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Multi-Way Conventional loudspeakers with crossovers

Directivity and Perception of Dynamic Range Compression
Directivity and Perception of Dynamic Range Compression
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Old 26th August 2016, 08:51 PM   #1
jf4828 is offline jf4828
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Default Directivity and Perception of Dynamic Range Compression

So I've been building dipole and monopole loudspeakers for quite a while. I also have a bit of experience mixing live sound. There is something I perceive but really don't understand and hoped someone could help me understand what is going on.....

All of the dipoles I've built including LX521, Orion and my own designs clearly reveal dynamic range compression in recordings. What I mean is that the recording has a bass level that is typically pretty constant approaching 0dBFS throughout. The peaks of these tracks generally do not increase the bass to midrange region sufficiently when vocals, instruments etc are full tilt. This makes many compressed tracks sound pretty awful on dipoles. This issue also seems to be more prevalent with speakers that have higher directivity in general. I've spent lots of time playing with EQ/DSP etc with all of these speakers and it doesn't seem to be frequency response related to me.....

When I live mix, I often have to reduce compression on drums/bass or ride the faders up as the peaks of the music come so that the mix does not get harsh. This increases the overall dynamic range of the music which of course makes it more fun to listen to.

What I'm trying to figure out is why is this the case? I initially thought that the bass decay of dipoles is much faster than monopoles leaving an empty space in the gaps making it sound more harsh. However, I would think that this would port to the planar magnetic headphones I've heard...... Is this related to reflections? I have a pair of monopoles in the same room where the design goal was a very even power response. With theses speakers, I don't notice the harshness with compressed music.....

As I'm planning some new designs, I'd like to understand the reason behind this.
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Old 26th August 2016, 09:17 PM   #2
eriksquires is offline eriksquires  United States
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First, you are sure this is not your electronics? This could easily be an after effect of missetting of a fancy EQ/crossover.

What you might try though is moving the speakers so they are not symmetrically placed. Shift them left/right and front/back by at least 2'.

Unusual it would happen on dipoles, but in a closed room, you can have ridiculous amounts of ringing. The thing to do is measure bass decay in your room.

The order of improvement is: Measurement -> Bass Traps -> EQ

Room EQ Wizard with an imm 6 ($20) or OmniMic will serve the first. Bass traps will bleed off energy, and allow the EQ's to work. Without the bass traps, EQ's are innefective.

Best,


Erik
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Old 26th August 2016, 09:36 PM   #3
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by jf4828 View Post
I initially thought that the bass decay of dipoles is much faster than monopoles leaving an empty space in the gaps making it sound more harsh.
Bass is sustained in the room long enough after it is produced that the speakers mightn't necessarily be involved in the decay process... The way they fill the room may be different.
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Old 27th August 2016, 12:02 AM   #4
Eldam is offline Eldam  France
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how is this decay if you stand near the back wall ? and in the corners of the back wall ?

And when you are seated farer or nearer to the Dipôles : there are highs and low compression nods in a room, sometimes it can help to move the chair forward or frontward, you may try by 50 cm step to see if the subjective perception of the decay is changing...
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Old 27th August 2016, 12:06 AM   #5
jf4828 is offline jf4828
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Originally Posted by AllenB View Post
Bass is sustained in the room long enough after it is produced that the speakers mightn't necessarily be involved in the decay process... The way they fill the room may be different.

So what I was getting at is that due to the reduced room interaction the bass decays quicker with dipoles than monopoles. This assumption might be completely wrong but it just sounds like bass stops on a dime with dipoles due to velocity vs pressure loading? Reminds me of bass outdoors, that's the maybe poor logic I'm using....


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Old 27th August 2016, 12:19 AM   #6
jf4828 is offline jf4828
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Thanks for the info Erik. I'm fully equipped for measurements and I'll see what results I get and post them back.

As far as nodes go, I'm well aware of the nodes and usually move the speakers until my chair is happy. This is something I'm thinking about as a broader observation that trends in my mind. This spans several years with several listening rooms.

Busy recordings that don't suffer from loudness war compression sound fantastic on dipoles....


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Old 27th August 2016, 12:50 AM   #7
AllenB is offline AllenB  Australia
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Regardless of how a (low frequency) room mode is excited, it involves bouncing around the room which means the same thing whether dipole or monopole. Bass tends to be heard within a frame (of timing) whereby it has made the rounds of the walls. This perception, the speed of sound, the size of the room and the nature of the patterns its modes develop are not affected by the source other than how it feeds into them.
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Old 27th August 2016, 01:31 AM   #8
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Hi Allen, indeed measurements indicate that there is no correlation between decay time in room and directivity pattern. The attached images are pretty close to level matched. BTW this is not a quiet room....
Attached Images
File Type: png monopole.png (51.0 KB, 396 views)
File Type: png dipole.png (50.6 KB, 396 views)
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Old 27th August 2016, 01:44 AM   #9
eriksquires is offline eriksquires  United States
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One thing that can cause this is really bad caps or connections. Depending on the metals used, yadda yadda they can act like diode's. This effect is usually a loss of low level detail, as opposed to a raising of low volume to high.
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Old 27th August 2016, 02:01 AM   #10
jf4828 is offline jf4828
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Originally Posted by eriksquires View Post
One thing that can cause this is really bad caps or connections. Depending on the metals used, yadda yadda they can act like diode's. This effect is usually a loss of low level detail, as opposed to a raising of low volume to high.


So the dipoles I'm using right now are the LX521 using ASP and miniDSP as I'm evaluating which crossover I prefer. I've measured the transfer functions and phase response of the ASP and configured DSP and everything looks to be in order. I've also noticed the exact same thing with my DIY dipoles and the Orion's I used to have in a completely different listening space.

I'm really trying to figure out if:
1. I'm just crazy and this is not related to dipoles at all
2. If it is related to dipoles why?

I'm in an 18x14 room with an adjacent kitchen and hallway now. Before I was in a room that was 24x30..... Noticed the same thing...




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