Serious Null at 160 hz

[davet]

I've been running some room acoustic tests with Real Traps "Sonar" test session. My room exhibits a really deep null around 160 Hz. Sitting in the room while the test is running, the test tones practically disappear around 160.

I'm using a Studio Projects C-1 and Grace 101 for the test. New monitors didn't help either.

The room is way too small (about 1300 cu. ft). I've got Real Traps in four corners. Of course Real Traps wants to sell me some more traps to fix this. I should add that they did offer some other solutions that might help, so thanks Ethan & Jim.

So, anyone else have this problem? Buy more traps?
DaveT

[Protools Guy]

Ethan & Jim are right (and 2 of the best in the business).
My room is about the size of yours and I have 11 bass traps in there...

[davet]

Originally Posted by Protools Guy

Ethan & Jim are right (and 2 of the best in the business).
My room is about the size of yours and I have 11 bass traps in there...

OK, have you run a similar test? Did you start with 11 or work up to that number?

[Sigma]

how "wide" is the null?...we had a 80hz hole at sigma..and it was so narrow that it didn't matter

ya think those great old rooms fom the 60's early 70's did room anal is sis?

how do your mixes translate outside the room

[Protools Guy]

Originally Posted by davet

OK, have you run a similar test? Did you start with 11 or work up to that number?

I have not run the test. I only used my ears and knew I was struggling with low end. Nulls around 160, and all the low end was loading up in the very back of the room.
At mix position, I couldn't tell what was going on with anything below 200.
After putting in these 11 traps in my control room (my drum room, which is a little bigger, has 13), I noticed a HUGE improvement.

[kafka]

What are the dimensions of your room?

[davet]

Originally Posted by Sigma

how "wide" is the null?...we had a 80hz hole at sigma..and it was so narrow that it didn't matter

ya think those great old rooms fom the 60's early 70's did room anal is sis?

It looks pretty wide in test file. I can get you some exact numbers tomorrow. It really affects the bass guitars in my mixes. I get it sounding good with headphones, then switch on the speakers and the bass just doesn't sit right. Usually ends up being to loud. Did some reading about mixing/recording bass and writer mentioned that 160 hz was a real problem area. Which is where I see/hear the bass drop out.

Before someone mentions it, I don't mix with headphones. I just check to see how things are sounding with phones. The room just makes me crazy sometimes.

[chris carter]

Originally Posted by davet

I've been running some room acoustic tests with Real Traps "Sonar" test session. My room exhibits a really deep null around 160 Hz. Sitting in the room while the test is running, the test tones practically disappear around 160.

I'm using a Studio Projects C-1 and Grace 101 for the test. New monitors didn't help either.

The room is way too small (about 1300 cu. ft). I've got Real Traps in four corners. Of course Real Traps wants to sell me some more traps to fix this. I should add that they did offer some other solutions that might help, so thanks Ethan & Jim.

So, anyone else have this problem? Buy more traps?
DaveT

My room's about the same volume. More important are the dimensions. I had a bad dip at 80 Hz (from the walls 14 ft. apart) that is no longer an issue from bass trapping.

I have bass traps in all four cornes from floor to ceiling (8ft tall) and they are 2 feet wide and six inces deep (3 2" panels thick) made from 703. So in total, it's 24 pieces of 703. All my absorbers are off the wall to increase bass response, but I seriously doubt those do anything below 200 Hz.

[davet]

Originally Posted by kafka

What are the dimensions of your room?

10 x 21 x 8. It's the space over my garage, so I have four foot side walls that hip 45% to the ceiling. It's not a good room for music. I've done the calculations. This is the first time I've run audio tests, so I'm not the surprised at the results.

What I really want is a Great River Pre, not more traps!!
Traps just aren't sexy, ya know. Hardware, that's the ticket, yeah....

[dubrichie]

perhaps some form of Helmholtz Resonator DIY project?

or "superchunk" every corner that you possibly can.

crack open a can of elbow grease man!

[davet]

Originally Posted by dubrichie

perhaps some form of Helmholtz Resonator DIY project?

or "superchunk" every corner that you possibly can.

crack open a can of elbow grease man!

I've got some DYI 703 4" traps in the corners with the Real Traps, so I've done some extra work. They just don't help much in the low frequncy range. But thanks for the input....

[Kiwiburger]

Very possibly you have something in the room that is acting as a tuned bass trap, and is absorbing all the energy at 160 Hz. Adding more bass trapping will make the supplier richer, but might actually make the problem worse.

The things I would look for are - for example - wall panels. These can act as a diapragm bass trap. If you have a few of them all the same frequency, it's a powerful notch filter. You can break up the frequencies with a few extra studs. You can soften the Q with absorbant.

Some diffusion might help to break up room nodes and spread the problem around a bit. What happens if you move some furniture around?

With these low frequencies, it's generally relatively large scale architecture that makes the difference. No point investing in lightweight cosmetic acoustic ornaments.

[dubrichie]

Originally Posted by Kiwiburger

Very possibly you have something in the room that is acting as a tuned bass trap, and is absorbing all the energy at 160 Hz. Adding more bass trapping will make the supplier richer, but might actually make the problem worse.

The things I would look for are - for example - wall panels. These can act as a diapragm bass trap. If you have a few of them all the same frequency, it's a powerful notch filter. You can break up the frequencies with a few extra studs. You can soften the Q with absorbant.

Some diffusion might help to break up room nodes and spread the problem around a bit. What happens if you move some furniture around?

With these low frequencies, it's generally relatively large scale architecture that makes the difference. No point investing in lightweight cosmetic acoustic ornaments.

good point about the fact that its a NULL as opposed to a peak. does bass trapping / absorption in general not help even out nulls AND peaks?

diffusion is a good idea, but in a room that small won't broadband absorption be more appropriate?

it is definitely too small for any kind of diffuser that would be effective at 160HZ.

[davet]

Originally Posted by Kiwiburger

Very possibly you have something in the room that is acting as a tuned bass trap, and is absorbing all the energy at 160 Hz. Adding more bass trapping will make the supplier richer, but might actually make the problem worse.

The things I would look for are - for example - wall panels. These can act as a diapragm bass trap. If you have a few of them all the same frequency, it's a powerful notch filter. You can break up the frequencies with a few extra studs. You can soften the Q with absorbant.

Some diffusion might help to break up room nodes and spread the problem around a bit. What happens if you move some furniture around?

With these low frequencies, it's generally relatively large scale architecture that makes the difference. No point investing in lightweight cosmetic acoustic ornaments.

Real Traps suggested I remove the traps and run another test. I hadn't considered that something is absorbing the energy. Don't have any overstuffed chairs in the room or anything like it. They did suggest re-arranging my desk, speakers and the like.

Thanks for the reply.
DaveT

[Sigma]

Originally Posted by davet

It looks pretty wide in test file. I can get you some exact numbers tomorrow. It really affects the bass guitars in my mixes. I get it sounding good with headphones, then switch on the speakers and the bass just doesn't sit right. Usually ends up being to loud. Did some reading about mixing/recording bass and writer mentioned that 160 hz was a real problem area. Which is where I see/hear the bass drop out.

Before someone mentions it, I don't mix with headphones. I just check to see how things are sounding with phones. The room just makes me crazy sometimes.

dag man..and there is no "null" spot? like i have a narrow null in my room and i can hear it phase out at that spot..luckily about 1.5 feet behind my mix position and at about 110hz and very localized area

[Sigma]

btw try taking measurements with the studio door open just for sheit and giggles

[davet]

Originally Posted by Sigma

how "wide" is the null?...we had a 80hz hole at sigma..and it was so narrow that it didn't matter

ya think those great old rooms fom the 60's early 70's did room anal is sis?

how do your mixes translate outside the room

The worst of it is 60 - 80 and 142 - 170. Mixes translate
pretty well, but I still have trouble getting the kic & bass just right. Seems to me that bass and kic energy is right where I'm seeing the nulls.

[davet]

Originally Posted by Sigma

btw try taking measurements with the studio door open just for sheit and giggles

I actually did some mixing with the door open and it helps. It must allow some of the standing wav energy to escape. I can't open the door all the time, but it does work.

[stuntbutt]

Your null is caused by cancellation. In other words you need more bass absorption. You could DIY some membrane absorbers. There are plans on Ethan's site.

[narcoman]

Originally Posted by davet

I actually did some mixing with the door open and it helps. It must allow some of the standing wav energy to escape. I can't open the door all the time, but it does work.

No it doesnt - it just changes the sound of your room and therefore alters where the nulls and peaks will be.

[Sigma]

Originally Posted by narcoman

No it doesnt - it just changes the sound of your room and therefore alters where the nulls and peaks will be.

well it works..my room design incorporates the french doors to my bedroom..i have theartre curtains in front of them..i leave then adjar and curtains closed and get more low low end as there is more volume in my space for waves to propogate

nick colleran advised that i do that as my room is small and it works well

i have 4 1/2 rounds traps and 1 1/4 round in the 6 sided roughly 14.5 x 11.5 control room [as well as 3 4x6 absorbers and a rear diffuser] ..and everyone thatcomes in is blown away by the low end clarity and the size of the sweet spot [basically 80% of the room]

[Ethan Winer]

Originally Posted by dubrichie

does bass trapping / absorption in general not help even out nulls AND peaks?

Bass traps improve both. Peaks and nulls are both caused by reflections combining in the air with each other and with the direct sound from the speakers. The only difference is the time delay and thus the relative phase when the waves combine. So in all cases adding bass traps makes the response closer to flat, reducing peaks and also bringing up nulls. Bass traps also reduce modal ringing which is just as damaging as the skewed response.

--Ethan

[Kiwiburger]

Would it be fair comment to say that IF this null is caused by room nodes alone, there should be an equally big peak at another frequency, because the same reflections caused by room dimensions will - depending on the frequency - create a null or a peak. There should also be visible harmonics of these peaks and nulls.

If that is the case, then more bass trapping will certainly even things out.

But if it's just a big sink at 160Hz, I would be looking for whatever is doing that.

What happens if you pump a strong 160 Hz sine wave into the room? Does anything resonate?

[Sigma]

Originally Posted by Kiwiburger

Would it be fair comment to say that IF this null is caused by room nodes alone, there should be an equally big peak at another frequency, because the same reflections caused by room dimensions will - depending on the frequency - create a null or a peak. There should also be visible harmonics of these peaks and nulls.

If that is the case, then more bass trapping will certainly even things out.

But if it's just a big sink at 160Hz, I would be looking for whatever is doing that.

What happens if you pump a strong 160 Hz sine wave into the room? Does anything resonate?

there are harmonics of build/nulls

i had a build ar 55 and a null at 110 depending on where i sat

[tINY]

Originally Posted by Kiwiburger

Would it be fair comment to say that IF this null is caused by room nodes alone, there should be an equally big peak at another frequency, because the same reflections caused by room dimensions will - depending on the frequency - create a null or a peak. There should also be visible harmonics of these peaks and nulls.

If that is the case, then more bass trapping will certainly even things out.

But if it's just a big sink at 160Hz, I would be looking for whatever is doing that.

What happens if you pump a strong 160 Hz sine wave into the room? Does anything resonate?

Don't forget boundaries - not as a closed-tube resonant feature, but just as a place for sound to bounce off. If you are about 4 feet away from two surfaces, you will get a big null at 160Hz, even in the corner of a huge concert hall.

With an 8 foot ceiling that comes to a point, you end up about 4 feet from the floor, vertical wall sections and ceilings in a lot of places you might put a chair...



-tINY

[Ethan Winer]

Originally Posted by tINY

you will get a big null at 160Hz, even in the corner of a huge concert hall.

Yes, and you can even get peaks and nulls outdoors in front of a single large surface like the side of a building.

--Ethan

[nosebleedaudio]

Try this test: find the same fundamental tone/note on a piano and see if you hear the same null.
Constant sine waves are the acid test; a real note will produce a different result.
Try it and see what I mean...
I've used this on a room I was tweaking, the null was pretty sharp, and the same note was not noticeable...
This is a very interesting thing...

[davet]

Originally Posted by Kiwiburger

Would it be fair comment to say that IF this null is caused by room nodes alone, there should be an equally big peak at another frequency, because the same reflections caused by room dimensions will - depending on the frequency - create a null or a peak. There should also be visible harmonics of these peaks and nulls.

If that is the case, then more bass trapping will certainly even things out.

But if it's just a big sink at 160Hz, I would be looking for whatever is doing that.

What happens if you pump a strong 160 Hz sine wave into the room? Does anything resonate?

Ethan's Sonar test program does use sine waves that are played back in the room. I'm playing the test loud enough to hear everything. Not sure a different tone generator would make a difference. I can hear the tone on my head phones, I know it's there.
DaveT

[davet]

Originally Posted by nosebleedaudio

Try this test: find the same fundamental tone/note on a piano and see if you hear the same null.
Constant sine waves are the acid test; a real note will produce a different result.
Try it and see what I mean...
I've used this on a room I was tweaking, the null was pretty sharp, and the same note was not noticeable...
This is a very interesting thing...

The only piano I have would be a soft synth. I can try it tonight.
DaveT

[davet]

Originally Posted by tINY

Don't forget boundaries - not as a closed-tube resonant feature, but just as a place for sound to bounce off. If you are about 4 feet away from two surfaces, you will get a big null at 160Hz, even in the corner of a huge concert hall.

With an 8 foot ceiling that comes to a point, you end up about 4 feet from the floor, vertical wall sections and ceilings in a lot of places you might put a chair...



-tINY

The speakers are about 4 feet from the front and side walls of the room. They are rear ported too. Anyone else concure with tINY?
DaveT