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Old 19th March 2014, 03:42 AM   #21
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Chris, its fantastic that Mark does that, but he is bound to a higher ethical standard than any DIYer. I can trash peerless, scan speak, eminence, you name it all I want. They're more than welcome to come here and defend their products. Mark chooses to step out and engage, and that's great. But if a scan speak engineer can here and said "what do you DIYers know about mid woofers" I'd take issue with that. If another DIYer said "what does tux know about mid woofers" I'd blow it off. manufacturers and users are on different ethical levels and that seems to be forgotten with Mark.

I dare Mark or anyone else to find a post of mine where I have criticized his product without warrant. I have on a number of occasions criticized his measurements. I've also criticized measurements by other manufacturers. In fact, I've even recommended his products, recently!! And not just on this forum!!!! Just a couple days ago I suggested someone look into MA drivers for a desktop setup over on AVSforum.

So I state my case, this isn't a matter of Mark bashing, this isn't me hoping Mark is run out of business (as he seems to think is the case based on his post on his forum), this isn't about how his drivers sound. This is ALL about his measurements and his attitude towards DIY measurements which have been consistently negative for as long as I've had an interest in his products. If his measurements aren't reliable, who is he to say one way or the other how a DIYer should do theirs.
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Old 19th March 2014, 03:45 AM   #22
chrisb is offline chrisb  Canada
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Ryan - no issue with any of that.
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Old 7th April 2014, 12:51 PM   #23
xrk971 is online now xrk971  United States
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Some recent measurements of A7.3 by BMS:
Cheap and FAST OB, Literally
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Old 7th April 2014, 01:45 PM   #24
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I'll stick with my Fostex's.
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Old 7th April 2014, 02:16 PM   #25
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Quote:
Originally Posted by xrk971 View Post
Some recent measurements of A7.3 by BMS:
Cheap and FAST OB, Literally
Not that I have a problem with the measurements per se -- they are pretty much what I would expect, I have an issue with technique.

It is really bad practice to use a speaker as a stand for another speaker, particularly with the driver facing the microphone. It is easy to get sympathetic vibrations that can muck up the measurements.

Bob
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Old 7th April 2014, 02:59 PM   #26
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by tuxedocivic View Post
He just deleted the post for no given reason.
I have found that many of the commercial forums are places where you have to tread on egg shells.

I had a similar experience over on Greg Ball's forum recently. He released his schematic and I designed and built a superb surface mount PCB. I posted it in his forum in the thread dedicated to others building his amp. He deleted all my posts pronto without reason.

What do we learn from all this - DON"T TURN A HOBBY INTO A BUSINESS if you want to continue to enjoy it and talk freely about it !


p.s. I built a pair of Pensils with the A10.3 for a friend last year - these are the best full range drivers I have ever heard for clarity, imaging, dispersion and coherence, just simply superb (I've heard Fostex FE127, EL70, AN15).
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Last edited by Bigun; 7th April 2014 at 03:03 PM.
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Old 7th April 2014, 04:17 PM   #27
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I don't think it's a matter of treading on eggshells as much as appreciating that they are commercial. The commercial forums have been paid for by the various manufacturers / whatever, and are not the same as the open DIY forums such as this one. In general, they exercise far tighter control over what is posted on their forums, and if they deem something is not in their interest, they may well delete it. Simple as that. Personally, I don't think the demarcation between the open & commercial forums is as clear as it needs to be, since different mind-sets are generally required, but what the solution is, I don't know. What I do 'know' (well, I don't actually know, but I have a suspicion) is that like it or not, the commercial boys are probably needed to ensure the survival of the forum as a whole. Forums like DIYaudio.com don't come cheap.
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Last edited by Scottmoose; 7th April 2014 at 04:21 PM.
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Old 7th April 2014, 05:22 PM   #28
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I had no idea that the commercial forums were paid for, I just thought they were done as a courtesy towards the manufacturers as a way of increasing traffic for the website whilst also providing a legitimate place for people with commercial interests to post.

That said, the attitude of the manufactures towards postings, changes quite dramatically from forum to forum. This makes it hard to know what is okay or not okay to post. The way the guys from Twisted Pear handle their moderation is quite different from how Mark does. Mark appears to simply delete anything that could be construed as negativity towards his drivers, even if you're actually trying to be constructive in your criticism. Or rather when you simply want to discuss objective stuff, backed up by scientific reasoning and understanding - ergo without any kind of apparent agenda - it makes no difference. He simply tries to dismiss you and if you push the issue you're seen as having something against MA and boom, deletion.

I think treading one eggshells is a very appropriate comment.

Even over at the Acoustic Elegance forums people have posted threads questioning certain aspects of their drivers, where they are then met with technical discussion. Then if the threads aren't completely resolved they are simply left, even if it counts against them and certainly aren't deleted out of hand.
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Old 7th April 2014, 06:25 PM   #29
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Quote:
Originally Posted by Bob Brines View Post
Not that I have a problem with the measurements per se -- they are pretty much what I would expect, I have an issue with technique.

It is really bad practice to use a speaker as a stand for another speaker, particularly with the driver facing the microphone. It is easy to get sympathetic vibrations that can muck up the measurements.

Bob

I gotta agree with Bob that BuildMeSomething's data is not useful here. The IR screams reflections or Bob's astute recognition of a symathetic vibration. Those peaks in the IR aren't from the box, they're far to strong.

To claim a manufacturer's data isn't reliable, I need to be confident the data is clean and accurate. That means well away from boundaries and windowed to remove the rest of the reflections if necessary. Otherwise Mark is right, we aren't at his level and can't make these claims.
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Old 7th April 2014, 06:32 PM   #30
xrk971 is online now xrk971  United States
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I see the point about not having another driver nearby for the measurements but how much of an effect is that really? I have done measurements of the fullrange tops (as BMS) has also on an OB with the woofer right below in an inactive state. The impulse response and frequency response seem to be the same as when I measured it without the woofer directly below it. I think the reflections you see are so close they must be coming from internal reflections in the box and back out the cone. Perhaps more internal damping needed? I think the A7.3 if tested in the OB will not have the same early reflections.
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