Portable Acoustic Treatments

The rear geometry of my music room is very complex and I’m looking to add a couple of portable treatments. I’d like to understand my options. I would love to build another house and specify the music room; however, I’m stuck with what I have and looking to understand options.

Are you looking for absorption or diffusion in that rear section? Absorption woulg be much easier to solve as there are lightweight, portable panel with feet/stands that you can move in and out on deman. Diffusion on the other hand is tricker as those are generally more cumbersome, heavier, and smaller in size.

You might want to check out Real Traps. I use their Mondo Traps (bass), RFZ Panels and Diffusion modules in my listening room. They all can be mounted on stands, although I have my diffusion sitting on top of smaller bass traps.

gikacoustics.com will create a solution with no obligation.

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The acoustical sweep of the room with no treatments was a 10dB drop from 20-30Hz… I assume the drop was due to the hallway on the back wall or opening on the back adjacent wall to the great room. This was interesting when I measured the room. I designed a P7 & P13 diffusion a month ago. Not sure about executing on that… the measurement was very interesting to say the least. So, absorbsion… no…

Brett66 - thanks, the sweep just blew me away… man was it ugly… I assume the rear of the music room is to blame; very complex geometry and going to be difficult to combat with my loved one.

The set up

Measurement with no treatments:

I would bump up the gain of the subs a bit and see if you can’t get the level a bit closer to your average. The phase adjustments will also have a huge impact on the peaks and nulls. This is the massive advantage of the dual (or more) subs.

You’re definitely going to hear the peak ~50hz as well as 120hz. Boost the gain and remeasure, then with just one sub active start slowly adjusting the phase in small increments and measure/note each change. Once you’ve got that as smooth as practical, introduce the other sub and try and smooth it more. You’ll also need to tweak the gain with both in play. Experiment, sound doesn’t work like we would like it to, it’s messy.

Your uncorrected response is very workable and you definitely do not need bass traps. GIK will take the individual speaker measurements and guide on the next steps. I shared with them my waterfall and they said it’s very likely not as bad as the graph shows. I’ve yet to create the individual measurements and get them to them…life has gotten in the way.

Brett66 - Thanks. Have never done waterfall. How is it done? I was depressed for over a week seeing this mess. My thoughts on the REL subs. Here is the subs increased amplitude.

Moved the REL subs amplitude up 6 clicks:

Brett66 - The sub phase is adjustable (2) ways: 0/180 switch and moving the sub position. I just took a week to catch my breath; was very depressed. I will be on travel for a week and when I come back will start the process of getting the best signature I can. I just started measuring and I want to make sure I am doing it correctly or have not done anything stupid. Please postulate anything I might be doing wrong, understanding, this is my first sweep.

I’d go a bit more. It can take weeks or months of tweaking to get it optimal. Don’t let the graphs get you down, it’s the sound that matters.

waterfall is one of the options further down on the top bar when viewing the graph. There’s a generate button at that bottom left.

Ah, I’m used to a phase dial with ~50 steps between 0 and 180 deg. Call yourself lucky then cause one click of the phase dial can send things into disarray…but I would try running the subs out of phase just to see what it does to the measurements.

What’s your processing stack look like, I forgot what you have? Are you running a music server with the ability to use convolution filters? Those peaks can be knocked down without issue, and the notch nulls are nothing to worry about and you can’t really do anything about them, don’t even try, they are the nature of the space and yours are not bad at all.

Brett66 - Here is the waterfall. I have no clue how to interpret this diagram. I assume it is the response with decay added on the Y axis. Assumption: Z axis is amplitude, X axis is frequency, Y axis is decay.

Subs are 6 clicks up:

You might try pulling the mains away from the walls a bit more and see if that long decay at 120hz improves. Some panels with tuned membranes can help that a few db/ms but don’t expect miracles.

At some point we have to remember to simply enjoy the fantastic sound despite its imperfections. I find a my mood has as much to do with the sound as anything. Thus I often improve my mood with very modest amounts of legal ‘mood improvers’. :wink:

And keep in mind, I’m just some dude on the internet, I only know what I’ve learned from experimenting and reading. I have no training or claim to know what the hell I’m doing here…but happy to share.

Brett66 - I got it; the heavy decay is caused by that wavelength is not absorbed. A good acoustic room is flat amplitude with a little decay. Waterfall is about absorbsion of energy at each frequency. Man that waterfall diagram is nasty.

I think long would be a better way to describe an undesirable decay time. It’s an unfortunate fact of having speakers in a room. The energy has no where to go so it builds up and creates a peak or sucks out and creates a null.

Don’t over absorb to improve decay times, it can kill the life of the room. Your waterfall isn’t that bad.

Brett66 - You are a kind soul and I appreciate the empathy. The room geometry is not going to change. I have a few levers: sub phase, sub amplitude, speaker placement, room treatments. I am going to go at this very slow and have fun with the process. I was just very depressed when I saw the initial measurements. I will keep you informed as to the process results. Do you think I am doing anything wrong as to the measurement methodology. I don’t want to make a mistake on methodology that pushes me in a bad direction…

Brett66 - Here is the block diagram of my system. So, to answer the mail, there is not much processing levers I have. I am using a DS DAC that is fed from the laptop through the TOSLINK you helped me set up (thank you). No access to filtering.

Your measurements look like what I get so I don’t think you’re doing anything wrong. However, I’ve learned they can be misleading in that its only one view of a complicated acoustic picture. Knowing how to integrate all the info REW produces is probably more of an art than a science. I know I ‘understand’ a little bit more each time I use it.

I know many don’t like digital music players, like Roon and JRiver, but I find the eq and convolution ability in the digital domain at 64bit a massive benefit with zero downsides. Convolution with x-over magic from https://www.homeaudiofidelity.com/ has been awesome! But it would mean a paradigm shift for your front-end that you may not be wanting.

I chose a ‘PC’ running Roon and HQP with I2S (though I don’t think the connection matters much). I still buy the occasional disc but it gets ripped to WAV or FLAC and stored away. I don’t have a transport anymore.

I like your drawing. What did you use to create it?

Brett66 - That would be a huge shift in the front end; however, may be something down the road after I squeeze everything I can out of setting up the room and system I have. I will research the strategy and understand the impact. I am a design engineer and have to lay out everything before I execute. I use VISIO, then Snag-It to do a screen capture. All of this can be done in power point, just like VISIO; been using it for 20 years. One thing for sure, I love streaming music 100X more than turn table and DS DMP. I thought I would have bought 50 SACDs by now with setting the system up in May, 2018… just got (3) SACDs and zero CDs… I was going to buy a Basis 2500 turn table and after 4 months of streaming there is no way I will go backwards. This system sounds amazing. This go around is about listening, not spending hrs cleaning crap and making sure there is a full moon when I buy a specific LP that the local music shop says is amazing… drama, drama, drama… I now sit with my laptop researching music and when I find something interesting it takes seconds to start listening using TIDAL (hi res subscription) & Mconnect (easy peasy; UPnP). I figure down the road I will reinvent the selection of the front end. I just needed to see if I liked streaming. My music depth has quadrupled in 4 months. I listen to music 10hrs a day and there is no limitations to exploration; other than the 50 million songs on TIDAL. Down the road there will be something else bigger and better… However, I will be streaming as long as there is a nice front end. Amazing how turntables are still around… must be a lot of romantics…

Brett66 - Just digested the link. It looks like you measure the room; send them a file, and you get back a filter. Convolution can be represented in the (s) domain using Laplace. Y(s) = H_filter(s) * X(s). The * is not multiplication, it is convolution in the (s) domain. The filter is the transfer function (H_filter) between the input and output. The output then is a signal, tailored for the specific music room signature… this is cool…

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