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Old 27th April 2011, 02:54 PM   #11
infinia is offline infinia  United States
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Quote:
Originally Posted by Bob Brines View Post
However, you could probably reverse engineer them ...:
Bob
yes esp since you provide Fb minima on your impedance chart ie probably not too much different than a slot loaded BR implementation given actual driver T/S specs.

there are some whoop-de-doos on the impedance chart. are those a concern for this design? maybe the big one is typical for outer edge suspension resonance? maybe most OEM charts try to smooth those over. haha

BTW Nice work and measurements there !
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Old 27th April 2011, 03:37 PM   #12
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Originally Posted by infinia View Post
there are some whoop-de-doos on the impedance chart. are those a concern for this design? maybe the big one is typical for outer edge suspension resonance?
I am reasonably sure that the dip at ~1500Hz is the edge reflection. Note also the the FR drops ~3dB at this point. That is a design feature of MA drivers. They have built in both BSC and a BBC dip. The speaker was free standing with no filters for these measurements.


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maybe most OEM charts try to smooth those over. haha
Yes and no. I realize that some here want to see raw data on the assumption that smoothing hides something. So what you get is a lot of noise, room reflections, etc. What I presented was ~1/50th octave -- a course as my instrumentation will allow. I use 1/12 octave smoothing for my design work and the awful fact is that you can't here anything more detailed than 1/6 octave. The brain simply applies its own smoothing.

One "trick" that manufactures are want to play is to use an excessively extended vertical scale. Tang Band uses 0-100dB and plots the impedance on the same graph. That means you can't see detail in either trace. I use a 50dB scale on my web site.

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BTW Nice work and measurements there !
Thanks.
Bob
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Old 27th April 2011, 03:47 PM   #13
infinia is offline infinia  United States
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Yes I appreciate more resolution except when it starts to look like noise, then trends are lost. I think your settings are perfect for my taste.
I was just wondering about the magnitude of the edge resonance how it compares to other FR drivers of similar Sd range? But calling it a designed in feature makes me wonder even more. where things dip they usually rise somewhere else. drive levels et al

Yes that's funny (not) about Tang Band vertical scale, my sentiments exactly!
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Last edited by infinia; 27th April 2011 at 04:10 PM.
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Old 28th April 2011, 04:06 AM   #14
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I'm going check it out. Should be a great time.
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Old 28th April 2011, 04:19 AM   #15
sonidos is offline sonidos  United States
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This will be my first. I'm looking forward to listening to some great systems!
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Old 28th April 2011, 05:32 AM   #16
ttan98 is offline ttan98  Australia
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Quote:
Originally Posted by Bob Brines View Post
The first graph is the FR. 0.5m, SPL is relative.

Colors:
White=0*
Red=10*
Blue=15*
Green=30*
Yellow=45*
Violet=60*

Second graph is impedance

Waterfall

THD

Colors:
White=1
Red=2
Blue=3
Green=4
Yellow=5
Violet=6

Enjoy,
Bob
Bob,

In most cases, the on axis freq. response of FR driver rises when the freq. increases(after 6-10kHz). Your FR driver is no different, the on axis response at about 10kHz rises above 15dB from mid-band say 3kHz. On a traditional 2 or 3 ways speakers, this type of rising response seldom occur, not preferred and hence not design for. Why is this kind of rising response tolerated in FR speakers? Would'nt I hear the rising response if I listen to them on axis? In fact my small FR has this kind of rising response, I can heard the rising response(a bump at around 8khz +5dB) hence I have to insert a notch filter.

I am quite puzzled.
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Old 28th April 2011, 01:31 PM   #17
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Originally Posted by ttan98 View Post
....I am quite puzzled.
First of all, FR speakers are never listened to on axis. Sound stage and imaging are usually best with the speakers toed in. I find that most of my speakers are best placed in an equilateral triangle and toed in to fire over the opposite shoulder -- ~15*. This is generally true of multi-way speakers also. So if you multi-way is voiced flat on axis, it is going to be something like 10dB down 15* off axis.

I had a discussion with Mark Fenlon about the strong response at 10kHz and he said that this is a design feature. WAF often dictates that the speakers be square with the walls. This makes the speakers toed out something like 30*. Look again at the 30* trace.

If you are listening more than 2m from the speakers, the high end begins to attenuate due to atmospheric absorption.

Many who use FR speakers also use low power SET amps that are weak at the top.

While many FR users abhor passive filters, if the exaggerated top bothers you, you can always apply a low-Q notch filter.

Bob
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Old 28th April 2011, 08:34 PM   #18
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Quote:
Originally Posted by Bob Brines View Post
First of all, FR speakers are never listened to on axis. Sound stage and imaging are usually best with the speakers toed in. I find that most of my speakers are best placed in an equilateral triangle and toed in to fire over the opposite shoulder -- ~15*. This is generally true of multi-way speakers also. So if you multi-way is voiced flat on axis, it is going to be something like 10dB down 15* off axis.

I had a discussion with Mark Fenlon about the strong response at 10kHz and he said that this is a design feature. WAF often dictates that the speakers be square with the walls. This makes the speakers toed out something like 30*. Look again at the 30* trace.

If you are listening more than 2m from the speakers, the high end begins to attenuate due to atmospheric absorption.

Many who use FR speakers also use low power SET amps that are weak at the top.

While many FR users abhor passive filters, if the exaggerated top bothers you, you can always apply a low-Q notch filter.

Bob
I suppose a little peak in a full range helps the off axis response. But not 15db+(!). Even at 2m in a highly damped room this will saw off most ears. Well at least mine. This particular Markaudio driver was designed for hippies with blown out ears. Or the ones who read these threads on the forums and follow certain gurus and take what they say for gospel.

This frequency response is not high end audio. However, I must admit that for short listening periods on certain types of music it will sound more detailed and hence "better", when compared to speakers with a flatter response. This is the business end of speaker design.

I don't blame Mark one bit as he's giving diyers' what they want or at least think they want. And to his credit he offers other drivers with a flatter response.
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Old 28th April 2011, 08:41 PM   #19
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And?

Rather than venting your spleen here, perhaps you might want to have this discussion with Mark.
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Old 28th April 2011, 09:00 PM   #20
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Originally Posted by ultrakaz View Post
I suppose a little peak in a full range helps the off axis response. But not 15db+(!). Even at 2m in a highly damped room this will saw off most ears. Well at least mine. This particular Markaudio driver was designed for hippies with blown out ears. Or the ones who read these threads on the forums and follow certain gurus and take what they say for gospel.

This frequency response is not high end audio. However, I must admit that for short listening periods on certain types of music it will sound more detailed and hence "better", when compared to speakers with a flatter response. This is the business end of speaker design.

I don't blame Mark one bit as he's giving diyers' what they want or at least think they want. And to his credit he offers other drivers with a flatter response.

Keep in mind that this is not a finalized design......as Bob stated the graphs include no filtering. Ultrakaz.....if your strong opinions are to be taken seriously please offer up your iteration of high end audio for the coin it takes to build Bob's TLs. I myself have heard 4 of Bob's designs, including my own FB20's, and all are no less than exceptional. Thanks for the teaser Bob....looking forward to hearing them.
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Last edited by steviedon; 28th April 2011 at 09:09 PM.
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