Booming from rear ports - suggestions? Problem now solved!

[Painy]

Recently I've been getting the sound I've been looking for for years full, warm lows, tight punchy mids and clear defined highs. Sounds great in the mix out front and from where I'm standing on stage too. Unfortunately my bandmates are not enjoying the experience quite so much. They've agreed it sounds great out front but on stage the low end is seriously mudding out the sound where they are which I can only put down to the rear ports in the cabs (which we have no option but to position close to the back wall pretty much everywhere we play).
I'm thinking of blocking off the ports to try and eliminate the boom on stage but I'm worried about how much I'll lose the low end out front. These are Aguilar DB112 cabs which have twin ports so I guess I have the option of just blocking one of them as a compromise but again not sure of the effect I'll get.
I'm also wondering if anyone can suggest something designed for the purpose which would fit rather than using a cushion or a balled up pair of football socks.
Any thoughts?

Edited June 15, 2016 by Painy

[mybass]

Getting front ported speakers would help so you can 'temper' the bass end more, ( I have MarkBass 2x10 front ported) Rear ported speakers away from the wall/ corner of stage may help or maybe as far away from the wall as possible. (Like my MarkBass 2x10 Traveller but actually, that cabinet doesn't boom too much at all) You know what, I've never had band members say my rear ported cabs where affecting them, hope they aren't being picky with you!
Maybe some deep foam plugs ( like some hi if speakers come supplied with) would help, your speaker cones would probably still want to move some air.
(I am not so sure on cabinet designs but I think speakers used in ported to those used in non ported cabinets have different design specs as a speaker generally moves air to operate efficiently).
Hopefully some very knowledgable Basschatter will carry on this topic for you!

[Painy]

Foam bungs that still allow the cab to 'breath' sounds like a potentially good idea. Be interested to hear from any techy experts. Where are Alex and Bill when you need them?

Edited June 5, 2016 by Painy

[barneyg42]

[quote name='Painy' timestamp='1465129069' post='3065458']
Recently I've been getting the sound I've been looking for for years full, warm lows, tight punchy mids and clear defined highs. Sounds great in the mix out front and from where I'm standing on stage too. Unfortunately my bandmates are not enjoying the experience quite so much. They've agreed it sounds great out front but on stage the low end is seriously mudding out the sound where they are which I can only put down to the rear ports in the cabs (which we have no option but to position close to the back wall pretty much everywhere we play).
I'm thinking of blocking off the ports to try and eliminate the boom on stage but I'm worried about how much I'll lose the low end out front. These are Aguilar DB112 cabs which have twin ports so I guess I have the option of just blocking one of them as a compromise but again not sure of the effect I'll get.
I'm also wondering if anyone can suggest something designed for the purpose which would fit rather than using a cushion or a balled up pair of football socks.
Any thoughts?
[/quote]
Problem is it's likely your great sound out front is enhanced by your rear ports, I'm no expert but that is my first thought!! Sorry for the band but we all suffer some sort of discomfort unless we're all plugging straight to the desk with in-ears.

[chris_b]

You need front ported cabs.

Blocking up the ports will totally change (almost certainly for the worse) the sound of the cab and might cause the speaker to overheat.

I had Aguilar GS112 cabs and moved to Bergs. A significant improvement in tone in my opinion. Now I'm using Barefaced cabs. I'd recommend checking both these makes.

[Bill Fitzmaurice]

Rear and front ports will give the exact same result, because the radiation from ports is omni-directional. The issue is that midrange and high frequencies are directional, so the only ones who hear the full output of the cab are those within a cone shaped zone in front of the cab that progressively widens as the distance to the cab is increased. The best cure is to put the midrange and highs, but not the lows, through the monitors. If that's not an option the next best is to put yourself on one side of the stage, aiming the cab to the opposite front corner of the stage to make the dispersion more uniform over a wider area.

[Painy]

Thanks Bill, that makes a lot of sense. I'll give that a go first then.

[Twincam]

I have this issue with my home made ported cab has great low end but with some lower voiced amps its boomy at certain angles close by. At a distance sounds great. But still has some issues no matter how you place it. Used with more mid focuses amps no issues. Eq ing sometimes works sometimes not.

This will sound extreme but if you can't get rid of the boom by the eq or cab placement and like your amp change speakers or vice versa. In my view that is the only way to actually fix the issue. Unless you want to redesign your cabs ports (unlikely).
As Bill said you can also put the lows through monitors etc.

[Guest bassman7755]

[quote name='Painy' timestamp='1465130767' post='3065474']
Foam bungs that still allow the cab to 'breath' sounds like a potentially good idea.
[/quote]

Cabs don't "breath" through the port - the air vibrations in the port actually reduce the speaker motion at low frequencies.

Chapter and verse [url="http://barefacedbass.com/technical-information/the-mysteries-of-ports.htm"]here[/url].

[molan]

Have you tried a Gramma pad? My Berg AE210, rear ported, can get boomy but I've found lifting it off the floor and isolating it seems to help quite a lot (especially with suspended wooden stages!).

[Painy]

[quote name='molan' timestamp='1465143499' post='3065566']
Have you tried a Gramma pad? My Berg AE210, rear ported, can get boomy but I've found lifting it off the floor and isolating it seems to help quite a lot (especially with suspended wooden stages!).
[/quote]

I do have it raised up on a stand to get it nearer to eat level already although not enough to de-couple it from the floor. Last night's gig was on a solid parquet floor though with no raised stage so doesn't look too be that simple a solution unfortunately.

[Bill Fitzmaurice]

[quote name='molan' timestamp='1465143499' post='3065566']
Have you tried a Gramma pad? My Berg AE210, rear ported, can get boomy but I've found lifting it off the floor and isolating it seems to help quite a lot (especially with suspended wooden stages!).
[/quote]Lifting, yes. 'Isolation', no. Thoroughly explained here:
http://ethanwiner.com/speaker_isolation.htm

[Phil Starr]

First of all the technical advice is good, rear ports won't make a difference unless you are hard up against the rear wall as the frequencies they radiate are non-directional. hard up against the wall the air mass trapped between the rear panel and the wall might come into play but moving the cab forward a few inches would prevent that, and to be frank I don't think it is your problem.

Any attempt to block your ports is going to stop them doing their job properly.

You say two things that may be relevant. You've achieved your sound, and that it sounds good out front but not on stage. The first point is that you have changed your sound and you describe it as 'warm' so I assume it contains more bass energy than before. The solution to this is to roll off some of that bass. What sounds best in practice often isn't the best solution for working live. You all have to compromise your sound a little in a band to help out the other guys. However you also say the sound for the audience is good so maybe there is a balance to be struck there.

I suspect the problem may be resonance caused by the acoustics of the rooms you are playing in. These room resonances are being excited by your new sound. This may be further muddying the sound if you are getting bass feedback through the mics. So many venues ram the band into an alcove at the back of the room which have particularly bad acoustics. I find low ceilings a particular problem. you may just have had a run of bad luck with room resonances.

Try the following. Filter subsonic bass with an HPF like a Thumpinator or turn down your bass a little if the mud is a particular problem. Apply the bass filters to all your mic's if your mixer allows this (apart from the kick mic if you use one) Keep your bass cab out of corners and move it away from walls as far as you can. If your PA can take it put some of your bass through the PA and turn down on stage. If you do this one trick is to roll off the bass a little on stage and boost it through the PA to compensate, so the audience hear a balanced sound but you reduce the bass energy on stage.

Edited June 6, 2016 by Phil Starr

[Dan Dare]

You can make foam bungs to fit a lot of round ports with sponge paint roller refills - available from DIY stores. They have a small hole through the middle for the roller shaft, so don't completely block the port.

[Painy]

[quote name='Phil Starr' timestamp='1465199015' post='3065938']
First of all the technical advice is good, rear ports won't make a difference unless you are hard up against the rear wall as the frequencies they radiate are non-directional. hard up against the wall the air mass trapped between the rear panel and the wall might come into play but moving the cab forward a few inches would prevent that, and to be frank I don't think it is your problem.

Any attempt to block your ports is going to stop them doing their job properly.

You say two things that may be relevant. You've achieved your sound, and that it sounds good out front but not on stage. The first point is that you have changed your sound and you describe it as 'warm' so I assume it contains more bass energy than before. The solution to this is to roll off some of that bass. What sounds best in practice often isn't the best solution for working live. You all have to compromise your sound a little in a band to help out the other guys. However you also say the sound for the audience is good so maybe there is a balance to be struck there.

I suspect the problem may be resonance caused by the acoustics of the rooms you are playing in. These room resonances are being excited by your new sound. This may be further muddying the sound if you are getting bass feedback through the mics. So many venues ram the band into an alcove at the back of the room which have particularly bad acoustics. I find low ceilings a particular problem. you may just have had a run of bad luck with room resonances.

Try the following. Filter subsonic bass with an HPF like a Thumpinator or turn down your bass a little if the mud is a particular problem. Apply the bass filters to all your mic's if your mixer allows this (apart from the kick mic if you use one) Keep your bass cab out of corners and move it away from walls as far as you can. If your PA can take it put some of your bass through the PA and turn down on stage. If you do this one trick is to roll off the bass a little on stage and boost it through the PA to compensate, so the audience hear a balanced sound but you reduce the bass energy on stage.
[/quote]

I think ultimately this is pretty much all spot on. I think I may have to compromise a bit here too for sure. When I stood in the guitarist's spot and played an open E the bass was so overpowering I literally felt disorientated and a bit sick so however good it sounded or front I wouldn't expect my band mates to deal with that!

[Painy]

[quote name='Dan Dare' timestamp='1465212773' post='3066107']
You can make foam bungs to fit a lot of round ports with sponge paint roller refills - available from DIY stores. They have a small hole through the middle for the roller shaft, so don't completely block the port.
[/quote]

Funny enough I do actually have half a dozen paint roller refills in the under stairs cupboard

[cheddatom]

when I use an amp, I like to stand on the opposite side of the stage/room. I feel like I can hear myself better and get a more realistic impression of the sound from a distance. It also means the guitarist does the same, so he too gets a better "picture"... plus we can both reach each others' volume controls if it gets out of hand

[Truckstop]

[quote name='Painy' timestamp='1465224917' post='3066275']


I think ultimately this is pretty much all spot on. I think I may have to compromise a bit here too for sure. When I stood in the guitarist's spot and played an open E the bass was so overpowering I literally felt disorientated and a bit sick so however good it sounded or front I wouldn't expect my band mates to deal with that!
[/quote]

Jesus Christ, how loud are you playing? Maybe just cut the bass a bit and turn down a little?

[machinehead]

[quote name='Truckstop' timestamp='1465228864' post='3066328']
Jesus Christ, how loud are you playing? Maybe just cut the bass a bit and turn down a little?
[/quote]

Jesus plays bass?

Frank.

[Truckstop]

Of course!!

[Painy]

That's the weird thing. It wasn't even all that loud. Everywhere else on stage it was just a bit woolly and muffled apart from where the guitarist was standing - literally a spot about 6 feet across - where the low end went berserk. Obviously something weird in the acoustics of the room but still something I'd obviously prefer to avoid.

[Bill Fitzmaurice]

Try moving your rig, and his.

[JTUK]

One stage only..or all stages?
If one stage, EQ for that stage, if all stages, take some bass off

[sunburstjazz1967]

This is yet another reason why I'm moving away from backline as FOH, I'm happy to remove a lot of low end off the stage, especially hollow wooden ones! Trying to get an nice even sound around a pub right to the back and still be at a reasonable volume and clarity 2 foot away from a cab is always going to be a huge comprimise.

[Bill Fitzmaurice]

[quote name='JTUK' timestamp='1465236319' post='3066405']
One stage only..or all stages?
If one stage, EQ for that stage, if all stages, take some bass off
[/quote]Response will be different on every stage and every room. Using EQ to fix the response in the hot spot where he's standing means losing low end everywhere else. Not having a hot spot by moving the cab and/or him is the solution.
[quote]Trying to get an nice even sound around a pub right to the back and still be at a reasonable volume and clarity 2 foot away from a cab is always going to be a huge comprimise.[/quote]It's impossible, because room response is different at every spot in the room, and varies the most as you move away from the stage. Use the backline only to drive the stage and the PA to drive the room and you'll get a lot better result.