Recording 5.1 Impulse responses in a Cathedral

[VinyDdutch]

A couple of days back I ran into an awesome oppertunity, being able to record the Impulse Response (for Convolution reverb)of the Toledo Cathedral, in Toledo Spain.

Now I´m looking for advice on gear and techniques, This is the setup i´m thinking of:

-Apple Laptop with the Apple Impulse response utility
-High quality sound card (Focusrite, MOTU, DIGI 003 recommendations Welcome)
-KRK Monitors
-I probably can get my hands on a HOLOPHONE H2-PRO, Otherwise I need to find a pair of Measurement mics (recommendations Welcome).

And I would need Extremely tall mic stands (+10M), Have no idea if they exist, any ideas how I could get or make these.

Any suggestions on techniques and gear are extremely welcome, Let me know if anybody has experience with recording Impulse Responses.

Thanks,
Ruben

[jude]

please excuse my noobish question, but why not record the impules at lower levels?

its not like we sit 15m in the air thinking "boy this sounds good

[videoteque]

I have been in Toledo's cathedral. Toledo was famous for the knives they made. They had a big crisis and then The Lord of the Rings arrived, they refloated the knive industry making swords!!!

Back to sound, you probably want to record by night or early in the morning, during the day there are visitors and probably car noises...

[Martin Kantola]

Have been recording impulse responses with my native B-format microphone (see link to panphonic below) with great success. The benefit is that you only have three or four signal to record, but also the reverb becomes very versatile, since you can choose the pickup type and direction in post, while listening to the convolution. In other words, have sometimes turned the reverb image to face the back of the church even if I had originally turned the microphone to the front. It's also great if you decide to use the impulses for stereo reverb later. A Blumlein pickup pattern probably sounds great on cathedral reverb!

Would also consider either a set of 5 high quality microphones or a Soundfield instead if you plan to use the reverb for music. Your impulses only sound as good as the microphone you had.

Have fun!

Martin

[t-hiho]

I'm doing impulse respones measurements since 5 years.
My experiences:
- very important: the preamp! use something very very clear! fav: grace 801. use good ADs! fav: lynx aurora. don't go for internal pres / combis: good for music, but way too noisy for being clean enough for gaining a good room response!
- also: use best mics possible! use at least 2, better 3 different sets of mics, so you have the choice later! I use: Schoeps MK4 cardis, DPA omnis, Neumann LDs. rent them, if You can! It's worth it! I did a big nice building reverb some years ago, and had only 4 AKGs. Guess what, I had to come back one year later and redo it with better mics, since the impulses were used really often in my studio, but were lacking the depth of a really good recording!
- use a really long sweep for church applications! 50 sec. or so! make several measurements! You can't be sure if there was something from outsinde disturbing the left rear mic, till You're home!
- rec at 2444, then at 2448 and then 2496! the build in SR-converters in the convolver-plugins suck!
- try different deconvolvers! try slight sample start offsets (just 1-5 samples!) before deconvolving - sometimes this can give You great results, despite being not completely natural!
- finally: share Your impulses with us! I give mine to whoever is interested in for free. It's the most interesting part on working with convolution reverbs, IMHO: Exchange!

[mintmix]

Originally Posted by VinyDdutch

A couple of days back I ran into an awesome oppertunity, being able to record the Impulse Response (for Convolution reverb)of the Toledo Cathedral, in Toledo Spain.

Now I´m looking for advice on gear and techniques, This is the setup i´m thinking of:

-Apple Laptop with the Apple Impulse response utility
-High quality sound card (Focusrite, MOTU, DIGI 003 recommendations Welcome)
-KRK Monitors
-I probably can get my hands on a HOLOPHONE H2-PRO, Otherwise I need to find a pair of Measurement mics (recommendations Welcome).

And I would need Extremely tall mic stands (+10M), Have no idea if they exist, any ideas how I could get or make these.

Any suggestions on techniques and gear are extremely welcome, Let me know if anybody has experience with recording Impulse Responses.

Thanks,
Ruben

Hey there, I spoke with the one of the guys from altiverb a couple of years ago and asked him about using the Holophone for recording impulse responses and he mentioned they took issue with their mono compatibility. I personally have never experienced a problem with this. I would love to hear about your success if you do end up using the Holophone. Please let us know how it turns out! thumbsup

Oh also you could look at the metric halo 2882 it has 8 firewire buss powered mic pres for only 2k$. It's compatible with Pro Tools.

Good Luck

[David Spearritt]

In my experience, by far the most difficult part of measuring IR's successfully has nothing to do with microphone choice or config. The hard bit is getting enough signal to noise ratio uniformly at all frequencies. This is difficult in mid to large halls (2500 seats) but in a large cathedral it will be even more challenging.

It is always good practice to have clean quiet mics and measure at 24bit, but getting a clean, undistorted loud sound power source and enough measured signal is going to quality control the result, assuming its for use in convolution reverb plugs for mastering.

[BLP]

Originally Posted by VinyDdutch

-KRK Monitors

I'd say that, if you're really going all out on this thing, try to get a solid, loud set of full-frequency drivers. B&W 802's seem to work well for this, but even they need subs to really kick it down to 20Hz... I know it's a tall order, but the output driver really does make a huge difference!

[VinyDdutch]

Thank you all for the responses,
I´ve also contacted Altiverb, to ask them how they recorded their IR,
they advised me to use Genelec Monitors, Because of their EQ, they also use DPA omni mics,
I´ll let you guys know how this all turns out.

Thanks,
Ruben

[just.sounds]

As noise is no big issue in convolution use mics that are very omni.
4060's are great. Also the speaker have to have low off axis coloration.
Metric halo is super. I recommend a 40 cm and a 3m square of omnis [edit]40cm gives a very pleasing stereo/surround image of the hall but al little monoish bass 3m gives that bass spread but a not so nice image, crossover and or mix to taste[/edit]

[Murton]

The little experience in Convolution response I have done have been done with Earthwork mic's - TC20's and a shitty monitor and it turned out quite great.

[monomer]

Hi people,

I'm plannig to do a recording of a hall in a building.

Wondering what a good setup is.

Since monitors are pretty directional, should i keep them close to the mics and pointed outwards or should i line them further away and inwards?

I guess i'm not sure how the deconvolving process works.
Does it remove the direct sweep coming from the monitors or does it include it in the IR as an early reflection?

(btw, i will use logics deconvolver.)

[VinyDdutch]

Take a look at the audioease page The Altiverb™ IR Pre-Processor this will explain the best ways to make IR´s

[jnorman]

just an FYI for those interested in IR's - Acousticas has released its sampling of the IR's from the Bricasti M7 for FREE (unreal!!), and they are fantabulous (many thanks to casey!). Several major concert halls, auditoriums, old churches, etc, are included. there is a link to the free IR downloads here on GS, i think in the "news" section of the forum.

[monomer]

Originally Posted by VinyDdutch

Take a look at the audioease page The Altiverb™ IR Pre-Processor this will explain the best ways to make IR´s

Thanks, that cleared things up a bit.