the Cat5 cable from the back of the Mini director and BAM, the noise is gone. I get the same result when I remove power from the CMB24D board that runs my lighting. Isolated the CMB24D and ran power to another circuit, same thing. I suspect the 12 volt power supply for the CMB24D board now. I will get that swapped out this afternoon and test again, but I think I'm getting closer. Thanks all. Edited October 26, 2021 by Rybo CMD24D to CMB24D correction. Link to comment Share on other sites More sharing options...
TheDucks Posted October 26, 2021 Share Posted October 26, 2021 Your Mini director CAN get power from the controller via the CAT5. Quick test: No power adapter, but the CAT5 is connected to a powered controller. If it is powered on. The controller is power source. What controllers do you have? can you make a adapter cable that only passes the blue pair (no connect pins 3 + 6, LOR power) between the director and controller .) You will then NEED the external power adapter. 1 Link to comment Share on other sites More sharing options...
Rybo Posted October 26, 2021 Author Share Posted October 26, 2021 Success! I swapped out the cheap 10 amp brick type power supply for a legit 30 amp supply that I was too lazy to install last Christmas and most of the hum was gone. I added the ground loop interrupter and organized my cabling better to keep audio away from power and light wires, which took out the last remaining hiss and now I'm left with just a slight 'pop' at startup. Even the audio itself sounds a bit cleaner. Just in time for thunderstorms tonight in Dallas haha. Thanks everyone, this thread got me thinking in a more useful way to troubleshoot the problem correctly. I'll be wiring up my first Pixie board for Christmas so I'm sure I'll be back with more questions. 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now