HT: Has anyone ever moved from high sensitivity speakers BACK to low sensitivity? - Page 23 - AVS Forum
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post #661 of 675 Old 11-30-2012, 01:51 PM
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This is a CSD chart for DE250 compression driver used in Pi horn designs followed by the NRT dome tweeter and RAAL ribbon used in Ascend Sierra Tower.







RAAL obviously has the shortest decay time. DE250 and NRT seem comparable to me.
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post #662 of 675 Old 11-30-2012, 02:00 PM
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Originally Posted by zheka View Post

This is a CSD chart for DE250 compression driver used in Pi horn designs followed by the NRT dome tweeter and RAAL ribbon used in Ascend Sierra Tower.



RAAL obviously has the shortest decay time. DE250 and NRT seem comparable to me.
The 1/6th smoothing on the DE250 can throw things off significantly.

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post #663 of 675 Old 11-30-2012, 02:03 PM
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It's kind of hard to tell because the scale is so different. Am I correct that the DE250 is being measured with a range of 20db and 3ms while the other two are at 36db and 1ms?

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post #664 of 675 Old 11-30-2012, 02:08 PM
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Originally Posted by mrlittlejeans View Post

It's kind of hard to tell because the scale is so different. Am I correct that the DE250 is being measured with a range of 20db and 3ms while the other two are at 36db and 1ms?
Yeah...the 1ms vs 3ms scale is a pretty drastic difference.

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post #665 of 675 Old 11-30-2012, 02:12 PM
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Originally Posted by mrlittlejeans View Post

It's kind of hard to tell because the scale is so different. Am I correct that the DE250 is being measured with a range of 20db and 3ms while the other two are at 36db and 1ms?

the time axes does not matter, it's in ms so you can see how long it takes for the signal to decay.

good catch about the dB scale though. I think it is 30dB vs 20dB floor.
so you are right, it is not easy to tell. the DE250 will look worse at -30dB level. the question is by how much.
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post #666 of 675 Old 11-30-2012, 02:25 PM
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Originally Posted by zheka View Post

the time axes does not matter, it's in ms so you can see how long it takes for the signal to decay..
In visual representation, it certainly does matter. Like I said, smoothing can make a big difference too.

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post #667 of 675 Old 11-30-2012, 02:32 PM
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zheka, can you find a energy vs time curve for the DE250?

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post #668 of 675 Old 11-30-2012, 02:46 PM
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Originally Posted by cschang View Post

zheka, can you find a energy vs time curve for the DE250?

I could not. we may have to ask BWalso, since he's done extensive testing of the DE250 and its clones
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post #669 of 675 Old 11-30-2012, 02:47 PM
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BW?

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post #670 of 675 Old 11-30-2012, 02:49 PM
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Originally Posted by cschang View Post

In visual representation, it certainly does matter. Like I said, smoothing can make a big difference too.
I agree about smoothing. it's not clear what smoothing was applied on the Ascend charts, but if I had to guess it is probably less than 1/6 octave
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post #671 of 675 Old 11-30-2012, 02:51 PM
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post #672 of 675 Old 11-30-2012, 02:58 PM
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Originally Posted by zheka View Post

I agree about smoothing. it's not clear what smoothing was applied on the Ascend charts, but if I had to guess it is probably less than 1/6 octave
No smoothing on the Ascend charts/measurements.

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post #673 of 675 Old 11-30-2012, 03:29 PM
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Originally Posted by zheka View Post

This stands to reason. But if you were to measure spectral decay in room, you would probably find that 0.3 ms difference between the tweeter and the ribbon in Sierra Towers is insignificant compared to the influence of the room. So the explanation for the difference in sound may have to be found elsewhere.
But I maybe way wrong here. At least this is a measurable difference unlike the HOM explanation Geddes is pushing.

zheka,

Correlation is not causation, but it just seems to me that time domain performance is an area where direct radiators tend to outperform CDs and may explain what some people are hearing. Just how senstive the human ear is to these differences, I don't know. It would be an interesting study, to say the least. It would be difficult to control the other variables, though. Perhaps the best you could do is conduct controlled listening tests with a horn loaded speaker with an active crossover and use different CDs with different diaphragm materials. At least in this case the on and off axis responses could be kept as close as possible.

I must confess I am not a horn guy, but I am capable of being persuaded. For example, the Danley Synergy Horns intrigue me and I would really like to hear them. They are ugly suckers, though.

Cheers,
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post #674 of 675 Old 11-30-2012, 06:03 PM
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Originally Posted by OldMovieNut View Post

zheka,
Correlation is not causation, but it just seems to me that time domain performance is an area where direct radiators tend to outperform CDs and may explain what some people are hearing. Just how senstive the human ear is to these differences, I don't know. It would be an interesting study, to say the least. It would be difficult to control the other variables, though. Perhaps the best you could do is conduct controlled listening tests with a horn loaded speaker with an active crossover and use different CDs with different diaphragm materials. At least in this case the on and off axis responses could be kept as close as possible.
I must confess I am not a horn guy, but I am capable of being persuaded. For example, the Danley Synergy Horns intrigue me and I would really like to hear them. They are ugly suckers, though.
Cheers,
OldMovieNut
I appreciate your reply, OMN.

A good way to measure importance of spectral decay for HF drivers would be by using DSP to artificially extend it. I think it can easily be performed as a double blind test. The subjects would be asked to tell apart naked RAAL response for example vs one with the decay time doubled or even tripled.
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post #675 of 675 Old 11-30-2012, 07:11 PM
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Quote:
Originally Posted by OldMovieNut View Post

zheka,
Correlation is not causation, but it just seems to me that time domain performance is an area where direct radiators tend to outperform CDs and may explain what some people are hearing. Just how senstive the human ear is to these differences, I don't know. It would be an interesting study, to say the least. It would be difficult to control the other variables, though. Perhaps the best you could do is conduct controlled listening tests with a horn loaded speaker with an active crossover and use different CDs with different diaphragm materials. At least in this case the on and off axis responses could be kept as close as possible.
I must confess I am not a horn guy, but I am capable of being persuaded. For example, the Danley Synergy Horns intrigue me and I would really like to hear them. They are ugly suckers, though.
Cheers,
OldMovieNut

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