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Old 26th February 2014, 10:47 AM   #1
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Default Future testing, data analysis and presentation

Hello Guys,
There's been some discussion and debate of a thread in the Full-Range forum debating issues of data presentation and analysis. The Alpair 7 features in the thread some polarised argument on the information relating to its performance. Sadly we know that data varies allot between the various makers. There's no single set standard for how drivers should be measured and how/what driver data should be published.

These issues are timely as we're about to upgrade our anechoic chamber facilities in our new workshops. The new dedicated anechoic chamber will be quite large (12.5 metres long X 8.5 metres wide X 5.5 metres high. Fingers crossed on finance, we will also consider investing in a new test system (Linear X500, Clio 10 et al.)

New drivers like the Alpair 12W, Alpair 7P, CHS70, Woofer No. 6 replacement and the Alpair 8 are being researched and tested, so using a new chamber and equipment could apply to these drivers.

So I'm open to ideas, seeking views and feedback from Markaudio driver users and forum members on these issues:

1 - Data testing (frequency and impedance). How much illustrated range is needed? What level of detail is sensible?

2 - Data presentation Type of graphs, scales and smoothing.

3 - How much should end users rely on published data?

4 - Home testing, what's good, what's not so good and what can be done to get reliable results. This topic is also important as I'd like to invite those members with a credible set-ups to become "testers" of the new drivers, to make their own tests and make the outcomes available.

On the conduct of this thread, we know these types subjects can generate some "heated" responses. Feel free to put your points across and debate with gusto; But no-below the belt stuff by personalising an argument, deal with the issue rather than attacking the integrity of the individual in an effort to win a point.

I'm keen to read any thoughts, opinions etc as i'll be doing much work in the coming weeks/months on facilities and equipment that I hope can best serve your needs.

Cheers
Mark.
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Old 26th February 2014, 11:21 AM   #2
xrk971 is online now xrk971  United States
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Mark,

Great idea to start a new thread to address testing of drivers both by the manufacturer and home testing.

Regarding data presentation, I think 50 dB dynamic range from 60 to 110 dB with major tic mark increments of 5 dB (minimum resolution).

No more than 1/12 octave smoothing.

Harmonic distortion data with up to 5th harmonic should be presented alongside frequency response or in separate graph.

Frequency response at 0 deg, 15 deg, 30 deg, 45 deg, 60 deg (5 minimum).

Also, if possible a very near-field measurement of a bare (no baffle) suspended driver with mic about 1 inch from the cone can be very useful to see the inherent HD present in the frame, membrane, etc.

I would be more than happy to "test" your new drivers - you can see the type of data I provided in the thread that led to all this.

Thanks,
xrk971

Last edited by xrk971; 26th February 2014 at 11:24 AM.
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Old 26th February 2014, 11:24 AM   #3
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Hi Mark,

Thanks for asking! Besides the common T/S data I'd like to see distortion at increasing levels until the driver starts to compress and full polar data. The user should be able to download original impulse responses for further examination. Are you willing to share that kind of data? If yes we could discuss details.

Hi Markus,
Thats one of the reasons to start this thread, to see what the bulk of members want and how extended information can be sensibly presented in the competitive world of driver making.

Sadly I see no way in taking more contributions from you on this thread in view of your conduct on the Full-Range thread. You were doing OK until you got into the business of attacking my professional integrity in order to hammer home your particular agenda. Comments that included the word(s) "misleading" are below the belt. There's no point to me entering a discourse with you, while you attempt to discredit Markaudio.

Mark

Last edited by markaudio; 26th February 2014 at 12:50 PM. Reason: Adding reply for ease of reading
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Old 26th February 2014, 12:31 PM   #4
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Quote:
Originally Posted by xrk971 View Post
Mark,

Great idea to start a new thread to address testing of drivers both by the manufacturer and home testing.

Regarding data presentation, I think 50 dB dynamic range from 60 to 110 dB with major tic mark increments of 5 dB (minimum resolution).

No more than 1/12 octave smoothing.

Harmonic distortion data with up to 5th harmonic should be presented alongside frequency response or in separate graph.

Frequency response at 0 deg, 15 deg, 30 deg, 45 deg, 60 deg (5 minimum).

Also, if possible a very near-field measurement of a bare (no baffle) suspended driver with mic about 1 inch from the cone can be very useful to see the inherent HD present in the frame, membrane, etc.

I would be more than happy to "test" your new drivers - you can see the type of data I provided in the thread that led to all this.

Thanks,
xrk971
Hello XrK,
Many thanks for these comments. Hope others comment similarly so we can start to get an overall picture of whats wanted.

Re the ultra near-field measurement, please can you give more detail (testing voltages, frequency spread etc). How would such data stack up against other makers presentation?

Re testing, sounds interesting, please tell us more about your testing methods, non-anechoic, semi or full anechoic, gear used.

Cheers
Mark.
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Old 26th February 2014, 12:57 PM   #5
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A very good idea, and I'm sure whatever our own views on the details of the data decided upon (since there is naturally going to be some difference of opinion), we'd all agree on one point: kudos to Mark for being, as far as I'm aware, the first manufacturer to ever actually ask users what they'd like.

OK. Starting point / some general thoughts from me.

-Ideally a 50dB dynamic range would be nice, but I think we need to be somewhat realistic on this point. It's fine for something like a midbass or tweeter, which are, relatively speaking, BW limited and somewhat easier to develop. A wideband drive unit, which relies on controlled oscillation to produce much of its HF output, is not going to have as flat a response as one of the aforementioned in their nominal (since that's a bit of a nebulous concept) piston range. That's the simple truth of the matter. Now, great if Mark's willing to do this, but we should also have a mind to commercial considerations & try to view it from MA's perspective also. Nobody else producing drivers of this type does that, with the arguable exception of a couple of tiny Vifas, and some of their larger units which, notwithstanding nomenclature, are more midbass drivers being driven very hard & in most cases are unlikely to be run wide-open. MA is a business that needs to sell product to survive, not a charitable institution, ergo providing data that deliberately makes the units appear inferior at first glance to laypeople / those with less experience, in comparison to rival products with data presented with a wider dynamic range and / or heavy smoothing, is at best very risky to sales. This is not about pulling the wool over people's eyes: if the scales & details provided, that by definition isn't happening. But it's also basic common sense and commercial reality.

-My own view, which I have expressed elsewhere, is that the current dynamic range[s] used are too broad, largely because it can lead to mistakes / misunderstandings. For the above reasons, I'd be cautious about 50dB total, but some reduction might be a good idea.

-One possibility: use a similar range to that employed over on Zaph Audio, since you don't find many complaining about that. John appears to use a 90dB dynamic range (35dB - 125dB). Since he is regarded as the objectivist Vulcan amongst the DIY / semi-DIY crowd, is widely respected for this, & his data is regularly used & accepted as a baseline comparative value with the kind of equipment that most serious DIYers could realistically aspire to, this may be a useful guideline / baseline for data sans smoothing.

-50dB dynamic range as noted above would be great providing it's anticipated that no drivers will be sold other than to those familiar with the general type and are able to make realistic comparisons to rather more heavily massaged data. This does not seem a realistic thing to ask, unless it's accompanied by something else.

-If 50dB dynamic range (very small for wideband drivers sans smoothing) is insisted upon for frequency response plots, I would suggest providing two sets; one that is smoothed to 1/6 octave so it's a reasonable equivalent to that seen from other manufacturers producing wideband drivers, and less likely to send those unfamiliar with this type of driver running away screaming, and one that is raw.

-0, 10, 15 & 30 degrees axis measures off would be very useful. I'd question if more than 45 degrees off is of any value for wideband drivers. I can see the value of out to, say, 60 for tweeters / midbass units since it has some value for XO design, but single driver types? Rather less.

-Harmonic distortion plots. Not THD, it's worthless, but 2nd, 3rd, 4th & 5th. If you can take it out to 7th, well & good but higher than 5th is rarely needed.

-Waterfall plot

-Polar response plot

-Measurement conditions (chamber, system, microphone used) listed

-Based on what I know of it (so I speak under correction), I would like to see Clio 10 employed if possible. The new version of LinearX will no doubt be excellent, but it's been 'coming soon' for several years, I've not seen any indications it might be released in the immediate future, & presumably we don't have confirmation on its feature set either. Clio is available, widely respected (so you're not likely to hear many people whinging about inadequate hardware) and has a huge feature set. Assuming compatibility with whatever your other hardware is & it can do the extra things you as a manufacturer will presumably wish / require, it looks to be the best thing out there.
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Old 26th February 2014, 01:04 PM   #6
xrk971 is online now xrk971  United States
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Mark,
The super near field is something new I just tried and as far as I know, not performed or shown by any manufacturer - so it would not be used for comparison with other vendors at this point. What I think it helps the user to see are the inherent resonances present in the mechanical structure if the driver without any effect of the baffle or speaker it is mounted in. It's like ringing a bell to see its natural resonances. With the mic being so close the SPL is rather high and I set the drive voltage to provide approx 10 to 20 dB of headroom. The info from this kind of data gives an indication of how well damped the frame or basket is, whether or not the suspension has inherent resonances that may contribute to HD peaks. Ideally one would like to see the HD plot to not have peaky resonances and be flat or broad. It is not a big deal but useful if you are able to provide.

I have a calibrated Dayton UMM-6 mic, a PC laptop running REW, several class A/B and class D amps, lots of speaker enclosures and open baffles for testing, and a dedicated speaker lab about 20 ft x 24 ft x 9 ft ceiling with carpeted floors - not anechoic by any means. But with proper orientation and speaker and mic placement I have been able to avoid major reflections.
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Old 26th February 2014, 01:29 PM   #7
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Quote:
Originally Posted by markus76 View Post
Hi Mark,

Thanks for asking! Besides the common T/S data I'd like to see distortion at increasing levels until the driver starts to compress and full polar data. The user should be able to download original impulse responses for further examination. Are you willing to share that kind of data? If yes we could discuss details.

Hi Markus,
Thats one of the reasons to start this thread, to see what the bulk of members want and how extended information can be sensibly presented in the competitive world of driver making.

Sadly I see no way in taking more contributions from you on this thread in view of your conduct on the Full-Range thread. You were doing OK until you got into the business of attacking my professional integrity in order to hammer home your particular agenda. Comments that included the word(s) "misleading" are below the belt. There's no point to me entering a discourse with you, while you attempt to discredit Markaudio.

Mark
I have no "particular agenda" I would want to "hammer home" other than obtaining meaningful data from a manufacturer. I've found your data misleading the way it was presented by a vendor (planet10). If it helps, I do find the data presented by other manufacturers/vendors and publications inadequate and therefore misleading too and I have good arguments why that is.

I was under the impression the intend of this thread is to learn why people might feel this way and improve on what data should be shown and how it is presented. If you're not interested in what I have to say, I'll respect your wish and stay away but how do you want to gather meaningful answers to your questions if you have already made up your mind about who is allowed to respond and who is not?

Hi Markus,
I have some sympathy with your general direction. Much as I try, I can't fight the whole industry, Markaudio has to live in the real world when presenting data. On the Full-Range thread, you've used Markaudio as a "whipping boy" to push your point of view, taking no account of the reputation damage you do to a very small maker, the only driver manufacture who actually listens to end-users, so your presence on this thread is bound to be considered hostile and therefore not welcomed.

You are very strident, believing that only you have the answers, that only your perspective is correct. Its time to give other members breathing space to express their views in a more positive atmosphere. Past experience has taught me that your type of commenting style does nothing to help gain a collective consensus on how to improve issues that affect forum members and end users.

I hope you'll take the time to get to know the Alpair 7. Its a well respected driver, many end-users around the world enjoy using them. I wish you all the best with your future projects.

Mark.

Last edited by markaudio; 26th February 2014 at 03:27 PM. Reason: adding reply for ease of reading
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Old 26th February 2014, 02:49 PM   #8
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Quote:
Originally Posted by xrk971 View Post
Mark,
The super near field is something new I just tried and as far as I know, not performed or shown by any manufacturer - so it would not be used for comparison with other vendors at this point. What I think it helps the user to see are the inherent resonances present in the mechanical structure if the driver without any effect of the baffle or speaker it is mounted in. It's like ringing a bell to see its natural resonances. With the mic being so close the SPL is rather high and I set the drive voltage to provide approx 10 to 20 dB of headroom. The info from this kind of data gives an indication of how well damped the frame or basket is, whether or not the suspension has inherent resonances that may contribute to HD peaks. Ideally one would like to see the HD plot to not have peaky resonances and be flat or broad. It is not a big deal but useful if you are able to provide.

I have a calibrated Dayton UMM-6 mic, a PC laptop running REW, several class A/B and class D amps, lots of speaker enclosures and open baffles for testing, and a dedicated speaker lab about 20 ft x 24 ft x 9 ft ceiling with carpeted floors - not anechoic by any means. But with proper orientation and speaker and mic placement I have been able to avoid major reflections.
Hello X,
Interesting idea. Let me give it some thought as to how it could be implemented. Others will hopefully comment on this idea of yours.

Your home testing set up sounds promising. You've given the isolation challenge some thought - well done for this effort. Can you post some pics, would be really helpful - thanks.

Cheers
Mark.
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Old 26th February 2014, 03:44 PM   #9
xrk971 is online now xrk971  United States
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Do you mean photos of the bare driver ultra-nearfield test setup?
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Old 26th February 2014, 04:14 PM   #10
dewardh is offline dewardh  United States
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Originally Posted by xrk971 View Post
What I think it helps the user to see are the inherent resonances present in the mechanical structure if the driver without any effect of the baffle or speaker it is mounted in.
I'm not seeing any usefulness to that, since I would be very unlikely to use the driver "un-mounted". I say that BTW as one of the few who actually has . . . the midrange in my ORION was magnet-mounted (the only plausible alternative). Since the driver is unlikely to ever be used in other than a basket-on-baffle configuration (with the damping/reinforcing that provides) I don't see what useful information is gained from the test.
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