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Figure 8 stereo techniques

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Figure 8 stereo techniques

Postby Ramirez » Sat Jun 06, 2020 3:06 pm

Having just acquired an AEA R84, I’m thinking how useful a pair could be.

Apart from mono spot-miking applications, how much use are your figure-8 mics seeing as a stereo pair?

Blumlein is an obvious one, though the R84s seem a bit cumbersome for that. Still doable in a controlled environment.

I think they’re supposed to have a slightly different tonality front and back, which makes them unsuitable for mid-side.

Are spaced figure-8 used often? I’ve seen the ‘Faulkner array’, but I read that it was devised specifically to deal with problematic reflections.

What I’ve never tried is a near-spaced and angled array of fig-8. In the absence of a studio I’m playing around with the Neumann Recording Tools app, and a 15cm spacing / 45 mutual angle seems a decent place to start.

I’m thinking string quartets/choir etc in a reasonably spacious (12x9 metres, high ceiling) professionally designed studio.
Also drum overheads, but it’ll take something special to steal that throne from the Beyer M160!
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Re: Figure 8 stereo techniques

Postby Hugh Robjohns » Sat Jun 06, 2020 3:37 pm

Ramirez wrote:...how much use are your figure-8 mics seeing as a stereo pair?

Quite a lot for me... but that's mostly choirs and orchestral ensembles in reasonable acoustics.

Blumlein is an obvious one, though the R84s seem a bit cumbersome for that. Still doable in a controlled environment.

The R84 is a bit cumbersome for everything. Small and inconspicuous it ain't!

But you have three 'official' options for stereo with fig-8s:

1. Blumlein XY
2. Blumlein Mid-Side
3. Faulkner spaced. (Parallel with both facing forward, spaced 20cm apart)

... although there's nothing to stop you from experimenting with other spacings and mutual angles. Both would tend to be relatively narrow/small, though, because of the limited angle of the fig-8's usable frontal pickup area.

I think they’re supposed to have a slightly different tonality front and back, which makes them unsuitable for mid-side.

Technically, yes, (it's because the ribbon doesn't sit symmetrically within the magnet motor structure). The result in an MS application is that the angular positioning of the reproduced images will be slightly different from the source's actual angular positions on one side. Whether you'd notice is another matter... it will depend on the nature of the source(s), room acoustics, and monitoring accuracy. It may well be a very subtle error...

Are spaced figure-8 used often? I’ve seen the ‘Faulkner array’, but I read that it was devised specifically to deal with problematic reflections.

Not often, no. And Yes, Tony's idea came in desperation over strong side wall reflections in a long, thin church. But you can still use the Faulkner array even if you don't have strong side reflections... it's just like any spaced pair, capturing both level and timing differences. But it doesn't have the bottom end of spaced omnis of course...

I used quite widely spaced fig-8 ribbons on a choir a while back specifically to try and null out the conductor who had a habit of humming and muttering ... :problem:

What I’ve never tried is a near-spaced and angled array of fig-8. In the absence of a studio I’m playing around with the Neumann Recording Tools app, and a 15cm spacing / 45 mutual angle seems a decent place to start.

Yes. The app is excellent for this kind of experimentation and visualisation.

Michael William's Stereosonic Zoom articles/books are excellent for this kind of theoretical planning too too.

https://www.soundonsound.com/reviews/microphone-arrays-stereo-multichannel-sound-recording

Here's Williams' chart for the Fig-8 Stereo Recording Angles:
Fig 8s.jpg


I’m thinking string quartets/choir etc in a reasonably spacious (12x9 metres, high ceiling) professionally designed studio.

Sure... lots of rearward pickup, of course, so a much roomier sound than ORTF cardioids.

Also drum overheads, but it’ll take something special to steal that throne from the Beyer M160!

It'll take some special steel to hold them up over the drum set too... (see what I did there... :D )
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Re: Figure 8 stereo techniques

Postby Ramirez » Sat Jun 06, 2020 3:44 pm

Hugh Robjohns wrote:It'll take some special steel to hold them up over the drum set too... (see what I did there... :D )

:clap: ! Plenty of heavy duty stands here! The R84 is surprisingly light though.Given its size I had expected it be closer to the monstrous 4038 in terms of weight! It's far from that! Neo magnets perhaps?

Thanks also for the rest of your reply, illuminating as always.

But when you say
...you have three options for stereo with fig-8s:

Are you suggesting that a near spaced/angled setup like I described (perhaps 15cm/45 degree starting point as I said) is unlikely to prove useful in pratice?
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Re: Figure 8 stereo techniques

Postby Hugh Robjohns » Sat Jun 06, 2020 3:50 pm

There's probably good reasons why it's not a standard rig! :bouncy:

I suspect sheer practicality rather than imaging accuracy... Although I imagine it could be tricky to maintain a balanced sensitivity across the centre of the image.

But it's always worth a play with these things!
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Re: Figure 8 stereo techniques

Postby Ramirez » Sat Jun 06, 2020 3:53 pm

Hugh Robjohns wrote:There's probably good reasons why it's not a standard rig! :bouncy:

I suspect sheer practicality rather than imaging accuracy... But it's always worth a play with these things!

Yes, worth a play I think. And I like the sound of it, so a second would be very useful in any case.

It strikes me as more practical to rig two R84 side-by-side like this rather than one above the other in a Blumlein array, I must say!
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Re: Figure 8 stereo techniques

Postby Hugh Robjohns » Sat Jun 06, 2020 4:39 pm

Depends on your mounting hardware and whether sight-lines are important.

For Blumlein XY/MS applications a proper stereo ribbon makes much more sense. The Royer stereo ribbon (SF12/SF24) is my preference as it's a lot more discrete and easier to mount than the AEA R88.

But there's also the (similar looking, but much cheaper) Prodipe RSL, and then there's the Sontronics Apollo, Cascade X15, and probably some others I've forgotten.
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Re: Figure 8 stereo techniques

Postby Ramirez » Sat Jun 06, 2020 10:05 pm

Hugh Robjohns wrote: I imagine it could be tricky to maintain a balanced sensitivity across the centre of the image.

This is interesting. Does this potential issue correlate to the area of brighter orange on the Neumann app where the two mics' polar patterns seems to reinforce each other? I had noticed that a lot of the 'official' stereo arrays seemingly had more even coverage (apart from the XY 60, 90 and 120 which have, as expected, a very wide acceptance angle, but also a clear central overlap between the polar patterns).
Blumlein XY seems to offer very even coverage (but a narrow angle) even if you're very close to the mics, and the ORTF, on the contrary, seems to require that some distance is kept from the mics as so much of the pickup is off-axis.

Or am I confusing unrelated things here, and reading too much into colours on an app?


Hugh Robjohns wrote:For Blumlein XY/MS applications a proper stereo ribbon makes much more sense. The Royer stereo ribbon (SF12/SF24) is my preference as it's a lot more discrete and easier to mount than the AEA R88.

Yes, I had seen the R88, but the singles will I think be more useful for most of my work. The problem is trying to deicde how useful a pair would be, or would I be better served with a single R84 and something different.

The studio is very well stocked with mics, so I'm trying to add a few different things to the 'standards'. R84 was top my list, I'm sorely tempted by the Austrian OC818 but I really can't justify that seeing as we have half a dozen C414-BULS and a pair of C$!$-XLS already!

Neumann TLM193 is the other main contender. Though I quite like the idea of buying pairs of everything for some reason...!
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Re: Figure 8 stereo techniques

Postby Arpangel » Sun Jun 07, 2020 11:03 am

Hugh Robjohns wrote:3. Faulkner spaced. (Parallel with both facing forward, spaced 20cm apart)

Sorry to come in here, not heard of this technique before, sounds interesting, just off to Google it.
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