If only two mics... ?

[Emmathom]

When you speak of the imaging of spaced omnis, you need to specify what their spacing was; the stereo image they produce is entirely based on the distance between them.

A spacing that combines fairly accurate imaging with a euphonic 'bloom' is right around two feet (Tony Faulkner uses 26-27"); as you get any wider than that the middle becomes weaker and weaker till you get just two 'pools' of sound around the left and right speakers with little happening in the center.

Here is an excellent online tool for graphically displaying the approximate image width produced by various stereo pairs: https://sengpielaudio.com/Visualization-AB60-E.htm

You'll find that the main arrays used by most of the major labels during the heyday of the Classical record business did not produce technically accurate stereo imaging; rather they produced a pleasing, engaging and 'plausible' stereo image. Only a couple of 'boutique' labels used coincident mics for the main pickup. Aubort referred to coincident techniques as "fat mono".

Yes Barry already sent me the sengpiel link

 

[Khron]

Thank you. Well it seems my "french Google version" does not perform as yours... (not first time you find what I don't)

Perhaps not surprising there aren't many French results, then I think i have my preferences set to US / English, just to get more (useful) results, despite not living there.

 

[k brown]

When I attended Marc's sessions with the St. Louis Symphony (and if I recall correctly) he used 10 mics, and told me when I interviewed him for "Studio Sound" magazine that it could be as many as 14 (which he did say was rare). The rest of what you say I know and agree with. I appreciate your posting! It's always fun to talk about Marc and Joanna.

Humorous anecdote: I'd heard about a church in my area that had good acoustics for recording, so I dropped in one day to see what it looked like, and lo and behold there was a session going on and it was Marc and Joanna! He was extremely gracious and without my asking, invited me to sit in and observe them at work. Nickrenz remained intensely focused on the score - they were recording her daughter's string quartet.

The humorous part was what I noticed he was using for mic pres: the direct outs from a Mackie 1202! When he saw my rather slack-jawed expression, he offered: "They sound great.". Direct outs straight into the SADiE. His backup was a portable Denon DAT machine (tells you how long ago it was).

 

[Barry Hufker]

When I met Marc he was using a Gately mixer he had built from a kit. I don't know that she minded the sound but Joanna hated that he was using something that didn't seem fully professional. Years later he was using a Studer mixer when doing digital recordings for the SLSO.

 

[k brown]

When I met Marc he was using a Gately mixer he had built from a kit. I don't know that she minded the sound but Joanna hated that he was using something that didn't seem fully professional. Years later he was using a Studer mixer when doing digital recordings for the SLSO.

This would have been about 1995, so don't know what mixer he using at that time; since it was a string quartet, it was just an omni pair to the Mackie pres then to the SADiE, so no mixer needed; the mixer part of the Mackie wasn't used.

https://artmusiclounge.wordpress.com/2020/12/14/the-angeles-quartets-haydn/

I also got a kick out of the fact that he was using AR Powered Partners (remember those?) as PB monitors. He also noticed me quizzically eyeing those and simply said "Just noise-makers" - man of few words. He famously used trusted headphones for actual monitoring and balancing, not speakers.

Attached is excerpt from Gramophone's review.

 

[cfanzalone]

To Emmathom, and others. Yes, Earthworks is known for 'measurement mics'. They make many models...as I recall, the QTC1 was re-named QTC40...A great mic with hi-frequency characteristics (flat up to 40KHz,) BUT it stands alone vs the QTC30 and QTC50...I'm not sure why, but the QTC40 is the mic for music, not just measurement. I'm of the David Blackmer (Founder of DBX and Earthworks) school that, although humans can hear only to 15K or so...18-20K if you're a child,...I believe and FEEL that the human body perceives far greater than 15K. (I'm not starting a debate here, I'm simply answering questions!!!!!!!)
As for Sahi's 'Little Blondies' ...I met Sahi when he first came out with his mics. They are used now in concert halls and opera houses around the world...Look up on GS " Anyone else using Sahiaman's Little Blondies?" and other threads ...I believe he has a website and is accessible on Facebook...I got mine in 2013 and will never sell them...I saw a pair go on Reverb.com for $255.00.
Last, my experience on multi-micing is that one ALWAYS has to experiment...No 'array' is absolute for any and every venue. Even close micing a singer...sometimes mm distance or a slight degrees off-axis makes a huge difference...Lean by theory, but practice with your ear!
Blessings to all

 

[k brown]

To Emmathom, and others. Yes, Earthworks is known for 'measurement mics'. They make many models...as I recall, the QTC1 was re-named QTC40...A great mic with hi-frequency characteristics (flat up to 40KHz,) BUT it stands alone vs the QTC30 and QTC50...I'm not sure why, but the QTC40 is the mic for music, not just measurement. I'm of the David Blackmer (Founder of DBX and Earthworks) school that, although humans can hear only to 15K or so...18-20K if you're a child,...I believe and FEEL that the human body perceives far greater than 15K. (I'm not starting a debate here, I'm simply answering questions!!!!!!!)
As for Sahi's 'Little Blondies' ...I met Sahi when he first came out with his mics. They are used now in concert halls and opera houses around the world...Look up on GS " Anyone else using Sahiaman's Little Blondies?" and other threads ...I believe he has a website and is accessible on Facebook...I got mine in 2013 and will never sell them...I saw a pair go on Reverb.com for $255.00.
Last, my experience on multi-micing is that one ALWAYS has to experiment...No 'array' is absolute for any and every venue. Even close micing a singer...sometimes mm distance or a slight degrees off-axis makes a huge difference...Lean by theory, but practice with your ear!
Blessings to all

For those not around at the time, for the first many years, the Earthworks omnis used the tiny $2 Panasonic electrets (WM-61, or similar). Supposedly Blackmer modded them somehow.

Similarly, the Blondies appear to use cheapy off-the-shelf electret capsules (even retaining the black fuzzy disc on the front). He once claimed to make the capsule himself from scratch, which I absolutely don't believe.

Only thing inside is the capsule, 3 resistors and the XLR (how that works w/o DC blocking caps, I don't know; any guesses how one could phantom-power a 2-terminal electret with just 3 resistors?). These mics seem to be all about putting as little 'stuff' as possible between the capsule's FET and the outside world. The vid seems to be of a very early model; don't how much they changed over time. However, Sahi's stated aim of "one workhorse microphone that did it all." is just ludicrous; no such thing, and never will be. Profits going to St. Jude's a cool thing, though.


_______

It's well known that people (especially males) over 30 or so, can't hear much of anything above 10-12kHz.

 

[ccaudle]

No phantom needed (electret)

Electret capsules are still condensor capsules, so very high impedance, and therefore need a powered buffer amp in order to drive more than a couple of inches of cable.

So you got 4 separate outputs = is it possible to mix them in a stereo way and how ?

The term you want to search for is "ambisonics," it was a method developed by Michael Gerzon in the 1970's to record surround sound in a way which could be processed to match the specific speaker arrangement after recording. Yes, it can be processed for typical 2-channel stereo, as well as multi-channel horizontal surround, and even full sphere surround (with speakers above and below the listeners).
Wikipedia has a thorough overview:
https://en.wikipedia.org/wiki/Ambisonics
https://en.wikipedia.org/wiki/Soundfield_microphone

You can read some of the original Michal Gerzon papers describing that as well as other writings here:
https://www.audiosignal.co.uk/Gerzon archive.html

 

[ricardo]

For those not around at the time, for the first many years, the Earthworks omnis used the tiny $2 Panasonic electrets (WM-61, or similar). Supposedly Blackmer modded them somehow.

He didn't modify them but he did select ... though the WM61 was by far the most consistent 6mm capsule. I think they did 'age' them.

When they were discontinued, Earthworks bought up the World's entire stock .. which led to much gnashing of teeth in da DIY community.

Dunno what they use now but I don't think a replacement with similar consistency has emerged.

 

[ricardo]

A (chinese) customer wanted a livestreaming Mic that was different. I tried to get him sold on a first order Amisonic Mic, on the principle that Ambisonic is de-factor VR audio and this could be used for example in nature for an immersive Audio experience.

Extensive DSP build in to reliably make livescreamers sound ok, so compressor, autotune, reverb, sampled sound FX. Nice Brass 25mm Electret capsules. Wired USB or Wireless (aptX . I had intended a secondary software option for "recording" use.

A HERESY!! Blasphemy to sully the pure output of an Ambisonic mike with digital ju ju

There's a bit more to a good Ambisonic mike than 4 capsules in a Tetrahedron but there's a couple of people on MicBuilders who have 3D printed the Tetrahedral mount.

What's lacking on many 'soundfields' is accurate calibration. Only TetraMic is correctly calibrated and it shows.

If you want to hear what a single Calrec Mk4 or TetraMic can do, have a look at ambisonia.com ... especially recordings by Aaron J Heller, Paul Hodges, John Leonard, Paul Doombusch, Len Moskowitz & Jean-Hugues Roy.

To convert the Ambisonic B-format files to stereo, I was going to recommend VVMic but this seems no longer available.

https://rode.com/en/apps/soundfield-by-rode is OK though I would take some of their claims with a large pinch of salt.

​

 

[ricardo]

- ORTF is great for sound spacing & precision (but not well suited for mono listening > but I don't care about those who listen in mono) > S502
...
- XY for small ensemble & close palyers (like a duo violin + cello for example) > "Schoeps-like" cardio pair

Actually one of ORTF's problems and even more for XY with cardioids is that it always sounds like mono.

May I suggest you try hyper or super cardioids for ORTF and XY instead of 'accurate' cardioids. Dunno what to suggest as the only good ones I know are the Schoeps at mucho $$$

Maybe a pair of AKG 414 or your favourite finely selectable pattern LDC.

 

[k brown]

Actually one of ORTF's problems and even more for XY with cardioids is that it always sounds like mono.

May I suggest you try hyper or super cardioids for ORTF and XY instead of 'accurate' cardioids. Dunno what to suggest as the only good ones I know are the Schoeps at mucho $$$

Maybe a pair of AKG 414 or your favourite finely selectable pattern LDC.

Well, ORTF and all near-coincident pairs are largely mono below frequencies whose 1/2 wavelengths are larger than the distance between the mics. Above that frequency the image is formed by both Interchannel Time Difference (ITD) and Interchannel Level Difference (ILD). Below it, there is only ILD, so the separation is quite small.

It's even worse when near-coincident stereo is done with LDCs, most of which lose a lot of directionality below about 150Hz, so you don't even have much ILD at the low end. All the formal near-coincident pairs were designed for use with SDCs.

 

[cfanzalone]

"Supposedly", "Appear"...there's always one in the bunch. Have you used these mics? Proof is in the Pudding. Comments like these 'turn me off'. I'm out of this loop for another while...'gonna go record with my mics...
Blessings

 

[k brown]

"Supposedly", "Appear"...there's always one in the bunch. Have you used these mics? Proof is in the Pudding. Comments like these 'turn me off'. I'm out of this loop for another while...'gonna go record with my mics...
Blessings

I made no comment on how they sound; why would you ask if I've used them? I'm simply stating what I observe. Those capsules look exactly like any number of mass-produced internal-FET electret capsules, and nothing like something hand made. They're even the two terminal type that has the FET source tied to ground, making it impossible use a source resistor that optimally biases the FET. If I were to hand build a custom capsule, why would I go out of my way to make it look exactly like one of those cheapies? - makes no sense.

The Line Audio Omni1 also uses similar-looking inexpensive internal-FET electrets, but they are of the three terminal type with the FET source having it's own terminal, making it possible bias the FET properly. Plus, LA modifies them to improve their performance, and provides them proper powering and output circuitry.

 

[Emmathom]

Actually one of ORTF's problems and even more for XY with cardioids is that it always sounds like mono.

Well it depends how wide you like your stereo... Natural ? Really spatial ? As I already said (many times) the sextet we I recorded last time with a Schoeps pair set in ORTF is fully detailled and I can re-position the instrument where they exactly were (can say so because I was there). I can post (on demand) an excerpt.

Anyway...

Since I'm the one who opened this thread does it allow me to change topic ? Because reading above (about the electret omni capsules) pushes me to ask a few questions :
- if DPA & Earthworks (to name those) use cheap electret capsules* then what makes their "magnificent" sound ? (btw I didn't know 4006 had an OPT...)
- I'm pretty sure some of you have already built a clone of these mics : reviewsome feedback ?

Here's the DPA4006 schematic & inside pict. (found on another thread and posted by RuuDNL & Whoops)

* cheap regarding some LDC high-quality capsules

 

[thor.zmt]

Well, ORTF and all near-coincident pairs are largely mono below frequencies whose 1/2 wavelengths are larger than the distance between the mics.

We come here to the multiplicity of logical fallacies in audio, arising from challenges in audio systems (full chain).

The microphone is nothing like the ear.

Human hearing has an extremely non-flat frequency response that is level dependent, has horrendous levels of THD, massive compression, uses amplitude differences for sound location at high frequencies, time of arrival at low frequencies and a mix in the "critical midrange" which incidentally is also the frequency range where the formants for human voice and many traditional acoustic instrument are found.

A speaker is USUALLY nothing like a microphone in reverse.

A living or listening room is nothing like a Jazz Bar or Philharmonic Hall.

So "connecting" a pair of "blameless" microphones (or a single soundfield mic) in a "blameless recording" space to a pair of "blameless speakers" in a "blameless" room similar to the recording space will still not magically transport the listener into the recording space.

Some arrangements of mic's and speakers may do better than others, but all are fundamentally and incorrigibly compromised.

So we have to correctly target the whole set-up and approach to the likely target to ensure our recording and the musicians performance translates to our target audience via whatever hardware they use to listen to music.

Does our target audience listen in a dedicated room, acoustically treated, with towering speakers that would impress the people who erected Stonehenge etc?
On a compact hifi or opmarket Bluetooth speaker? Apple homepod or Alexa Dot? In their car? On 5 USD earbuds.

To make something that sounds good across the board and translates into an involving and immersive experience on all options is impossible.

Which is interesting to me, as I reject actively J. Gordon Holts concepts and ideas of "Fidelity" as given in his essay "Why HiFi Experts (and by extension sound engineers) disagree":



To then discuss the ineffable nature of specific microphone setups that mostly originate in theory and rarely in practice and almost never in both seems to me, perhaps frivolous, perhaps hilarious.

Thor

 

[thor.zmt]

- if DPA & Earthworks (to name those) use cheap electret capsules* then what makes their "magnificent" sound ?

The numbers of zeros you write on cheque and possibly the fact that they extensively test each capsule and pick only "peaches" and dispose of "lemons" which end up in all the other vendors microphones, which have two zeros less (-40dB on price) and objectively give up a small amount of response flatness at the extremes and might distort a little early (-3dB on performance) and subjectively probably sound 80%+ identical (or 99.9% in an ABX Test, like everything else).

Thor

 

[thor.zmt]

A HERESY!! Blasphemy to sully the pure output of an Ambisonic mike with digital ju ju

Today even LP's are digital.

There's a bit more to a good Ambisonic mike than 4 capsules in a Tetrahedron but there's a couple of people on MicBuilders who have 3D printed the Tetrahedral mount.

In volume I can get Rayking's 25mm "no FET" naked brass electrets binned by < 1dB matching 100Hz to 5kHz.

Having full DSP on board means calibration is actually easy and can be automated.

If you want to hear what a single Calrec Mk4 or TetraMic can do, have a look at ambisonia.com ... especially recordings by Aaron J Heller, Paul Hodges, John Leonard, Paul Doombusch, Len Moskowitz & Jean-Hugues Roy.

Yes. My problem, LF is not great, even with the original electronics and in the lower midrange and down the magic disappears.

I think we would need a number of progressively larger nested tetrahedrons with mic's attached to overcome this limitation. At a minimum a second 2' tetrahedron.

To convert the Ambisonic B-format files to stereo, I was going to recommend VVMic but this seems no longer available.

The math is well documented, it's a job for DSP.

Thor