Australian Sound Artist

Tuesday, February 25, 2014

North East England: Sonic Postcard NEE03

:: NEE03 - Caris Clocks, Alnwick Town 15th Nov, 2013. General clock-ticking ambience and gentle chimes ::

Recording Technical Specifications:
Recording device: Sound Devices 788T
Microphones: DPA 4060 (stereo pair) and DPA4017
Multichannel recording and mixdown

Recording taken within Caris Clocks, Alnwick. Time keeper is 4th generation clock repairer, Gordon Caris. His son is 5th generation. Lovely sounds of ticking, a few gentle chimes. Clocks are irregular with their times (they are in for repairs...) so chiming is a bit erratic.

Many-thanks to Gordon for accommodating that which was so unfamiliar......

Sunday, February 23, 2014

Hydrophone Test #1

:: Hydrophone Test #1 ::

For almost three weeks now I've had a pair of the much coveted Teledyne Reson TC 4033 hydrophones sitting on my studio floor and waiting to be tested. Today was the day where I woke to find basic getting-by essentials had been caught up with for the time being, (food; check, money; check, cleanliness-factor; check-ish-will-do-for-now-hey-it's-the-weekend-I-don't-need-to-shower/change-for-anyone-today-anyway), so I was finally allowed to get back to my real work.......

I think it's safe to say that at a certain point in a field recordists practice they get their hands on a hydrophone and the less-known world of auditory sensation begins to reveal itself. If you are like me, this experience never leaves you only providing more fuel to the fire of your sonic-gathering obsession. 

And so begins the hunt for your very own hydrophone.

My hunt began in 2009 when on attendance at a 'Chris Watson' masterclass at the Wired lab I experienced the DPA 8011 and my world was changed forever. These hydrophones were ceased from production in 2011 (? there abouts) - which despite the fact this was not really relevant to me (there was no way I could afford such high quality equipment anyway) - still saddened me in that there seemed to be a gap in (almost) affordable, high quality hydrophone technology, that needed to be filled.  

**A word of advice: The final 'kit' that I have been fortunate enough to be able to access for testing took quite a bit of research and phonecalls to far-away lands. If you have technical questions about such specialised gear then calling the company direct is the way to go. While Australian distributors may do their best to help it's not safe to assume they know ALL the answers. After some confusion I made the direct call to discover that the hydrophones I was originally envisioning purchasing would require an additional two hardware modules (small boxes but...) and connecting cables in order to function. The Australian sales person I spoke was not aware that this was the case.

Item #1 & #2 - hydrophones: The TC 4033. 
:: TC4033 ::
While it is still a long-term, once-in-a-lifetime investment that means you won't be eating for a few years (let's not forget you typically want TWO of them for stereo...). Their price is less than that the DPA 8011 was and the sound quality (while not as crisp) is still miles above the other truly affordable, domestic/high quality models that I have had the pleasure of experimenting with. Unlike Teledyne Reson's pricier-but-impressive TC 4032 model, the TC 4033 does not have an inbuilt preamp that requires 9V power. TR do sell preamps that can be used with the TC 4033 BUT, these also require 9v power (an external battery box) and more money to purchase them with....

Item #3 & #4 - preamps: Avisoft's Charge amplifier and high pass filter #42003
:: Avisoft's preamp #42003 ::
As a solution to the loss of recording level I decided to try Raimund Specht's (Avisoft) pre amps. The #42003 model runs off the phantom power of your recording unit and connects in via BNC and out via XLR. Unfortunately there is not a stereo module so I used two of them (as per the image). On looking at the modules in person there were two aspects I was not too sold on. The first is the fact that there is no setting to completely bypass the high-pass filter - you have to use it no matter what (and I typically do not like to use any filters on original field recordings). Second, the high-pass settings on the rotary knob were marked by an attached sticker that was very much like a slightly heavier-than-usual piece of paper. As these preamps work with hydrophones it's safe to assume there will be water around. It would only take one wet hand touching the label for it to start to deteriorate and the general wear and tear of moving your portable recording kit around would only assist this process.  I'd much prefer the industry standard of engraving the numbers into the module itself. 

Item #5 - recording device: Sound Devices 788T
:: Sound Devices 788T with Avisoft's 42003 preamps ::
-With fresh firmware update and recording at 24bit/96K, my favourite recording tool..............................

The following are three sample recordings for you. All were recorded one following the other, in the exact same conditions (see top image) with the only variable being the gain on the 788T. Other than converting files to MP3 @ 320kbps for the audio players I have left them completely untouched.

Gain: 34.7
Preamp high pass cut-off: 10Hz

Gain: 38
Preamp high pass cut-off: 10Hz

Gain: 42
Preamp high pass cut-off: 10Hz

SUMMARY: I'm very happy with the frequency response of the hydrophones. The few affordable models I have tested often lack responses below 100Hz so I am glad to hear there is nice depth to these recordings and a sharp crispness to the high's. The preamps were very handy in that they solved two problems that arose from these hydrophones. First is the problem of recording level - the boost was wonderful and the second, was the conversion from BNC to XLR. They achieved both of these things whilst also being powered by phantom power - whereas other preamps required an external power box to drive them. As handy as this was - I am a bit concerned about the humm that comes through. This becomes more apparent as the gain increases on the 788T. I normally record general ambience at a gain of about 50 so that fact that the humm was well and truly present at 42 was noted. Having said that though - the next step will be for me to try the hydrophones with an impedance transformer (no preamp at all) and see how they perform. I'm hoping that as I have the quality preamps in the 788T that I may be able to get as much level as with Avisoft's preamps but without the humm.