Room Eq Wizard (REW) Room Acoustic Measurement


#21

Brett66 - Looks pretty good. I now have all of the HW equipment to do the REW measurements. I had to change the fluids in my wife’s 56 Thunderbird. I also had to change my 32 Deuce Coupe electric fuel pump and all the fluids. I will start measuring this week. I will be asking questions and sharing results. First will be a baseline with zero acoustic treatments. Then I will add the corner base traps and see how it goes. Then I will add the sidewall traps… this is going to be a lot of fun. I have added pics of my wife’s 56 Tbird I built for her from a shell to trophy winning on her first show. Also added my 32 Deuce that has won shows.


#22

I worked in a shop in my teens, the owner had a T-bird of similar vintage with a bad tranny. 4 of us would push it out of a bay each morning and back in each night. Heavy beast.

I always have to relearn a bit when I pickup REW again. Take you time and start with simple freq response.


#23

Please post in the car thread, here.


#24

For my education, what constitutes a good plot for room acoustics?
We can see some resonances and nulls.
Just trying to understand what constitutes good (or bad, for that matter).
Thanks!


#25

jgrilo - This is the first time I will measure my music room. Brett666 is a better source of deeper information. So, the room should be a flat as possible from 20Hz to 300Hz and that is hard to do in a smaller room. The resonances and nulls are common, it becomes a question of the peak amplitude and where they are located as a function of room geometry. If you can measure, you can then effect measurable differences adding acoustic treatments. In the end, it’s about how good the room sounds. Measurement just proves ideas.


#26

Cardio nailed it. I’m still a rookie at using REW. I have a small space so bass builds up and doesn’t decay as fast as I’d like. I focus on freq response and getting it as smooth as practical using gain, phase and crossover. Nulls cannot and should not be boosted, rather focus on attenuating peaks.

First step, of course, is to measure. Hope this helps.


#27

If I have HDMI out from my laptop what sort of cord would I use into my BHK preamp? What is the advantage, if any, of using HDMI rather than headphone out?

Thanks!


#28

Wakethetown - If you read the whole post you would see that my situation is unique in the sense that I don’t have a preamp for turntable. I just have a DS DMP and DS DAC. I went the HDMI to TOSLINK route because my DAC does not have a L/R RCA input. I’m using the optical input to the DAC from the HDMI output of the laptop. One advantage for HDMI might be if you are looking to measure 5.1 and have equipment to support 5.1 configuration. I don’t know your system configuration completely or your intentions. If you are looking to go 5.1 measurements, I don’t think you would have the BHK pre/BHK250 assume you have a 2 channel system. If you do, laptop HDMI would give you nothing that you could not get from the laptop headphone output. I just finished my baseline REW measurements and this set up works great for 2 channel with optical input to the PSA DS DAC from laptop HDMI using a J-Tech convertor. Now, the results on the other hand - there is a lot of meat left on the bone…


#29

Thanks so much! I did read the whole post, but missed this point. I appreciate your clarification. Cheers!


#30

Wakethetown - no issues, glad to help


#31

Hey Brett,

I have been messing with REW with my U-Mik. Here follows my SPL results. Also I am suffering from some deep bass ringing. Thinking about some serious room treatment.


#32

Looks better than mine. I tried to match your settings so the ‘picture’ is comparable.

Good luck with reducing the ringing. I simply don’t have enough free volume to lose to bass traps to be effective so I live it with…


#33

yeah, you’ve got some nasty ringings. When the acoustic project is over (it will take a while) I’ll post the results.


#34

Plaster/concrete walls and raised wood floors. Such is life. Still sounds pretty good!

I should do some sweeps with eq/convolution in play and see how it impacts decay. I have two subs which helps a bunch, and I’m sure the convolution filters could be tweaked to help more as I didn’t have the subs in play when I made the filters.


#35

In terms of bass frequency response, what is ringing? I’m familiar with the terms “dips” and “bumps”. What in the graph represents the ringing? Thanks.


#36

Ringing is sound that continues in the room well after the speaker has ceased making it. It creates muddy, non-descript bass.

The lower left of the waterfall that is solid indicates long decay times. Both of our graphs are set to 500ms. Ideally, the sound produced by the speaker would be gone in say 200ms so that the next sound it makes is heard clearly without the room continuing to bounce around the last.

The axis are time is coming towards us, freq along the bottom and db along the vertical. Many say these waterfalls are misleading, and they can be depending on how they are presented.

Hope that helps. Few people manage excellent decay times in the bass region in domestic sized rooms without being able to set the dimensions of the space, along with bass absorption and eq.

My graph is without any correction though I do have my few ‘bass traps’ in the space during the measurements. I simply cannot fill my space with enough material to do much good, so I rely on equalization/convolution and phase cancellation using multiple subs.


#37

Brett said it all. A good way to test the “resolution” of your bass response is by a MATT test. It is a series of bass tones, that goes from 20hz to mid-bass. You should hear each tone clearly, without mixing itself with the next one. You should try. Likely you will find out that you can distinguish the mid bass tones perfectly, but struggles to identify the lower frequency ones. In my room, they begin to get muddy by 70-80hz.


#38

http://www.asc-hifi.com/matt-test.htm