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.
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.
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
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
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.
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...
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...
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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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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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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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.
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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I've come to the same conclusion, that OB's have less "overhang" as they do not rely on a resonating air mass to boost response.
High Qm drivers have less mechanical damping. You could also try less electrical damping (higher output impedance amplifier) to see if you like the result...
Cheers,
Mike
Looking at the plots it seems you are trying to suggest that the room is dominating the response over time. I wouldn't disagree with that. The dipole appears to be interacting differently with some of the modes but the room behaviour as a whole has similar characteristics.
It may be semantic but the concept of directivity would have to lose its meaning at some point. Take the example of a room dimension of only a fraction of a wavelength, where the wave might travel but not so much spread, and it comes down to where in the room the energy culminates.
An important question in my mind is what are the modes doing and how can they be dealt with.
If you look at Floyd Toole's book--Sound Reproduction: Loudspeakers and Rooms--starting on page 128--8.2.1 Testing the Effects of Loudspeaker Directivity on Imaging and Space, but culminating on page 137, I believe that you'll find the answers that you're looking for. I believe that it's related to the "spaciousness" of the sound dimension, especially in the midbass region where dipoles have the least amount of off-axis energy relative to monopole loudspeakers. A quote from page 137:
"Listeners appeared to prefer the sound from wide-dispersion loudspeakers with somewhat colored off-axis behavior to the sound from a narrow-dispersion loudspeaker with less colored off-axis behavior. In the years since then, it has been shown that improving the smoothness of the off-axis radiated sound pushes the subjective ratings even further up, so it is something not to be neglected."
Chris
Putting directivity aside for the moment, Often I notice lower frequency content can mask higher frequency,
With less overhang (dipole bass) on the low frequency, that would imply less low frequency sound in "total amount" over time (as in lower total vs time and less constant). This could be a contributor to this harsher mix effect.
With less overhang (dipole bass) on the low frequency, that would imply less low frequency sound in "total amount" over time (as in lower total vs time and less constant). This could be a contributor to this harsher mix effect.
You can go to the 156th page of the following to read Toole's research and summary comments on the subject (his book) and on other researchers' work in the following section (8.2.2 The Audible Effects of Loudspeaker Dispersion Patterns—Other Opinions) :
https://docs.google.com/file/d/0B_l...JlZC00NmM0LWFiMGUtNTcyMWY4MTUxYmM4/edit?pli=1
https://docs.google.com/file/d/0B_l...JlZC00NmM0LWFiMGUtNTcyMWY4MTUxYmM4/edit?pli=1
Thanks Chris, I have that book in my Safari queue but haven't taken the time to read it. I respect his work and the subjective test results definitely help back up the scientific explanation of what's going on. I think I need to read that entire book and the revisit my own thread
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So with a little more playing and careful thought this afternoon I added in some monopole subs and enabled the dipole processors low cut. Matched it all up with RTA which put the subs crossover at around 50hz. This alone seems to reduce my perception of compression.
I'm starting to wonder if the ears built in protection mechanism is not sufficiently activated by the velocity source of a dipole but is by a monopole (Partial basis for fletcher-Munson curves). I seriously have close to the same RTA response in room.....
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Not to belabour the point, but if pressurising the room in a certain way is the point, and the room is also the primary determinant of the behaviour in the bass then how much difference does it really make? Ie, if you could create the same room states at all frequencies with a dipole or monopole based setup then haven't you achieved the same thing?
Certainly each method changes the way you achieve this, ie a practical consideration but does this change the outcome, all else equal?
On another note, is a monopole vs dipole a clear cut pressure vs velocity scenario? Is the acoustic impedance of the room absolutely resistive? ..or of the modal behaviour?
Certainly each method changes the way you achieve this, ie a practical consideration but does this change the outcome, all else equal?
On another note, is a monopole vs dipole a clear cut pressure vs velocity scenario? Is the acoustic impedance of the room absolutely resistive? ..or of the modal behaviour?
jf4828-
Sure would be helpful if I (or others) could have a better notion of what you are experiencing. Try not to torque the sensory description by inserting words with lots of theoretical baggage like "compression".
BTW, always disappointing to have people make comments (on almost any psychoacoustic topic) who haven't read Toole.
I'm a big fan of dipoles, esp. electrostatic. Maybe you are hearing room-filling (AKA ambient) sound that is "large" but the bass isn't getting "loud" as fast as the room sound is getting large when you crank the volume control?
Playing music recordings at home the way everybody likes it, just barely resembles the sound in a concert hall.
Ben
Sure would be helpful if I (or others) could have a better notion of what you are experiencing. Try not to torque the sensory description by inserting words with lots of theoretical baggage like "compression".
BTW, always disappointing to have people make comments (on almost any psychoacoustic topic) who haven't read Toole.
I'm a big fan of dipoles, esp. electrostatic. Maybe you are hearing room-filling (AKA ambient) sound that is "large" but the bass isn't getting "loud" as fast as the room sound is getting large when you crank the volume control?
Playing music recordings at home the way everybody likes it, just barely resembles the sound in a concert hall.
Ben
Hi Allen,
I don't know the answer to your question. I know my sense of hearing tells me that dipole bass sounds much different than monopole bass. I'm not clear on velocity versus pressurization when it comes to dipole bass. I've read this quite a few times with little explanation regarding acoustics/physics. I threw out the idea that dipole bass may not engage the same hearing protection at the same SPL as pure speculation. I guess I'm trying to find a reasonable basis for my observation.
I'd like to also understand why dipole bass sounds so much different. I suspected that the decay in room was faster but my measurements disproved that. I need to read more as I'm better on the EE side than acoustics but it's fascinating to me. If only I had more time or could make a career of this
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