About The Sub Zone: Testing Methodology and Environment - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 37 Old 10-30-12, 08:12 PM
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Re: About The Sub Zone: Testing Methodology and Environment

Loving the Sub Zone and looking forward to it's evolution.

"I left in love, in laughter, and in truth and wherever truth, love and laughter abide, I am there in spirit." - Bill Hicks
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post #12 of 37 Old 10-31-12, 01:26 PM
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Re: About The Sub Zone: Testing Methodology and Environment

Looking forward to the sub-zone results, and the neighbors reactions/comments as this unfolds.
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post #13 of 37 Old 10-31-12, 01:31 PM Thread Starter
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Re: About The Sub Zone: Testing Methodology and Environment

It's all about the barbecue. As long as I am feeding the neighbors, they don't complain.

Regards,
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post #14 of 37 Old 11-01-12, 10:32 AM
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Re: About The Sub Zone: Testing Methodology and Environment

Hi Dale, I had responded to your SVS sub post, thinking that the responses do not look correct to me. Sorry if my "tone of voice" seemed harsh in those posts. It appears to me, as I reread them, they appear curt. (insert "sorry" smilie icon)

Anywho... myself and others appreciate your efforts, I am sure.

I do have some thoughts and questions though, to help in "our" pursuit of measuring accuracy and its implications.

Since we are using REW and REW has its standards, those standards must be adheard to. The reason for my insistance on your graphs are so myself and others can directly compare and collaborate what we are measuring with what we are hearing.

You should attach the mdat with all measurements.

You should start out measuring at 75db, the REW standard, and then increase your measurements 5 or 10 db till compression sets in. I myself never measure past 75db, so I would need to compare my graps directly to yours at the same level.

Also you should post the SPL level that you are measuring at for each graph. For instance looking at the Emotiva SPL graph what is its measured SPL level? Where would I put my line looking at that graph? IE 100 db or 95db, it makes a difference.

Which SPL meter are you using?

Since you do review the subs giving descriptions of the woofers sound characteristics should you also not give the measured freq response in the listening room along with the measured response of the entire system as you listen too it?


Thanks,
Bob
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post #15 of 37 Old 11-01-12, 11:13 AM Thread Starter
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Re: About The Sub Zone: Testing Methodology and Environment

Quote:
acoustat6 wrote: View Post
Hi Dale, I had responded to your SVS sub post, thinking that the responses do not look correct to me. Sorry if my "tone of voice" seemed harsh in those posts. It appears to me, as I reread them, they appear curt. (insert "sorry" smilie icon)

Anywho... myself and others appreciate your efforts, I am sure.

I do have some thoughts and questions though, to help in "our" pursuit of measuring accuracy and its implications.

Since we are using REW and REW has its standards, those standards must be adheard to. The reason for my insistance on your graphs are so myself and others can directly compare and collaborate what we are measuring with what we are hearing.

You should attach the mdat with all measurements.

You should start out measuring at 75db, the REW standard, and then increase your measurements 5 or 10 db till compression sets in. I myself never measure past 75db, so I would need to compare my graps directly to yours at the same level.

Also you should post the SPL level that you are measuring at for each graph. For instance looking at the Emotiva SPL graph what is its measured SPL level? Where would I put my line looking at that graph? IE 100 db or 95db, it makes a difference.

Which SPL meter are you using?

Since you do review the subs giving descriptions of the woofers sound characteristics should you also not give the measured freq response in the listening room along with the measured response of the entire system as you listen too it?


Thanks,
Bob
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"If the first 100db suck, why continue?
Hey Bob, first off I want to say thanks for your input on the SVS thread the other because it helped identify a consistency issue between all of the graphs and I have since gone back and reposted the measurements setting the same limitations on each so again, thank you a bunch it really helped us identify that issue.

Quote:
acoustat6 wrote: View Post
Since we are using REW and REW has its standards, those standards must be adheard to. The reason for my insistance on your graphs are so myself and others can directly compare and collaborate what we are measuring with what we are hearing.

You should attach the mdat with all measurements.
While I am using REW as a tool for measuring, the emphasis should be on the methodology. While 75db is the default for REW it is hardly a standard per se. There has been a lot of emphasis over the years on 75db being a standard of some sort but it is really just a reference guideline for level setting speakers.

Quote:
acoustat6 wrote: View Post
You should start out measuring at 75db, the REW standard, and then increase your measurements 5 or 10 db till compression sets in. I myself never measure past 75db, so I would need to compare my graps directly to yours at the same level.
The purpose of the Sub Zone is to compare to manufacturer specifications and published measurements not general guidelines such as the 75db reference level.

Quote:
acoustat6 wrote: View Post
Since you do review the subs giving descriptions of the woofers sound characteristics should you also not give the measured freq response in the listening room along with the measured response of the entire system as you listen too it?
I actually thought about this and you have convinced me that it would be helpful in the reviews to include this measurement so I will start doing that moving forward.

Thanks again for all of your input Bob, it has been very beneficial to the forum!

Regards,
Dale Rasco



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post #16 of 37 Old 11-01-12, 11:24 AM
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Re: About The Sub Zone: Testing Methodology and Environment

I want to comment on a few of these as well...
Quote:
acoustat6 wrote: View Post
You should attach the mdat with all measurements.
These are extremely large files that we really do not care to host. If Dale wants to offer them on a one on one basis, he is happy to do so.

Quote:
acoustat6 wrote: View Post
You should start out measuring at 75db, the REW standard, and then increase your measurements 5 or 10 db till compression sets in. I myself never measure past 75db, so I would need to compare my graps directly to yours at the same level.
Are you measuring at 2 meters, outside in the same environment? This is the only way you can compare graphs.

75db is merely a recommendation... not necessarily a standard. I rarely use 75db when I measure because it is not where I listen. I measure at the level I listen to most.

Quote:
acoustat6 wrote: View Post
Since you do review the subs giving descriptions of the woofers sound characteristics should you also not give the measured freq response in the listening room along with the measured response of the entire system as you listen too it?
Dale can include this, but I am not sure how helpful it will be due to the varying listening rooms, yet it might be interesting to see.

Quote:
acoustat6 wrote: View Post
"If the first 100db suck, why continue?
This word is not allowed in the way you are using it... please refresh on our forum rules, thanks.
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post #17 of 37 Old 11-01-12, 12:15 PM
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Have you considered performing IMD testing? I'm kind of out on HD usefulness in these applications. Notably because it's a lower frequency driven measurement. Until you get to the point of breakup, (which will likely be outside the passband on a woofer (especially the smaller sized woofers)), HD matters little compared to higher frequency content. In some cases, the HD from breakup isn't even relevant because the issues that cause it are the audible distortion issues (ringing, high Q artifacts, etc). IMD will tell a better story for higher frequency distortion content and will show weaknesses of driver design higher in frequency, especially when inductance control isn't implemented. Even when this is outside the passband, it can still have audible negative effects.

Just making a case and asking a question. Not trying to assert a judgmental POV.


As far as these "standards", I say if its logical, who's to stop you from making your own. You (us/we) can't guarantee all manufacturers derive specs the same way. Some follow an IEC spec, some make it up as they go. Personally, there are a handful of companies who's stuff I don't see a need to test because their specs have been proven true numerous times. Of course, there are many others who I feel have downright lied in their spec or were too ignorant to understand their results and therefore mislead consumers. As long as you have logic on your side and are repeatable, do what you need to do.

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post #18 of 37 Old 11-01-12, 10:51 PM
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Do you mind providing more information on the compression testing? I may have some suggestions here based on what I'm seeing in your results and what you've written.
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post #19 of 37 Old 11-02-12, 05:13 AM Thread Starter
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Hi Erin, I can and need to flesh that out a bit more so I should have that up later today. Thanks for mentioning it as I had not noticed that I did not have that out there. Thanks!

Regards,
Dale Rasco



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post #20 of 37 Old 11-02-12, 10:00 AM
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Re: About The Sub Zone: Testing Methodology and Environment

Hi Dale, you said "because it helped identify a consistency issue between all of the graphs and I have since gone back and reposted the measurements setting the same limitations on each so again, thank you a bunch it really helped us identify that issue".

Thats great, we have to show consistency and that is why you should start measuring at 75db. That is what everyone else is holding to at REW forum, unless there is a house curve or for measuring for compression.

"While 75db is the default for REW it is hardly a standard per se. There has been a lot of emphasis over the years on 75db being a standard of some sort but it is really just a reference guideline for level setting speakers. "

Right, so stick with it! If you started at 75db then you could go up in 10 db increments and have this reapeatable for all of your measurements. Would this not make sense from a sciencetific/reference standard.

Looking at your graphs of the 5 woofers that you measured there are no target lines. If you are not measuring at 75db you then need to state the target level for the measurenent taken. IE: on the graph for the Emotiva where would you place the target level? And in the graph for the SVS is the target level 116db? If so you missed it by 20db!

You did not answer my question of which SPL meter you are using, so if you would be so kind....


"I actually thought about this and you have convinced me that it would be helpful in the reviews to include this measurement so I will start doing that moving forward."

Of course it would, you are describing what you hear in your room, we need to see the actual in room freq resp to correlate what is measured with what is heard.

Thanks,
Bob
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