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Buying an extra NT2A or 414 B-ULS to form a pair?

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Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Guitarking » Mon Mar 11, 2019 8:23 pm

Hi everyone,

I'm experimenting with recording my upright piano.
-Tried my NT55's matched pair in omni in spaced pair, lovely, natural.
-Tried XY NT55 cardioid, didn't like it.
-Tried ORTF NT55 cardioid, like it!
-Tried Mid-Side with Neumann 102 cardioid & NT2A fig8. I liked that sound, but I'm not sure whether this is because of the MS-technique or the fact that I used LDC's on this recording.

So I wanted to have a pair of LDC's to, for example, try the spaced pair technique. I already own a NT2A and a 414 B-ULS. So I could buy: an extra NT2A or an extra 414 B-ULS ;-). Obviously the B-ULS is more expensive.
1. would the B-ULS be better for stereo recordings and worth the extra cost? I'm not interested in it as vocal mic as I have that served by e.g. the TLM 102.
2. In both cases I won't have a matched pair. Is that a problem? Is that a problem for recording piano or is matched pair (if it is necessairy anyway) only a must when you say record a choir in a church...?

Thanks in advance!
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Mon Mar 11, 2019 10:53 pm

If its just for recording the piano with a closely-positioned spaced pair, I'd stick with the NT2 and 414. The fact that they aren't the same won't matter because they'll be picking up very different sounds anyway. Just try them in both positions to see which works best for the high end and low end...

But, if you want to use a pair for recording choirs etc at some point, I'd find another 414 B-ULS. The matching between random examples is usually pretty good in my experience, and better than NT2s.

And testing the matching is pretty straightforward. As for it's importance, accurately matched frequency and polar responses Is absolutely critical for coincident arrays (XY and MS setups) if you seek stable stereo images. It's not quite so critical for near-and far-spaced stereo arrays, but better if they're matched. And for split miking -- as on the piano soundboard, or when miking a guitar at the neck and tail, it's not critical at all.



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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby MOF » Tue Mar 12, 2019 1:34 am

matched frequency and polar responses Is absolutely critical for coincident arrays (XY and MS setups)
Not for MS recording surely?
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby ef37a » Tue Mar 12, 2019 7:42 am

AFAICT the B-ULS is no longer available new? The AKG search engine does not even find it.

I would have thought a second hand unit would be quite a gamble when you want close matching?

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Guitarking » Tue Mar 12, 2019 7:47 am

Thank you!

What to expect from going from sdc to ldc on upright piano?

Im always confused about M-S because some say the advantage is that you dont need matched or even the same type of mics.

Would you record a choir with two 414 u-bls that arent matched?

If I understand correctly one can record overheads perfectly fine with 2 different types of mics in spaced pair?

Thanks again!
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Tue Mar 12, 2019 10:31 am

MOF wrote:
matched frequency and polar responses Is absolutely critical for coincident arrays (XY and MS setups)
Not for MS recording surely?

Yes, surely!

if you think about the decoding works with combining the responses of the two mics, it becomes obvious that it is just as critical as for an XY array. If they are not closely matched, the decoded virtual XY mics have really weird polar and frequency responses themselves!

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Sam Spoons » Tue Mar 12, 2019 10:52 am

So, given that I only have one fig 8 mic (Blue Reactor) and that is clearly very different from the SDCs I have to complete the MS setup (AKG C451/CK1, Calrec or SE-H1 but I also have an SE 2200A Cardioid LDC). Am I looking a 'matched' frequency response or levels and is there a way to guesstimate which would be most likely to produce good results with the Blue Reactor?
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Wonks » Tue Mar 12, 2019 10:58 am

A lot of ribbons have different frequency responses on the two sides. So these are no good for getting decent M/S recordings?
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Ariosto » Tue Mar 12, 2019 11:39 am

ef37a wrote:AFAICT the B-ULS is no longer available new? The AKG search engine does not even find it.
Dave.

I think you are probably right. I don't think it is available new. I bought the AKG C414 XLS a few months ago. I find it is good for recording piano and I like it generally as a mic, especially for recording my voice (narration).
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby ef37a » Tue Mar 12, 2019 1:36 pm

Hugh, maybe you could give us some (VERY!) simple algebra about MS and mic responses?

I recall learning about stereo FM (and PAL) and I would have though any response differences would appear in both the difference and sum signals and cancel out?

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby ronmac » Tue Mar 12, 2019 2:41 pm

I will be the outlier here and suggest a second TLM102. Although they have only a cardioid pattern, a pair is very well suited to the tasks the OP listed.

They are very nice mics!
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Tue Mar 12, 2019 3:39 pm

Sam Spoons wrote:... is there a way to guesstimate which would be most likely to produce good results with the Blue Reactor?

Select which ever mic sounds the closest in terms of its frequency response.

Response differences will result in the stereo width of the image from the decoded MS pair varying with frequency, so some elements of the sound sources in front of the mics will seems to be wider apart than others. Whether that is noticeable or matters depends on what you're trying to do!

It's certainly true that you can get away with mis-matched mics more easily (or less obviously) in an MS array than the equivalent XY array.

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Wonks » Tue Mar 12, 2019 3:41 pm

Possible SOS article with sound examples?
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Tue Mar 12, 2019 3:47 pm

ef37a wrote:Hugh, maybe you could give us some (VERY!) simple algebra about MS and mic responses?

The algebra is very simple:

Left = Mid + Sides ...and... Right = Mid - Sides (or more practically) = Mid + (-Sides)

When teaching this stuff I find it often helps to think about it graphically in terms of polar patterns:

MS decode cardioids.png


So in this example, the Mid mic is a cardioid, and the Side mic sensitivity is about 6dB lower than the Mid mic. The Side mic is obviously a fig-8, and we need to disassemble the cardioid pattern into its component parts which is equal sensitivities of Omni and Fig-8, with the fig-8 element facing front-back.

So when adding Mid and Side for the left output we have an omni and two fig-8s at 90 degrees to each other. They combine to a single fig-8 at 45 degrees, and when combined with the omni we're left with a virtual cardioid facing 45 degrees left. The same process for the right output produces a virtual cardioid facing 45 degrees right.

Changes to the relative levels of Mid and Side mics changes the resulting polar pattern and its direction... and differences in the two mics' frequency and polar responses have the same effect.
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby kinglouis » Tue Mar 12, 2019 3:48 pm

There are 414 B-ULS kicking about but all second hand - they stopped making them a while ago. I bought mine from the US and its fantastic but there was a matched pair in Stroud for around the £1200 mark a few months ago. Obviously a bit of a risk buying used but definitely worth the risk imo.
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby MOF » Tue Mar 12, 2019 4:05 pm

Not for MS recording surely?

Yes, surely!

if you think about the decoding works with combining the responses of the two mics, it becomes obvious that it is just as critical as for an XY array. If they are not closely matched, the decoded virtual XY mics have really weird polar and frequency responses themselves!

The typical MS mic’ pairs are figure of eight and cardioid so they are different polar patterns.
A difference in frequency response between the two mic’s is less critical than in the XY pairing, the symmetry of the figure of eight microphone’s response would have more of an effect I would have thought than a difference in the pair’s frequency response.
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Tue Mar 12, 2019 4:05 pm

ef37a wrote:AFAICT the B-ULS is no longer available new?

Hasn't been available for a long time -- that model was two if not three generations of 414 ago... But it is commonly available second hand, which is what I assumed the OP was planning on buying. The B-ULS sounds noticeably different to the current models in a direct comparison.

I would have thought a second hand unit would be quite a gamble when you want close matching?

Models of that era were built to tight specs and close tolerances, and from my BBC years I've found that randomly selected 414B-ULS mics are all pretty closely matched. The same is broadly true of most high-end professional mics from the likes of Schoeps, Sennheiser, Neumann etc.

Of course, components and capsules can age and drift, but it's dead easy to check how well two mics are matched. You simply place the two mics one directly above the other as close as possible and facing in the same direction (with the same settings if appropriate). Best to do this in a dead studio or outdoors (on a windless day!). The height should be mouth height of your assistant!

Get the assistant to talk into the front of the mics from a few feet away and adjust preamp gains for identical levels with mics panned hard left/right. (Set monitoring to mono, flip polarity on one mic, and adjust for deepest null is the best and quickest way.)

Reset monitoring to stereo and remove polarity invert. The talker image should be central. Next, ask assistant to continue talking but move slowly around the mics in a circle maintaining a constant distance. The level will vary according to the polar patterns of the mics, but the image should remain central and stable. Any significant differences in polar or frequency response will cause the image to flick to one side or the other, so the amount of image instability indicates the degree of 'unmatching'.

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Hugh Robjohns » Tue Mar 12, 2019 4:10 pm

MOF wrote:The typical MS mic’ pairs are figure of eight and cardioid so they are different polar patterns.

Yes... obviously, although you can use a fig-8 Mid mic to advantage in some situations in which case they will have the same polar response. ;-)

A difference in frequency response between the two mic’s is less critical than in the XY pairing

Yes, as I said above. You can 'get away' with less precise matching than the equivalent XY array because response differences cause image width variations which are less obvious to casual listeners... but where critical stable imaging is required, precise matching is as important as in a conventional XY pair.

... the symmetry of the figure of eight microphone’s response would have more of an effect I would have thought than a difference in the pair’s frequency response.

Side mic asymmetry certainly does degrade the decoded stereo image accuracy dramatically, yes.

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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby MOF » Wed Mar 13, 2019 7:01 pm

you can use a fig-8 Mid mic to advantage in some situations in which case they will have the same polar response. ;-)
I knew that you can do this though I've never tried, I have had a MKH30/60 combination for years for my work, probably not a very even stereo image for anyone talking while going left to right, but fine for stereo atmos.
You can 'get away' with less precise matching than the equivalent XY array because response differences cause image width variations which are less obvious
That's what I was getting at.
Thanks Hugh.
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Re: Buying an extra NT2A or 414 B-ULS to form a pair?

Postby Guitarking » Sun Mar 24, 2019 8:45 pm

Could one compile a decca tree with 3 different omni mics?

Also, what would recording my piano with 2 LDC's bring me in stead of the 2 SDC's?
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