Hey Everyone, I am a musician and unfortunately tasked with handling my band's sound requirements. I recently upgraded our PA system from a powered mixer setup to a more sophisticated system and am now getting horrible feedback through two of the mics. Haven't had any luck figuring it out and hope someone might have some advice. Here's our set up... We have 5 vocal mics (4 sennheiser e835, and 1 EV D767a) We run them into a yamaha MG206c mixer. The 2 lead vocals mics run through a dbx 166 compressor via the "insert" plug on the mixer. All input signals then are sent out the aux 1 and aux 2 ports to a dbx 31 band 2ch EQ, then into a Behringer 2500 amp. From there, aux 1 goes to 2 floor monitors for drummer and bass player, aux 2 to 3 monitors for guitar players and keyboardist. Two of the mics (the ones using the compressor via "insert") feedback terribly if they are both on at the same time and turned up beyond med/low volumes. I can mitigate it to an extent with the EQ to get some more volume, but by the time I get it to where it needs to be, i've cut so many mid/high frequencies that most of the tone is gone. We're good about all the mics facing away from monitors. Again, the two culprit mics seem to feed off each other. Incidentally, i run the main signal through a Lexicon MX200 effects processor before going into the amps, then mains. However, I don't use the mains for rehearsal....only floor monitors. Thoughts???
Help me with my classic rock band's feedback problem
- Thread startertgt007
- Start date
So are you saying it feeds back during rehearsals with just the monitors? What is the space like? Are you simply running them too loud for the space?
Have you tried it without any compression? You could be compressing based on some non-critical frequencies and then applying makeup gain that raises all frequencies including the ones causing feedback. Also, your mixer has a compressor for each mic input and the inserts are post the high pass filter, compressor and EQ so with an external compressor you are stacking compressors, so consider how that may be affecting the signal.
You mention having five vocal mics and say you are good about the mics facing away from the monitors but you also mentioned that the monitors are for drums, bass, keyboards and guitars. So how are the monitors and mics physically related? What is in the two monitor mixes? Because you have three monitors on one send you may have to be very careful about what is in that mix since it will probably affect multiple mics.
Have you verified the overall system gain structure?
Just out of curiosity, why are you running the mains through an effects processor? As noted in the MX200 manual, the most common configuration would be an aux send form the mixer to the MX200 and then the MX200 output back into a return or stereo channel or two mono channels.
Have you tried it without any compression? You could be compressing based on some non-critical frequencies and then applying makeup gain that raises all frequencies including the ones causing feedback. Also, your mixer has a compressor for each mic input and the inserts are post the high pass filter, compressor and EQ so with an external compressor you are stacking compressors, so consider how that may be affecting the signal.
You mention having five vocal mics and say you are good about the mics facing away from the monitors but you also mentioned that the monitors are for drums, bass, keyboards and guitars. So how are the monitors and mics physically related? What is in the two monitor mixes? Because you have three monitors on one send you may have to be very careful about what is in that mix since it will probably affect multiple mics.
Have you verified the overall system gain structure?
Just out of curiosity, why are you running the mains through an effects processor? As noted in the MX200 manual, the most common configuration would be an aux send form the mixer to the MX200 and then the MX200 output back into a return or stereo channel or two mono channels.
It's difficult to diagnose feedback without hearing it, but I would start by losing the comp. Strange as it sounds, an over compressed and hyped mic will feed back quicker than an uncompressed mic. If the feedback goes away when you lose the comp, you are squeezing way to hard or applying to much makeup gain. Are your monitors mixed pre or post fade. I've also seen monitors mixed post fade cause similar problems, because on a post fade send you bring up the monitor level when you bring up the fader, possibly beyond the feedback threshold in the monitors. If both vocals are sent to your monitor mix, that could explain why both mics seem to feed of each other.
To reinforce one thing you already caught, if you've notched out enough frequencies on the EQ to ruin the sound and not fixed the problem, this isn't an EQ problem. It's probably either a routing thing, or a positional thing.
Matt
To reinforce one thing you already caught, if you've notched out enough frequencies on the EQ to ruin the sound and not fixed the problem, this isn't an EQ problem. It's probably either a routing thing, or a positional thing.
Matt
WooferHound
Well-Known Member
The compressors will reduce the volume when the signal is significant enough to induce compression. When the signal is no longer there the compressor will raise the volume back up to Unity Gain. If you put the compressor on a channel it will also compress the monitors which is bad. When the compressor is raising the level back to unity gain, it causes feedback in the monitor system, and in the mains if the compression is to much.
Set your compressors to lower the compression, or put them on the group outputs so the monitors are not affected.
Remember that compressors are controlling your gain, if you turn up the volume while in compression, the gain will eventually return to full volume and cause the feedback.
Set your compressors to lower the compression, or put them on the group outputs so the monitors are not affected.
Remember that compressors are controlling your gain, if you turn up the volume while in compression, the gain will eventually return to full volume and cause the feedback.
Last edited:
TimmyP1955
Well-Known Member
Compression in the monitors is not recommended (neither are effects). Use wye cables to run each vocal into two channels: One with compression for the house, and one without compression for the monitors. (To keep things more tidy, you can make your own like this: TP Audio Special Mic Wye )
