Ljudmätning 2

[Nicke Löfgren]

Vad ska man inhandla för att mäta ljud?

Låt säga jag vill ha 2st mätpunker som loggar nivåerna dygnet runt året om!
Det ska vara lätt att "backa" och ta fram info samt att skriva ut den.

[Andreas Vinnberg]

Live-Capture Pro från wavecapture?

[Michael Christiansen]

Vad ska man inhandla för att mäta ljud?

Låt säga jag vill ha 2st mätpunker som loggar nivåerna dygnet runt året om!
Det ska vara lätt att "backa" och ta fram info samt att skriva ut den.

Häpp!

Good danish shit skapat av Jacob Navne som är teknisk chef i VEGA:

10EaZy systemet övervägar och loggar ljudnivået på spelställen, diskotek etc.

Kolla på http://www.benum.se" onclick="window.open(this.href);return false;

Används även på Roskilde Festival osv....

Och sen har du ju själv omtalat Soundear - dom har även satteliter som mäter och ett loggningssystem.

Jag tror att Jacobs system funkar bäst för plånboken...

Bästa hälsningar från København

[Michael Christiansen]

Hej Nicke

Mera info:

http://www.dk.soundear.org/index.php?op ... &Itemid=64" onclick="window.open(this.href);return false;

Fast dyrt, dyrt och alltför dyrt....!!!

[Nicke Löfgren]

har tittat på det, ja det är dyrt

[Nicke Löfgren]

vet du vad 10EaZy systemet kostar?

[Jacob Navne]

Hei Nicke och andere.

Jeg skriver følgende på engelsk da jeg som dansker er elendig til svensk på skrift - jeg håber i vil bære over med mig for dette.

Michael, who posted earlier in this thread pointed my to this forum, and asked me to do a little speech
As written in his post, I'm the inventor of a sound level meter solution dedicated to the live sound industry, a product called 10EaZy - which is a complete measurement chain featuring both software and hardware. Having said that, this is not an advertisement forum and the following text is more a general information, based on the topics I very often meet when talking to potential customers - The topic "measuring dB" is not very sexy and there is quite a lot of confusion on the up and downs of what can and what cant be done in our industry.. so I'll try and connect the boring facts of sound level measurements with the real world for sound guys and affiliates.

All boiled down the requirements for sound level measurement equipment is defined in IEC61672. This is a standard used in all of europe, and ensures that sound level meters from Germany may be used in spain, because the values measured are the same. The IEC standard lists a number of requirements that the producer of the sound level meter (from now on shorted to SLM) need to comply with. The most important once are the accuracy of the microphone, the frequency response of the microphone and the tolerances for the different frequency and time filters used (for instance the A-frequency weight, and the peak, fast, slow options) The IEC standard defines two levels of precision, class 1 and class 2, class 1 being the most strict with very little tolerances and thus more expensive hardware, and class 2 being a bit more loose in the demands for precision.
When looking for a SLM one of the first things you will notice is the wast price range.. a quick look at thomann will show you that you can get a class 2 sound level meter for around 100 €'s and if you call large SLM manufacturs like bruël & kjaer (B&K) or norsonic they can offer you systems that on paper does exactly the same for 10.000 €'s ... how comes?? are they just making a whole lot of money by fooling customers or are there actually a difference.

The obvious answer is the correct answer - yes there is a huge difference, you actually get what you pay for.. Then what is the difference, if they both claim compliance with IEC and which of these diffenrences should be considered before buying a SLM for measurements at live events?
First of, the preamp used with the microphone makes a difference. On the cheap sound level meters the preamp is very poorly done and as such it is only capable of measuring sound levels at above say 50 dB. The expensive B&K meter will be able to measure levels at 10 dB (if you can actually achieve such a quite place) - This is not really a concern to a "concert -SLM" since just letting in 4 people into the venue will elevate the background noise with them talking to above 50 dB.

The next major difference is the microphone. Alot of condenser microphone exhibits a near linear frequency response which is one of the requirements to the microphone according to the IEC61672 standard. however, another demand is how the microphone reacts to changes in relative humidity and temperature. The diaphram of a normal microphone found in a house box changes its sensitivity with temperature and humidity. This is why a professionel SLM not just connects to the SM81 or AKG535 from the housebox but to a special designed 1/2" microphone, build to exhibit the exact same sensitivity at any temperature and humidity combination.. This is a very important aspect when picking up a SLM that needs to be used to measure sound levels at live events, because the climate will change - if it's an outdoor show the temperature will rise and fall during the day as well will the humidity, and if it is indoor the addition of x nu,ber of sweating and dancing people will equally change the temp / humidity during the event. Ultimately what was 99 dB in the morning may very well be 103 or 95 dB in the evening, and this is off course on accetable, both for the sound engineer who has to mix a show under limit regulations, but more importantly - since the measurements are being used to document an event, the numbers need to be absolut and reliable since they may end up being the make or brake for an event organizer struggling in court with local authorities or audience claming hearing impacts due to loud levels.
Need less to say, the 100 € SLM is not capable of compliying with this as the quality of the microphone is no way near high enough. This is the most overlooked aspect of SLM's and I hope that by writting this thread the knowledge will spread slowly to our industry.. in essence, if you are a sound engineer who just wants to get an indication on how loud you are playing, 100 € slm may very well suit your need.. you will not be able to measure average Leq values, as are required in many countries these days, but putting the meter to "slow" will give a good indication on how you are doing.. On the other hand, if you are a PA company or a festival organizer, who may very well be held responsible for the sound levels at an event, buying a quality SLM with logging capabilites to ensure post documentation to authorities is a must and may even be required by law! Just like the 500 W RMS of a meyer sound speaker is very different from a chinese 200 dollar speaker who claims the same ability to produce 500 W rms, the chinese are not really lying, they just "adjusted" the parameters of the measurement to make the product look better than it really is.. The same way, the manufacture of the 100 € sound level meter, is not really lying when they claim class 2 capability, they are just not telling the whole story of under which conditions the sound level meter is compatible.. The majority of cheap units will fully comply with the IEC standard at room temperature, but unfortunately, this is not always the conditions under we as engineers are working

Last key element in SLM purchase decision is the calibration of the system. The calibration is a process in which the microphone is mounted in a "calibrator" which is a unit that produces a very precise pure sine wave at 1kHz and either 94 or 114 dB. This is the only way to ensure that the sensitivity of the measurement chain is known and correct. This is also why the majority of microphones from our housebox can never be used for SLM applications as they will not fit into a calibrator who supports microphone with 1/4", 1/2" and 1" diameters.
The calibration is a very important aspect of a SLM as well. Not having a properly calibrated measurement chain invalidates the entire measurement, regardless of the quality of the microphone and other associated hardware units. This is also why software sound level meter applications are a difficult beast to handle because the majority of soundcards will have a gain button which are accesible wither on the hardware or in the windows driver.. It does not take a whole lot of science to figure out, that if you calibrate a system to display 94 dB on a soundcard with a gain button, then during the day some person may turn this button down, by act of god or just to cheat, and then the measurement will be incorrect and void!

So when you buy "just" a SLM software, it becomes YOUR problem to find a measurement chain that can not be adjusted to ensure proper calibration throughout the event and that the microphone has the correct specifications to fully comply with the IEC standard. It may very well be that the sofware it self complies with the IEC standard, but that is the least thing. Finding a hardware solution that can actually ensure the above requirements are by far the most expensive part of the total solution. A calibrator alone is around 300 € and then you will need to find the soundcard that can not change gain and a qualified microphone!

I hope this has been informative - at least it is a long text

ADVERTISEMENT BIT:
Since people asked about the pricing, i'll allow my self to do a short presentation of 10EaZy, if moderators disagree, please let me know and i'll remove this bit ASAP.
Touring as a sound engineer in the majority of Europe and the US, i've come across a wast amount of dB limits and hardware used to measure it. What has always pissed me off, was the total lack of understading of what was being measured and how by the system engineer, and even by the representatives of the authorities issuing the limits. This is why I sat out to design a SLM system that was easy to use, and more importantly easy to understand for the sound engineer, and for the user to avoid user errors. The solution became 10EaZy.

Main points are: 10EaZy is a software SLM but ships complete with hardware. And please note, the hardware is not a digigram or M-audio card with gain buttons everywhere, it is a fully locked generic USB audio card and a 1/2" certified microphone that ensures the correctness of the calibration in all temp / humidity situations - apart from the extremes, so if any one from the Lapland regions read this, please write me for details on how to measure at 2 Km altitude in -20 degress:-) -
It is designed to be fool proof and "hands off" operated, meaning that the measurements will start by them self, log what needs to be logged, and you can rest assured that the calibration is accurate everytime, yielding correct and legally valid measurement logs. This does off course make the 10EaZy more expensive than 100 € SLM's from Thomann or stand alone software solution, and the systems ship at approximately 2100 € excl VAT.. But again, if you are to buy hardware and calibrators that actually fulfills the IEC requirements, you will spend an equal amount of money, and since they come with gain buttons you may touch, you will also need some guy looking at the soundcard all day to ensure that no one cheats..

There is a lot more info at http://www.10EaZy.com" onclick="window.open(this.href);return false;, so if anyone is interested please feel free to drop by - it is also possible to download a demo here, which off course will not yield precise measurement results, as it uses your onboard soundcard - there is also a contact form so if you have further questions please write the 10EaZy HQ from there.

Have a nice day and a hopefully nice and sunny festival season.