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Old 4th August 2009, 01:04 AM   #101
sendler is offline sendler  United States
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Default Clean above 1k

Why do you think all of the charts become suddenly clean above 1k? Is it the woofers cone diameter getting directional? A limitation in the measurement scheme? Or, just that all of the important differences between dipole and monopole are over with above that frequency?
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Old 20th August 2009, 09:11 AM   #102
Elias is offline Elias  Finland
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Diyaudio is back, nice
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Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
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Old 20th August 2009, 09:22 AM   #103
Elias is offline Elias  Finland
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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

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Originally Posted by gedlee View Post
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.
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Old 20th August 2009, 09:31 AM   #104
Elias is offline Elias  Finland
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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!

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Originally Posted by catapult View Post
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.
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Originally Posted by KSTR View Post
.. all this types of signals are not too far away from real music signals unless one were very limited in genres.
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Old 2nd October 2012, 08:51 PM   #105
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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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Old 2nd October 2012, 10:21 PM   #106
gedlee is online now gedlee  United States
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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.
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Old 2nd October 2012, 10:36 PM   #107
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Earl, did you follow the Fazenda papers in JAES?
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Old 2nd October 2012, 10:45 PM   #108
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Quote:
Originally Posted by gedlee View Post

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
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Old 2nd October 2012, 10:54 PM   #109
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Originally Posted by weltersys View Post
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.)?
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Old 2nd October 2012, 11:29 PM   #110
gedlee is online now gedlee  United States
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Quote:
Originally Posted by weltersys View Post
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.
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