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I have used hydrophones for several years, mainly Aquarian H2a XLR and JFR piezo’s. But I have never been happy with the sound quality.
Comparison is hard to find on the internet and most hydrophone recordings there have been fixed in a post process so it doesn’t give me clear  information how it actually sounds. Most hydrophone manufacturers don’t give a standard or important information so buying a quality hydrophone for thousands of dollars can be a risky task. 
Last summer (2020) I spent several hours recording on Jökulsárlón Glacier lagoon. I noticed behind the sound of H2a was something very interesting soundscape which H2a couldn’t clearly capture.
So I decided  to get a better hydrophone before I continue to record in this lagoon.
I contacted both B&K and Teledyne Reson to check the price and options. Both his manufacturers gave me useful information but the price was higher than I was ready to pay for a good car so I continued the search. Ambient has two interesting hydrophones but they do not show important information. When I ask for Frequency and S/N graphs, Ambient just sends me the user manual which is already on their website. Same with Cetacean Research and Dolphin Ears, which either give me strange answers or no answer  So I continue to search through several manufactures.
Suddenly and surprisingly I found Benthowave, a company which was ready to custom made hydrophones for me, hydrophones where I got all necessary information for my needs. It was almost too good to be true, so it takes me several weeks to decide to let Benthowave build my dream hydrophone.
The base was built on BII-7122 but additional with balanced output w. BII-1082 ultra low noise amp and 15meter long cable.
No problem, I would get it after 6 to 8 weeks! But that was too late for me. My recording project actually started that time in late May. Before that project starts it is necessary to build a customized floating platform and power supply for the new hydrophone which can take two to three weeks. 
So I ask Benthowave which low noise hydrophone they have in stock. It was only a single output BII-7121 with internal BII-1081 amp.
Two weeks later they were in my hands.
 My first impression was a huge disappointment. I was almost sure I had thrown money out of the window. But after I build my second power supply, these hydrophones start to rock. It was two key figures that were important to know to let them work without problem.

1. While this hydrophone is so sensitive at low frequency, higher voltage means better performance to avoid internal amplifier overload/dropout.
2. These hydrophones are sensitive for EMF. From the power supply box (made out of metal) must be a wired ground connection to the water which will be recorded if any EMF pollution is around

Other things must be kept in mind because these hydrophones use an external battery power supply, but NOT Phantom power. Use a recorder which has „Combo input“, (XLR and jack input) or 3,5mm jack input. Use only Jack to connect the hydrophone to the recorder so you will never mistakenly get Phantom Power into the hydrophone. It might be possible to use Triton Big Amp for recorders that don’t have Combo input. But I haven’t tested it yet. I will write an update when it has been tested. I use non-standard XLR connectors in and out of the battery box so even blind men can not connect the hydrophones without correct cables.

Conclusion of the comparison
I am not sure if this comparison gives a correct picture of the Aquarian H2a. Mine have a LOM phantom power adapter which has a small amount of gain and probably makes tiny changes in the frequency curve.
Anyway, with this adapter it sounds similar to the original. I put this adapter to avoid extra noise which I got only in the SD744 recorder and with HPF off. This adapter also avoids other strange and unusual noises which I think is caused by the 48Volt phantom power which I think is too high. But with the adapter the H2a  is driven by 5Volt.
This comparison was done in Sundahöfn port of Reykjavik. In a corner which is mainly used for depreciated ships so it was quiet, without loud ship engine noise.
The hydrophones were placed side by side in 1,5m depth with 2,5m separation, from a floating pier with two bonded boats. The gain on the MixPre6 was at 30dB for both hydrophones and HPF was off 
There is pretty much difference between these two hydrophones, both in frequency range and sensitivity. Benthowave BII-7121 frequency range is from 0,5 hz to 60 Khz at +/-3dB V/μPa. On spectrograms I can see it can as well detect sound up to 80Khz  or as high as I can record at 192Khz.
The hydrophone sensitivity is -158,7 +/- 0,2dB plus +26dB BII-1081 amplifier gain (-185dB) and self noise is 25dB μPa/1KHz.
Aquarian H2a frequency range is 20Hz-4.5KHz +/- 4dB and the self noise is  „low noise“ whatever it means. Sensitivity is -180dB re: 1V/µPa. My Aquarian hydrophones are not new, so new model might have increased sensitivity. Compared to BII-7121 it seems be close to -165dB. With the LOM Phantom power adapter the sensitivity is closer to -170dB re: 1V/µPa  and the frequency range seems to be on spectrogram close to 100-7Khz.
It was not easy to normalize the level of these hydrophones while they have so different frequency ranges. To do that I tried to normalize the level by listening to constant pump noise in the background in the recordings and make it as equal as possible in combination with the level meters. 
At the moment I can’t say much about the self noise. It could be difficult to compare these two hydrophones while they are so different in frequency ranges. I somehow expected to hear lower self noise in BII-7121. But it might be as good as it gets.  It is -24dB below sea state zero at 1Khz,  which is very good, even for much more expensive hydrophones. But to know exactly what it means for me I need to test them in quiet lakes.  I will put an update here as soon as I have done that.
I must say, the BII-7121 has very nice sound quality, Just as I expected. It is almost possible to hear the depth of the field, while H2a sounds flat and all high frequency is missing. But keeping in mind these two hydrophones have very different prices so in fact it is unfair to compare these two hydrophones.  One piece of BII-7121 cost about USD 1,244.- (base price), while H2a XLR cost USD 194.  I should rather compare Benthowave to Teledyne Reason like TC-4032 which cost EUR 3,640.- or Bruel & Kær like 8106 which cost DKK 86,470.- I think they will all sound similar.
Benthowave seems to be built on rather cheap plastic materials and glue, it looks very fragile and seems to be not as robust as Teledyne or B&K. But as long as Benthowave can offer me the same or similar sound quality at a lower price I am happy with that.
BII-7121 could have been heavier.  It weighs only 95gr while H2a weighs 125gr which is even too light. The BII-7121 cable is Gepco MP1201 Quad Star.      
In the recordings below you can hear in some headphones an unpleasant „low frequency noise“ due to the wind. This is because there was a lot of wind on the day when this was recorded. The cables to the hydrophones were mostly up on the pier where the wind got an awkward amount of play around them.  
This „wind sound“ will usually disappear once I have built the „floating platform“ for the hydrophone.
I will post pictures when its done, plus other experiments too.

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Recording straight from the recorder, only add +12dB in post
Benthowave BII-7121

Recording straight from the recorder, only add +12dB in post
Aquarian H2a 

Normalized recording BII-7121  

Normalized Recording H2a 

Recording with BII-7121 of a Tugboat propeller 250-300 meter away. This recording is straight from the recorder, no extra gain.
Notice at 3:55 the amplify goes up and down. I am not sure what it is. I think it could be a strange behavior of the hydrophone when they are in „strong“ current or water flow, in this case from the tug propeller, which was though not very strong. It could be as well the ground cable which lost contact to sea while waves pass the pier.
H2a normally makes a low frequency noise in water flow or current. But I am sure this current was not strong enough for H2a to make a noise.  
I will write an update as soon as I figure out why BII-7121 acts like this.
All updates will be added here below by date. 

More information about hydrophones & underwater sound:
Construction and testing of low-noise hydrophones (pdf)
Sound in the sea
Hydrophone Review: Ambient ASF-1, ASF-2, Aquarian Audio, JrF by Sach Poff

Quality open headphones are recommended while listening at mid level.
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Update 9th of May 2021 ——-

Hydrophones with frequency range down to 1Hz are very sensitive for all movement in water or water flow, which seems to cause an overload for the internal amplifier so the audio output turns on and off while it happens.
At the moment I would recommended for everyone who like to order Benthowave hydrophone to ask for custom HPF at 10Hz or 20Hz, otherwise the hydrophone will be only usable during calm days 
If default HPF is in the hydrophone then is it necessary to make some kind of „flow noise reduction“ for the hydrophone, similar protection cages which CRT make for its own hydrophones. 
Rycote BBG 25mm fits perfectly for this BII-7121. But that is not the final solution. Original BBG did not work well so it needs some changes which I am working on.
I will post an update later when I think I have found the final solution.

Update 30th of August 2021 ——-

The BIG-7121 tested with a 25 volt power supply (with six 18650 Li-Ion cells).
It does not completely fix the overload / dropout in the amplifier.
Compared to 16 volt and recording from SOT Kayak the hydrophone can now withstand much higher waves (up&down) and tide current (@8m depth)

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It is not everyone who knows that when recording the finest detail in natural silence a large-diaphragm condenser microphone can be much better choice than a small-diaphragm condenser microphones.
But there are just few microphones which can fit into this category because they must have the lowest noise possible on the microphone market. Of course it is possible to use a noise reduction software but that will never give as good of a result as recording with the best separation between signal to noise ratio. Many microphones have very low noise, but are not sensitive for the finest details, so low noise number in manufacturer specification is not telling you everything.
So what microphones are the best to record fly’s footsteps?
For a many years Rode NT1a has been the best microphone in this category. But now we have at last two other microphones to choose. They are Lewitt LCT540s  and Rode NT1. All these three microphones are almost equal when it comes into self noise, but they are slightly different by characteristics. Rode NT1a is extremely well focused on midrange <8Khz so for most natural sounds they can give a stunning result. But for whole natural soundscape they sound rather flat and without depth, I guess mainly because NT1a has a poor low frequency response. It is also very sensitive for handling noise so using NT1a outdoor in a windshield is very difficult.
Rode NT1 is an improved version of NT1a. Anyway it is not as well focused on the mid range, but instead it sounds slightly more natural with better low frequency response and has also less handling noise.
I recently discovered Lewitt LCT540s which sounds overall fantastic. Different from NT1 and NT1a which is mainly good for voices and spoken words, the LCT540s sounds very natural for everything, as for quiet open natural spaces and for music. It is even possible to hear the depth of the field in all sound pressure levels which is not usual with many other microphones.
I think many are curious how this large capsule withstand humidity. I can only say, in Iceland humidity is not a big problem, I just remember one time I had some strange noise in NT1a, But that was in a bog after several hours in fog and rain so the windshield was soaking in water.
This comparison is mainly focused on LCT540s and NT1 while they sound so close. Their main difference is the output sensitivity which is about +7dB higher in LCT540s than in NT1. MKH8040 is in other hand just for comparison, to show the difference between a small and large diaphragm microphones and how they react in quiet environment.
This recordings was made in 50m2 garage in the countryside. This recording contains mainly two ticking clocks, both sides of the mic rig, also a buzzing fly and a mouse jumping somewhere in the garage. Outside is a traffic in a distance
If you interest how NT1a compare to LCT540S, then you can read and listen to this older blog post HERE

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First three audio samples are straight from the recorder at 50dB gain, so it sounds in very low level. *

Sennheier MKH8040

Rode NT1

Lewitt LCT540S

Same audio samples again but with +24dB added gain to the original recording, combined 74dB of gain. *

Sennheier MKH8040

Rode NT1

Lewitt LCT540S

Audio samples goes through 80Hz HPF and normalized up to 0dB which increased the gain on MKH8040 about +16dB, NT1 about +14dB and LCT540S about +9dB *

Sennheiser MKH8040  See spectrogram

Rode NT1  See spectrogram

Lewitt LCT540S   See spectrogram

See the whole picture gallery

* All audio samples above are mp3 at 256kbps 44kHz.
Original recording at 24bit/48Khz on Sonosax SX-R4+ & SX-AD8+

See a windshield solution for Rode NT1a and Lewitt LCT540s

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When using a cardioid microphone in nature recordings Rode NT1a has been my favorite for a years. With its ultra low noise and sound clarity exactly on the bird song frequency ranges. But it also has a several bad futures. It is mainly made for studio recordings, so it is bulgy, heavy and sensitive for humidity. It has also a rather „flat sound“ and worst of all it is very sensitive for handling noise, so it is sensitive for wind noise and other vibrations, mainly through the microphone stand. All of these flaws has given me a good reason to use more often omni mics and AB setup rather other arrangement with cardioid mics
Searching for the perfect cardioid microphone for nature recordings can be difficult. They usually have higher self noise than omni or/and many large capsule microphones. But some of them have low handling noise and some work better in humid environment than other.
Here is a comparison of three cardioid condenser microphones which give an insight on how they detect the finest details in silence which is often very important issue in nature recordings, especially natural silence.
Sennheiser MKH40 has been well known for a many years as one of the best microphone available for field recording. But since Sennheiser offers the smaller brother MKH8040 at affordable prices, then that microphone has been its successor, especially because of its high frequency ranges up to 50Khz.
It is nearly two years since the Russian company Nevaton introduce their new compact microphone MC59 with two capsules omni (O) and cardioid (C).  It is made with similar modular system as Sennheiser MKH8000 series with an independent amplifier and capsule. One type with integrated 3-pin XLR connector and a smaller version “S” with a break-out cable.
As my previous comparisons this was made in the countryside in a 50 m² garage, in as much silence as possible. Gain on all channels was at 50dB and HPF off.  To focus on a sound source in this silence, I used a pocket radio and two ticking alarm clocks.  (See picture)

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First three audio samples are straight from the recorder so it sounds in very low level. *
MKH40   RX6 spectrogram   RX6 WAV

MKH8040  RX6 spectrogram  RX6 WAV

MC59C  RX6 spectrogram    RX6 WAV

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Same audio samples again but with +20dB added gain to the original recording, combined 70dB of gain. *
MKH40  RX6 Specrogram    Spek spectrogram

MKH8040  RX6 Specrogram    Spek spectrogram

MC59C  RX6 Specrogram    Spek spectrogram

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Audio samples goes through 100Hz HPF and normalized up to 0dB which increased the gain between 18 to 20dB, or combined 90db *

MKH40  RX6 Specrogram

MKH8040  RX6 Specrogram

MC59C  RX6 Specrogram

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Audio samples in more silence with +30dB added gain to the original recording, combined 80dB of gain, no radio or traffic noise. *
MKH40   RX6 Specrogram at +12db added gain

MKH8040   RX6 Spectrogram at +12db added gain

MC59C   RX6 Spectrogram at +12db added gain

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The comparison

MKH40 was in this comparison connected to the additional Sonosax SX-AD8+ mixer which was connected to the SX-R4+ recorder. When I put the recording through spectrogram I saw a strange buzz noise around 11Khz and above. I have seen this several times before on spectrograms, usually only when I have used the Sound devices 552 mixer. But not always and different from this one. I was not happy to see this happens on the SX-AD8+ mixer, so I checked if I could see this noise if I connected other microphones to the mixer. They all passed that test with success, even MKH20. But both MKH40 and MKH30 fail with this high frequency buzz. I am still not sure what is exactly going on. But I think it is some kind of ground problem in the microphone, not the mixer, even though it does not appear when using preamps in SX-R4 or MixPre recorders. I can change the shape and the frequency of this buzz by just putting a contact lube under an assembling screw on MKH40 and tie them again firmly.
This must be fixed. So I will continue testing and look into this issue with different microphones, recorders, mixers, cables and power supplies.
Except this high frequency buzz MKH40 sounds surprisingly nice. It sounds even more transparent than MKH8040 which surprises me because I have always thought it was the opposite. Saying that it might be because my ears barely hear anything above 11Khz anymore, so I can for example not hear the loudest part of the MKH40’s self noise which is between 12 and 23Khz, with highest level at 18Khz. That means I can only hear the self noise below that frequency range which anyway is a very important frequency range, because most of the nature sounds I record are below 8 Khz (at least in Iceland). So ultra low self noise at the midrange is more important than self noise on higher frequency range. This is what I noticed between MKH40 and 8040. The MKH40 seems to have slightly lower self noise at mid range and therefor the silence is more transparent with better fine details and better focused.
MKH8040 is a wonderful mic and one of my favorites, especially after Sennheiser fixed the noise problem which seems to have appeared in many MKH8000 mics some years ago. This pair comes nicely matched from the factory, it is suitable to record anything and as far as I know seems to withstand humidity as well as MKH40. For most recordings MKH8040 and MKH40 sound identical, These two mics have almost the same sensitivity and same characteristics. But the MKH8040 frequency range goes up to 50Khz which is useful for sound design and/or bat recordings. The 8040 self noise is not high but is the highest in this comparison. The self noise starts around 15Khz and is strongest around 50Khz. The sound quality seems to be a bit „gray“compare to the other two.
Nevaton offers MC59C sound samples of concert recordings to download. It was something in these recordings which told me that MC59 could be an interesting microphone  So I ordered four matched pieces of MC59C, from Bluetone mainly for music recording, but as well to keep it in mind to use them for surround nature recordings. This microphone is wonderful for music. It was confirmed after I did a concert recording last November. But that does not necessary mean it is as perfect for nature recordings. So here was a good reason to make a comparison to other well known microphones.
What surprises me in the comparison is the low noise and how clean this Russian wonder sounds above 10Khz. I just wished I was 40 years younger to hear this upper frequency clarity because I can mostly or only see it on a spectrogram which shows this microphone is outstanding compare to other small condenser microphones I know, as MKH´s. The mid range noise level is similar below 10Khz as in MKH40, or slightly more. But it has no additional self noise above 10Khz as most or all other microphones. In fact the self noise seems to be at same level through the whole frequency ranges up to 65Khz when it starts to increase.
Nevaton says the frequency range is 20-20Khz, but on the spectogram the frequency range seems to go much higher. When I recorded a noise from switching power supply it detect sound up to 30Khz almost as clearly as MKH8040 and without mic’s self noise.

Conclusion

In the sound world where it is possible to make a noise reduction with only several mouse clicks in a software it seems like microphone self noise does not matter. But it is not true. No NR software is so good it will not affect or harm the sound quality. So low noise microphones are important, especially at mid range (>8khz) for quiet nature sound and upper frequency (<8Khz) for music recording.
All three microphones in this comparison seem to have similar „low“ handling noise
MKH40 seems to have the lowest self noise at mid ranges and MC59C overall lowest self noise.
MKH8040 is a very versatile mic which can pick up sound up to 50Khz and is always a nice sounding microphone.
The MKH40 behaved strangely by creating this frequency buzz in individual frequency ranges above 10Khz. It is something I need to figure out as soon as I can and add information about it here in this blog.
MKH40 is anyway a good work horse. It is possible to rely on this mic in high humidity, record everything and always get highest quality you can get from a cardioid microphone. In my opinion, the MKH40 sounds slightly better than MKH8040 probably because it has less mid range noise than 8040. I have owned mkh80 for some years now, but not used it much. It is worth keeping this mic in action again.
MC59C is on the other hand the big success in this comparison. It has outstanding sound quality for classical music recording. Saying that, it must be kept in mind I have only used it once in a concert. In this comparison, sound quality seems to be the best I’ve heard or seen before on a small condenser microphone. It can clearly record the weakest sound effects between 10 KHz and 20 KHz without drowning that sound in the microphone’s self noise. The comparison did not exactly show which of these mics was the best to stay in a windshield, record everything from a birdsong to falling snowflakes, but MC59c is definitely an outstanding microphone and ready to record everything.
There is some rumors about MC59 can’t withstand high humidity. I have not tested it, but I think that humidity is not be a problem in Iceland.
It is a surprise to me how equally they sound compared to the price ranges. Nevaton MC59 is only half price of the MKH8040 and the MKH40 is more expensive**. But price is not everything because they all have a tiny specific difference.

See the whole picture gallery
* All audio samples above are mp3 at 256kbps 44kHz.
Original recording at 24bit/48Khz
** Update: Just overnight 18th of January 2020 the price of Nevaton MC59 microphones increase about 50%.
For one mic, both XLR or S version price was last week at €620 excl. VAT
But now is XLR at €868 and S version at €898

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Recording the silence of nature is a difficult challenge. Nevertheless. it’s worth it because it can be so rich of interesting microscopic sounds. Finding this silence is not easy and finding an acceptable microphone is yet another challenge.
Sennheiser MKH20 has been for many years a very popular omni mic for nature recordings. It has a very low self noise and is a natural sounding mic. It is a mic which can always make a perfect recording, for every task on the field.
Later Sennheiser made MKH8020, a smaller version with similar character but with frequency range up to 50Khz which is perfect for FX.
I have searched for other omni mics, but never found any that were comparable.
But now Nevaton seems to have made something interesting with its new MC59. In this case MC59O, which is a omni microphone. I have still not had a long experience with this mic so I should not give my opinion about it. But anyway this mic seems to be outstanding in many ways. It has the lowest noise floor I have ever seen in spectrogram and it is going to be at last one of my favorite mic for music recording.
So lets talk about how I compare these three mics.
I went to the country side to aware traffic and got as much silence as possible. I have access of around 50 m² garage, which is an ideal size and a perfect place for microphone comparison, if I get a calm weather and low traffic in the county. To have the „sound source “ of silence to focus on. I used two small ticking alarm clocks in around two meter distance, each side from the mic rig. Also a pocket radio within three meters in front of the rig at as low volume as possible (see picture). All of those items give an incredibly low sound, it was necessary to stop breathing to hear something. The sound sources gave a perfect insight how clearly the microphone could detect the weakest soundwaves in the silence. If you can hear this low sound reflecting between the walls inside this 50m² garage, the microphone is even better for nature sounds recording.
Sadly there is a lot of background noise in the audio pieces because of extreme traffic in the county this November day when I made this comparison. Most cars on their studded winter tires, which made an endless noise pollution in dozens of kilometers all over the county.
I placed the microphones in the middle of the garage (see picture) and used a Sonosax SX R4+ recorder & SX-AD8+ additional mixer.
All mic pairs were on their own Tbar (see picture).  MKH8020 on Ch.1&2, MC59O on Ch.3&4 and MKH20 through the mixer on Ch.5&6. All gain was at 50dB and LPF filters, 24bit / 48Khz.
I think the AD8+ mixer had the same preamps as the recorder. But because it is not in the „same case“ as the recorder, I think you should keep that in mind as it can probably affect the results of MKH20 in its comparison.

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First three audio samples are straight from the recorder so it sounds in very low level. *

MKH20   Spek spectrogram & Frequency

MKH8020   Spek spectrogram & Frequency

MC59O   Spek spectrogram & Frequency

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Same audio samples again but with +19dB added gain to the original recording, combined 69dB of gain. *

MKH20   RX6 spectrogram & RX6 WAV  & Frequency

MKH8020   RX6 spectrogram & RX6 WAV  &  Frequency

MC59O   RX6 spectrogramRX6 WAV  &  Frequency

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Audio samples goes through 100Hz HPF and normalized up to -5dB which increased the gain between 27- 30dB, or combined 97 – 100db *

MKH20   RX6 spectrogram

MKH8020   RX6 spectrogram

MC59O    RX6 spectrogram

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The comparison
Looking on the spectrograms, it shows that Nevaton has a notably lower noise floor. All of them have a similar noise below 10Khz but on MKH20 & 8020 it starts to increase between 12Khz -15Khz.
The MKH8020 has slightly higher overall noise compared to the MKH20 and MC59O seem to have the same low level of noise through the whole frequency range. Something I have not seen before .
MC59O shows a nice clarity above 10Khz. The weak clicking sounds from the alarm clock in the MC59O spectrogram is clearly visible up to 18KHz, but it almost disappeared behind the self noise above 10KHz in both MKH20 & 8020.
But listening to the audio samples of MKH8020 and MKH20 they seem to have higher a mid-range between 2KHz to 8KHz. It means that Sennheiser can be a better choice for most common nature recordings because most of the natural soundscape is actually below 8Khz (at least in Iceland). That leads to the thought that  MC59O can be a very good mic for live music recordings, because of a less „aggressive“ midrange can mean a warmer sound. I have already used the MC59O once over an orchestra with a very nice result.
MC59O seems to be very sensitive for air pressure. Those moments when a light gust of wind hit the garage, the dBfs meter jumps much higher on the MC59O channels than on the MKH channels. Most of the strongest subsonic waves seem to be below 5Hz (see picture). If this is really an air pressure, not a mic failure, I can see lot of challenging and interesting recording projects for this mic in the future.
But this MC59O pair seem to have a downside. They are badly matched, even though I ordered a matched pair**. It is clearly audible, when I record constant wide frequency background sound the balance is not the same as on the MKH20 & 8020. So as it is, I am not sure I can use this pair for nature recordings. In this test one of the capsules seem to have sharp 30dB drop at 85Hz and another 25dB drop at 145Hz (see picture). It is a lot in such a sensitive and important frequency. But the problem can be as well something else so I need to make more tests and comparisons as soon as I can. I will post the result here when it is done.
Nevertheless I have used the pair over an orchestra in combination with MC59C (cardioid) which gives a wonderful result.

Conclution
All of the three mics are pretty equal in quality so it is almost impossible to choose which one is the best.
I will always love the old MKH20 workhorse. It has never failed on the field, does not matter what kind of foul weather it has to go through. It has proof it can withstand high humidity anywhere on this planet. I have even lost the pair in glacier lagoon, highly polluted with sulfur without any measurable damage.
Those two MKH20’s in the test were not a matched pair, as Sennheiser does not offer these mics as a matched pair. Anyway they sounded like they were matched.
After a very bad experience with my first MKH8020’s when they made a high noise under the cold environment at -5°C, I am now going to trust them more and more each year. It seem like Sennheiser have fixed the problem. This MKH8020’s are nicely matched as they are intended to.
The surprise in this comparison is the Nevaton MC59O. I finally found a omni mic which has lower noise floor than MKH20, without loosing the finest details, plus with extra sound clarity above 10Khz.

See the whole picture gallery
* All audio samples above are mp3 at 256kbps 44kHz.
Original recording at 24bit/48Khz
** 20th of February 2020 I got new nicely matched capsules from Nevaton

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For a long time I have used Rode NT1a for nature recordings. It is a very good mic to capture the finest details in quiet soundscapes. But at the same time there is something missing in the sound quality, especially when it comes to low frequency and „audio depth“.
Last summer I got interest in IRT cross mic setup, so there was a perfect opportunity to invest in other microphones. There were not many mics to choose from with extra low self noise. Nevaton in Russia makes very interesting low noise & high sensitive mics. But my experience with MC50Quad was it did not capture the finest details of the silence as clearly as NT1a or MKH20. So I decided to invest in Lewitt LCT540s which I got for a acceptable nice price (See comparison)
I built a special shock mount for the LCT540s inside Rycote AE windshields (ORTF WS kit P/N:080210). That AE windshield is wider than normal WS windshield, especially made for stereo rigs so it is very good for large capsule, side address mics like LCT540s. Low handling noise is important for less rumbling wind noise and when it comes to LCT540, it is slightly better than NT1a.
Everything was ready for a field test in late Mars so I followed the silence into the country side. I was lucky with the weather, dry and calm, maybe too calm because it makes the silence too quiet for this field test. Anyway sometimes light gust gently wipes the top of trees and bushes which sounds fantastic in the headphones, moving slowly from left to right. It was much easier to feel the depth of the field with LCT540 than it has been with NT1a.
Nothing interesting was audible until in the early morning, about half hour before sunrise, when two Rock Ptarmigan started to „sing“. First in distance, but suddenly, maybe because of curiosity, they flied closer to the microphones and walked around the rig. The following recording is actually this moment.
It was recorded in IRT cross, which gives lot of opportunities in mixing. It gives me four different stereo recording in to four directions, all in NOS, plus many other versions too with different channel mix. It can be useful when looking into specific soundscape. It is for example possible to avoid traffic noise or other unexpected sounds from one or another direction.
The two first enclosed recording below have go through noise reduction process (above 3Khz). But the last one is a short peace without noise reduction, just as it comes from MixPre6, so you can hear the LCT540 self noise, which is about 2dB higher than in NT1a. It was recorded with 48dB gain and HPF at 40Hz. In post, I only normalize the gain level up to max, which rise the gain about +10dB. I did not change the EQ so audience can hear the sound quality at the low frequency. My feeling is that LCT540 have almost same low frequency quality as the MKH series & Nevaton which is very good
This is two versions of the same recording where I mix four channels differently into stereo. Counting channels 1-2-3-4 clockwise to L-R-Ls-Rs and the second one L-R-Rs-Ls (which is usually normal IRT setup).
This is a „high dynamic“ recording of silence, so I don´t recommend it played loud. It might destroy some speakers (ears too) if it is played too loud without attention.
Good monitor headphones are recommended or quality open headphones while listening at low to medium level.

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Recording L-R-Ls-Rs
(mp3 256Kbps / 35,6Mb)

Recording L-R-Rs-Ls
(mp3 256kbps / 35,6Mb)

Short version of recording L-R-Ls-Rs without NR
(mp3 256kbps / 7,4Mb

Recorder: Sound devices MixPre6
Mics. Lewitt LCT540s (IRT cross setup) Running on 70m Sommer Mercator CAT7 S/STP cable
Pix: Canon EOS M50
Weather: Calm, dry, between -2 to +4°C, about 7:30 o´clock

Location: 64°40’23.7″N 21°37’43.7″W

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It is difficult to compare LCT540 and NT1a in details. I am not sure which one is better for silence recordings. Both have same specification of lowest self noise on the market, they have their own characteristics and after my NT1a mod, they seems to have slightly different polar pattern.
I record this audio samples at 24bit/48khz with 45dB gain (40Hz HPF) on MixPre6
In post I increase the gain approximately another 45dB and normalized to -5dB
The outcome is shown on the spectrograms on recording A and recording B. The LCT540 is above. NT1a below.

NT1a is extremely well focused in the mid-range 500hz – 5Khz. which is exactly the frequency where most common birds sing. So NT1a is very good for nature recordings. But sometimes NT1a sounds „flat“ because NT1a is rather poor on low frequency, sometimes like out of phase (which could be as well caused of wrong setup).
I have not a long experience recording with LCT540s, but at the moment the overall sound quality seems to be better than NT1a, especially in lower frequencies which give better „juicy“ sound and „depth feeling“. But at the same time it is not as „clear“ as NT1a in the mid range.

Following audio samples will give some insight how LCT540s compares to NT1a in silence. You can clearly compare the mics self noise which sounds almost equal.. You can also hear how this two microphones pick up the details in two alarm clocks and a pocket radio at the lowest level in ca 2,5m distance, inside ca 45m2 garage. Other background sound is a light gust outside which swipe the garage walls and roof, a fly in the window and a traffic in air and ground in the county. Anyway this is a silence which most people will barely hear anything else than just their own heartbeat. See pictures

How do they withstand humidity or handling noise in windscreen? I can only say this.
Both need DIY shock mount if they should be fit in Rycote windshield. Both are sensitive for handling noise especially NT1a. High humidity is usually not a problem for microphones in Iceland, but there are stories about problem with NT1a in other countries.
I will update this information/comparison as soon as I have got more experience with LCT540s. You can also search for NT1a and LCT540s on this website and listen to nature recordings.

Listening with quality headphones will give best result.
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Lewitt LCT540s Recording A (mp3 256kbps / 7Mb)

Rode NT1a Recording A (mp3 265kbps / 7Mb)

Lewitt LCT540s Recording B (mp3 256kbps / 4,8Mb)

Rode NT1a Recording B (mp3 256kbps / 4,8Mb)

Short comparison of both LCT540S & NT1a

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When I use boom in recording I have used Audio Technica BP4025 stereo mic in Rycote windshield. It is not too heavy and it gives me stereo recordings. But very often I have been disappointed with the „musical“ sound quality, so I don´t often get quality ambiance recordings with this setup. Saying that, it does not mean BP4025 is a bad mic. BP4025 has a very low noise floor. It is the perfect mic for special circumstances like where size does matter and for very quiet environment/nature recordings.
DPA4060 is a pretty sounding miniature mic, sold in pairs and much lighter than any original stereo mic on the market. That means it is perfect to use for boom recordings. But because DPA4060 is an omni mic it is necessary to separate the capsules to get stereo. It is done in two ways. Separate the capsules with space (around 40cm) to get time difference, or place them in two sides of some sonic baffle materials.
The BP4025 was in a short Rycote WS2 windshield which has overall length (wide) 34cm. So it was important to place the capsules each side of some baffle material to get acceptable wide stereo.
I end up with a simple „binaural“ project I made out of wooden leftover (see pictures).
I decided not to use silicon artificial human ears because the ears will change the frequency curve at 2,5Khz and 5,5Khz, which means I needed to fix the EQ afterwards on all recordings made with this rig.
The result was stunning. The rig I made was lighter and better wight balanced than previous BP4025 setup. The overall wight is only 750gr (mics+wood baffle+WS2 basked+fur). It also gives me wider „stereo image“. But best of all, it withstands wind- and handling noise much better than previous BP4025 setup.
Following recordings are 4 and were made in three locations. The two first one are waves on seashore, then one from a cliff, 300 m above sea level with seabirds and the last one is from a football game in Reykjavik. All where recorded on Sound devices 744.
All recordings are straight from the recorder. Just cut and paste, fade in and out and then down grade from WAV to mp3.

(256kbps / 29Mb)

The two first recordings are big and then small waves. The mic have fur, HPF is off and gain at 45db. The mics are faced from the beach to the fjords. You will hear car pass by „behind“ the mic. Notice, you will hear a short „drop out“ when it pass. It is because it passes my car which was located on the road side. See location.
In the cliff recording the mic is without fur. It is possible to hear how strong gust sounds on the Rycote basket, but that is anyway much better (or different) than the my previous BP4025 setup. HPF at 40Hz and gain at 45dB. The boom with the mic reaches the cliff edge about one meter. See location.
The last recording is from a football game celebration in downtown Reykjavik. No fur, HPF at 40Hz and gain at 40dB. The mic stood on a boom about 1 meter above the crowds head. See location.

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The summer 1978 I got a job at Sogsvirkjanir power stations, about 50 km east of Reykjavik capital. There are three power stations close to each other in the river Sog south of Þingvallavatn lake.
This place was familiar to me because my grandparents lived at a nearby farm, Efri Brú.
For me, as a tanager, this summer was very important. It was the time to decide what I would like to do for a living; a technician, farmer, engineer, or something else. I was not sure.
My job at Sogsvirkjanir was miscellaneous, gardening, cleaning and painting. But what interested me most was working in the power stations when generators were shut down for cleaning and overhauling. As a thin, lithe teenager I was used to go into and work inside places in the generators where older, fatter and stiffer engineers could not access or work. Afterwards I think it was very damaging environment for my health. Working almost every day with 1,1,1Trichloroethane and other toxic liquids with useless mask. But in these days nobody took care of it, and I did not take care of it either.
All this machineries fascinated me so I decided to start learning electrician in the autumn 1978.
The following recording is a combination of five recordings I made in and around Ljósafoss power station the summer 2013. This is the oldest power station in the river and was built on my grandfather’s land 1934. The birdsong in the recording is from a nearby county at Laugarvatn which is my grandmothers’ birthplace. It reminds me of my childhood at my grandparent’s farm, especially in the swamp behind the cowshed, so it is worth to keep it with this recording.
Even though all these sounds gives me some nice memories, they sound also far in my mind. It feels like a memory from my “last life”, not something that happened in my life about 40 years ago. Every thing has changed fast in this county. My grandparents are long gone and almost all farming in the county too. Land in many places has been broken up in peaces for cottages. Farming and animals have disappeared.
Instead of narrow gravel roads, all roads now have asphalt. Fast driving, noisy traffic, day and night seems to be the only human activity.
Sadly, in just thirty years, this beautiful countryside has changed into “American style suburb”
The following recording gives you a flight as a ghost, or a spirit from my grandparents farm to Ljósafoss power station. Your flight goes above and through water, concrete and steel. It starts over the reservoir, then trough the intake, penstock, power house, transformer and to the outflow canal.
The flight ends as it starts with “quiet bird song” far away from the nosy power station.

Miningar frá sumrinu 1978.

Sumarið 1978 fékk ég sumarvinnu við Sogsvirkjanir. Þetta sumar varð mér heldur örlagaríkt, en þá tók ég ákvörðun um að læra rafvirjun. Eftirarandi hljóðmynd var tekin upp sumarið 2013 í og við Ljósafossstöð. Segja má að það sé í raun minningabrot frá sumrinu 1978 og þremur næstu sumrum á meðan ég vann þar við ýmis störf.

Download mp3 file (192kbps / 36,0Mb)

Recorder Sound devices 788
Mics. Sennheiser MKH8040 (ORTF setup)
Pics. Canon EOS-M (more pictures)
Rafn sigurbjörnsson’s picture gallery

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About 30km east of Reykjavik capitol is Hellisheiðarvirkjun a geothermal power station. This power station uses energy from drilled wells in the surrounding area.
In the drilling process it is necessary to let the wells “breath” or “blow” for a while. When it happens it is extremely noisy when the energy is wasted into the atmosphere, mostly as a hot steam in mixture with toxic gas like carbon dioxide (CO2), hydrogen sulfide (H2S) and also substantial quantities of hydrogen (H2). Other gases such as nitrogen (N2), methane (CH4) and argon (Ar) are in the gas mixture, but in lesser extent.
The rumbling noise from blowing wells is so loud that it can be easily heard in far distances (up to 20-30km, depends of condition).
It was easily audible when I was on my way east of Reykjavik on a cycle trip last summer. I was cycling Nesjavallavegur (road) when I decided to record this noise. The power station was in about 10 km distance, but the blowing wells were somewhere between in 10-15km distance, probably behind the mountain Hengill.
This recording was made at 3am, 24th of July 2013 at Mosfellsheiði. The weather was calm, but cold, very humid and fogy.
Keep in mind, this is a “quiet nature recording” so you should not play it loud. On the field the birdsong was barely audible.

Orkusóun

Hér er á ferðinni upptaka frá því 24. júlí 2013, þegar ég fór í stutt helgarferðalag austur fyrir Fjall. Þegar ég lagði af stað var vel liðið á kvöld og skollin á blaut og köld þoka.
Þegar á Nesjavallaveginn var komið varð ég var við miklar drunur ofan af Hellisheiði en þar blés borhola út orku og eiturgasi engum til gagns. Drunurnar virtust fylla loftið fremur en að koma úr tiltekinni átt svo ímyndunaraflið fékk að blómstra. Það var ekki laust við að maður léti hugann reika, því þar sem maður átti að venjast þögn á þessum tíma sólahringsins voru nú þungar drunur allt um liggjandi sem hér um bil kaffærðu söng sumarfuglanna. Nálægð við helvíti eða heimsendi var manni efst í huga þar sem maður sniglaðist einsamall eftir veginum fremur kaldur og blautur í dimmri þokunni.
Rétt eftir að hæstu hæð Mosfellsheiðar var náð ákvað ég að staldra við og taka upp þetta sérkennilega andrúmsloft sem þarna ríkti þessa júlínótt.

Download Mp3 file (192kbps / 28,2Mb)

Recorder: Sound devices 788
Mics: Sennheiser MKH20 (AB40 setup)
Pics: Canon EOS M (see more pictures)

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In Iceland it is possible to find many hot springs all over the country. Many of them have optimal temperature for bath and to relax. For centurys people have piled stones and turf around some of this known natural hot springs.
In the beginning of last centuries many of this natural hot springs were used to teach people to swim. Soon, many communities all over the country built real swimming pools of concrete near these springs.
One of these places can be found at Krossholt at Barðastönd, Southwest Iceland. There is Krosslaug, a 12 meters long swiming pool, built in 1948. There is also newly built natural hot tub, build on a hot spring in traditional style. It was the Youth Association of Barðaströnd County who piled this tub with stones, gravel and turf.
From the bottom through the ground of the tub comes the warm water with bobbles that gives relaxing sound while laying there with the ear below the surface. You can hear the bobbles moving upwards trough the gravel deep from the ground under the tub.
This recording was made with hydrophones at 15th of June 2012.
Another interesting recording from Krossholt, nearby place is: Opus for power line, bass, wind and birds.

Krosslaug í Mórudal við Barðastönd.

Á Birkimel við mynni Mórudals, hefur myndast þjónustukjarni Barðastrandar.
Það hefur reynst mér ótrúlega erfitt að afla sögulegra heimilda um þennan stað á vefnum. Því segi ég aðeins það litla sem ég tel mig muna.
Á sjöunda til níunda ártaugar síðustu aldar var þar skóli, félagsheimili, kaupfélagsútibúð og litilsháttar iðnaður. Þar var einnig reynt að koma upp fiskeldi. Það fór á hausinn.
Í dag er staðurinn líklega betur þekktur fyrir ferðaþjónustu. Stéttarfélög eru þar með orlofshús sem og ferðaþjóunsta sem rekin er frá nærliggjandi bæ.
Víða í Mórudal er að finna volgar uppsprettur. Sundlaug var reist við eina slíka í fjörunni neðan við Krossholt 1948. Hefur hún átt það til að fara nokkuð illa í vondum veðrum. Vorið 2011 var laugin tekin í gegn og var þá hlaðinn heitur pottur að ég held yfir volgri uppsprettu fremur en borholu..
Það er ákaflega notalegt liggja í þessum potti í makindum með eyrun undir yfirborðinu og hlusta á volgt vatnið og loftbólur streyma upp úr jarðlögum pottsins. Meðfylgjandi upptaka var gerð í pottaferð 15. júní 2012.
Önnur áhugaverð upptaka sem gerð var við Krossholt er: Tónverk fyrir háspennustrengi, bassa, vind og fugla.

Download mp3 file (192kbps / 28,8Mb)

Recorder: Sound Devices 744
Mics: Aquarian H2a-XLR
Pics. Sony CyberShot DSC-P120 & Olympus 4040 & EOS 30D (see more pictures)

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