Cabinet Positioning and Feedback

[Buddster]

👆

Very good words there. 

Add in a loud drummer, a guitarist who has to play on 11 all the time, a vocalist who needs their vocals loud in the monitors,  keyboard player without their own monitor, a room with concrete walls, a small stage... 

I dont know why I did it for so long 🤦🏼

[Pirellithecat]

4 minutes ago, Buddster said:

👆

Very good words there. 

Add in a loud drummer, a guitarist who has to play on 11 all the time, a vocalist who needs their vocals loud in the monitors,  keyboard player without their own monitor, a room with concrete walls, a small stage... 

I dont know why I did it for so long 🤦🏼

When did you see us play???  (minus keyboard)  🙄🤣

[Chienmortbb]

1 hour ago, Pirellithecat said:

Still need to remove all the knobs on the monitors to stop the band member deciding to tweak their monitors tone/volume during the gig!!  

Not ideal but put volume on the speakers at max and take the monitor out faders down to your desired level Or just take off all the knobs on the monitor speakers.

[Pirellithecat]

28 minutes ago, Chienmortbb said:

Not ideal but put volume on the speakers at max and take the monitor out faders down to your desired level Or just take off all the knobs on the monitor speakers.

Great idea - I'll try it tomorrow!!!

[mike257]

On 28/03/2024 at 10:55, Chienmortbb said:

I am actually subscribed to that channel but somehow missed that  video. I think the centre fill  speaker is meant to help although the height, on top of the subs, does not get through to the middle. However, as he says do the best you can and don't fret.  

 

Centre fills are normally something that comes in to play in larger venues with a big stacked or flown PA to fill the gap in coverage for the folks right up on the barrier. They're usually on the front lip of the stage, or occasionally on Sunday stacks if they're spaced appropriately to make it work.

 

They're not meant to hit the middle of the room because if the main system is properly deployed, it'll be covering that space - they're just filling in where the horizontal dispersion of the main hangs/stacks don't reach.  Not really something that you can translate to a small portable setup, unless you're carrying a 4ft high stage with you too!

[mike257]

On 28/03/2024 at 10:55, Chienmortbb said:

I

 

Edited March 29 by mike257
*double post*

[Phil Starr]

Interesting experience of feedback last Sunday. We were on the edge of feedback all evening which i just about managed to tame. It's possibly a good illustration of the problems anyone who gigs regularly is bound to encounter. Just to give some background this was a decent sized venue and it is expanding it's music evenings so was very much an event I wanted to work well. This was their first event with a 'band' in the bar rather than their function room. It was a big rectangular space inside an industrial unit and pretty crowded with people. We ended up in the corner at the back of the room with very little space. To one side was the door to the toilets so we couldn't expand sideways and we couldn't expand forwards because it was so crowded. We'd been hired as a duo because they knew space was limited so no point complaining. For them it was a test to see what could be done.

 

So the space allowed for us was around 4m wide and 3m deep hard against one wall and the rear of the room. Set up is two of us, guitar and bass with self programmed drums. We use two RCF ART310's as PA and two more as floor monitors, no backline and monitors levels are quite low, to give you an idea I don't get any ringing in my ears after a set and the sound of our voices can be heard clearly over the monitors. Because of the lack of space we were only about a metre behind the FOH and so around 1.4m diagonally from them. There was a lot of bass coming back to our stage area from the PA easily drowning out the bass from the monitors which I filter at 50 Hz and also shelve quite heavily. The bass was at a level where it was setting off low frequency resonances in the acoustic guitar. The cause of our bass feedback was very simple; bass frequencies from the PA speakers too close to the guitar. Bass frequencies are omnidirectional, just as loud behind as in front and with the PA loud in a big room bass levels on stage were crazy.

 

There's not a lot you can do, it only happened when Mke used certain settings on his pedals and then only when he wasn't touching the sound board on the guitar. We moved the speakers as far forward as possible and stuck some LED strips onto the speaker stands to reduce the chance of them getting knocked over. We couldn't really move back, I could have reduced the bass on the desk but couldn't have got out to the FOH to hear the results on the overall sound and I'm really reluctant to fiddle with settings whist I'm playing. I reduced the volume 1db pulled back the guitar a couple of db in the mix (my mixer allows 1db adjustments) and Mike tried not to let go of the guitar. We recorded the set so we can go back and work out which of his settings is causing the problems and see if it can be tweaked.

 

Sometimes you just have to put up with a compromised sound and the solution cannot be done in the room. I struggle to multi task and my bass playing and contact with the audience takes precedence over mixing once the gig is going and the dance floor full. The gig went well the venue want us back and are sorting dates. The audience had a good time. I hated the sound being compromised but I'm not going to let that spoil a good gig and it was only two songs in the end.

[tauzero]

Might one of those sound hole stoppers help with the acoustic?

 

https://www.amazon.co.uk/Planet-Waves-Screeching-Acoustic-Soundhole/dp/B0010SHU18

[Phil Starr]

Problem solved it seems. I've put an 80Hz HPF on the guitar channel and Mike has made some adjustments to his fx, we gigged last night (at a different but still cramped venue) and not a hiccup. When we go back to the venue where the problem happened we'll sound check those patches before we start but I don't anticipate any issues.

[Al Krow]

19 hours ago, Phil Starr said:

Problem solved it seems. I've put an 80Hz HPF on the guitar channel and Mike has made some adjustments to his fx, we gigged last night (at a different but still cramped venue) and not a hiccup. When we go back to the venue where the problem happened we'll sound check those patches before we start but I don't anticipate any issues.

 

Bit of a basic question from me, but...

if the low E string fundamental is 81Hz, will setting the HPF at 80Hz for the guitar channel have an impact?

 

I guess it's a string harmonics question ie do strings generate sub harmonics as well higher ones?

[Bill Fitzmaurice]

It won't. For that matter it won't bother bass either. Better FOH engineers will high pass the bass channel at 60 to 80 Hz, to have the bass response in PA the same as that of back line speakers. I high pass guitar at 125 Hz. Strings don't create sub-harmonics. They have to be artificially generated.

[Phil Starr]

33 minutes ago, Al Krow said:

 

I guess it's a string harmonics question ie do strings generate sub harmonics as well higher ones?

I'm assuming the frequency of the filter as quoted is the -3db point so yes it would probably be noticeable if you did an A/B test but only just. The likelihood though would be the audience wouldn't notice it at all in the mix. Guitarists don't generally play single notes much and don't bang away on a single string open E anyway. I can't actually remember which song Mike uses this particular patch but iif the keywas in anything  above E... So like Earth in the Hitchhikers Guide To The Galaxy it's 'mainly harmless'.

 

I think we are often too scared of HPF and set it too low. That's why I was so intrigued by @VTypeV4's comments on setting HPF on vocals. An operatic Baritone will normally sing from F2-F4 so just above the bottom note on a guitar. Nobody really sings that low on pop music so setting the filter even higher for vocals makees sense and the 80Hz filter on most analogue mixers looks pretty conservative, I'm thinking of pushing mine up to 160 and seeing what dfference that makes. I'm no Baritone

 

Maybe we should start another thread on HPF now that those of us with digital mixers have the chance to set it where we want?

 

 

[Al Krow]

33 minutes ago, Phil Starr said:

I'm assuming the frequency of the filter as quoted is the -3db point so yes it would probably be noticeable if you did an A/B test but only just. The likelihood though would be the audience wouldn't notice it at all in the mix. Guitarists don't generally play single notes much and don't bang away on a single string open E anyway. I can't actually remember which song Mike uses this particular patch but iif the keywas in anything  above E... So like Earth in the Hitchhikers Guide To The Galaxy it's 'mainly harmless'.

 

I think we are often too scared of HPF and set it too low. That's why I was so intrigued by @VTypeV4's comments on setting HPF on vocals. An operatic Baritone will normally sing from F2-F4 so just above the bottom note on a guitar. Nobody really sings that low on pop music so setting the filter even higher for vocals makees sense and the 80Hz filter on most analogue mixers looks pretty conservative, I'm thinking of pushing mine up to 160 and seeing what dfference that makes. I'm no Baritone

 

Maybe we should start another thread on HPF now that those of us with digital mixers have the chance to set it where we want?

 

Agreed. Coming back to the string harmonics point - my understanding (as I've just seen Bill has confirmed) is the guitar string won't be able to generate a sub harmonic (ie a string can't vibrate at a lower frequency than its fundamental) but it may trigger sympathetic resonance eg the kick drum to resonate and start producing lower harmonics and boominess? Is that right?

 

If so, may indeed be worth setting the hpf cut off on the guitar, higher also?

Edited April 8 by Al Krow

[Bill Fitzmaurice]

With guitar as well as bass low frequencies that you don't hear through a standard back line amp plus cab can be present when DI'd to the PA. High passing gets rid of them. If you could see the actual frequency response charts of guitar and bass amp cabs you'd be quite surprised, if not shocked. That's one reason why you can't find them.

[VTypeV4]

3 hours ago, Phil Starr said:

I think we are often too scared of HPF and set it too low.

 

Maybe we should start another thread on HPF now that those of us with digital mixers have the chance to set it where we want?

 

I think the main issue with using an HPF (on any instrument) is when we're making changes, we're nearly always making them in isolation rather than actually in 'full mix' context. Sometimes components within a mix need to sound 'worse' to make them fit the big picture in a 'better' or more useful way. The oldskool desks with fixed HPF frequencies and slopes went a good way to improve mixes and make life easier but with digital we can now better fine tune the instruments in our mix. From tiny gigs to full-flight festivals, I use a HPF to some degree on every channel with the exception of the sub / kick.. 

[Bill Fitzmaurice]

High passing the vocal mikes is critical as otherwise they'll pick up unwanted low frequencies as well.

[mike257]

[DaleASmith]

True Dat!! 😂

 

If your speakers can't reproduce it, what bother sending it to the power amps in the first place. Everything including the kick drum gets it.. 

[Bill Fitzmaurice]

If you have mains that go low or subs the problem is that they will reproduce what you may not want. Backline speakers don't go low. F3 on an SVT 8x10 is 58 Hz. The main components of electric bass should be the second and third harmonics. When you corrupt that by having the fundamental as loud or even louder than the harmonics the result sounds like a teenager driving past with his 5,000 quid sub in his 500 quid car. 🤔