Live Sound Newbie + Mixer with No Manual...Help?

[nelsonizer]

Hi Everybody,

I’m new to the forum and new to live sound. I’m a guitarist who just started playing live gigs in my city. This off-brand mixing board below is the equipment that I have. I live in an African city with no shops, so I don’t have any way to get any new equipment besides maybe some cables, so I’m making due with what I have. I’ve got some problems and I need some advice from people who know.

I am suffering from very bad feedback. I try moving the speakers away, pointing in different directions, but huge feedback after turning up the Blue FX SEND knob to get more volume.

- I cannot figure out how to turn the effects from the mixing board off. I don’t want the built in reverb or delay. It’s causing massive feedback. There appears to be no button that says effects bypass or effects on/off. Do you see any way to bypass the effects?

- The FX SEND knob seems to be controlling the volume, but if I try to make it loud, it creates huge feedback and then I am forced to turn down again. I try compensating with the gain, but then the vocals become very distorted.

- I cannot get the guitar effects pedal (POD HD500X) to show up in the monitors. It comes out fine from the speaker, but doesn’t want to come to the monitors. I am using Aux1 SEND and Aux 2 SEND outputs to run the in-ear monitors and using the AUX1 and FX/AUX2 to control the sound levels of each instrument.

- What do the small white G1/G2 buttons do under each channel. I cannot see the function.

- What is the purpose of the UNBALANCE RIGHT; UNBALANCE LEFT; G1 G2 ports at the top. Are these output channels?

Thank you so much for your help and patience for advice. I am new but trying to learn.

SET-UP

Inputs:
Channel 1 - Lead Vocal: SM57
Channel 2 - Backup Singer: SM57
Channel 3 - Lead Guitar: Amp Cabinet mic’d with Audio Technical Cardioid Condenser
Channel 4 - Bass “REC OUT” from Cube Amp
Channel 5 - Rhythm Guitar: Line Out from POD HD500X Guitar Multi-effects Floor Processor

Speakers:
- 2 Passive Speakers Speak-on Cables

Monitors:
- Band Member 1 Behringer P1 to In-Ears
- Band Member 2 Behringer P1 to In-Ears
- Drummer Headphone out from board with really long cord
- Band Member 4 Earplugs, stand close to PA

[shufflebeat]

Master section - "FX to L/R" and "FX to G1/G2" should both be out.

Channel section - for now every channel the L/R button should be in and the G1/G2 button should be out.

Now pull the G1/G2 fader down and leave it.

The routing (white) buttons above each fader dictate where the signal goes post fader, either to the main L/R outputs subject to pan position and/or to the groups (G1/G2) and I would expect also subject to pan position

Pre/post channel buttons dictate whether the signal send from each channel aux fader is affected by channel fader position. Monitors are usually pre fade for independent (monitor vs front of house) control and reverb/FX are normally post fade. The pre/post button will probably apply to aux 1 but check. I suspect your issues with no guitar in the monitor may be connected to this.

Whether you use the balanced (XLR) or unbalanced (TS jack) outputs will depend on what is next in the chain. What is next in the chain (i.e. PA amplifier)?

[James Perrett]

Whether you use the balanced (XLR) or unbalanced (TS jack) outputs will depend on what is next in the chain. What is next in the chain (i.e. PA amplifier)?

The words 'power mixer' make me think that it possibly has built-in amplifiers so the speakers plug directly into the back of it.

[shufflebeat]

Whether you use the balanced (XLR) or unbalanced (TS jack) outputs will depend on what is next in the chain. What is next in the chain (i.e. PA amplifier)?

The words 'power mixer' make me think that it possibly has built-in amplifiers so the speakers plug directly into the back of it.

The thought had crossed my mind but that would usually be plastered all over the front panel, i.e., "five squllion watts of Pure Music Power".

Also, balanced XLR out?

Are there Speakons out on the mixer back panel?

[nelsonizer]

Thanks for the replies. Is becoming a bit more clear.

Does anyone have any ideas ideas on how to disable the built in effects or bypass this section entirely?
When you turn on the mixer, there are digital numbers that come up on the screen from 1-16. Setting 1 Seems to be some kind of mild reverb. All the other settings are delay or reverb effects. There is no setting for 0 and no clear way to disable.

In the master section, whenever I move the (blue) dial for FX SEND, I get a massive feedback spike. So, I am forced to reduce the volume. But then, my volume goes away and the PA speakers are not loud enough. So, I try to compensate and increase volume by adding gain on all the channels, but then the sound becomes very distorted and clipping. So, how can I increase the volume without all the horrible feedback.

This is the back of the panel. The speakers do not have any electricity cord.

BACK OF MIXER:


BACK OF SPEAKER:

[Hugh Robjohns]

Does anyone have any ideas ideas on how to disable the built in effects or bypass this section entirely?

Keep the FX return fader on the far right of the desk fully down, and make sure the 'FX to L/R' and 'FX to G1/2' buttons are up (ie. not pressed in).

In the master section, whenever I move the (blue) dial for FX SEND, I get a massive feedback spike.

If you don't want to use the internal FX, then keep this control fully anticlockwise (off).

I am forced to reduce the volume. But then, my volume goes away and the PA speakers are not loud enough. So, I try to compensate and increase volume by adding gain on all the channels, but then the sound becomes very distorted and clipping. So, how can I increase the volume without all the horrible feedback.

It sounds like you're not using the console correctly (or it's broken!). It sounds like you are routing a lot of your signals through the FX chain, rather than direct to the main outputs.

I'd suggest starting with all of the channel Aux1 and FX/Aux2 controls set to minimum (anticlockwise). Same with all the Aux and FX controls in the master section. You can worry about using the aux sends for monitors etc once you have sorted out the rest of the desk routing!

Press the PFL button on each channel and adjust its input gain control to get a healthy signal level on the meters. You can audition with headphones if you like to check for quality/distortion etc. Repeat for all other channels.

Now press the L/R button on each channel to route that channel's signal direct to the main stereo outputs. Raise the main L/R output faders to about -20dB to start with, then raise each input channel fader to its reference mark (0) and build a rough balance. You can then raise the main faders as necessary to achieve the volume you need from the speakers....

The G1/2 buttons route the signal to a subgroup controlled by the blue G1/2 master fader. I presume that then feeds back into the main stereo mix. The idea is that you could control a sub-mix of several inputs -- such as a bunch of drum mics, or vocal mics -- on just one fader for convenience. Or, if there are outputs for the G1/2 submix at the back of the desk, you could use it to create a separate output for recording or to feed separate power amps driving additional speakers.

If you're using the G1/2 as a submix you would select either L/R or G1/2 on the channel, but not both at the same time. But if you're using it to provide a secondary output you would probably want both selected together.

H

[shufflebeat]

This is the back of the panel. The speakers do not have any electricity cord.

Ok, the plot thickens.

The situation you describe could be the result of:

1) the L/R button not pressed on each channel
2) channel fader being down but FX send being "pre-fader" (not the usual way of things
3) something not working properly.

As previously mentioned there are several opportunities to disable the FX, one is to turn the channel FX controls to zero except by the sound of things you are using this for a monitor send, which is fine as long as the FX is disengaged elsewhere.

If you're using the built-in amps, which you are, then the other balanced and unbalanced outputs can be used to send the L/R signal somewhere else, or just ignore them.

[nelsonizer]

Keep the FX return fader on the far right of the desk fully down, and make sure the 'FX to L/R' and 'FX to G1/2' buttons are up (ie. not pressed in).

You can worry about using the aux sends for monitors etc once you have sorted out the rest of the desk routing!

<-- best advice right here

Thanks everybody for the help! I figured it out.

There were indeed problems with the board:
- The L/R buttons are corroded and sometimes they cause the sound to cut out entirely or they send it to only one speaker at a time. A little jiggling of the L/R buttons restores everything as usual.
- Channel 4 Line is just plain dead
- Board doesn't like too much heat. For some reason if the board gets hot it floods the aux outputs with static or cuts them out

So, as long as I have a dedicated button jiggler and keep a fan pointed at the board I can run 5 channels. Worst case scenario we double up on microphones, give the bassist some plain earplugs, and use only three channels at a time. The show must go on!

Time to start searching for a decent import/export man.

[Wonks]

I'd look around for some electrical contact cleaner spray. Deoxit or Servisol are the ones normally recommended here, but I don't know what you've got available to you. WD40 now also do a dedicated contact cleaner as well (don't use normal WD40 as that is just for dispersing water and leaves a sticky residue if you can't get to it to wipe it off). Normally easily available on-line if no shops near you stock anything like it. If you aren't sure if you've got the right thing, then post a link here.

If you can get the cleaner, then disconnect the mixer from the mains, then spray it into dirty switches, operating each quite a few times directly afterwards and you should get at least some of the switches behaving as they should afterwards. Likewise, spray into jack sockets and insert/remove a jack plug quite a few times to get rid of corrosion on the internal contacts.

[DGL.]

Most auto parts places like Halfords or the like will sell contact cleaner.
Plus if it hasn't already been mentioned I guess there is a switch that selects whether or not the amplifier outputs are fed from the aux sends or the main out, that could also be part of the problem esp. if said switch is faulty.

[Wonks]

Most auto parts places like Halfords or the like will sell contact cleaner.

Except that the OP is based somewhere in Africa with limited access to shops, so it's not just a case of a 10 minute car journey for them. But certainly I'd expect a shop selling automotive products (if there is a local equivalent of the UK's Halfords) to have contact cleaner, if there isn't an electrical/electronics shop around.

[shufflebeat]

...Words, techie numbers, self assured politeness...

<-- best advice right here.

Usually the way with Big H.

All the best.

[Hugh Robjohns]

Nice!