Topic: Blumlein matrixed?

[WiFiJeff]

Has anyone tried recording Blumlein with one capsule pointed straight forward and the other to the side, then mixing them (X+Y) to get the left facing figure-8 and (X-Y) for the right?  This is the way Josephson suggested to me for their C700 stereo mic, theoretically looks right but does anyone have any experience with how it sounds?

Jeff

[boojum]

Jeff - sounds like a M/S decoding.  What about the back lobe of the X?  Is that just ignored??

[JasonSobel]

check out this thread:
http://taperssection.com/index.php/topic,66414.0.html

basically, if you run M/S with a Fig-8 mic for both the mid and side, when you decode the Mid-Side signals to left-right signals, you get the equivalent of Blumlein.  by changing the amount of each signal, you can essentially change the "rotation" of the blumlein config.

[Tim]

check out this thread:
http://taperssection.com/index.php/topic,66414.0.html

basically, if you run M/S with a Fig-8 mic for both the mid and side, when you decode the Mid-Side signals to left-right signals, you get the equivalent of Blumlein.  by changing the amount of each signal, you can essentially change the "rotation" of the blumlein config.

thanks Jason

[WiFiJeff]

check out this thread:
http://taperssection.com/index.php/topic,66414.0.html

basically, if you run M/S with a Fig-8 mic for both the mid and side, when you decode the Mid-Side signals to left-right signals, you get the equivalent of Blumlein.  by changing the amount of each signal, you can essentially change the "rotation" of the blumlein config.

I understand that, my question is really about how it sounds, given that the Side figure-8 will be severely off-axis.  When I do "normal" Blumlein, each cap is 45 degrees off-axis for sound coming from dead center, this method will have the front facing figure-8 directly on axis for such sound.  If I were recording just two instruments, and the "normal" Blumlein figure-8s were pointed at each one so that one is in the left channel and one in the right, they would each be on-axis; with this setup each instrument will be 45 degrees off-axis for each cap.  I can't believe it sounds exactly the same.

Jeff

[Gutbucket]

.. my question is really about how it sounds, given that the Side figure-8 will be severely off-axis.  When I do "normal" Blumlein, each cap is 45 degrees off-axis for sound coming from dead center, this method will have the front facing figure-8 directly on axis for such sound.  If I were recording just two instruments, and the "normal" Blumlein figure-8s were pointed at each one so that one is in the left channel and one in the right, they would each be on-axis; with this setup each instrument will be 45 degrees off-axis for each cap.  I can't believe it sounds exactly the same..

I've wondered this as well.  Mathematically, Blumlein and M/S with two fig8's is equivalent.  You could send a Blumlein recording though a M/S encode/decode chain and adjust width just like the M/S recording. 

This would be interesting and simple to test. Tape one set in Blumlein, rotate rig 45deg clockwise at set-break, Tape second set M/S.  Matrix the second set with equal weighting and compare.  If the mics are set up truly coincident, the only difference is the quality of your summing when setting up the matrix (pretty much a non-issue when done digitally), the and the on/off axis observation you mention. 


Most multi-pattern mics have more accurate off-axis response in fig-8 than other directional patterns, so the 'on/off-axis' difference you'd be comparing in the test may not be as significant as comparing a more typical M/S recording using a cardioid mid (dematrixed with equal 50% weighting) with the equivalent X/Y configuration of hyper/supercardioid-ish patterns set at a 120 degree recording angle.  But there is no way to really set up that comparison accurately. 

[Gutbucket]

Found this but haven't had time to read it.  Skimmed though and found some plots of 'real world' derived M/S patterns that are much more ragged looking than the idealized M/S plots normally seen.  Don't know if this thesis paper addresses your 'on/off axis' question directly or not.

[boojum]

Found this but haven't had time to read it.  Skimmed though and found some plots of 'real world' derived M/S patterns that are much more ragged looking than the idealized M/S plots normally seen.  Don't know if this thesis paper addresses your 'on/off axis' question directly or not.

Insanely great find, GB.  I will read it when I get finished doing some post work.  Thanks for finding it.

Cheers

[John Willett]

Has anyone tried recording Blumlein with one capsule pointed straight forward and the other to the side, then mixing them (X+Y) to get the left facing figure-8 and (X-Y) for the right? 

This is exactly how Blumlein did it.

Two fig-8s in an MS configuration.

Matrixed to stereo gives the equivalent of crossed fig-8s - but easy to adjust the stereo width. 

[it-goes-to-eleven]

Whacky blumlein question that has been bugging me so I need to ask...  What if you ran two blumlein mic setups and split them like omnis?   Each pair of figure 8's would need to be mixed down to a single channel. 

Would the result be more or less split omnis? (I know the bass response would be lacking compared to omnis).

[boyacrobat]

nice work

g

[Brian Skalinder]

This is exactly how Blumlein did it.

Two fig-8s in an MS configuration.

Matrixed to stereo gives the equivalent of crossed fig-8s - but easy to adjust the stereo width. 

Never would've thought of this on my own, but now that I know it's doable (and I've been running M-S more and more frequently), it makes perfect sense.  I'm going to try this next opportunity I have that's suitable for Blumlein.

[macdaddy]

This is exactly how Blumlein did it.

Two fig-8s in an MS configuration.

Matrixed to stereo gives the equivalent of crossed fig-8s - but easy to adjust the stereo width. 

Never would've thought of this on my own, but now that I know it's doable (and I've been running M-S more and more frequently), it makes perfect sense.  I'm going to try this next opportunity I have that's suitable for Blumlein.

me, too. it looks like a fabulous idea.

+t

[DSatz]

Freelunch, no--if you mix together the two microphone signals from a Blumlein pair, what you get is about equivalent to the signal from a single, forward-facing figure-8 microphone. But it's not as clean, since phase conflicts result at high frequencies from the actual impossibility of placing two microphones at the same exact point in space. ("Coincident" placement is possible in only one spatial dimension at a time at best.)

Thus you will end up with about the same as a spaced pair of single figure-8s--and from experiment, I can tell you that that isn't a particularly useful setup when the microphones are more than short distance apart, since the lobes of a figure-8 are so narrow.

--best regards

[it-goes-to-eleven]

Thanks Dave..  Didn't think it would be useful but I was curious..