Now this is a null! ... but no harmonics?

[timothyallan]

This is one of the the responses I get in my mix position... depending on about 6" movement of the mic or so, sometimes 50hz is there, sometimes it's not!

1st Question: I've just trapped the hell out of my room and still have this. Superchunked every corner, back wall is all traps , ceiling is all done except for a hole where the light is, and top wall/side corners are trapped as well. All traps are 6" thick dense polyester. How do I get rid of it?

2nd Quesetion: Why is there no dip @ multiples of +/-50hz, shouldn't it appear in multiples as well?

[Ethan Winer]

Without knowing the size of your room and where you and the speakers are placed I can only guess. But I can tell you that peaks and nulls are not necessarily at harmonic intervals. If for no other reason, your bass trapping probably does a fine job at 118 Hz and above, but obviously it's not enough at 59 Hz where the null is.

--Ethan

[timothyallan]

Well, I had my mix position at 38% from the back wall. This surprisingly seemed to have the worst 59hz null, so I started nudging closer to the 50% and it got better. From about 40db to 8db worth of null!

After taking the closet doors off and stuffing the whole thing full of traps (the top unwrapped tubes are stuff I had from ages ago and are just there temporarily), the room is 4m long, 2.7m wide and 2.4m high.

All the traps are 60cm x 120cm (2' x 4'), 150mm thick (6" ish) - 48(kg/m3) dense polyester. The superchunks are 34" faced. The floor is hardwood with a thick throw rug covering most of it.

You can also see that I have 3 extra white traps either sitting on a chair, on the toolbox or stuffed behind the chair. I'm moving those around trying to find the best place to permanently attach them.

I've attached a bunch of pics I just took, the only things in here are a throw rug, my monitors and a chair. I took the desk out for now just to make things easier to move... plus the desk didn't seem to make much of a difference according to my sweeps I'm doing through fuzzmeasure.

There isn't a whole lot of space left for me to put traps, and I really need that low area to be flat for the mixing/music I do!

Oh, and that little tiny black square in between my speakers on the floor is a tiny trap made from the leftover insulation I had... I found a fabric that had skeletons playing electric guitar so I had to make at least one thing with it hahah.

[timothyallan]

After 10 hours of testing, moving, testing, hanging, testing, and testing. I've got the 20hz-1.5kHz graph now looking like this:

Green is left speaker, Red is the right speaker.

This is as good as I can get the low end with the traps I've got. The green dips I believe are from the window that is on the left of my left monitors. I've moved the left monitor as far center as I can without going totally lopsided in the room. The bass still is a bit wonky, and the left channel has those very sharp dips, is this normal for small rooms, and is there much I can do short of trying to find room for more traps?

Anything else in this low end chart that I should be noticing, good, bad or otherwise?

Thanks,
Tim

[Ethan Winer]

I believe the best way to measure LF response is to measure both left and right speakers playing at the same time. The reason we measure a room's bass response is to know how things will sound at the listener's ears. In most pop music the bass and kick drum are panned to the center, meaning it comes from the left and right speakers equally. So from my perspective, at bass frequencies anyway, measuring a room with both speakers active more closely emulates how real music will be played. That said, I think it's good to also measure each speaker separately for additional confirmation.

As for those nulls, this is a very tiny room! At some point you'll have as many traps as you can possibly fit, and then all you can do is get back to mixing. I'm sure it sounds much better than before you had any traps, yes?

--Ethan

[timothyallan]

It's a tossup really, it's reached the point where people come in and open their mouths to try and pop their ears because of all the trapping. However, it does sound better for mixing to me then it originally did... and I don't do any substantial recording in here.

As for testing more than one speaker at once, I could have -sworn- that I was testing both speakers on FuzzMeasure at the start... then I accidently unplugged my Motu while running a test, and ever since then FuzzMeasure has only let me select one channel at a time. I'll have to rig something up so both play and see how the L&R interact on the frequency chart.

Cheers,
Tim

[Weasel9992]

Looks like those dips are only about 8 or 9dB...that's actually really good for a space like that. It's better than most rooms I see. A really *excellent* treated room is +/-6dB from front to back. I think You're in good shape. I would do as Ethan suggested and plot both speakers at the same time though.

Frank

[Ethan Winer]

Originally Posted by timothyallan

I'll have to rig something up so both play and see how the L&R interact on the frequency chart.

A simple $2 "Y" splitter will do the trick.

--Ethan

[Chris Kress]

Originally Posted by timothyallan

........it's reached the point where people come in and open their mouths to try and pop their ears because of all the trapping.

Consider adding a polyurethane finished birch 1/4" plywood to return the high frequency to the room. Start with a 4x8 sheet cut in half and move each piece around. I think they should be placed over the top of your other treatments if necessary since proximity to the speakers will be the most important factor. I have always seen a lot of birch in the expensive rooms I work in and surprisingly on the front wall or ceiling.

After all of the work you have done, it is worth the $30 to try...

[Ethan Winer]

Originally Posted by Chris Kress

Consider adding a polyurethane finished birch 1/4" plywood to return the high frequency to the room.

Plywood in front of a bass trap will reduce the trap's effectiveness, and plywood in front of a sheet rock wall won't do much. I prefer using cardboard in front of fiberglass bass traps because cardboard reflects mids and highs but lets bass pass into the trap.

--Ethan

[peeder]

Looks like you're a victim of gearslutz fella...

[timothyallan]

Thanks guys, I might look into that in the next bit... I'm still not happy with the way things are sounding with that 50hz dip.

Of course, once I moved my desk and gear in, the response of the room changed again so I will get everything set up and do another test to find an optimal mix position. The problem I have now is that the sweet spot is about a 2 inch circle by the sound of things!

I finished a dance remix last night, and if I even slouch my back, I can hear the sub/low end completely vanish. It's great for my posture and crap for generally everything else! :D

[Chris Kress]

Originally Posted by Ethan Winer

Plywood in front of a bass trap will reduce the trap's effectiveness, and plywood in front of a sheet rock wall won't do much. I prefer using cardboard in front of fiberglass bass traps because cardboard reflects mids and highs but lets bass pass into the trap.

--Ethan

Thanks for that tip and important notes about placement. And cardboard would be much cheaper and easier to install for this application.. Otherwise, I still love birch in a studio. It makes a room feel very musical.

[timothyallan]

Instead of a splitter, I setup Fuzzmeasure to output on a Soundflower audio bus, and then used Audio Hijack Pro to route the L channel of that bus to both the L & R speakers coming out of the motu. Saved $2 and a trip to the Radio shack :)

Attached is the 'final' graph from 20hz-10kHz in my room after everything is moved in. Still not really pleased with my uber small sweet spot, but for the size of the room (and without covering the window) I think it's close to the best I'm going to get.

I don't mind the 'deadness' in here... I might try the cardboard trick, but it seems like to much of a pain right now!!