Most of the time, I'm looking at amp specs, so I've gotten accustomed to the -3dB 'standard' which seems to be used when specifying frequency response.
I'm shopping for new speaker drivers these days.
Quiz:
One of the following speakers has a freq range advertised as (40Hz to...) and the other is advertised as (51 Hz to.....)
Can you guess which from the freq response curves?
I think I need some education here - please help!
I'm shopping for new speaker drivers these days.
Quiz:
One of the following speakers has a freq range advertised as (40Hz to...) and the other is advertised as (51 Hz to.....)
Can you guess which from the freq response curves?
I think I need some education here - please help!
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Well, for one thing, Mark's published specs are much more "conservative" than Fostex's from the past (AFAIK, the published specs for the 168Ez haven't been revised)
There's approx 10dB difference in the sensitivity between these two, as well as almost half an octave in the "published" Fs 21Hz for the Fostex and 36 for the Alpair 10.
Further, while this particular model of Fostex will perform very well indeed, it does want to see a larger enclosure of the BLH or Voigt pipe family, while the Alpairs work very well in much smaller ported enclosures, MLTL / Scott Lindgren's Pensils, or the "Fonken" style tuning.
Secondly, Mark intentionally designs a fair degree of compensation into his drivers FR. Have you actually heard any of them? It's only a 15min drive away.
Thirdly, I won't say published FR specs are meaningless, but you already own the most accurate and calibrated set of test gear you really need, and they're entirely portable. 😛
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Hi, Chris-
Thanks for the quick reply.
IF the Alpair curve is accurate and IF one were to use the -3dB convention, then the freq response should be 100Hz to..., no? And the Fostex driver should be about the same......
I really don't like to waste your time and Dave's any more than I have to; you've been quite generous in the past for little profit from me.
Calibrated and accurate?? My ears?? LOL...
Yeah, I know... that's why I have a pair of woofers under my 'Full Range' speakers in the Fonkens. So the bass specs of FR speakers are a definite interest......
;-)
John
Thanks for the quick reply.
I didn't say I 'believed' either of the curves, but the Alpair is something like 30dB down at 40 Hz...
IF the Alpair curve is accurate and IF one were to use the -3dB convention, then the freq response should be 100Hz to..., no? And the Fostex driver should be about the same......
I'm not criticising Mark's speakers- it's the general issue of published specs and how they are interpreted that I'm interested in. This comes up from time to time online- last time I was watching it was the AudioNirvana specs that were in question. At least Mark is apparently publishing accurate curves, which is a start.
I really don't like to waste your time and Dave's any more than I have to; you've been quite generous in the past for little profit from me.
Calibrated and accurate?? My ears?? LOL...
Yeah, I know... that's why I have a pair of woofers under my 'Full Range' speakers in the Fonkens. So the bass specs of FR speakers are a definite interest......
;-)
John
Trying to compare the two graphs is of dubious value. They've been measured differently, with different equipment, are of different resolutions, with different levels of smoothing applied, the drivers are of different sizes, different efficiencies, and with completely different design priorities.
I think you may have a fundamental misunderstanding of how a driver works. If you wish to confirm the Fs of a driver, you are better off checking the impedance graph to confirm the peak is at the stated figure (in both cases it is).
I think you may have a fundamental misunderstanding of how a driver works. If you wish to confirm the Fs of a driver, you are better off checking the impedance graph to confirm the peak is at the stated figure (in both cases it is).
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John:
accurate enough for your brain, which is wherein the calibration and signal processing occurs 😉
if it wasn't obvious before, I frankly don't get too stressed about driver specs or math (that's for the geeks, who are in abundance here, and always eager to "educate" us 😀 ) - it's certainly been my experience that one can hear what they see - my easy solution is to avoid understanding of the technical aspects and simply let the degree of my emotional reaction decide the matter - to each his own
the offer still stands to listen to any of several pairs of the Alpairs that are compact enough to travel ( I think you might like the 12s)
Yes, that's true...I was comparing the graphs to the manufacturer's interpretation of their own graph, not really to each other. Do we have a 'new standard' for frequency response in the speaker world, with -30dB defining the range?
You are definitely correct in that! For instance, 'Full Range' to me means what my somewhat worn ears can hear at a musical performance.
John
Off-topic...
Thanks, Chris. Very kind.
I'll probably take you up on the offer, as soon as I get a couple of things cleared away here.
Are the Alpair 12s on offer 'stock' or 'eNabled' ?
I'm interested in hearing how they do - the competition here is modest - Fonkens with FE167+woofers (biamped) and AudioNirvana10s, in a pretty small room.
John
BTW - to be clear (I'm not sure if there's an emoticon for the occasion), my use of the term "geek" in prior post (could have said "boffin" - but how many would get that?) is respectfully exactly the opposite of derogatory
This pair is EnABLed, in a rough (ie unfinished) prototype box. Small room would be perfect. Send me a PM to confirm convenient time.
Here is an overlay of the 2 with scales normalized to the Fostex chart. What happens in the bass is very heavily box & room dependent. Both of these were, i beliee, measured anechically, but i don't know what sort of enclosure. The "official standard" enclosures are certainly not optimized for bass or the drivers used in them.
dave
dave
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I would recognize the Fostex FE168E-Sigma anywhere. It looks like the mountains where I live 🙂 Fs of ~51Hz right on the money. The peak at 7k is audible but it seemed to calm down over time.
The Mark Audios are also outstanding and I couldn't choose between them. Efficiency and midrange magic vs. monster bass and beautiful extended treble. Get them both 🙂
The Mark Audios are also outstanding and I couldn't choose between them. Efficiency and midrange magic vs. monster bass and beautiful extended treble. Get them both 🙂
It's nothing to do with 'manufacturers interpretation.' You seem to be claiming that the drivers have a resonant frequency substantially higher than claimed -however if you care to study the impedance graphs, as I advised you to, you will see it is exactly where it is stated to be for both drive units. Resonant frequency does not imply the driver is flat to that point; the LF response shape of a drive unit / below mass controlled BW is a function of its electromechanical damping properties (& any Eq the manufacturer may have built into the response).
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None AFAIK; to the best of my knowledge both Fostex & Mark use IEC standard baffles for anechoic measurements.
I didn't mention 'resonant frequency' or impedance at all. That is not at all what I am talking about here.
It is quite simple: What is the meaning of the term 'Frequency Range'?
When a manufacturer states:
"Ultra wide frequency range (40Hz to 23kHz)",
what does that mean?
Does it mean:
Frequency Range (-3dB) 40Hz- 23kHz
or
Frequency Range (-30dB) 40Hz- 23kHz
or
Frequency Range (you can hear something) 40Hz- 23kHz
??
You seem to be taking the peak in the impedance curve as the 'marker' for the low end of the frequency range; how do you determine the high end of the range? Are you using some -dB spec there?
Low-frequency performance seems to be a particular challenge with small, full-range drivers. I'm sure I'm not the only potential buyer who looks at the low end spec right away. It's interesting that for the Alpair, the high end of the claimed frequency range is about -5dB and the low end is about -30 dB.
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The impedance indicates where Fs is (& any breakup modes for that matter); I thought it was fairly obvious why I refered to it. 'Frequency range' (viz. the functional BW of a drive unit) isn't a specification so the details will vary slightly depending on the manufacturer. Generally it will be taken from Fs to whatever minus point in the HF they use.
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The actual low frequency response is highly dependent on the enclosure. The resonant frequency is indicated by the impedance spike and is part of what one needs to determine response potential in different enclosures but is not enough. You need several other parameters.
When the response is stated for a raw driver I interpret it as an approximation of the usable range of the driver in a proper enclosure. Some enclosures will start to roll off above fs and some below fs depending on the other parameters of the driver.
So specifying a +/- dB range would be to imply a precision that is not possible absent a specified cabinet design so not very useful.
When the response is stated for a raw driver I interpret it as an approximation of the usable range of the driver in a proper enclosure. Some enclosures will start to roll off above fs and some below fs depending on the other parameters of the driver.
So specifying a +/- dB range would be to imply a precision that is not possible absent a specified cabinet design so not very useful.
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