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Understanding Speaker Measurements (Video)

DWPress

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Awesome. Only regret is you didn't do it sooner.

This will help many assess a purchase or evaluate what they already have and a perfect primer and segway for a follow up to your Room Measurement Tutorial for Dummies threads in video form.

;)

 

OCA

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Per popular demand, I recorded a long (1 hour) video on how to read speaker measurements but also, the underlying research (and physics) that mandate some of those concepts. Also covered is equalization and listening tests (briefly). As usual, my videos are "one take" directly recorded and uploaded (and in this case, with no reharsal). So please take it easy as far as critiquing it in that regard. :)


A personal note: as you all know, I don't allow advertising in my videos, nor do I pester people to subscribe, give likes, etc. in the video. Alas, it seems some out there are keeping score on popularity of my content as proof point of whether their audio videos are more correct than mine. So let's even the playground and subscribe to my channel if you have not before. Click on this link to go to my youtube channel (youtube.com/@audiosciencereview) and do that. Appreciate it in advance.
Amir, I just watched your video (twice). Thank you for an informative and honest tutorial. I have two questions:

1. What is the far field simulation Klippel is performing to produce early reflections? These are fully dependent on driver height, speaker's distance to walls and room dimensions all of which will vary wildly from room to room. These must be based on a certain room size so treatment based on merely these graphs didn't make sense to me. I also cannot see the first cancellation and the first peak at double that frequency in any of these early reflection graphs.

2. You correctly EQ for speaker resonances (and btw that 590hz peak is the box reflection IMO, they have not put enough insulation material inside the box) but do not correct for any of the room modes which are the causes of the major distortions in frequency magnitude. Is that because your room is so heavily treated that you don't even have peaks (and dips) below 200Hz?
 
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amirm

amirm

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1. What is the far field simulation Klippel is performing to produce early reflections? These are fully dependent on driver height, speaker's distance to walls and room dimensions all of which will vary wildly from room to room. These must be based on a certain room size so treatment based on merely these graphs didn't make sense to me. I also cannot see the first cancellation and the first peak at double that frequency in any of these early reflection graphs.
Klippel simply computes the far-field model of the speaker. The early reflection is a summary report based on CEA-2034 which gives a formula for half a dozen reflections. This is based on research into a number of listening rooms by Alan Devantier. It is a statistical model and doesn't match any one specific room. I can dig up the AES paper if you are interested in the research.
 
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amirm

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2. You correctly EQ for speaker resonances (and btw that 590hz peak is the box reflection IMO, they have not put enough insulation material inside the box) but doesn't correct for any of the room modes which are the causes of the major distortions in frequency magnitude. Is that because your room is so heavily treated that you don't even have peaks (and dips) below 200Hz?
The volume of my room is very large (open space with 25+ feet ceilings) so my room modes are not severe. But they are surely there and would need correction for best response depending on the speaker. For my main system where I test consumer speakers, I routinely dial a PEQ at 105 Hz for this purpose (I note it in the reviews). I don't usually bother for near-field.

Net, net, EQ for bass is mandatory in all situations. Even rooms that are heavily treated still have modes.
 

OCA

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Klippel simply computes the far-field model of the speaker. The early reflection is a summary report based on CEA-2034 which gives a formula for half a dozen reflections. This is based on research into a number of listening rooms by Alan Devantier. It is a statistical model and doesn't match any one specific room. I can dig up the AES paper if you are interested in the research.
Thank you and no need to go that deep :). I guess they show how much a speaker's directivity will contribute to early reflections and one can derive the rest from his own room dimensions.
 

OCA

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The volume of my room is very large (open space with 25+ feet ceilings) so my room modes are not severe. But they are surely there and would need correction for best response depending on the speaker. For my main system where I test consumer speakers, I routinely dial a PEQ at 105 Hz for this purpose (I note it in the reviews). I don't usually bother for near-field.

Net, net, EQ for bass is mandatory in all situations. Even rooms that are heavily treated still have modes.
I couldn't agree more on mandatory bass EQ and I start understanding your room size from the 105Hz peak! I could get rid of also your 52hz dip by a VBA filter if you're interested ;)
 
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JktHifi

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Is there any portable tools like this so we can bring it to audio expo such as Axpona?
 

Romario

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What a great video! A question though. How do you measure or compute the distortion at 86 and 96 dbfs?
 

Ra1zel

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If you get dedicated haters you are doing something right
 

thecheapseats

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great presentation - making the fine points of testing understood from the physical process to interpreting the printed results... a necessary tutorial for understanding the biggest hardware variable in the sound reproduction chain...
 

DanielT

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Superb! Good job Amir.:D

I thought of one thing regarding EQ, which might be worth mentioning. EQ can lead to more amp power being needed, so it may be worth weighing into the equation how much amp power you need for the speakers (in addition to how much dynamics there is in the music being played, speaker sensitivity and what volume being played).

As for the amp to drive sub-bass, which can require a lot of EQ, it's hardly even possible to have too much power, I think. Then it's best to make sure you have plenty of headroom.:cool:
(plus that the subwoofer in itself is powerful, can handle a lot of power)
 

juliangst

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Is there any portable tools like this so we can bring it to audio expo such as Axpona?
There is a portable Dayton measurement mic and an app called Audiotools that can do similar stuff like REW.
But I don’t think most manufacturers would allow you to play sine sweeps and pink noise to expose their bad speaker designs
 

Jeromeof

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Great Video @amirm - if you do decide to do a talk at a future AXpona or similar event - a cut down version of this would surely go down well (with most open minded audiophiles) there :D

But a quick question, and I know you mentioned you think the step response is useless - but I am still curious as logically it would seem to me that an 'ideal' woofer would have a faster step response to be able to handle very 'fast' music, e.g. play something at 90db @ 200hz followed say 1 millisecond's later by being told to play something a 70db @ 500hz - if the woofer is still 'recovering' in time from playing the 200hz tone surely that would interfer with playing the 500hz tone correctly?
 

delta76

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Internet...

Where "popularity" gives you more credibility than the actual truth. :rolleyes:

Didn't watch the video yet, but I'm sure it's comprehensive content. Glad to see you back on YT!
I for once used the likes/dislikes ratio as the first filter of videos
then I quickly realized, on average, how well informed/educated a Youtube viewer is ...
 

Ajax

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I can't stress enough how important it is to me to have an independent objective resource such as ASR. I have learnt so much here, even though I have being buying HiFi for over 40 years. It simply wouldn't occur to me to buy gear that ASR hasn't tested.

Many thanks for your work, Amir, your a gem.
 

TheBatsEar

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I forgot that (extremely low) trolling quality in YT comments...
The comments come from people typing unfiltered and unreflected what they feel. Most people don't know the difference between thinking and feeling.

It's a bunch of primates out there, i tell you. Luckily I'm a bit more sophisticated.
Picture is me getting a haircut:
93e.gif
 

TheBatsEar

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The video is using M-Audio speakers as examples, but the preview picture on Youtube was about the Focal Chora 816.

I was a bit disappointed and give the video a sleeping panther.
PXL_20220418_185055526.jpg
 

OCA

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Great Video @amirm - if you do decide to do a talk at a future AXpona or similar event - a cut down version of this would surely go down well (with most open minded audiophiles) there :D

But a quick question, and I know you mentioned you think the step response is useless - but I am still curious as logically it would seem to me that an 'ideal' woofer would have a faster step response to be able to handle very 'fast' music, e.g. play something at 90db @ 200hz followed say 1 millisecond's later by being told to play something a 70db @ 500hz - if the woofer is still 'recovering' in time from playing the 200hz tone surely that would interfer with playing the 500hz tone correctly?
Amir doesn't exactly say step response is useless. He says such a signal doesn't exist in real World and the dynamics of the drivers to recover (in your words) are irrelevant. However, he mentioned the time delay between the tweeter and midbass driver the step response illustrates. Minimizing this delay in speaker design is important for heightened sound stage. Some high-end speakers even come with adjustable tweeter, midbass angles and lots of instructions to set it up correctly for the actual LP distance.
 
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