SBIR?- help with Null From 80-105hz

[nqikz]

I have an annoying dip starting from 80 and ending at 100hz. I think maybe a 6-7db dip. This is a bit of a problem for me since I’m trying to setup my home studio for mixing.

Now I did some research and it seems likely to be an SBIR null. My space is limited in terms of moving speakers and mix position. I have push my speakers back as much as possible but I’m not really seeing any difference of the null moving up.

I’m also seeing dips at 200-400hz if I push the speakers close to the wall as much as possible. Idk maybe desk reflections?

It’s such a headache I just can’t deal with anymore.

 

[janbth]

My guess is that it’s not SBIR, but effects from room modes. It your speakers or listening position, or both, is located in a null of a mode, then you will hear dips. I suggest to read up on room modes, and learn how to map them out in your room. Check out amroc, which will help to visualize the lowest lying modes.

 

[nqikz]

My guess is that it’s not SBIR, but effects from room modes. It your speakers or listening position, or both, is located in a null of a mode, then you will hear dips. I suggest to read up on room modes, and learn how to map them out in your room. Check out amroc, which will help to visualize the lowest lying modes.

My guess is that it’s not SBIR, but effects from room modes. It your speakers or listening position, or both, is located in a null of a mode, then you will hear dips. I suggest to read up on room modes, and learn how to map them out in your room. Check out amroc, which will help to visualize the lowest lying modes.

I moved my bed and added my setup where the bed was located. The 80hz null was gone but then a 50-60hz null appeared and I just went back to my old position because at least being able to hear the kick drum is more important to my ears. Still unfortunate I have to deal with the null.

 

[janbth]

Still unfortunate I have to deal with the null.

You may need to get a sub or two…

 

[DVDdoug]

It's hard to fix a dip caused by standing waves because the direct and reflected waves are combining out-of-phase and canceling. It requires "infinite" power and "infinitely" large" woofers to overcome cancelation. You might be able to get-away with a 6dB boost for correction, which requires 4 times the power.

A common solution is multiple subwoofers at different locations to "randomize" and smooth-out the wave interaction throughout the room, but since subs usually only go up to around 80Hz that wouldn't help with your 80-100Hz issue.

Or, bass traps which trap the waves that would otherwise be reflected, and that smooths-out the dips and the bumps. There are "thick" bass traps that eat-up a lot of space in "small rooms" or or thin "membrane" traps. Either way you have to cover a significant percentage of wall area which tends to be costly and sometimes esthetically undesirable in a home environment. "Regular" acoustic treatment doesn't help with the bass.

Or, although headphones are generally not recommended for mixing & mastering, they don't suffer from room mode issues so headphones with good deep-bass response can be used as a reference and you can compare your mix to a known-reference mix.

Your ears should adjust to a large extent if you have a good reference recording but if there's "something funny" going-on in the problem-range you might miss it.

 

[janbth]

A common solution is multiple subwoofers at different locations to "randomize" and smooth-out the wave interaction throughout the room, but since subs usually only go up to around 80Hz that wouldn't help with your 80-100Hz issue.

Subs usually go higher than that. My SVS PB-100 Pros can easily do up to 200Hz.

 

[nqikz]

You may need to get a sub or two…

Not sure if that will help my situation. My mix position is pretty narrow I can only put a sub under my desk. Might make the null worst? Not sure.

 

[nqikz]

It's hard to fix a dip caused by standing waves because the direct and reflected waves are combining out-of-phase and canceling. It requires "infinite" power and "infinitely" large" woofers to overcome cancelation. You might be able to get-away with a 6dB boost for correction, which requires 4 times the power.

A common solution is multiple subwoofers at different locations to "randomize" and smooth-out the wave interaction throughout the room, but since subs usually only go up to around 80Hz that wouldn't help with your 80-100Hz issue.

Or, bass traps which trap the waves that would otherwise be reflected, and that smooths-out the dips and the bumps. There are "thick" bass traps that eat-up a lot of space in "small rooms" or or thin "membrane" traps. Either way you have to cover a significant percentage of wall area which tends to be costly and sometimes esthetically undesirable in a home environment. "Regular" acoustic treatment doesn't help with the bass.

Or, although headphones are generally not recommended for mixing & mastering, they don't suffer from room mode issues so headphones with good deep-bass response can be used as a reference and you can compare your mix to a known-reference mix.

Your ears should adjust to a large extent if you have a good reference recording but if there's "something funny" going-on in the problem-range you might miss it.

I appreciate the lengthy response. I can’t have subs at multiple spots since I don’t have the space for that. As for the boosts, not sure if it’s good idea compensating a 6-7db boost. I’d say if I boost maybe 3db I’ll be happy with that

I am aware headphones aren’t the most ideal to use mixing but I won’t be doing the bulk of my mix on headphones since I overcook mids and high mids on them.

I will only use the headphones to make sure I don’t overcook that 80-100hz and do some tweaks if need be. I will mention using spectral analyzers as well here.

 

[Mort]

Subs usually go higher than that. My SVS PB-100 Pros can easily do up to 200Hz.

I bet there isn't a person in this sub that plays their subwoofer at 200hz. They aren't designed for that, especially low end models.

 

[janbth]

I bet there isn't a person in this sub that plays their subwoofer at 200hz. They aren't designed for that, especially low end models.

I was commenting to a statement above that «subs usually only go up to around 80Hz».

 

[william2001]

Owens Corning OC 706 (the 6lb stuff) in 4" or 6" works well in that range. An air gap at 50% of fiberglass thickness (2-3") helps, but extend the frame to the wall (touching, not sealed) to trap the air cushion in operation (builds pressure to maximize efficiency). Or the BBC A12 style LF membrane absorber if you're up for some DIY. On those I would flip it around so that the membrane is facing the wall, 3" gap in between. If 80Hz is quiet at one spot, it's loud somewhere else. So that's where the absorber would need to live. You may need several of these. Spread these around where 80Hz is loud. Don't pile them up together, membrane traps each need to operate in their own space or unwanted interaction happens that messes with the tuning.

 

[nqikz]

Owens Corning OC 706 (the 6lb stuff) in 4" or 6" works well in that range. An air gap at 50% of fiberglass thickness (2-3") helps, but extend the frame to the wall (touching, not sealed) to trap the air cushion in operation (builds pressure to maximize efficiency). Or the BBC A12 style LF membrane absorber if you're up for some DIY. On those I would flip it around so that the membrane is facing the wall, 3" gap in between. If 80Hz is quiet at one spot, it's loud somewhere else. So that's where the absorber would need to live. You may need several of these. Spread these around where 80Hz is loud. Don't pile them up together, membrane traps each need to operate in their own space or unwanted interaction happens that messes with the tuning.

I’m pretty sure 80-100is boomy on one corner that i have in my room. You’re saying I should use a membrane bass trap on that corner? This indirectly helps the null?

 

[william2001]

The velocity based absorbers I described will be effective down to 80Hz. But as these guys have already mentioned a null is difficult to fill in. It's like trying to blow into a vacuum cleaner. You quickly lose that battle. Multiple subs and/or optimized source and listening position will have the big effect on frequency response. Properly applied room treatment helps excess decay and ringing that gives the low end better clarity and pitch definition, but doesn't radically alter the frequency curve usually. Treatment wise, I would definitely do a cloud overhead if that hasn't been done.

 

[nqikz]

The velocity based absorbers I described will be effective down to 80Hz. But as these guys have already mentioned a null is difficult to fill in. It's like trying to blow into a vacuum cleaner. You quickly lose that battle. Multiple subs and/or optimized source and listening position will have the big effect on frequency response. Properly applied room treatment helps excess decay and ringing that gives the low end better clarity and pitch definition, but doesn't radically alter the frequency curve usually. Treatment wise, I would definitely do a cloud overhead if that hasn't been done.

I’m at least trying to reduce it a bit. I know eliminating is hard. I have a cloud above my head 7.5inches thick from GIK.

 

[RickS]

thread closed at OP's request.