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REW / mdat assistance? Reverb/Delay Processors (HW)
Old 8th August 2018
  #1
Here for the gear
REW / mdat assistance?

Hi All,

I realise that this is something that people spend their careers learning to do, and it's not to be asked lightly. So to that end, I'm trying to do a lot myself, to minimise the begging I have to do.

I've ordered a copy of Sonarworks to help out my listening from that perspective (I realise that this software only solves some problems and is by no means a "fix all"; and will be making a donation to the REW team as thanks for their efforts on the REW software.

I wonder if someone would be able to take a look at the mdat file for my recent test. I won't post images, since after reading that super-long pinned thread it's become clear that pictures aren't super helpful. My mdat file contains, Left Test, Right Test, and L/R combined. I set the layout of my room in the room sim section if the mdat file contains that?

One caveat, is that I don't have an SPL meter so I had to guesstimate the SPL calibration (set to about 70, what a hack I am!!), I can calibrate better when I have purchased one.

I'm happy to contribute to a slush fund too; I just want to get a feel for the "worst points" of my problem overall, and what measures I might investigate to help with them. Not looking for in depth analysis and fix by any means.

I note with interest that my graphs for left and right are significantly different, due to the placement of my desk in the room I'd imagine?

Looking at the results below 1KHz, I note that I have a large peak (on L+R graph) around 140Hz; and a significant dip at around 640Hz; this 140 peak seems to be indicated in the individual L/R graphs too. I note that on the right speaker I have a pronounced dip at around 720Hz that isn't really present on the Left; but the Left does have two notable dips at 465 and 513. Of course this might not be notable at all since I'm greener than green with this.

Link to .mdat (this should work) - https://www.dropbox.com/s/mn7a5mfevk....mdat.zip?dl=1

Thanks in advance for making it to the end of my incoherent ramblings.

Cheers.
Old 8th August 2018
  #2
I can't offer as much guidance here as others on the forum, but there's some strange looking things going on in the low end below 58Hz on the L+R measurement.

It may help if we knew a bit more:

Room diimensions
Basic room construction details (sheetrock/concrete wall/basement/etc)
Speaker type
Speaker location
Measurement location
Any treatment?

Generally it's better to focus on everything from 300Hz (ish) down because that's the hardest part to get right and then we can look at other anomalies.

Perhaps some more info might bring out some of the smart folks here.

I'm sure we can help you make heads or tails of this and come to some kind of improvement.
Old 9th August 2018
  #3
Here for the gear
I was hoping that the measurements would save into the mdat in the "room sim" section.

My Room is 3.6m front to back, 4.55m wide, ceiling is a standard 2.4m.

It's an old Florida room so there's a lot of windows, most of which have moving blankets hung over them, which helps remove the "bathroom" vibe. The floor is tile but has a lot of rugs on it, again to help remove the bathroom vibe. In the corner behind me to my right I have a 7ft polar bear which does a fine job as a bass trap (I think). There are book cases and acoustic foam tiles dotted about randomly to try and break up the largest flat surfaces on the walls.

Speakers are full range KRK 6s (not great but they do the job until I can afford the Adam or Genelec I want). The screen shot attached shows where they are located.

Construction is mostly sheet rock walls and ceiling.

We plan to move at some point, so anything I use right now needs to be non permanent modification if possible.

Can you confirm if any of the room details were saved in the Room Sim section?

The funky low end stuff might be due to the ceiling fan I forgot to shut off before I measured, or the vibrations from the AC... hard to say.

Does this help?
Attached Thumbnails
REW / mdat assistance?-screen-shot-2018-08-08-7.41.24-pm.png   REW / mdat assistance?-screen-shot-2018-08-08-7.41.05-pm.png   REW / mdat assistance?-screen-shot-2018-08-08-7.40.12-pm.png   REW / mdat assistance?-img_2734.jpg  

Last edited by TonyHolmes; 9th August 2018 at 12:55 AM.. Reason: Added Polar Bear Bass Trap
Old 9th August 2018
  #4
OK, that helps some...

The room sim stuff wasn't in the mdat that you uploaded; at least not on my end.

There's something really weird going on with that mdat that you sent, in that the full display in the main window doesn't all show up at first. As I dragged the mouse around it started gradually appearing. Eventually it was all there. Weird. I have never seen that behavior from any of my mdats nor any I've downloaded.

After several minutes I could finally see everything.

But I digress...

It's still not completely clear to me how the room is setup, though I am aware that there's a polar bear. He's probably not a good bass trap, but were he alive, could certainly do a number on a seal.

If you could either do a diagram of the room,or take pictures of each wall, or both, that will help a bunch too. I need to know where doors and windows are.

Based on the room simulator, your listening position is really in a bad spot. Blankets over windows is not helping anything either, frequency response-wise. I understand why you're doing it, but it's not helping improve what's really wrong.

If I can see a full layout and what exactly is where, I'm happy to try and figure out what could improve it all. I'm like you in that all of my treatments are portable. It can still be really good.

Just get a little more detailed and I'll see what I can figure out.
Old 10th August 2018
  #5
Here for the gear
I've done a sketch that is mostly to scale and attached it here....

There's a few boxes and odds and ends that will be going soon, so I didn't include them... the two bookshelves across from my desk can easily be moved. I've included the doors and windows (60cm / 2ft wide). Both doors are exterior, steel faced, doors to help sound with isolation, they're pretty solid.

The floor is tile, but I have area rugs down... changing the flooring wouldn't be easy to do.

I understand after watching a couple of videos that the ideal position (correct me if I'm wrong), would be to turn the desk 90 degrees clockwise so I'm facing the two windows, so I'm aligned with the length of the room rather than the width. This would be trivial, I could probably do it this week sometime, and then remeasure.

The wall behind my chair has the moving blankets along the length, these serve a dual purpose (it's an exterior wall so it keeps it cooler in summer and warmer in winter) so if it doesn't cause too much problem to stay that'd be good, if not, then c'est la vie! The wall to the right of my desk also has moving blankets... none of the remaining two walls do.

Ceiling is sheetrock (like the walls) with some ugly texturing on it that someone obviously thought was a great idea at some point.

The 6" KRK monitors are on isolation pads on my desktop, in an equilateral triangle with my listening area.

Did I miss anything useful?
Attached Thumbnails
REW / mdat assistance?-screen-shot-2018-08-10-4.30.22-pm.png   REW / mdat assistance?-screen-shot-2018-08-10-5.12.25-pm.jpg  

Last edited by TonyHolmes; 10th August 2018 at 09:35 PM.. Reason: added info
Old 10th August 2018
  #6
That helps to visualize, thanks!

The tile floor is a good thing-no need to change anything. You are correct about rotating 90º to the right so the speakers are on the short wall firing into the longer dimension. That's all good. You'll want to get the speakers as close to the front wall (without touching) as you can. If you could get the speakers off of the desk and onto some stands, that will help as well (this may not be possible for you? Don't know).

The moving blankets are not a huge problem but to do it right, you really want the room to be as symmetrical as possible. In other words, a moving blanket on one side means one on the opposite side. The two sides should be as much of a mirror image as possible. I understand that may not be possible with your room so do it where you can.

Having said that about the moving blankets, they're really not gonna do much below 1-2kHz, I would guess.

Using REW to measure and using the room simulator in REW will tell you a bunch about what should happen when you move the speakers. It won't be perfect because of the windows/wall construction details/etc. but it should give you a general idea of what kind of response to expect in different parts of the room.

Are you planning on building acoustic treatments at some point? I'm not exactly sure how far you'll want to go with this. Sonarworks seems cool (I know some love it) but you should take care of everything else before you go that route, I think.
Old 10th August 2018
  #7
Here for the gear
Thanks for the detailed info.

I'll look into the room sim to see how it might help turning the desk.

Putting the monitors on stands isn't a huge issue I just have to buy them. Are floor stands better, or should I get proper risers for the desk?

I can add some blankets on to the other side too if it will help, they are just hung with 3m command hooks. I'm wary of "killing the high end" which others have told me to be careful of.

Regarding acoustic treatments, I was looking into making some 2' x 4' x 4" panels with OC703 in it ... I could even make some free standing panels (2' x 8' x 4") if I needed to. Would this help at all?

I moved the monitor position as you suggested, I've added the two scenarios below...
Attached Thumbnails
REW / mdat assistance?-screen-shot-2018-08-10-6.04.57-pm.jpg   REW / mdat assistance?-screen-shot-2018-08-10-6.08.13-pm.jpg  
Old 11th August 2018
  #8
According to the room simulator that new position is clearly better. Good.

Is it centered on the short wall? It may be, I just can't tell.

The free standing, larger panels will be better than more blankets, absolutely.

Stands on the floor are the way to go. If you can afford them the Sound Anchors are really excellent. Anything will be better than on the desk. If you can't get the speakers off of the desk maybe get something to decouple them from the desk. These are supposed to work but I've never tried them.

I wouldn't be too worried about killing the high end at this point. People worry about that more when they're doing a lot of treatment, and you're no where near that yet.

In general:

Treat the corners with some deep traps, with SuperChunks being pretty well accepted as a great way to go.

Treat the first reflection points on the side walls

Add a cloud over head in the listening area-4" deep plus a 4" airgap if you can do it.

As much deep treatment on the back wall as you can fit or afford.

That doesn't really address the whole layout and the best way to do things, but it will give you some stuff to research and look into as you get further along.
Old 11th August 2018
  #9
Pno
Gear Maniac
Firstly, forget your first layout.

Experiment with positions first, before you even think of treatment...I would try the wall on the right and the bottom wall first (speakers pointing into room in both cases, as close to the wall as possible...try have the back of the speaker away from the windows, or equally (symmetrically) overlapping windows if not possible)...some actual pics of the room would be helpful...also what speakers are you using...

Set up each position you try correctly (same height, equilateral triangle, same SPL (use pink noise; even a phone app will do)), measure L/R at listening position...listen to 2/3 reference tracks...then, vary the size of your equilateral triangle (thus moving listening position closer to wall/further into room)...repeat for a couple of positions, or ad nauseam...answers will begin to reveal themselves...
Old 11th August 2018
  #10
Here for the gear
Ok, so now I have a plan moving forward.

1. Move desk to work with the long side of the room. Remeasure. ($0)

2. Isolate monitors better. I’m considering isolation stands that work with the mopads. Space is an issue, so the may have to stay on the desk for now. Remeasure ($100)

3. Make two 16” x 16” x 8’ square bass traps (soffit traps?) on wheels for each rear corner using Roxul safe and sound (OC is simply too difficult to source). It has to be on wheels because it’ll block the door at the rear so has to be moveable. Remeasure ($400)

Is it worth making another trap for the front right corner of the room if I cant place in the left corner symmetrically?

4. Make some? (Maybe 4 to start); 2’ x 4’ x 4” acoustic panels (Roxul safe n sound). Return to here with latest measurements for guidance on placement. Apply advice. Remeasure. ($200)

5. Figure out how to make a cloud without making permanent fixtures in the room.

Does this sound reasonable? Any corrections or clarifications or guidance here? This is probably a 6 month plan (3 kids have a claim most of my time). Like I said the goal is budget friendly, non permanent, max bang for buck. I plan to post updates as I go once my plan is solidified.

Thanks for all the help so far.
Old 11th August 2018
  #11
That all sounds good to me.

Yeah, I'd treat one front corner rather than none, only because more is better.

Since I couldn't drill into my ceiling, I had a metal frame built for my clouds which was more expensive than I wanted it to be and wasn't as sturdy as I wanted it to be! With the benefit of hindsight, I recommend something built out of wood if you want to do something like that.

Definitely keep us posted on the measurements and progress. Looking forward to seeing how it all turns out.
Old 8th December 2018
  #12
Here for the gear
Quote:
Originally Posted by TonyHolmes View Post
Ok, so now I have a plan moving forward.

1. Move desk to work with the long side of the room. Remeasure. ($0)
point 1 done.. here's up to 200 Hz ... looking better already I think?

I will take a little while to do the next steps, due to a new floor being laid, with extra acoustic insulation (I needed to lay a new floor anyway)
Attached Thumbnails
REW / mdat assistance?-screen-shot-2018-12-08-11.30.50-am.jpg  

Last edited by TonyHolmes; 8th December 2018 at 08:20 PM.. Reason: Clarification
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