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Romy the Cat

Boston, MA
Posts 10,076
Joined on 05-27-2004

Post #: 1
Post ID: 15534
Reply to: 15534
Mystery of bass horn calibration: Radiating Surface Deequalization

I initially meant to put this post into my midbass thread (linked above) but then I decided that the subjects is self-important and it worth to separate in standalone thread.  In fact this idea was formulated to months ago but I was holding to post it. I am still not absolutely convinced with correctness of my conclusions. I have a gut feeling that what I propose “might” be accurate but I have no way to confirm it at the level of absolute confidence.  At the absence of certainty I treat my feeling as an acceptable for myself working hypothesis. If you are an idiot and wish to have absolute certainty in everything then do not read me but read a self-help book for autopsy.  Ok, now when we filtered out 90% of Morons who too feeble and do not deserve to read farther I might explain what meant to explain.

Back in the midbass thread I wrote that my midbass horn is since mid of December is perfectly calibrate with ½ db precision and it does not sound like any other midbass horn I heard. It is not a statement of quality of midbass sound but rather my addition that it sounds different from any other horn I know. The main difference is that it has absolutely no sound reference to what topology used, location or anything that that indicate the presence of midbass channel. The midbass is just comes up when music call upon it, come from nowhere and goes to nowhere, what is VERY important that it come and does ONLY WHAT IT NECESSARY, never too much and never too little. This absolutely phenomenal precision of midbass execution I NEVER hears from any playback. Mind you that I am very critical and the references points are very high.

Sound like I am kissing ass of my midbass horns, doesn’t it?  It is does then feel free to believe that the purpose of my life is to make YOU to like my midbass horns, well, congratulation - you are a certifiable idiot. If it doesn’t and if you expect more then read on.

Over the course of the last 2 month I ask myself why my midbass sound so “interesting” and so differently. Surely the extreme narrow bandwidth is very much helps but there is something else that I did not divulge to you before and am willing to share now. If you read my late comments in the midbass horns thread that you might noted that I stated that did not use any measurements to fine calibrate of my midbass. Partially I lied. Of cause I did all necessary measurements but I absolutely discarded them. I did not have any sensible correlation between measurable and auditable and as result I use ONLY hearing to fine tune my midbass horns.  The measurements showed something absolutely ridicules. With all my experience in sound and with my absolute confidence that my midbass is within ½ db dean-on my measurements showed to me that I was 3-4dB short.

Over the last 2 months I many times set my midbass horn flat with my uppers bass and the rest of the system (I do not use lower bass channels during those experiments) and then again and again I was feeling the I had too much midbass and that my channel become to sound as an impressive audio horn.  Eventual I have capitulated and I left my playback with 3-4dB softer measuring but perfectly sounding horn.

Of cause it made me to think why it is so and if my specific experience is not a sign of something bigger then just my own case. So, thinking about is for a while I propose my hypothesis that I decided to call the Radiating Surface  Deequalization:   with lowering frequency and increasing the traducing surfaces  [larger mouth of horns]  relative to the room size the demand to amplitude equalization drops.

Take a look at the HF and cylindrical waves if you use any HF line-arrays then you know that you must stay a few dB under the level you would use with conventional single point tweeters. The higher frequency the stronger effect is. With lower frequency is look like if the size of the LF radiator approaches the dimensions of the room then it looks like similar that the effect takes place, those for different reasons of course.

I can’t not confirm how universal my hypothesis is, frankly I have no craving to do it. It works in my case and since most  of the midbass horns that I heard run too hot I feel that it might be an more widespread rule than my private case.  It might be that in my specials room and with my specific horn something else in work that makes my Radiating Surface Deequalization is an inspiration of my inflated imagination.  Well, it is what it is. I share my observation with you and you have a royalty-free reuse. If you do run a large-mouth midbass horn in your listening room then this article of mine might make you to think again about the Sound you are getting.

Romy the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 1 of 1 (1 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Midbass Horns and Real Estate...  Just a youtube video......  Horn-Loaded Speakers Forum     247  2098851  07-26-2009
  »  New  Macondo’s Midbass Project – the grown up time...  Vitavox 15/40...  Horn-Loaded Speakers Forum     455  2901553  05-20-2010
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