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Playback Listening
Topic: About HF Binaurallism

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Posted by Romy the Cat on 11-27-2010

Sine I finished the acoustic room treatment and the final setup of my playback in my new room I got good Sound. There are some minor aspects with which I will be working on – I know exactly what I need to do but they will be minor and incremental moves for minor  targeted improvements. The whole sound was very nice, very soft and kind but powerful and authoritative – my type of Sound.

Suddenly 4 days ago I turned playback and heard some very ugly “harsh frequency pushing”, with horribly hard of upper range. It sound was like I have a pair of Spectral amplifiers and some of those cotemporary high-tech speakers. There were HF in there but they never mixed with midrange. If violas need to pick thyme from fist violins then they sound like they come from two different orchestras where one is tune is different scale.  I did a lot of changes in my playback during the last 2 weeks but whatever I use was well tested by me and shell not produce this result. I was even blaming my new PP2000, in fact I was blaming everything imaginable. Over the last 3-4 days I was retesting everything imaginable trying to find out what got broken and was not able to find.

They today I paid attention that there was a position in my room, right next to my listening chair where I was turned my head and suddenly I go back my wonderful soft and kind Sound. Sure, the farther research indicated that my right tweeter was disconnected.

This was very interesting. For the last 5 days I have my playback operating juts with one tweeter and I gave me that super hard sound with very harsh unbalanced HF, not excessive HF but unbalanced and unused HF. That effect I was absolutely did not expect. However, upon the further thinking I concluded that in my playback an absent of one tweeter creates a unique phenomena of HF time miss-alignment. I will explain the nature of it, I never seen it described, as this knowledge is a powerful tool for playback debugging.

I have a single tweeter in left channel that crossed at 12.5K with third order. Since the tweeter sits on extreme left then it signal arrive to left and right ears with delay, it is alight for left ear but arrive with delay to right one. They brain apparently can’t not compute it all together and it destroys all sound. Now we have another tweeter on the right. Now the right tweeter arrives to the right ear at the same time as left tweeter arrives to the left ear. Furthermore, each tweeter title own ear and overrides the signal from the tweeter of other channels, creating sort of HF Binaurallism.

As you understand I got hooked on the idea and made a number of interesting experiments. With R and L channels tweeters are matched at arrival with .25dB precession the sensitivity of hearing to HF dropped. It means that I am able to driver my tweeters + 3-4dB with no negative impact, in fact with a lot of positive impact. As soon I match the R and L channel tweeters with 1dB precession then I begin to feel discomfort with each 1dB at HF manipulation.

This discovery opens at a lot of room for taking advantage for those few people who are use playback thinkfully and creatively. For them I dedicated this post. I did fix my problems with Sound but I did not pay attention for acoustic matching of my tweeters. I use the clicks on my amps, presuming that it will be fine. It is not and my saga of the last 4 days do clearly indicates it.

Rgs, Romy the Cat

Posted by Romy the Cat on 11-28-2010

In a few weeks the series of this post about this subject will be lost among other posts. Still the readers of my site who read my site regularly are able to put together the number of the posts from other threads, particularly those: 

…and a few others.

Following the path of the thoughts that I went over the last two weeks you mish to view the current thread in context of the other subjects. What I can tell you is that my discovery of practical implications of binaural nature of HF has a remarkably high practical impact. For instance this weekend I was able very dramatically to change the width of Macondo presentation just by tuning the precisions R and L channels of Macondo MF and HF. It is not just the width itself but the way how Macondo deal with width – very interesting and positive impact what I went to 0.1dB matching.

The most important is that I learned how and what to listen in sound in order to get an instant recognition of time discrepancy that come from asymmetry of the R and L channels.  Interestingly that I do not call for symmetry but I do call for absolute absence of time discrepancy distortions caused by HF asymmetry…

Very education time and very good practical results.

The Cat

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