Is it possible to cover the whole spectrum, high SPL, low distortion with a 2-way?

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#12,243
camplo said:
Like others have said, I perceive a difference between headphones and 1 meter monitoring. Modes obviously are complex and can surround you at your listening position, close or far.

Listening close, lessens the faults of the room.

I can hear the room as ambience, above the modal region, when sitting 1 meter. I believe there is a common thread between low reflective energy and large concert halls and large rooms. By lowering Early and Late reflective Spl, the room sounds bigger. So increasing DI and increasing proximity have similar effects on this aspect of increasing the direct sound portion of the summed SPL.
Everywhere the DI is significantly lower the room will sound more involed and thus smaller. In so many words, outside of modes... larger rooms have lower reverb levels than smaller rooms... somehow force gets traded for distance, that is, Spl level traded for longer decay times. Im guessing that this is directly tied to the increase of path length to boundaries.

The two examples would be one very large room like a large theater and a living room. Listening Distance and source level would have to remain the same in each example..the larger room would measure lower Spl at the listening point...

With that being said, High DI and sitting closer causes one the impression of being in a larger room. Sounding like headphones... in my untreated living room, that never happens. Headphones are still much much drier. In a very large room, sitting at 1m will be much closer to "headphones" but honestly, I don't think that even that would work. The position of the sources and sound fields created are so different. I would compare decay and rt60.
When the rt60 of the system+room nears or matches the rt60 of headphones, then we can say the presentation is as dry as headphones

The decay measurements of my horn measured outside, might of been similar to some measurements I took of my headphones. I can't imagine that this would be remotely true in a small untreated room listening at 1m. The lack of the equilateral triangle in headphone monitoring is the other aspect, removing loudspeakers at 1m from becoming "headphones" not to mention the lack of cross talk in listening experience
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A lot of times people think of music like a non stop stream of notes.
In reality this is rarely the case.

So that you can hear the difference between headphones and nearfield/close range speakers isn't so strange.
This is in particular noticeable after a high dynamic peak followed by silence.
Something like a well recorded kick drum or so.

Also, something like a high DI cardioid system helps, it will still move sound in other directions. Just with a well attenuated signal.
Which again works great for a relative difference, when sound is being played.

But I think can still be noticeable when there is sudden silence. Which could work on an absolute way.

Obviously this depends on the reverberation time as well as level of it.
 
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#12,244
Is there a meaningful difference between reflections from a wall immediately behind the listener, vs. early reflections from the "speaker side"? I'm familiar with live end dead end approaches but they do seem reductive. In my space I'm able to make a pretty decent space around the speakers and accordingly minimize early reflections there, but the rear wall behind the seating is very close. It seems like an obvious answer- brute force absorption closer to the seating, then perhaps bring in some HF scattering further from the seating as the distances become sufficient for the reflections to be 10-15+ms. It would seem that the seating itself would be best to have decent absorbtion characteristics, cloth over leather for ex.
 
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#12,245
Consider the timing of a reflection off a near wall behind you. It arrives in a very short time interval. This is a bad thing for imaging and timbre. The ear does tend to diminish sound from the rear, but not enough that the timing is not a problem. Moving away from the wall or damping it helps, but timing is the key.

Regarding seating, it can be very important. Once at our factory in Thailand we built a listening room. We had trouble with the bass sound and it turned out that the sofa was the culprit. It was not rigid enough and resonated transferring this resonance to your butt. Reinforcing and damping the sofa fixed this issue. Earlier at Ford, we had found that resonances in car seats could strongly affect the perceptions of car noise as well as the sound system. In my room I use oak frame sofas with leather seating because I want them rigid but not highly damped.
 
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#12,246
camplo said:
Imd can be low but imd high, potentially. Even that is leaving out whether we are talking about AM or FM.
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As stated before, IMD and THD are completely related - I can derive one from a knowledge of the other, they are not independent. They are created from the exact same nonlinearity but using different stimuli. And FM and AM will be subjectively the same as only the phases of the sidebands differ and in this context we are not sensitive to these phases.
 
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#12,248
camplo said:
larger rooms have lower reverb levels than smaller rooms...
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The facts are directly opposite this. Larger rooms tend towards much longer reverberation than small rooms with much great time lags before reflections. Hence, high damping tends to make the room sound smaller, not bigger. But the most significant difference is in the timing of the reflections. In large rooms there is no fusing of a reflection with the direct sound at any audibly important frequencies. And the high RT enhances the perception of bass due to the longer signal length.
 
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#12,249
Jumping in with a question related to the overall theme of the thread - I've got a 2 way TAD based setup: the TD-4001 on a Yuichi clone 290 hz horn, and a 1601b on the bass. Though I really enjoy how it sounds, I am curious about adding a tweeter to the top end, maybe just to try it and see if I'm "missing anything."

Can anyone provide guidance on what that might look like/if it would be worth doing? My current system is crossed at 600hz. I'd be looking at crossing to a dedicated tweeter at or above 3khz, subject to the needs of the prospective tweeter itself of course. I'm primarily considering either the TD-2001 with an appropriate horn, maybe one of the Fostex super tweets, or possibly a ribbon. I'm not sure which way would be best...but part of me also doesn't want to lose sight of the 2 way dream!
 
#12,251
gandalfandula said:
Jumping in with a question related to the overall theme of the thread - I've got a 2 way TAD based setup: the TD-4001 on a Yuichi clone 290 hz horn, and a 1601b on the bass. Though I really enjoy how it sounds, I am curious about adding a tweeter to the top end, maybe just to try it and see if I'm "missing anything."

Can anyone provide guidance on what that might look like/if it would be worth doing? My current system is crossed at 600hz. I'd be looking at crossing to a dedicated tweeter at or above 3khz, subject to the needs of the prospective tweeter itself of course. I'm primarily considering either the TD-2001 with an appropriate horn, maybe one of the Fostex super tweets, or possibly a ribbon. I'm not sure which way would be best...but part of me also doesn't want to lose sight of the 2 way dream!
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Why xover at 3khz with such a setup?
Something like an et703 a bit below 10khz would give 40khz high bandwidth and solve the breakup in the 4001.
In other word exactly why Tad developed the 703 initially. 😉
 
#12,254
There is a pretty simple reason why T60 increases with room size.… T60 being a widely used unity for reverb one should not have to explain that one 😊 . Classic reverb definition of course assumes diffuse field conditions, which rarely are met in living rooms below -say- 500Hz.
 
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#12,256
gedlee said:
I would strongly agree that "Classic reverb definition" of RT60 is ill applied to small rooms. They decay very fast compared to a large room owing to the shorter distance to the walls - the dominate absorption.
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Or in other words, far field and near field become basically the same.

RT60 ONLY is valid when there is adequate distance between source and receiver.

It was actually one of the first questions I asked when I just learned about RT60.
What happens to very small rooms? (like a bathroom).
Answer from general acoustics: you don't.

Small living rooms (like in Europe) are exactly for this reason often problematic.
 
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