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Hi-Rez Highway: Re: The reality of figure of 8 microphones: by regreene New high resolution SACD releases, players and technology. |
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In Reply to: Re: The reality of figure of 8 microphones: posted by Jean-Marie Geijsen on July 30, 2005 at 17:59:09:
I have limited time at this very moment, so I cannot respond to all of Mr. Geijsen's interesting remarks. I shall return to this later, if I may.
But I do want to clarify one point. When I was talking about the moving away from the central axis with the same pink noise signal in each of two speakers, I was trying to give people a way to hear time-delay comb filtering, not commenting on stereo playback itself. This was not very clearly expressed perhaps. The point is that when one listens to the same source with a time delay, as when picking up a live (single) source with spaced out microphones, comb filters are introduced when the microphone signals are combined subsequently.
It is of course the case that stereo playback itself introduces time delays when one moves off the central plane.Let me suggest a test. Imagine walking across a stage carrying a pink noise source and that this source is going to be recorded.
If you record with a Blumlein pair, there is no time delay and all that changes is the relative intensity of the signal in the two channels. If you record with two (say) spaced omnis, then each microphone will pick up the same signal with slightly changing intensity but very substantial time delays.Now imagine playback. In the Blumlein, the two speakers are playing each an uncolored signal with no time differential. The ear/brain is receiving no time information but is locatiing the source by intensity stereo. As it happens, up to around 1500 Hz, the signals combine around the head to give almost exactly the phase and frequency response that would have happened in reality. In the higher frequencies, reconstruction is not perfect on account of head shadowing effects, but it is quite good.
Now imagine the spaced omni playback. When the signals arrive at the listening position, there are substantial time shifts. This moves the tonal character around.
You do not have to take my word for this. Buy J. Boyk's(Performance Recordings) test CD. This is a straight forward test. Recordings were made of click sounds from a collection of identical speakers spaced along a line. It is analogous to my walking across the stage.
Blumlein plays back to locate the clicks correctly and ALL THE CLICKS HAVE ESSENTIALLY THE SAME TIMBRE. But the spaced omnis not only locate the clicks in the wrong places, they also makes teh clicks from different locations sound quite different in timbre.
Of course, three mikes(with three channel playback) would do better. And even more would do even better. Indeed according to Huygens' Principle from physics if one had infinitely many mikes and channels and playback speakers one would end up with... Blumlein actually, for all practical purposes.
I know it is complicated to compute what happens with more than two mikes(mixed to two channel playback), although it can be done.
But one really cannot get the comb filters out once they are in.
Moreover, the test is very convincing. Everyone interested in this subject really ought to get this CD and listen.
As to time difference stereo: yes of course time differences shift images. But these time differences in the spaced omni technique are FAR larger than the ones which occur naturally. In fact if one is anything but very far away, they are VERY FAR larger. The differences presented could not occur with a natural sound source ,exceeding as they do the max interaural time-of-difference from a natural source in any location at all(eg that directly to the side).It is not believable, and in my experience is not true, that such a thing produces anything like convincing and precise imaging.
Of course Blumlein erases the interaural time differences altogether. This might be expected to cause trouble(and it is one argument for ORTF--but not for spaced omnis which are over the top exaggerated in this regard). But surprisingly it seems not to. I have to go now but I discuss this point in my article on Boyk's test CD on my website www.regonaudio.com
To save me typing time I would be most grateful if everyone interested in this discussion would read that article before we continue.
Thank you,
Robert E. Greene
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Topic - WARNING! Sad to say I am very disappointed in the new Water Lily Acoustic SACD - Teresa 20:47:06 07/19/05 ( 80)
- Re: The reality of figure of 8 microphones: - Jean-Marie Geijsen 13:17:25 07/27/05 ( 11)
- Re: The reality of figure of 8 microphones: - regreene 14:48:46 07/29/05 ( 4)
- Re: The reality of figure of 8 microphones: - Jean-Marie Geijsen 17:59:09 07/30/05 ( 1)
- Re: The reality of figure of 8 microphones: - regreene 07/30/05 20:24:58 07/30/05 ( 0)
- REG I have just one question ... - Teresa 00:43:39 07/30/05 ( 1)
- Re: REG I have just one question ... - regreene 09:10:56 07/30/05 ( 0)
Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 01:37:36 07/28/05 ( 5)
- Re: The reality of figure of 8 microphones - Jean-Marie Geijsen 13:21:38 07/28/05 ( 4)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 21:18:03 07/28/05 ( 0)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 17:32:15 07/28/05 ( 2)
- Re: I've heard the some... - unclestu52 21:56:40 07/28/05 ( 1)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 23:09:29 07/28/05 ( 0)
Re: WARNING! - BS 20:01:35 07/22/05 ( 0)
Waterlily recordings - regreene 09:55:36 07/21/05 ( 42)
- Re: Waterlily recordings - Chris from Lafayette 21:11:22 07/22/05 ( 31)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 00:47:44 07/23/05 ( 30)
- Re: Water Lily Russian Recordings - Chris from Lafayette 11:04:27 07/23/05 ( 29)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 11:41:12 07/23/05 ( 28)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 13:39:43 07/23/05 ( 27)
- Re: Water Lily Russian Recordings - Chris from Lafayette 17:06:12 07/23/05 ( 26)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 18:59:13 07/23/05 ( 25)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 22:09:50 07/23/05 ( 24)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 02:14:51 07/24/05 ( 23)
- Re: Water Lily Russian Recordings - Chris from Lafayette 12:10:31 07/24/05 ( 22)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 23:06:33 07/24/05 ( 10)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 07:06:06 07/25/05 ( 1)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 01:00:36 07/26/05 ( 0)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 07:05:23 07/25/05 ( 7)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 00:51:32 07/26/05 ( 6)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 16:14:42 07/26/05 ( 5)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 23:56:13 07/26/05 ( 1)
- Re: Water Lily Russian Recordings and turning the other cheek.... - regreene 11:14:58 08/1/05 ( 0)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 19:56:41 07/26/05 ( 2)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 23:52:38 07/26/05 ( 1)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 10:36:26 07/27/05 ( 0)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 17:05:07 07/24/05 ( 10)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 19:11:06 07/24/05 ( 6)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 22:40:40 07/24/05 ( 5)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 00:45:52 07/26/05 ( 0)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 08:47:06 07/25/05 ( 3)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 10:18:50 07/25/05 ( 2)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 01:04:49 07/26/05 ( 0)
- Re: Water Lily Russian Recordings and turning the other cheek.... - Chris from Lafayette 00:39:25 07/26/05 ( 0)
- "The dog may bark, but the caravan moves on..." - Great quote! Dave555 18:04:39 07/24/05 ( 2)
- killer set- Sufi Soul - tunenut 22:15:47 07/24/05 ( 1)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 21:09:04 07/24/05 ( 1)
legality and morality - tunenut 09:23:03 07/22/05 ( 0)
The SKRYABIN / SVETLANOV Water Lily SACD is a sonic travisty and a slap in the face to anyone who loves realistic sound! - Teresa 19:26:11 07/21/05 ( 8)
- Re: The SKRYABIN / SVETLANOV Water Lily SACD is a sonic travisty and a slap in the face to anyone who loves realistic so - dmeinwald 09:24:22 07/23/05 ( 2)
- Brahms No. 1 with Artur Rubinstein, Fritz Reiner and the CSO on RCA LSC SACD - Teresa 17:40:06 07/23/05 ( 1)
- what about the lack of low frequency response on the Svetlanov? - Teresa 11:14:00 07/23/05 ( 1)
Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 16:43:53 07/22/05 ( 4)
- Hi Kavi, I have always loved and been a big supporter of Water Lily Acoustic Recordings - Teresa 20:15:04 07/22/05 ( 0)
This happens to nerdy folks who buy music based on the - Kristian85 09:22:00 07/21/05 ( 0)
Theresa, different listening positioning may be necessary - jim nj 09:04:53 07/20/05 ( 1)
- Teresa, sorry about extra h in above name! (nt) - jim nj 09:14:01 07/20/05 ( 0)
Thanks, and reading things like this..... - Sordidman 08:47:59 07/20/05 ( 1)
- he's not right - tunenut 09:32:01 07/20/05 ( 0)
umm yeah... my experience is completley reverse of yours... - danny kaey 20:55:36 07/19/05 ( 18)
- Great - We can have Dueling Reviews! - Chris from Lafayette 23:16:26 07/19/05 ( 13)
- Re: Great - We can have even more Dueling Reviews! - raffells 01:42:14 07/20/05 ( 12)
- About The Music? I Don't Feel That Is The Main Priority Here - Robertc88 03:46:59 07/20/05 ( 11)
- correct Robert, the music is excellent it's the recording quality that leaves me cold. - Teresa 08:13:11 07/20/05 ( 10)
- they are recorded correctly... - danny kaey 09:05:55 07/20/05 ( 9)
- I listen to orchestral music live and it has a solid bass foundation and lots of energy below 100Hz - Teresa 20:45:25 07/20/05 ( 8)
- again, my experience is the exact opposite... - danny kaey 21:51:15 07/20/05 ( 7)
- Agreed. - Kal Rubinson 05:42:06 07/21/05 ( 0)
- perhaps there's 2 versions of this Water Lily SACD? - Teresa 23:26:51 07/20/05 ( 5)
- Re: perhaps there's 2 versions of this Water Lily SACD? - Kal Rubinson 08:46:14 07/21/05 ( 4)
- I tried playing really loud through speakers and even though my Sennheiser HD580 headphones. - Teresa 19:31:08 07/21/05 ( 3)
- you can very well derive proper MCH from a 2ch 2mic recording... - danny kaey 20:56:53 07/22/05 ( 0)
- Your headphone rig sucks - BS 15:02:39 07/22/05 ( 0)
- Re: I tried playing really loud through speakers and even though my Sennheiser HD580 headphones. - Kal Rubinson 04:34:57 07/22/05 ( 0)
Attention all registered posters: E-mail me to listen to this SACD free, we will do like the Blues In Orbit SACD - Teresa 21:48:55 07/19/05 ( 3)
- Re: Attention all registered posters: E-mail me to listen to this SACD free, we will do like the Blues In Orbit SACD - cf@tiscali.se 09:44:04 07/31/05 ( 2)
- Hi Chris click on the "A" after my name and you will go the page to submit email. - Teresa 17:38:12 08/4/05 ( 1)
- Water Lily Russian Recordings and turning the other cheek.... - music@waterlilyacoustics.com 17:58:16 08/5/05 ( 0)