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Discussion Starter · #1 ·
Mir (Megalomaniac) and I had an interesting conversation a few weeks ago. Mir was telling me about how he was told a certain sub was able to play flat, in a car with a specific box, to something like 18hz. Mir commented that upon listening to it, he didn't think it was flat. He said that the sub lacked bottom end and was a tad bit deficient. I had yet to have the opportunity to hear the sub so I can't comment on that matter.

However, it did spawn an interesting conversation. He and I got to thinking about the idea of graphical flatness (actual measurable SPL) vs. perceived flatness by the listener and whether it differed inherently based upon the limits of the threshold of human hearing. We also considered the hearing abilities of different people as well.


I'm interested to hear what you guys think on the matter.
 

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Discussion Starter · #6 ·
Flat is pretty lackluster on the bottom end ;)
Yeah, I think that's what Mir was thinking when we began that convo.
set your EQ in a shape similar to the Fletcher Munson Curve , then carank the sub amp so the low notes can be perceived:D




Minimum audibility curve - Wikipedia, the free encyclopedia
Thanks for posting that! This reaffirms Mir and my suspicions. I had been noticing lately that most of the tweeters that we consider to be "good" have a steady rise in output towards the top of the frequency spectrum where our hearing tapers. This was actually why I thought to post this today.

I'm surprised this isn't something that is discussed or referred to more. :confused:
 

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Yeah, I think that's what Mir was thinking when we began that convo.


Thanks for posting that! This reaffirms Mir and my suspicions. I had been noticing lately that most of the tweeters that we consider to be "good" have a steady rise in output towards the top of the frequency spectrum where our hearing tapers. This was actually why I thought to post this today.

I'm surprised this isn't something that is discussed or referred to more. :confused:
I've noticed that a lot of people are afraid of the higher frequencies and a majority of the Tweeters used tend to fall off a cliff around 10kHz.
 

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Discussion Starter · #9 ·
I'll be perfectly honest and admit that I'm having a hard time deciphering that graph. From the looks of it, I should add nearly 20db of gain at 20hz and I know that's not right.
 

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When you say afraid of them is this when picking out tweeters or when actually using them?
Using them.

With some of the A Pillar installations if the peaks aren't addressed it will sound like there's too much Treble when in actuality it's lite and there's probably peaks in the Mid Range. That's one reason why an RTA is so helpful.
 

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Steven, I didnt get to play with said sub either, but I hope to, if I ever get the stupid amp installed permenantly. This discussion reminds me of when graphic EQs were so popular in home audio, and the big thing was to have your smiley face shaped EQ. A boost at both the tweet side and the low end.

I wonder how much of that was what was "popular" and cool vs what sounded good to many?
 

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I'll be perfectly honest and admit that I'm having a hard time deciphering that graph. From the looks of it, I should add nearly 20db of gain at 20hz and I know that's not right.
The graph tells you how we normally percieve sound and how it's amplitude and frequency dependent.
Check out how at low amplitudes you would need to raise the low notes a lot to percieve them at the same level as the higher frequencies, but how that "low bump" decreases with volume.
That's what the "loudness" button or the Dynamic EQ on the BitOne compensate.
You don't need to make your eq look like that.
On the other hand, that's why a flat RTA tune sounds so bad.

Jorge.
 

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Discussion Starter · #13 ·
Steven, I didnt get to play with said sub either, but I hope to, if I ever get the stupid amp installed permenantly. This discussion reminds me of when graphic EQs were so popular in home audio, and the big thing was to have your smiley face shaped EQ. A boost at both the tweet side and the low end.

I wonder how much of that was what was "popular" and cool vs what sounded good to many?
Funny you should mention that. I was just thinking about my dad's old Kenwood system that has a separate graphic EQ and how it was shaped the same way. From the graph posted above it seems like that, and a dip centered around 3.7k with a very lare Q, would be the proper starting point for most. I think I might give this a try later just to hear what type of results it yields, good, bad, or just plain interesting.
 

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Discussion Starter · #14 ·
The graph tells you how we normally percieve sound and how it's amplitude and frequency dependent.
Check out how at low amplitudes you would need to raise the low notes a lot to percieve them at the same level as the higher frequencies, but how that "low bump" decreases with volume.
That's what the "loudness" button or the Dynamic EQ on the BitOne compensate.
You don't need to make your eq look like that.
On the other hand, that's why a flat RTA tune sounds so bad.

Jorge.
Cool beans. That makes sense. How much of a db increase does that equate to on an equalizer? For instance. The left most part of the graph is 20hz. If I were to try and get 20hz to have the same perceived loudness as 1000hz, how much would I likely have to boost it? The graph makes it look like it would be well over 40db which is just plain absurd. Plus, no EQ I've ever seen even does that.
 

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The graph tells you how we normally percieve sound and how it's amplitude and frequency dependent.
Check out how at low amplitudes you would need to raise the low notes a lot to percieve them at the same level as the higher frequencies, but how that "low bump" decreases with volume.
That's what the "loudness" button or the Dynamic EQ on the BitOne compensate.
You don't need to make your eq look like that.
On the other hand, that's why a flat RTA tune sounds so bad.

Jorge.
I'm still dialing in the Dynamic EQ on the Bit One.
 

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There is still a hole in my headrest and burns on my face from my last tweeter audition :laugh:. My perception was that it was very hot above 7k, but the curve shown explains why. It also explains why the troublesome 500 hz hole in my car isn't as audible as you would expect.

I have heard the concept here, and in other research that a falling line starting from the low extension of the sub to the end of the hearing should follow a about 1.5 to 2 dB per octave drop. There were studies with double blind tests as well as SQ competition winners stating that this would be better than a flat response across the hearing spectrum.

The ISO 226:2003 curves mostly support this concept as well, even if they exceed the 10db drop before 10k.
 

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Cool beans. That makes sense. How much of a db increase does that equate to on an equalizer? For instance. The left most part of the graph is 20hz. If I were to try and get 20hz to have the same perceived loudness as 1000hz, how much would I likely have to boost it? The graph makes it look like it would be well over 40db which is just plain absurd. Plus, no EQ I've ever seen even does that.
You have to remember that this is a human's perceived loudness. It does not take into account what you are listening to. If you set your EQ like that exactly you'll blow your sub with many recording at decent volume.

They don't record music with all the frequencies at the exact same level.

And yes, to hear 20 hz at the same perceived loudness as 1000 hz you would have to add about 40 db of boost there (though it really depends on the spl of the 1000hz signal too).

I can play 23 hz at 80 db in my house and you can barely tell it's there. Turn it up to 110 and you can certainly hear it then. 80 db of 1000 hz is certainly audible. 110 db and I would punch whoever hit play without me putting in my ear plugs first.

I honestly can't hear 20 hz. I now know that after installing 4 IB 15s in my house. I can hear things shaking...but can't hear the fundamental...
 

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How much of a db increase does that equate to on an equalizer? For instance. The left most part of the graph is 20hz. If I were to try and get 20hz to have the same perceived loudness as 1000hz, how much would I likely have to boost it? The graph makes it look like it would be well over 40db which is just plain absurd. Plus, no EQ I've ever seen even does that.
It's pretty hard to say how much to boost or cut.
Remember that a car is a pretty bad environment for audio.
To get those results and match the graphs on those tests you would need a perfect setting.
Do you have an RTA?
If you do, try to dial it in as flat as you can with it.
Now take track 96 of the 1997 IASCA Set Up and Test Disc and try to get a "flat" response by ear.
Now RTA it and report back.

Jorge.
 

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set your EQ in a shape similar to the Fletcher Munson Curve , then carank the sub amp so the low notes can be perceived:D




Minimum audibility curve - Wikipedia, the free encyclopedia
I touched on this in another thread:
http://www.diymobileaudio.com/forum...-fr-measuring-c-weighting-loudness-curve.html

Chad and Dang had some good points on this.


In my little bit of knowledge and experimentation, I've found it's best to find the weakest link in the chain and start from there. In my case, I set the tweeters gain a bit higher than I would have initially and then tuned out the rises. I then backed everything else down to match with this. The subs at that point didn't need any increase because they were more closely matched via the loudness curve.

I dunno if that makes sense... but I try... :/
 

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So, Lee (pyropoptrt) and I were talking about Audison’s Dynamic EQ earlier and kind of got to talking about this same topic so I figured I'd paste some of what was said here.

Maybe you could use the ‘loud’ feature on your headunit… I know its frowned upon, but maybe this is why you’re supposed to use it?
Use the RTA at low/med/high to see what it looks like and try to tune accordingly... finding a good middle ground.
Turn 'loud' on and just leave it on. tune with it on. Really the loud should only affect the areas from 200hz and down, and around 4k if it works like it should. Hell, you might not have a problem at all. Tune it flat with it on at a medium level and then see what it does as you increase/decrease volume. may just work out.
I'd try it, but no means... no loudness curve for me.

I'd be curious to see just how a 'loud' feature does work. If it really follows the curve, then, man, that just might be the ticket. But, I have a feeling it simply boosts the low end. Lee mentioned that it probably varies from company to company... I think he's right.
 
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