Interpreting speakers graphs: Take the quiz!

[oohlou]

I love Amir's measurements. I trust them in that I believe he is measuring each speaker the same way and the result show the overall quality of the speaker. I know the standard for speaker measurement and science in general is repeatability and testing each DUT under the same conditions. However, what I really care about is how a set of speakers sounds to ME in MY room (and to a lesser extent where I put them). I have a basic measurement microphone and a love for tinkering, so I'd like to try and correlate results with Amir's.

One thing I struggle with is interpreting the graphs. I understand the basics of SPL, dB scale, frequency response, room modes, etc. but I find that I cannot really look at a graph and "know" how the speaker sounds. I mean clearly speakers like that Genelec are going to sound great but I'm more of a mid-fi guy which means I have to choose which faults I can tolerate. Also, while I enjoy measuring and tinkering I'm not methodically enough to test all speakers in the exact same way or play with placement for hours on end (some placement tinkering is expected). Not only that, I enjoy doing blind ABX tests with my friends.

So... I have gone overboard with deal hunting and I currently have 7 pairs of speakers setup in my room in a wall of sound stack. I only use one pair at a time but I can switch between them live. 6 of them are passive; all going to the same amp via a 6-way speaker selector. 1 pair is active. I put my measurement microphone in one spot and ran REW measurement sweeps on all 7 pairs of speakers. So the microphone is not ideally placed for any of the speakers really and these are all listening position, in-room measurements.

When I started this thread I was planning on just posting the graphs for you guys to help me interpret and correlate to my listening impressions but then I thought why not make a game of it. (All graphs have been normalized to 70dB SPL at 1kHz, 1/12 octave smoothing).

1. One of these pairs of speakers sounds significantly worse than all of the others. Which is it?

2. The microphone is placed at listening position which, given the 7 speaker stack, is only on tweeter axis for one of the pairs of speakers. Which is it?

3. (Poll question) One of these pairs of speakers is clearly preferred by all listeners. 5 of 5 so far (3 people who care about sound, 2 barely willing to participate spouses). Which is it?

4. Any of these speakers warm? Bright? Crap? Awesome? <insert adjective here>? Let me know your thoughts.

5. Extra credit. None of these speakers have been tested by Amir. However, he has tested 3 speakers from the same families. So I would expect some correlation between measurements but then again my measurements are off axis so I think this would be next to impossible. Prove me wrong: If you are the first one to identify any of the speakers below I will give you a small prize.

One:

Two:

Three:

Four:

Five:

Six:

Seven:

(Answers in this post: https://www.audiosciencereview.com/...graphs-take-the-quiz.11820/page-2#post-341987)

 

[oohlou]

All together:

 

[muza_1]

1. Worst sounding is No. 3 (maybe 6)
2. Tweeter axis No. 7
3. No. 4
4. No. 3 Bright, No. 6 Warm, No. 4 and 5 Mostly neutral

 

[wwenze]

However, what I really care about is how a set of speakers sounds to ME in MY room (and to a lesser extent where I put them).

One scary thing about this is that without room correction, luck can play a part e.g. a flat until 40Hz speaker can sound "boomy and uncontrolled" compared to a flat until 100Hz.

I group these under the broader term of "system matching", an umbrella term of why something sounds good in a situation and not others.

5. Extra credit. None of these speakers have been tested by Amir. However, he has tested 3 speakers from the same families. So I would expect some correlation between measurements but then again my measurements are off axis so I think this would be next to impossible.

Probably the correlation would be there if we removed room effects. However different speakers react to room differently so it can be all random. Would have to guess how to remove the room effect. At least glaring problems don't change with room acoustics.

1. One of these pairs of speakers sounds significantly worse than all of the others. Which is it?
2. The microphone is placed at listening position which, given the 7 speaker stack, is only on tweeter axis for one of the pairs of speakers. Which is it?
3. (Poll question) One of these pairs of speakers is clearly preferred by all listeners. 5 of 5 so far (3 people who care about sound, 2 barely willing to participate spouses). Which is it?
4. Any of these speakers warm? Bright? Crap? Awesome? <insert adjective here>? Let me know your thoughts.
5. Extra credit. None of these speakers have been tested by Amir. However, he has tested 3 speakers from the same families. So I would expect some correlation between measurements but then again my measurements are off axis so I think this would be next to impossible. Prove me wrong: If you are the first one to identify any of the speakers below I will give you a small prize.

1. 3. It produces a cheap and screechy sound.
2. Honestly can't tell. I tried looking for reduced HR as well as the dip at XO frequency but all speakers look on-axis enough. So I'm going to say speaker 2 because it is flat and the dip at >10kHz looks like a design choice.
3. 6. Warm and nice. And the clear outlier in the amount of midbass.
4. TBH I feel FR graphs are better than English at describing a speaker...
5. Is it a Klipsch but bigger size

 

[Blumlein 88]

What is the size of your room? Or more what is the Schroeder frequency for your room? It might have told us more about the speaker if you had measured around 1.5 meters from each speaker on the proper axis. It looks like all speakers die away after some sort of peak at 40 hz which likely is room related.

 

[oohlou]

One scary thing about this is that without room correction, luck can play a part e.g. a flat until 40Hz speaker can sound "boomy and uncontrolled" compared to a flat until 100Hz.

I group these under the broader term of "system matching", an umbrella term of why something sounds good in a situation and not others.

I do use room correction in general, but not in these measurements. My approach has been to find speakers I like and then use room correction to fix minor problems. The thought that I may prefer speakers I previously ruled out once room correction is in play has crossed my mind. However, at a certain point you have to decide how many variables you are willing to tinker with for optimal performance.

 

[Blumlein 88]

I'd probably choose 4 narrowly over 5 with just the info you present here. Without some directional info however this is really a wild turkey shoot.

 

[oohlou]

What is the size of your room? Or more what is the Schroeder frequency for your room?

I don't know. I need to learn how to figure that out.

It looks like all speakers die away after some sort of peak at 40 hz which likely is room related.

Astute observation. My amp has a 40Hz high pass filter switch which I have enabled.


In general these sweeps were run with a low enough SPL (70dB) that I don't think room modes came into play much but I definitely defer to you experts. For example here is the waterfall graph of speaker #1 (all of them look similar. No resonances).

 

[wwenze]

There looks like some zig-zagging in the FR that is shared by most speakers tho.

Does it happen that 5 speakers are rear-ported while two are front-ported, or vice-versa?

Also, 3 speakers are one size while 4 are another size?

 

[oohlou]

One hint before I go to bed: The speaker box sizes vary significantly. The smallest is less than 400 cubic inches which the largest is more than 7000.

 

[wwenze]

One hint before I go to bed: The speaker box sizes vary significantly. The smallest is less than 400 cubic inches which the largest is more than 7000.

Well I'm going to place my bet on the 400 being speaker 6.

I prefer to go by woofer size, even though I understand cabinet size also plays a part in the Fs.

 

[oohlou]

There looks like some zig-zagging in the FR that is shared by most speakers tho.

Does it happen that 5 speakers are rear-ported while two are front-ported, or vice-versa?

Also, 3 speakers are one size while 4 are another size?

@wwenze I lied, one more hint. Of the 7: 2 are front ported. 3 are rear ported. 1 has a passive radiator. And last but not least 1 is sealed.

I am already really impressed you seem to be able to figure out the porting based on these graphs. If I didn't have my legend in front of me I would fail my own test. Teach me your ways!

 

[wwenze]

@wwenze I lied, one more hint. Of the 7: 2 are front ported. 3 are rear ported. 1 has a passive radiator. And last but not least 1 is sealed.

I am already really impressed you seem to be able to figure out the porting based on these graphs. If I didn't have my legend in front of me I would fail my own test. Teach me your ways!

At 65Hz, two speakers are at 80dB, two are at 70dB, three are at 60dB. The dip at 65Hz is clearly due to room resonance. But front ported and rear ported have different resonant behavior in a room.

And since there are three groupings I suspected a third group too, like a passive radiator. But I thought the chances of one would be low.

If the sound-emitting elements (woofer, port & passive radiator) are all in front then I expect the zigzagging to be undisrupted as frequency is reduced. If it's at the back then there will be a clear disruption, which is obvious in speakers 3 & 4.
And there are 3 speakers with uninterrupted zigzagging...
I'm pretty much guessing based on available information, which answer fits the data better via commonality matching.
The speaker with passive radiator has it rear-mounted. The three speakers at 60dB @ 65Hz are the two front-ported plus the sealed.
And if the above is true, 6 is the sealed.

-------------

Or the answer can be entirely opposite with the 3 rear-ported at 60dB @ 65Hz, while the front ported + front radiator + sealed are the rest. In fact at first I guessed the two speakers at 80dB are front ported.

 

[RayDunzl]

In general these sweeps were run with a low enough SPL (70dB) that I don't think room modes came into play much but I definitely defer to you experts.

From my small experience, for the lower frequencies room modes inhabit, the amplitude doesn't alter room modes, although amplitude does change whether you hear it or not.

The measurements (humps or dips) remain similar at high or low volume, though at very low volumes the lower frequencies may become obscured by the noise floor.

 

[solderdude]

For example here is the waterfall graph of speaker #1 (all of them look similar. No resonances).

One is looking at the decay response of the REW filters themselves (incorrect settings) and NOT the speaker decay so these plots say absolutely nothing.

The same can be said about FR plots. They may look nice and flat but one cannot say which one prefers as there is such a thing as preference and not all folks have the same preference, the same room conditions nor the same taste in music.
Person A may prefer 4 or the severely boosted bass of 6 while someone else may have a preference for something else.

What the plots CAN show you is how some of the aspects of speakers perform under equal circumstances.
You need to know a LOT about interpreting all the plots to make an educated guess as to what someone may like.

Speakers (and headphones) one should audition at home in 'normal' circumstances.
You can use reviews and/or measurements to get an idea, its an aid not something one should decide on.

 

[tomtoo]

6 Sounds boomi has no deep bass and is missing highs. I think it's the worst sounding?

 

[Hipper]

Whilst I admire your efforts and intentions I don't think it is fair to measure all the speakers lined up with a mic in one place.

From my experience of trying to set up speaker and listening positions using measuring with the mic at the listening position, you will get significant alterations to the frequency response, and what you actually hear, with even small movements of the speakers. There is only usually one or maybe two best places for each speaker in your room. You could try this by using one speaker pair and placing them at the different locations of your seven speaker line up.

I'm afraid your best solution is to measure each pair on their own in their best position, or if you are limited to a particular position, then that one spot. That way you will find the best speaker for your room and locations. A good starting spot is 'The Thirds' - speakers out from each wall a third of the wall length and your listening position/microphone a third out from the back wall.

If you need to find the Schroeder value and information about the likely problems you'll have in your room you could try this calculator:

https://amcoustics.com/tools/amroc

I should add that probably all speakers will need some sort of room treatment or DSP to sound their best in a particular room. The idea is to get ones that get closest to your ideal (or THE ideal if there is one) so that they require less adjustment from DSP etc..

 

[Pio2001]

1. One of these pairs of speakers sounds significantly worse than all of the others. Which is it?

I'd say speaker 6. The amplitude variations are just insane ! 150 Hz is playing 30 dB louder than 8000 Hz.

2. The microphone is placed at listening position which, given the 7 speaker stack, is only on tweeter axis for one of the pairs of speakers. Which is it?

I won't try to guess. From the listening position, it should make no difference for the microphone (our ears are more sensitive to this, as they are able to filter out the direct sound).

3. (Poll question) One of these pairs of speakers is clearly preferred by all listeners. 5 of 5 so far (3 people who care about sound, 2 barely willing to participate spouses). Which is it?

I would say speaker 4. I Don't pay attention to the variation in high frequencies. Neumann KH-120 exhibit the same when measured from the listening position. And speaker 4 has a good low extension.
But it could be speaker 2. Everything is better except the peak at 110 Hz.

Well, actually, it might rather be speaker 2. Vote changed.
The variations in the curve of speaker 4 are too large. We are mistaken by the vertical scale that is zoomed out.

4. Any of these speakers warm? Bright? Crap? Awesome? <insert adjective here>? Let me know your thoughts.

1 : bright
2 : awesome, but with little bass.
3 : boomy and very bad.
4 : well balanced, with a lot of bass
5 : balanced, but with resonances from low frequency to low mid. These frequencies must sound very artificial.
6 : horrible. Too much bass, no treble. Is the tweeter broken ?
7 : quite bad. Should sound artificial at all frequencies.

 

[QMuse]

I'd probably choose 4 narrowly over 5 with just the info you present here. Without some directional info however this is really a wild turkey shoot.

Room EQ won't change directional characteristic of the speaker.

If we assume the optimal curve to be 10dB tilted down over 20Hz to 20khz here it is how 4 looks vs 5:

I'd say I would also choose 4 narrowly over 5.

 

[Pio2001]

In general these sweeps were run with a low enough SPL (70dB) that I don't think room modes came into play much but I definitely defer to you experts. For example here is the waterfall graph of speaker #1 (all of them look similar. No resonances).
View attachment 52504

As RayDunzl said, SPL doesn't affect resonances.

We can see that your rise time is 100 ms, which means that everything happening in less than 100 ms is hidden. You Don't see resonances on this graph because REW is told to hide them.
In the settings, decrease the rise time to 6 or 10 ms instead of 100. The resonances should become visible.