by bordonbert Sat May 06, 2017 5:20 pm
Billgwx....
Interesting post for me. I've done a lot of research and testing on the beaming issue. There is so much myth and lies around the subject it is untrue, (errrm, should I say just alternative truth?
). The cause of beaming is easily explained according to strict correct Physics but that of course get's totally ignored in favour of "common knowledge" and "mojo"! Jay Mitchell, the guy who put forward the idea and gave us the "Mitchell Donut" foam ring solution, is a highly regarded guy in the audio world who runs his own audio company with a high end research and testing arm. He is loved and loathed in the audio community as he is a very straight talking guy, to the point of bluntness. I mean he takes no prisoners in a debate where incorrect information is involved. His Physics is always above question and debunking audio myths and exposing poor design and untruthful marketing claims is something he loves to do, an aim I share!
Beamblockers - shouldn't be allowed to be called that, they are physically unable to prevent beaming, they actually have to make it worse as they emphasise the difference between sound sources across a single speaker cone not reduce it! This is backed up in properly performed testing where the beaming can be seen to be exaggerated. They may make the sound better overall for a user, that is certainly a matter of taste, but it is due to other changes they may make and nothing to do with improved beaming. Simple Physics 101 shows that they can't work unless there is some new piece of Physics theory that they exploit which has not been made public, and the one fundamental scientific point that Weber says their action is based upon is laughably wrong! Ted Weber never commented on that one before he sadly died to my knowledge.
Mitchell donuts (what you describe) - the dog's bollocks for beaming! They actually address the beaming problem properly, according to the physics of what causes it. They are shown to be really effective in properly engineered anechoic chamber testing. They do have limitations. They can only work to their best advantage with a single speaker, multiple speakers do reduce the effectiveness, again down to the physics of the cause of beaming. This is the case for any attempted solution anyway, as beaming is caused by the addition of sound at a specific frequency from multiple points and speakers are multiple sound sources, multiple speakers cause beaming as do sound from single bigger speaker cones like our own favourite 12". And they alter the tonal balance a little as well which makes the results a matter of taste again but if you do it properly, not by so much that you can't compensate easily. And the whole idea was given to us with full disclosure of the theory and implementation absolutely for FREE! The Mitchell haters have never responded to criticise his explanation of the theory to my knowledge.
Don't want to hijack the thread so if anyone wants to point out anything else on that topic we'd best start a new thread for it.