Measured monopole and dipole room responses

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I think you are lacking a definition of transient.

Anyway who cares about decay since the attack may be much more important!

The thing is with real music like signals the room may never reach the steady state condition. Thus using steady state method of measurement is a poor choice.

The bursts will capture the transient behaviour, attack and release, of the room.

Never forget that when humans are included in analysis there allways will be number of subjects that shows the results which will not fit inside the confidence limit of the distribution of the results. Training is one of the most significant factors to make a difference, for example.

- Elias

I have no idea what the attached link is supposed to show, but you would have to go a long way to convince me that we can hear a transient for a sound with a period of 10 ms or more. And hearing the envelope is not the same thing as a transient. From all that I know what we sense at LF is a steady state sound. There were studies of "modal decay" in the AES which showed that people did not hear these decays. They heard the integrated sound level, i.e. a more steady state sound.
 
Hello,

Yes and Yes! This was excatly my starting point to do these tests. Because I can A/B/C switch monopole/dipole/dipole line array with digital cross over by a single button press right here right now, and I can hear big differences between them! Then, I started finding out the reasons behind it all. Now, I think I'm at the right track because I think the big difference can be found in the time domain!

- Elias


I think the fact that we can all hear the bursts is significant. It shows that there's more to bass than the steady-state condition. The bursts are similar to certain musical sounds so it's not an unrealistic test.

.. all this types of signals are not too far away from real music signals unless one were very limited in genres.
 
Very interesting experimental findings by the OP....but the debate reached no conclusion ??!!
For the following discussion, I will assume use of the bass units in a very large room, or an average sized room in a "common" house that has lots of doors and windows to be sufficiently leaky to not pressurize easily.

In my experience with Alpha 15 in Hframe, I have found that the transient natural mid bass achieved by these cannot be beaten by monopoles. However, although these sim on MJK sheets to be flat down to 41 Hz, I still miss the bottom end on most music and have to use another 15" (AE IB15) in a 120 liter MLTL tuned to 25Hz to do the bottom digging.

Now I want to have similar sound as above in a much smaller package with a single 10" woofer on each side. I am willing to compromise on efficiency and max SPL, but not on bass extension and midbass transients. Going active with LF equalization like Orion seems the only way out. But I want to keep it passive. So Hframe is definitely out of question. The only ways would be a Uframe cardioid like Nao woofer, or sealed woofer.

This brings me to the findings by the OP. It appears LF extension is difficult to achieve with Hframe but perhaps a little easier to achieve with sealed and stuffed Uframe aka cardioid. So although it is virtually impossible to have the same LF extension with sealed and cardioid in the same sized box, does somebody have experience with using both these (sealed and cardioid) with similar LF extension and comparing the bass transients ?

1)Does a cardioid with limited LF extension really sound better than sealed that will have lower extension than the same sized cardioid ?

2)AND, even if a cardioid is equalised to have same bass extension as the equal sized sealed, does it still have better transients ?

3)If a cardioid has better transients than a similar sized sealed, is it just because the stored energy and backwave seeping out of the woofer, smearing the transient of the sealed monopole that is shown in the RTA graphs by the OP ?

4) If the above is true, a sealed TL with line length of 1/4 wavelength of Fs that "transmits" away and absorbs the backwave completely, should have transients as good as a dipole or cardioid and also significantly better LF extension. This would be in line with the B&W Nautilus design. I wonder if the Nautilus has been A/B compared with a dipole for mid bass transient quality ??!!

The above only applies to the bass region, as in the mid to high frequencies where low end extension is not much of an issue, a dipole radiation pattern is unrivalled by its ambience and colourlessness.

Any thoughts please...
 
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Dredging this thread back up?

My position on this whole topic is quite different than most and has changed somewhat over the last couple of years.

First, I am talking about LFs where the modes are discrete and not anything above say 200 Hz. - those are entirely different issues and have to be dealt with seperately.

I have long believed that the "type" of sub makes no difference, and I basicaly still believe that, but I am now of the opinion that closed box subs, in multiple locations, are by far the most effective way to go. Everything else is simply more complex with no real advantage.

The modal region has to be EQ'd so just used closed box subs and EQ them. This approach can get as low as you care to go as long as the subs can handle the power and excursion and it can go as high as you care to take it as well. It can achieve any SPL that you are willing to pay the price for the drivers in terms of numbers of boxes or power handling. It works in any room with equally excellent results. The tuning of the boxs is irrelavent (its all EQ'd) and so all the talk of TS parameters, tuning, etc. become moot. It's a dirt simple (except for finding the required EQ) and it always works. Whats not to like?

The "transient response"? Do subs have a "transient response"? That's all above 200 Hz and does not apply here.
 
I have long believed that the "type" of sub makes no difference, and I basicaly still believe that, but I am now of the opinion that closed box subs, in multiple locations, are by far the most effective way to go. Everything else is simply more complex with no real advantage.

The modal region has to be EQ'd so just used closed box subs and EQ them. This approach can get as low as you care to go as long as the subs can handle the power and excursion and it can go as high as you care to take it as well. It can achieve any SPL that you are willing to pay the price for the drivers in terms of numbers of boxes or power handling. It works in any room with equally excellent results. The tuning of the boxs is irrelavent (its all EQ'd) and so all the talk of TS parameters, tuning, etc. become moot. It's a dirt simple (except for finding the required EQ) and it always works. Whats not to like?

The "transient response"? Do subs have a "transient response"? That's all above 200 Hz and does not apply here.
Transient response describes the behavior of a system following a sudden change in its input.
Transient response not limited to frequencies "above 200 Hz".

Many sub designs suffer from the persistence of cone movement or stored energy in the system after the signal has stopped, underdamped transient response.

In an A/B listening test with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

As far as "Whats not to like?" in a sealed sub, the added amplifier and transducer expense to achieve a similar LF output using a more efficient cabinet is a real concern for those not willing to pay the price required for inefficiency.

Art Welter
 
In an A/B listening test with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

Could you please describe that test in detail (location of sub and listener, type of test signal, method of equalization, blind or sighted listening, etc.)?
 
In an A/B listening test with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

Art Welter

So you are saying that the Fourier transform is not valid? Because if it is then the two systems with identical FR with have identical transient response.
 
Could you please describe that test in detail (location of sub and listener, type of test signal, method of equalization, blind or sighted listening, etc.)?
Subs equalized outdoors for the same target response through the passband of 40-120 Hz using a DBX Driverack PA, Smaart Magnitude response, one a small bass reflex, the other a bandpass box.

I was the listener and builder of both cabinets.
I am sighted.
 
Subs equalized outdoors for the same target response through the passband of 40-120 Hz using a DBX Driverack PA, Smaart Magnitude response, one a small bass reflex, the other a bandpass box.

I was the listener and builder of both cabinets.
I am sighted.

The exact curve of the frequency reponse particularly the roll off of the bottom end, that is the Q is what reflects the transient response...and to me seems very difficult to replicate by equalization in two different subs having different loading....unless very sophisticated means are used. Simmed or modelled FR curves might not be as close to real world radiated sound from the woofer.

Unless the Q and also the LF extension, after equalisation of the two differently loaded or not subs is exact, the subjective sound perception is bound to differ, due to differing Q of the system.
 
So you are saying that the Fourier transform is not valid? Because if it is then the two systems with identical FR with have identical transient response.
I never mentioned the Fourier transform being invalid, though perhaps you could elucidate your proposition that two different cabinet designs equalized for identical FR would have identical transient response.

One can equalize a Wurlitzer jukebox to have the same response as a sealed woofer, but they won't sound the same to my ears.
And obviously, a horn loaded woofer's transient would lag by the path length difference, though it's frequency response could easily be equalized the same as a sealed box.
Perhaps you are more sensitive to HOMs and I'm more sensitive to LF differences, to each his own ;).

Art
 
Subs equalized outdoors for the same target response through the passband of 40-120 Hz using a DBX Driverack PA, Smaart Magnitude response, one a small bass reflex, the other a bandpass box.

I was the listener and builder of both cabinets.
I am sighted.

And then you put them in a room and listened A/B? Where did you place them in the room and where was the listening position (was it always exactly the same)? Did you also take in-room measurements at the listening position?
 
I can't say that I have, but I do get JAES and I usually read papers that interest me, but I skip those that look like "old news". What do they say?

They look at low frequency reproduction not only from the perspective of magnitude response but they also look at the influence of modal decay. There seems to be a modal decay threshold that greatly influences the perceived quality.
They also looked at different sub configurations and how they perform. The systems reducing modal decay (like CABS) performed best.
 
They look at low frequency reproduction not only from the perspective of magnitude response but they also look at the influence of modal decay. There seems to be a modal decay threshold that greatly influences the perceived quality.
They also looked at different sub configurations and how they perform. The systems reducing modal decay (like CABS) performed best.
I find those papers pretty interesting. Unfortunately, they did not include any gradient woofer system in their tests like a dipole or cardio. Since they excite less modes and to a different degree, there is less energy in the room to decay to begin with. That doesn't change the decay properties of the room but the threshold is potentially reached faster.
Here is the link to the abstract:

AES E-Library Subjective Preference of Modal Control Methods in Listening Rooms
 
I find those papers pretty interesting. Unfortunately, they did not include any gradient woofer system in their tests like a dipole or cardio. Since they excite less modes and to a different degree, there is less energy in the room to decay to begin with. That doesn't change the decay properties of the room but the threshold is potentially reached faster.

I partly agree.

The problem with dipoles is their very, very low efficiency below Fequal. How to get 20Hz or even 10Hz at movie reference level (115dB SPL) out of a dipole?
 
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