In-Room Response

aboroth00

Just got my Minidsp umik-1 in and ran some REW sweeps. After an hour tinkering with the XO points, volume levels got the smoothest response in my room with my capabilities at this point. The high pass for the speakers and low pass for the sub is set at 50hz. My room gives me a huge peak at ~80hz. I tried setting the XO point at 80hz and tried to get rid of the peak but reducing the peak resulted in nulls at other points. I plan on bass trapping the corners, will this help the situation? Thoughts?

Conradicles

What size is this room and how tall is your ceiling? I need to try one of these myself.

aboroth00

It's an irregular sized room. The main area is 13x15 with a little nook that's 5x3.5 in the rear right corner. The ceiling is about 94" which slopes to 90".

You should give it a shot. I tried integrating my sub by ear with a 80hz XO point. I had thought I was doing a good job but turns out I was just hearing the 80hz peak. No surprise considering our ears are much more sensitive in the upper midbass than the lower 20-50hz bass. Having a variable phase control helps immensely as well.

BlueMDPicker

Neat! I want to try REW in my new main listening area. Do you imagine the mic that came with my Denon AVR would work at all? Sorry if that's a dumb question, I know zero about room EQ (but want to learn).

Face

BlueMDPicker wrote: »

Neat! I want to try REW in my new main listening area. Do you imagine the mic that came with my Denon AVR would work at all? Sorry if that's a dumb question, I know zero about room EQ (but want to learn).

It may work, but they're really not that great of quality.

aboroth00

BlueMDPicker wrote: »

Neat! I want to try REW in my new main listening area. Do you imagine the mic that came with my Denon AVR would work at all? Sorry if that's a dumb question, I know zero about room EQ (but want to learn).

As long as you have an accurate calibration file for it, it'll work well with REW. With that being said, receiver Mic's aren't terribly accurate and the receiver probably does some internal calibration to bring the mic flat when measuring. You may or may not be able to get your hands on a cal file.

You can even go and use a Rat Shack SPL meter though it may not be as accurate, but at least it'll give you an idea of what's happening. I was initially hesitant buying the umik-1 because I always thought I could put the 90 bucks or so toward something more useful like room treatments or cables. But in my eyes now, it's definitely worth it. I can literally see in real time how a small adjustment to a knob, placement of the sub affects the entire bass region in real time.

BlueMDPicker

Hey! I have a Rat Shack SPL as well. I'm double marginal!

Thanks for the info. I'll get to reading about REW and try to find a laptop around here that has a mic input (my MacBook Air has USB only).

aboroth00

BlueMDPicker wrote: »

Hey! I have a Rat Shack SPL as well. I'm double marginal!

Thanks for the info. I'll get to reading about REW and try to find a laptop around here that has a mic input (my MacBook Air has USB only).

Gotta start somewhere! I used the Ratshack SPL meter for some cursory stuff while I waited for the Umik-1. It did the job but didn't seem too accurate. The cool thing about the Umik-1 is that you don't need a sound card or to worry about finding cal files. It's already made for REW and REW will recognize it automatically. Just a USB into the laptop and a usb out to my DAC.

After some more fiddling in REW, I decided to start rolling the speakers at 80hz and bringing the sub in at 50hz. I would've never thought to try this without seeing the data in REW. However, with speakers in the positions they're in to create the most convincing sound stage, causes large peaks at 70-80hz. The gem's have extension all the way down to 30hz in my room, but it's not very smooth as their location is not ideal for bass reproduction (several big nulls). My room rings noticeably at ~50hz and ~80hz and it causes some smearing of the mid range. Hopefully some corner bass trapping will decrease the decay times and tame the peaks. While initially I thought I would need to bring in EQ to solve the boominess, seems like the FR is pretty flat without any. All in all, quite happy how a bit of tweaking has resulted in dramatic improvements.

gmcman

What level of smoothing are you displaying?

aboroth00

No smoothing.

Phasewolf

If you could post the rew file I want to open it and look at the waterfall and see what is going on with the room. The flat looking curve is great but the waterfall shows the rest of the story.

aboroth00

Waterfall shows the problems around 50hz and 20hz. Pretty sure I can't do anything about the decay at 20hz but not too often do you hear music go that low. Corner bass trapping might help the 50hz problem. I solved the 80hz ringing by having the sub come in significantly lower than where it typically would. The bass is definitely affecting intelligibility of dialogue so I'm thinking the ringing at 50hz is probably the cuprit. 50hz XO.zipThe forum won't let me upload the REW file as-is but it would let me upload the file once it's zipped.

Phasewolf

Yes I see some issues also the the 40hz range . It may take tuned membrane traps to get that low but corner traps will not hurt as long as they do not suck out all the upper frequencies and leave the room to dead. The issues at 20hz are all but untouchable remember the wall ceiling is a corner too and will not take up floor space and trust me it takes more traps then one may think to effect any given issue.

Phasewolf

Ok the issue at 141hz looks like the height of the room that is a dip you can hear. There is what looks like a nasty null from 83 to around 120hz that should be easier to treat sense it is not as low and there is a -20 db dip at 186hz and 340hz that needs to be addressed too. I would build some panels and move them around both L and W of the room and run a scan and see how each move effects those dips and look at the interaction between the floor and ceiling as you may want to treat one of them if need be.

Is there carpet on the floor or is it like a wood floor if it is wood try a large area rug and move it around as you take a reading and see if it effects anything.

Have fun.

aboroth00

I'm currently over tile. I'm not so sure, an area rug would absorb too much in the ranges I'm concerned about, but an area rug is definitely on my to-buy list. I was planning to buy a pair GIK traps http://gikacoustics.com/product/gik-acoustics-tri-trap/ and stick em in the corners to see how well it does and then fill the entire corner floor to ceiling in both front corners if the pair works out well. It looks like the traps absorb into the 50hz range which is what I'm hoping to do. But overly deadening the room is a concern and thus not the entire front wall is treated, only the space in between the speakers where the first reflections would bounce.

The 20hz issue is not really concerning as music is a priority and I won't be listening to too much organ music in the foreseeable future. I'm hoping the corner trapping will make a dent in the room's problems, but of course i'm well far away from a well treated room. Another solution is to bring the LP 1-2 ft closer to the speakers and place a big bass trap behind and see how that goes. However, this isn't as aesthetically pleasing.

Phasewolf

The largest issue with bass traps that people don't get is it takes a lot of them to really fix a issue. A other thing you need to be aware of is sometime fixing one issue shows a other issue that was being hidden so as you place traps you could end up seeing the real responds of the room.

I fixed one issue to end up with a 20db peek at 50hz that was being covered by a dip at a other frequency. You never know until you try. Let me know if you need help and try moving your speakers around and see what that changes as well. I got rid of a -40db dip at 107hz just by moving the speakers 3" back.

aboroth00

Phasewolf wrote: »

The largest issue with bass traps that people don't get is it takes a lot of them to really fix a issue. A other thing you need to be aware of is sometime fixing one issue shows a other issue that was being hidden so as you place traps you could end up seeing the real responds of the room.

I fixed one issue to end up with a 20db peek at 50hz that was being covered by a dip at a other frequency. You never know until you try. Let me know if you need help and try moving your speakers around and see what that changes as well. I got rid of a -40db dip at 107hz just by moving the speakers 3" back.

Thanks for the tip. I'll try moving the speakers around to see how they respond in the room. I really like where they are right now because of the imaging they give, but I'll see what I can do. Perfectly understand that the amount of bass trapping required to fully solve room problems. We'll try and see, but I think it'll be beneficial in the time domain. It might alter the FR, but that might be a job for EQ. Can't win all around I guess. But I think only way to solve the time domain problems is more treatments...

Phasewolf

That is true. They may work better or worse with just moving them a few inches so go slow and keep the mic in the master spot and just move the speakers. Sometimes you and move the chair or couch one way or the other a few inches and gain as well but do one at a time.

cmy330go

Am I understanding this correctly? For $75 I can order the mic, software is free, and I can take room, and speaker measurements? If so, I really need to get out from under this rock.

aboroth00

cmy330go wrote: »

Am I understanding this correctly? For $75 I can order the mic, software is free, and I can take room, and speaker measurements? If so, I really need to get out from under this rock.

Yessir! I kicked the rock down the road for nearly 3 years hearing and seeing what people were doing with REW. The only caveat when I got to the checkout screen is that the mic would be shipping from Hong Kong which would cost 20 bucks.