soundfield mic for stereo application

[John Willett]

The AES have a Conference in the UK in June on "The Ins and Outs of Audio" - I really really hope Harpex will be there giving a paper on this as I am extremely interested in this.

[harpex]

Originally Posted by John Willett

The AES have a Conference in the UK in June on "The Ins and Outs of Audio" - I really really hope Harpex will be there giving a paper on this as I am extremely interested in this.

I am pleased that this triggers your interest! Unfortunately, we don't have any new research results to present since our last presentation at AES' spatial audio conference in Tokyo last fall. We might be appearing at conventions and trade shows in the near future, but nothing has been fixed yet.

[John Willett]

Originally Posted by harpex

I am pleased that this triggers your interest! Unfortunately, we don't have any new research results to present since our last presentation at AES' spatial audio conference in Tokyo last fall. We might be appearing at conventions and trade shows in the near future, but nothing has been fixed yet.

Ahh well.

I'll send you a PM. Please can you let me have a pdf copy of your Tokyo paper.

I was talking about Harpex to Ken Giles of Soundfield while I was at Frankfurt recently and made sure he had all the links.

[aracu]

I'm curious to hear samples of the Harpex conversion from Blumlien
to spaced pair. There's a free conversion service on the website but
it didn't work when I tried it... anyone else have any luck with it?
I recieved an empty file.

[harpex]

Originally Posted by aracu

I'm curious to hear samples of the Harpex conversion from Blumlien
to spaced pair. There's a free conversion service on the website but
it didn't work when I tried it... anyone else have any luck with it?
I recieved an empty file.

There was a problem with the online conversion service. If you try again now, it should work.

[aracu]

Ok, I made a test converting a short file of string quartet recorded with
spaced omnis, with a narrow stereo image and ambiguous localization, to stereo in phase. The result had much clearer localization with no obvious negative side effects.

Another test converting a coincident recording to ortf was harder to
evaluate.

In any case, I'm initially impressed with this software.

[surflounge]

Originally Posted by Chorum Records

I have a MKV system and a DSF-1 system.

Can the DSF-1 handle rock and roll stereo recording with it's limiter on, above a stage,
or a MKV with added outboard gear?
Is the DFT-1 much quieter because it's digital?
You must be pleased to own both. The DSF-1 in US dollars is about $12,000

[Lucas_G]

I have read all the posts here, and listened to the recording samples. I am considering buying a SPS200, but I cannot find examples that sound convincing. Strangely enough there are some samples from people who use the coresound Tetramic that sound reasonably convincing, even when this seems to be a somewhat less sophisticated piece of hardware. Apparently the individual equalizing let these capsules perform at a higher level?
Anyway, I would love to hear a good sample of a recording made with a SPS200 in a good venue of an orchestra or a piece of chamber music. It seems however that 99% of the SPS200 owner only do outdoor recordings of streetnoises etc, and I really cannot judge those samples.
The soundfield site has a few B-format samples, but they sound awful. Not much of a teaser.
Is the SPS200 really good? Is its frequency response relatively flat? Does the Surroundzone plugin that goes from A to B-format do all the necessary Eq? Are the MBO capsules sufficiently close to their specs to go without individual measuring?
Too many questions, I know. If only a few could be answered, I would probably risk to make the jump.

[John Willett]

Originally Posted by Lucas_G

I have read all the posts here, and listened to the recording samples. I am considering buying a SPS200, but I cannot find examples that sound convincing. Strangely enough there are some samples from people who use the coresound Tetramic that sound reasonably convincing, even when this seems to be a somewhat less sophisticated piece of hardware. Apparently the individual equalizing let these capsules perform at a higher level?
Anyway, I would love to hear a good sample of a recording made with a SPS200 in a good venue of an orchestra or a piece of chamber music. It seems however that 99% of the SPS200 owner only do outdoor recordings of streetnoises etc, and I really cannot judge those samples.
The soundfield site has a few B-format samples, but they sound awful. Not much of a teaser.
Is the SPS200 really good? Is its frequency response relatively flat? Does the Surroundzone plugin that goes from A to B-format do all the necessary Eq? Are the MBO capsules sufficiently close to their specs to go without individual measuring?
Too many questions, I know. If only a few could be answered, I would probably risk to make the jump.

Where are you based Lucas?

You may find that a dealer may loan you an SPS200 to try for yourself.

[aracu]

Originally Posted by Lucas_G

I have read all the posts here, and listened to the recording samples. I am considering buying a SPS200, but I cannot find examples that sound convincing. Strangely enough there are some samples from people who use the coresound Tetramic that sound reasonably convincing, even when this seems to be a somewhat less sophisticated piece of hardware. Apparently the individual equalizing let these capsules perform at a higher level?
Anyway, I would love to hear a good sample of a recording made with a SPS200 in a good venue of an orchestra or a piece of chamber music. It seems however that 99% of the SPS200 owner only do outdoor recordings of streetnoises etc, and I really cannot judge those samples.
The soundfield site has a few B-format samples, but they sound awful. Not much of a teaser.
Is the SPS200 really good? Is its frequency response relatively flat? Does the Surroundzone plugin that goes from A to B-format do all the necessary Eq? Are the MBO capsules sufficiently close to their specs to go without individual measuring?
Too many questions, I know. If only a few could be answered, I would probably risk to make the jump.

It makes sense to be cautious and wait until you can find at least one
recording made of classical music with the mic that you really like before
investing in it.

[boojum]

I believe Core Sound (Tetramic) has a 30 day return policy. Yes, they do: Core Sound — TetraMic

[Larry Elliott]

PM Sent Lucas

[ljudatervinning]

I too would like to hear a convincing recording with SPS200.
I have now played with the Harpex demo software. Really nice! Now I need to find a low noise ambisonic microphone. What version is having the lowest noisefloor?

[Lucas_G]

Originally Posted by John Willett

Where are you based Lucas?

You may find that a dealer may loan you an SPS200 to try for yourself.

Yes, that is a possibility... and when I get a favourable impression, I will go that route. It is great however to have this forum for some serious advise.

Someone said that the SPS422B should be much better than the SPS200 because it uses the same capsules as the MKV. If I understand it rightly, these are larger capsules which isn't always andvantage (colouring on off-axis).

Do you think the MHBO capsules in the SPS200 are really good enough?


Larry is giving me some practical help which is very kind of him.

John, I saw from your profile that you own quite about the same collection of mics, except for the SPS of course. What is your opinion on the SPS200? Does it give a satisfactory sound on a chamber orchestra for instance? Or is it not comparable to the Sennheiser MKH mics you use?

Of course, the whole recording technique is different, but what I am curious about is whether one can get the same colour and bite of sound with the SPS200 as with a Sennheiser MKH or DPA 4006 setup (with Jecklin disc for instance).

Some people complain that with the soundfield method they do not achieve the same kind of spaciousness and liveliness as with a spaced omni setup. What is your opinion? Could one get this little extra space by adding a bit of spaced omnis sound to the SPS mix? Anyone experience with this?

[John Willett]

Originally Posted by Lucas_G

Yes, that is a possibility... and when I get a favourable impression, I will go that route. It is great however to have this forum for some serious advise.

Someone said that the SPS422B should be much better than the SPS200 because it uses the same capsules as the MKV. If I understand it rightly, these are larger capsules which isn't always andvantage (colouring on off-axis).

Do you think the MHBO capsules in the SPS200 are really good enough?


Larry is giving me some practical help which is very kind of him.

John, I saw from your profile that you own quite about the same collection of mics, except for the SPS of course. What is your opinion on the SPS200? Does it give a satisfactory sound on a chamber orchestra for instance? Or is it not comparable to the Sennheiser MKH mics you use?

Of course, the whole recording technique is different, but what I am curious about is whether one can get the same colour and bite of sound with the SPS200 as with a Sennheiser MKH or DPA 4006 setup (with Jecklin disc for instance).

Some people complain that with the soundfield method they do not achieve the same kind of spaciousness and liveliness as with a spaced omni setup. What is your opinion? Could one get this little extra space by adding a bit of spaced omnis sound to the SPS mix? Anyone experience with this?

Hi Lucas,

When you say "Larry is helping you", I presume you must be in NZ?

If you were in the UK I may have been able to pop over and we could have tried mine out on a session so you could hear how it sounds.

If you are close enough to him is it possible to hear some of his stuff? (SPS200 and Nagra VI, like me).

Personally I rate the MBHO stuff up with the likes of Schoeps and Neumann in quality, and I know that Soundfield had long discussions with them to get the very highest quality capsules for the Soundfield microphones and all four very well matched capsules.

As my own SPS200 is relatively new, I have not had the chance to use it extensively on many projects - and those that I have used it on were actually sent to someone else to edit; so I cannot really comment too fully. Larry has used his more than me, so I would keep talking to him, I think.

The main saving in the SPS200 over the others is more in the fact that it does not have hardware controllers, which basically halves the price of the microphone. Though the others do have the capsules slightly closer and they also have a heater for outside work that prevents condensation which the SPS200 does not have.

I hope this helps.

[Plush]

Here I use the SPS 422B because I like having the hardware and traditional xlr hook-up. Also 4 channel B format output is standard on this model.

I don't use a laptop for recording although I have no objection qtomworking with software in post.

It is a great system, there is no noise in the system and it uses the traditional SF mic. The mic is equalized for flat response so, for example, you can record with the best Blumlein set-up ever and have much greater bass than one would normally obtain with normal figure-of-eight mics.

The other fellows can advise on the newer models.

from a birch forest in Poland,

PlushFluSsssh

[John Willett]

Originally Posted by Plush

Here I use the SPS 422B because I like having the hardware and traditional xlr hook-up.

Plush has more money than me [/jeaous mode off]

If you can afford it, the more expensive Soundfield mics. are definitely the better option.

But the SPS200 gets close at less than half the price.

I have wanted a Soundfield microphone for many years and it was only when the SPS200 came out that I could actually afford one.

Originally Posted by Plush

from a birch forest in Poland,

Enjoy yourself, I really love that part of Europe.

If you were there a couple of weeks ago and I had known I would have popped over the border from Slovakia and had a meet (I was over there for three weeks celebrating my birthday).

[Lucas_G]

Originally Posted by John Willett

Hi Lucas,

When you say "Larry is helping you", I presume you must be in NZ?

If you were in the UK I may have been able to pop over and we could have tried mine out on a session so you could hear how it sounds.

If you are close enough to him is it possible to hear some of his stuff? (SPS200 and Nagra VI, like me).

Personally I rate the MBHO stuff up with the likes of Schoeps and Neumann in quality, and I know that Soundfield had long discussions with them to get the very highest quality capsules for the Soundfield microphones and all four very well matched capsules.

As my own SPS200 is relatively new, I have not had the chance to use it extensively on many projects - and those that I have used it on were actually sent to someone else to edit; so I cannot really comment too fully. Larry has used his more than me, so I would keep talking to him, I think.

The main saving in the SPS200 over the others is more in the fact that it does not have hardware controllers, which basically halves the price of the microphone. Though the others do have the capsules slightly closer and they also have a heater for outside work that prevents condensation which the SPS200 does not have.

I hope this helps.

Actually, I live in the Netherlands, so we are divided by quite a lot of seawater, but not as much as in the case of Larry...
Larry is helping me over the internet.

It is good to hear these things. I am more and more attracted to the versality of the Ambisonic system. The price for the 442B is about the double of the SPS200 but you do get the decoding unit including preamps of course. I don't know how good this preamp actually is.
My concern was whether those larger capsules (placed more closely) are really better than the small capsules of the SPS 200, but your remarks on the MBHO production are reassuring.

Has anyone on this forum actually tried to mix the outcome of an Ambisonic recording with some extra omni mics?

Regards,

Lucas

[richgilb]

Originally Posted by Lucas_G

Some people complain that with the soundfield method they do not achieve the same kind of spaciousness and liveliness as with a spaced omni setup. What is your opinion? Could one get this little extra space by adding a bit of spaced omnis sound to the SPS mix? Anyone experience with this?

I use omnis with the Soundfield SPS200 in the middle when the room is large. If the room is smaller or the musicians are fewer, I choose the SPS200. More important to me is flexibility of post-editing than the spaciousness that you may have heard about. I cannot be so sure that my Elations with omni caps are more spacious sounding than my SPS200. Perhaps yes, but then that is the nature of omni, right? So it is unfair to criticise the SPS200 for this, them having cardioid caps and clustered together.

Another thing, I think that when people say it has restricted usefulness (ie only good for distance miking or room sounds), this is unfair. John has mentioned previously its ability as a drum overhead and I have had great results close up with a nylon string acoustic guitar.

[Larry Elliott]

Originally Posted by Plush

you can record with the best Blumlein set-up ever and have much greater bass than one would normally obtain with normal figure-of-eight mics.

The other fellows can advise on the newer models.

PlushFluSsssh

I have found the decoding to Blumlein from the SPS200 A format files is superb and is what I use most often. Especially for choral groups.

Like John W I couldn’t consider one of the earlier models of Soundfield because of the cost.

Larry

[Larry Elliott]

Originally Posted by Lucas_G

Has anyone on this forum actually tried to mix the outcome of an Ambisonic recording with some extra omni mics?

Regards,

Lucas

My last two recordings with SFS200 included a pair of Omnis as well. Still to compile these files but initial thoughts are that it is a great combination. Thanks to richglib for the suggestion!

Larry

[johnsound]

Worth reading:

Working with B+ Format

Regards,

John

[Petrus]

I did some fresh recordings with SPS200 last sunday. The flexibility in post is nothing short of amazing! I ran the mic with a 40cm pair of 8020 and ORTF of Gefell M950. Working on some samples now...

[aracu]

Theoretically, the Harpex software can emulate spaced omnis or other
spaced pairs from b-format, which could eliminate having to use extra
mics with an ambisonic mic to achieve spaciousness or other qualities
of an omni or near coincident array.

In my limited understanding of soundfield mics, it looks to me like one of the basic differences between a soundfield mic and mid-side recording is that in mid-side recording there is a fixed side mic, used with any polar pattern as the mid mic. A soundfield mic does not appear to work like that, instead, it emulates two coincident mics which always have the same polar pattern as one another. This would suggest that there are many mid-side arrays
which cannot be emulated with a soundfield mic, apart from a mid-side
array using a figure 8 as mid (if this is wrong I'm sure someone will correct
me).

However, according to the Harpex designer, it is possible to open two
instances of the program, in such a way, as to create one fixed figure
8 pattern from the b-format, and another polar pattern of any type, which would allow for the possibility of emulating any type mid-side array.

[leddy]

Originally Posted by aracu

Theoretically, the Harpex software can emulate spaced omnis or other
spaced pairs from b-format, which could eliminate having to use extra
mics with an ambisonic mic to achieve spaciousness or other qualities
of an omni or near coincident array.

In my limited understanding of soundfield mics, it looks to me like one of the basic differences between a soundfield mic and mid-side recording is that in mid-side recording there is a fixed side mic, used with any polar pattern as the mid mic. A soundfield mic does not appear to work like that, instead, it emulates two coincident mics which always have the same polar pattern as one another. This would suggest that there are many mid-side arrays
which cannot be emulated with a soundfield mic, apart from a mid-side
array using a figure 8 as mid (if this is wrong I'm sure someone will correct
me).

That is wrong.

Take for example, mid side with a cardioid mid. You end up with a virtual pair of hypers. To match that with a soundfield mic, you simply decode it to a pair of hypers.

Want to simulate an omni mid? Make the soundfield decode with two cardioids pointing 180 degrees apart. Adjust the pattern to match the effect of altering the proportion of side mic in the traditional mid side array.

End result is the same, except of course the decisions can be changed in post with the soundfield.

[aracu]

Originally Posted by leddy

That is wrong.

Take for example, mid side with a cardioid mid. You end up with a virtual pair of hypers. To match that with a soundfield mic, you simply decode it to a pair of hypers.

Want to simulate an omni mid? Make the soundfield decode with two cardioids pointing 180 degrees apart. Adjust the pattern to match the effect of altering the proportion of side mic in the traditional mid side array.

End result is the same, except of course the decisions can be changed in post with the soundfield.

You may be right, but I am not totally convinced that each mid-side array corresponds exactly to a coincident array with two identical polar patterns.
It seems to me that the different arrays are picking up sound from different areas of the room, and especially if the arrays are close to the source, have different on or off axis relationships to the source material.

[John Willett]

Originally Posted by aracu

Theoretically, the Harpex software can emulate spaced omnis or other
spaced pairs from b-format, which could eliminate having to use extra
mics with an ambisonic mic to achieve spaciousness or other qualities
of an omni or near coincident array.

Yes, Harpex looks extremely interesting.

Originally Posted by aracu

In my limited understanding of soundfield mics, it looks to me like one of the basic differences between a soundfield mic and mid-side recording is that in mid-side recording there is a fixed side mic, used with any polar pattern as the mid mic. A soundfield mic does not appear to work like that, instead, it emulates two coincident mics which always have the same polar pattern as one another. This would suggest that there are many mid-side arrays
which cannot be emulated with a soundfield mic, apart from a mid-side
array using a figure 8 as mid (if this is wrong I'm sure someone will correct
me).

Wrong.

If you take the "A-format" signal from a Soundfield - it is the raw signal from each of the four capsules.

The matrixed "B-format" signal is four microphones

• Fig-8 side mic.
• Fig-8 mid mic.
• Fig.8 up/down.
• Omni

Harpex uses these to matrix many different stereo and multi-channel configurations.

[aracu]

Originally Posted by John Willett

Wrong.

If you take the "A-format" signal from a Soundfield - it is the raw signal from each of the four capsules.

The matrixed "B-format" signal is four microphones

• Fig-8 side mic.
• Fig-8 mid mic.
• Fig.8 up/down.
• Omni

Harpex uses these to matrix many different stereo and multi-channel configurations.

I see your point, and it is a good one.

What I was referring to in my post was the way in which the traditional Soundfield and other b-format software that I am aware of, was processing the b-format (to the best of my limited knowledge about it).

I mentioned in my post that the Harpex software overcame this limitation.

[John Willett]

Originally Posted by aracu

I see your point, and it is a good one.

What I was referring to in my post was the way in which the traditional Soundfield and other b-format software that I am aware of, was processing the b-format (to the best of my limited knowledge about it).

I mentioned in my post that the Harpex software overcame this limitation.

The Soundfield software can manipulate B-format into surround and can pan and tilt the microphone.

But only Harpex can, in effect, move the capsules apart and make the equivalent of an ORTF pair (for example).

[Tom McC]

Originally Posted by John Willett

But only Harpex can, in effect, move the capsules apart and make the equivalent of an ORTF pair (for example).

I'm struggling to get my head round how Harpex manages to pull off this remarkable coincident -> ORTF trick.

In a thread some time ago, I pondered the notion of mapping a coincident pair to ORTF (assuming for now one would wish that) - by converting the interchannel intensity difference to a sound-source arrival direction and thence to an ORTF intercapsule arrival time difference. Petrus pointed out the futility of that, the flaw being that one needed to consider distance as well as direction, for there is an infinite number of sound source locations (lying along a hyperbola curve) that satisfy the condition of producing an identical arrival time difference at the ORTF capsules.

So what's then different with the (coincident) Soundfield? Does the extra dimension of spatial information allow the maths to be solved?. In abstract superficial terms, something akin to finding the intersection point of two hyperbolas - one derived, say, from info from the B-format X-Y pair and one from the X-Z pair? .