Fuzzmeasure Pro Graph Help

[tobacco_slammers]

Hi all, new to the forum.

I've just done a few measurements using Fuzzmeasure and would like some help if possible understanding what the graphs are telling me

Firstly, I only have the evaluation version of the software so was limited to 2 measurements per session so I have done 3 in total which are on separate images that i've uploaded.

And secondly, I did the measurements using an SM58 as this was the only mic I had suitable for the job (although I know a LDC would have been better).

Can I also just point out that the room hasn't been treated yet, this is why I'm doing these tests to see how good/bad a starting point I have.

Below is the first image:



This graph contains details of the full frequency range test that I did first.
Purple - Left Monitor
Red - Right Monitor

Below is the second image:



This graph contains details of the full frequency range test again but this time I have fitted isolation pads (Auralex Mopads) underneath each monitor to isolate them from my workstation.
Blue - Left Monitor
Orange - Right monitor

Below is the third image:



This graph contains details of the lower frequency range test with the isolation pads underneath each monitor.
Purple - Left Monitor
Red - Right Monitor

Looking at the last graph, I know it's not exactly that flat a frequency response but i'd be lying if I said I knew exactly what was going on here!

From what I can see, the left monitor appears to have a better response than the right. That's about all though!

Can someone give any advice, pointers?

I have looked through the manual and at a few sites online but can't seem to find anything in-depth or similar to what I need to know. Even a link to a typical looking graph response would be great.

I can fill in more info on my setup if needed, feel free to ask

[tobacco_slammers]

Here is some more info, questions:

I know an SM58 is not the correct type of mic to be using but would it give a hint as to what is going on in my room or is it a complete no no?

I set up the mic at ear level at my listening position relative to my monitors. The mic was connected to an input on my audio interface.

I have Mackie MR8 monitors and an M-Audio Fast Track Ultra Interface.

For the first 2 images that I uploaded I played back a short sweeping sine wave (1,000ms) ranging from 20 Hz to 20 KHz.

For the third image I played back a long sweeping sine wave (10,000ms) ranging from 20 Hz to 300 Hz.

The SPL meter was reading approx. 50 dB SPL at the time of the measurements.

The dimensions of my room are:

L - 4980mm
W - 2980mm
H - 2280mm

I'm looking at putting 4" broadband traps in each corner (with the possibility of the ceiling corners too), some 2" traps at the early reflection points to the side of my monitoring position, above me on the ceiling and to the rear of the room. Also a rug underneath me.

I can take some images of the room if required but I was really just looking at what the information in the graph means and how I should be reading it.

[liscio]

Originally Posted by tobacco_slammers

Here is some more info, questions:
I know an SM58 is not the correct type of mic to be using but would it give a hint as to what is going on in my room or is it a complete no no?

Probably not a good idea to use one of these for testing, but it might be OK just for looking for peaks/dips in the critical range.

Check out Ethan Winer's great article comparing a wide range of mics here, if you're in the market: RealTraps - Measuring Microphones.

I set up the mic at ear level at my listening position relative to my monitors. The mic was connected to an input on my audio interface.

I have Mackie MR8 monitors and an M-Audio Fast Track Ultra Interface.

Sounds good to me.

For the first 2 images that I uploaded I played back a short sweeping sine wave (1,000ms) ranging from 20 Hz to 20 KHz.

For full-range tests, I recommend you use the default sweep range in FuzzMeasure Pro 3, which goes from 1Hz up to nyquist. Limited range sweeps can demonstrate artefacts at the start and end frequencies.

For the third image I played back a long sweeping sine wave (10,000ms) ranging from 20 Hz to 300 Hz.

The SPL meter was reading approx. 50 dB SPL at the time of the measurements.

You might want to compare these results to the full-range sweeps just to make sure the measurement isn't being tainted by the limited range of the sweep before jumping to any conclusions based on just this graph.

Furthermore, you may want to experiment with the window shapes (a half-bingham would work good here) to ensure that your low-end response isn't being affected by the rectangular window used for the FFT.

The dimensions of my room are:

L - 4980mm
W - 2980mm
H - 2280mm

I'm looking at putting 4" broadband traps in each corner (with the possibility of the ceiling corners too), some 2" traps at the early reflection points to the side of my monitoring position, above me on the ceiling and to the rear of the room. Also a rug underneath me.

I can take some images of the room if required but I was really just looking at what the information in the graph means and how I should be reading it.

This is where my expertise ends, and the others in the forum can chime in to help you with the room setup side.

Cheers,

Chris

[Ethan Winer]

Thanks very much for chiming in Chris.

[tobacco_slammers]

Thanks for the advice there Chris and the link to Ethans article. Ethans site has a lot of very useful info on there (some of which i've been using already).

I think i'm going to take a step back here and go through the correct procedures as advised

I don't have any spare cash for purchasing a mic just now but i'm pretty sure I can borrow one from a friend so i'll look into this first.

I've never done this sort of testing before so is there any pointers that you could give me that would ensure I am going the correct way about things? Even a link to a tutorial maybe?

The only thing I think I know for sure is where to position the mic. Could you give an idea of what dB SPL I should be playing back the sine waves at? What speed I should be playing them at? Should I stick to only testing the low end or carry out measurements upto the nyquist freq?

Although I have Fuzzmeasure on my mac would it be advisable to maybe try out Room EQ Wizard also?

Sorry for asking a lot of questions but you guys know your stuff and I want to make sure I can do my best to get my room sounding good.

Any info anyone can give would be fantastic!

Thanks

Bryan

p.s. If it helps I can upload some images for recommendations of treatment.

[Ethan Winer]

Originally Posted by tobacco_slammers

I've never done this sort of testing before so is there any pointers that you could give me that would ensure I am going the correct way about things? Even a link to a tutorial maybe?

How does that sound look?

Using ETF

Could you give an idea of what dB SPL I should be playing back the sine waves at?

It needs to be loud enough to get well above the room's ambient noise level, plus another 30 dB to be able to see the full extent of nulls. So maybe 85 dB SPL.

Although I have Fuzzmeasure on my mac would it be advisable to maybe try out Room EQ Wizard also?

FuzzMeasure is great and it's all you need.

--Ethan

[Weasel9992]

See, I would say that you're not getting anything like an accurate picture of what's happening with an SM58. Fuzzmeasure is amazing, but it can only work with what it "hears", and a 58 is the wrong tool for the job. Second, The graph doesn't look right to me at all...it's not realistic unless your room is better than most of the others I see. Plus that low shelf looks pretty suspicious to me...

Frank

[tobacco_slammers]

Thanks for the link Ethan, interesting stuff there.

I'll try and get a mic sorted out over the weekend and get some graphs, waterfall plots up when I can.

I've uploaded a few images to give a better understanding of how my room looks for anyone interested.

West View



I plan on putting 4" portable bass traps running from the floor to the ceiling at the left and right corners at either side of the window, with the posibility of a wedge trap either side where the ceiling meets the walls.

East View



I plan on putting a 4" bass trap in the left corner above my pc, possibly a wedge at the ceiling too. On the right I plan on putting a 4" trap on the far right wall and also one on the back of the door (inside the room) as i'm kind of restricted at this area.

I also plan to put a thinner 2" panel up on the east wall to catch some reflections.


North West View




South West View



I also plan on putting 2" traps at the early reflection points either side of the sweet spot, a 2" panel on the ceiling above the sweet spot and a rug underneath the sweet spot (due to wooden flooring).

If there is anything else I should look at (or i've said something that I really shouldn't do!) then feel free to let me know.

As it is just now, the room actually doesn't sound that bad but I guess i'm just used to it. There is a bit of flutter echo however so hopefully I can treat it as best as I can.

[tobacco_slammers]

Hi again guys, I've finally managed to get round to doing some measurements as recommended.

Here are some details on equipment used and how I carried out the measurements. I'll try to give as much info as possible:

Mic - Behringer ECM8000 Omni-directional measurement mic
Audio Interface - M-Audio Fast Track Ultra
Monitors - Mackie MR8 (Auralex Mopads used to isolate monitors from workstation)
Measurement Software - Fuzzmeasure Pro 3 & Room EQ Wizard

Room Dimensions:

Length - 4980mm
Width - 2980mm
Height - 2280mm

Monitor Location In Room (sizes are where tweeter centers are sitting):

Left - 1370mm from front wall/window (approx)
870mm from L/H side wall (approx)
1380mm from floor (approx)

Right - 1370mm from front wall/window (approx)
870mm from R/H wall (approx)
1380mm from floor (approx)

Distance between monitors - 1240mm
Distance from L/H monitor to left ear - 920mm
Distance from R/H monitor to right ear - 920mm

The Mopads are sitting at the maximum angle possible downwards(8 degrees) and are hitting at approx 30-40mm above the center of my ear. This is the best I could get them pointing directly at each ear without butchering my unit as I made a slight error when building it! (Which I probably would adjust if it really would make a difference so let me know).

Both left and right speakers were set to normal (flat) on the frequency filter EQ switches at the rear.

Procedure:

I tried out various positions of both the mic placement and speaker placement and the graphs that i've uploaded were the optimum results that I could get within the room.

I used both Fuzzmeasure Pro 3 & Room EQ Wizzard as it was mentioned before that it would be of advantage to have a waterfall plot also but I couldn't get one from Fuzz as I'm limited to functions due to trial expiry.

(I'll point out just now that I found Room EQ a lot harder to understand so please forgive me if i've done anything wrong with it! I think I managed ok with Fuzzthumbsup)

So...

Basically, I had the mic connected to input one on my interface, adjusted a few parameters and tried out different positioning within the room and from what I can make out the position I had them set up in already was pretty much close to the best I'm going to get (without treatment yet of course).

In the following graphs the mic was placed at ear level where the optimum listening position from the speaker positions was:

(I took a screen shot of the graphs as I feel this would give greater info than the print option available within the programs).

Full Range Graph (Fuzzmeasure)



Bass Range Graph (Fuzzmeasure)



Bass Range Graph (Room EQ)



Bass Range Waterfall Graph (Room EQ)



If anyone has the time to take a look over this info that would be excellent and i'd love to find out what knowledge you can give me on improving my existing setup.

Obviously adding as many Bass Traps as mentioned frequently on the forums will help but it would be good to know exactly how good/bad my room is just now and what other additions will make it that little bit better.

If i've missed anything please let me know and i'll sort it.

One additional question that I do have:

What is the impulse response in the graphs?
Is this simply the delay time between the signal being picked up by the mic and the time it takes to convert it to digital? (or am I totally wrong!)

Many Thanks

Bryan

[Weasel9992]

Hey Bryan. Well, the plots from Fuzzmeasure don't still look realistic to me and they conflict with the waterfall data from REW. The REW waterfall shows a very deep null around 60Hz where the plots show a very minor dip at the same place. It's just not at all what I would expect of an untreated room that's as small as yours is. I would also expect to see a bunch of interference in the high mids that I don't see.

Frank

[tobacco_slammers]

Hi Frank, thanks for the reply.

Could you maybe go into a bit more detail on why you think the graphs are wrong? I'm confused trying to work them out myself as it is without them not being correct! lol

When you say "null's" does this refer only to the negative dips on the graph or can these be the positive peaks which might cause problems also.

All I can make out from the graphs is that on the REW one there is an ideal flat frequency response line in blue and most of the graph from my measurement sits underneath this apart from 4 peaks.

My guess is that the lack of bass response here is due to the fact i've not treated the room yet and these frequencies are building up in the corners but I'm not entirely sure on how to read this info correctly from the graph.

I know i'm going to have to just treat the room and see how it goes but i'm just one of those people who like to try and understand things a little bit more...

If you or anyone else can give anymore on the subject that would be great.

Thanks

Bryan

[Weasel9992]

Originally Posted by tobacco_slammers

Hi Frank, thanks for the reply.

Could you maybe go into a bit more detail on why you think the graphs are wrong? I'm confused trying to work them out myself as it is without them not being correct! lol

When you say "null's" does this refer only to the negative dips on the graph or can these be the positive peaks which might cause problems also.

All I can make out from the graphs is that on the REW one there is an ideal flat frequency response line in blue and most of the graph from my measurement sits underneath this apart from 4 peaks.

My guess is that the lack of bass response here is due to the fact i've not treated the room yet and these frequencies are building up in the corners but I'm not entirely sure on how to read this info correctly from the graph.

I know i'm going to have to just treat the room and see how it goes but i'm just one of those people who like to try and understand things a little bit more...

If you or anyone else can give anymore on the subject that would be great.

Thanks

Bryan

What I'm saying is that a room like yours should look much worse than that. I would expect a couple of deep nulls and a bunch of comb filtering in the mids. To read the plots you posted it looks like your room is nearly flat...it's within 6 or 8dB of flat almost everywhere. Really, *really* good rooms are +/-6dB...most non-purpose build rooms can expect to get to +/-10dB or so...that's very good. That's what I meant when I said the plots didn't look realistic. That, and the fact that the waterfall conflicts with the 2-D plots in a big way around 60Hz.

Frank

[tobacco_slammers]

Do you think that i've maybe set up the mic incorrectly then when I was carrying out the measurements? Or even set the software up wrong?

I tried to do it as described on various forums and recommendations but i'm thinking that I must have done something wrong somewhere!

Could you give me an idea of what a graph should typically looklike for a room my size, untreated?

[Weasel9992]

Look at the waterfall display...that's what I would expect to see from your room. There are some big peaks and deep valleys...typical of a small room. Try it without any smoothing maybe?

Frank

[Tomer1]

Maybe its because he used 1\12 Smoothing instead of 1\32 ?

[tobacco_slammers]

Ok, thanks guys, i'll look into the smoothing and see if I can get some more graphs up. Unfortunately I don't have the mic to do another test right now but I can borrow it again for next week if needed.

Bryan