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low frequency recording

Discussion in 'Microphones' started by chrapladm, Jan 8, 2011.

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  1. chrapladm

    chrapladm Active Member

    I am slowly trying to buy equipment so I can do some recording of very loud and sometimes very low things. I am wanting to record Fireworks, canon blasts, F1 racing, dragsters, monster trucks, Icebergs cracking and other more normal things such as piano, Viol Da Gamba and others.

    So being very new at this I was just going to be using a Tascam or Zoom portable recorder and use an external mic. Which mic I have know idea. This will be a very very slow buy. I am trying to do alot of other things so I am mainly seeking advice. I cant afford mics that are 1500 right now but maybe in the future.

    I think in a few years I can save up for a SD 702 and maybe a AEA 84 but please enlighten me with some budget friendly advice and guidance.

    Thanks

    David

    Oh and I forgot I like to listen to recordings that have content down to around 6hz. It is very fun on my subs and my friends subs. Not saying I need all recordings to go that low just saying why I put the thread title up.
     
  2. audiokid

    audiokid Staff

    Sounds like some fun! especially Rails /dragsters and Funny cars. . I just love the races and have always thought about recording them too. Be sure to protect your hearing.
     
  3. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Fireworks, monster trucks, dragsters, racing...I can see. Where in the world are you going to go to record canon blasts and icebergs? Just curious.

    Also, what playback equipment do you have that allows you to reproduce 6Hz? Is there a microphone that will capture that?

    Anyway, you may want to think about buying a matched pair of whatever you will get so you can try to record in stereo.

    Kapt.Krunch
     
  4. chrapladm

    chrapladm Active Member

    Not sure which mics to get but I have seen many recording devices able to record down to 2hz or DC. Now in regards to my playback system I have been on audio visual forums forever and love watching movies and audio. Incredible hulk for instance has stomps with hulk running around 6hz. War of the Worlds has lighting strikes that are around 4hz. WOW.

    My subs will play 12hz right now. I am building my new pair of subs that will play down to 4hz no problem. My friends sub is also able to play down to 3hz no problem. I know I cant hear that but it sure is fun feeling it.

    I also dont know what mics are able to go down to, say, around 5 hz and not distort. I have a recording of the space shuttle taking off from 3.5miles away and the equipment was still clipping.

    Canon blasts aren't usually a problem to get around. I was in the military and know quite a few people who have large....devices I could record. But that will have to wait being that I live in OZ now.

    I look forward to the other recordings and am saving up the money for a trip to the Antarctic to see if I could get some iceberg recordings.

    But like I said I am extremely new at this.
     
  5. audiokid

    audiokid Staff

    pretty sure anything that could reproduce 6 hz could also kill you.
     
  6. dvdhawk

    dvdhawk Well-Known Member

    You'll have a hard time doing that kind of thing on a budget - unless you have extensive DIY capability.

    A mic that would straddle the line between lab-grade and something an individual could afford -
    like an Earthworks M50, measurement mic. It specs at 3Hz - 50kHz ±3dB and will run you about $1300.

    Alternatives might include recording a good general purpose mic along with a specially built transducer like a DIY subkick mic on separate channels then combining them later.

    If it vibrates you should be able to convert it into an analog waveform, assuming everything else in your system can record and playback below 20Hz.

    (I'd try to keep DC out of my speakers if I were you)

    Good luck, sounds like a fascinating project.
     
  7. chrapladm

    chrapladm Active Member

    Thanks DVDhawk. I will have to look into your suggestions. I know alot of the stuff for transformers used the AEA R84 which is around 900 but doesn't spec like the Earthworks. I will have to buy probably an Earthworks in the next year as in 2012. And seeing that I think the SD 702 only goes down to around 10hz I think I might have to have another portable recorder. But what is capable or has a lower frequency response?

    And when looking into the Mics do I need to pay more attention to their Max Acoustic Input?

    I know the AEA R84 I think is around 160db and the E M50 says 142db. When recording say dragsters I guess it would be just a matter of dialing it back until I am not in the clipping but how do I not damage the mic?

    I know after I have done this for awhile it should become easier but instantaneous sounds will be difficult for me to tame. Like dragsters and white burst fireworks where there is a bright light then a BOOM oh and of coarse canon blasts.

    Are there any stickies on DIY subkicks?
     
  8. dvdhawk

    dvdhawk Well-Known Member

    We had a member a few months ago record the demolition of a house with a PMD661. *sorry all text, no audio of the end-result :(


    Obviously anything below 20Hz is considered sub-sonic so normal (reasonably priced) gear doesn't focus much attention, waste a lot of R&D, or components, to go much lower than that. Some others may chime in with some suggestions on portables that do.

    I guess I have a few questions to follow-up:
    How close do you plan to be (need to be) to these super-loud noises? Like with the concussion mortar fireworks, the big boom is downrange. The canon blast would have a big boom near the canon and another potentially big boom where it hits. Will you have the luxury of picking a safe spot not too near the business end? Is pristine audio quality the goal? What's your end product? SFX Library? Whatever the market, it had better pay well enough to cover the occasional mic repair - or it could turn out to be an expensive hobby.

    It will hazardous duty for any mic - especially a condenser mic, the high SPL sources and the outdoor factor will increase the chance of the mic getting damp. In which case, (although it won't have the frequency response on paper) a good old-school dynamic kick mic might provide adequate boom, cost 80% less and last 5000% longer.

    No subkick stickies that I know of, but numerous mentions of one built by one of our illustrious site admins - here.

    And some more recent discussion here.
     
  9. chrapladm

    chrapladm Active Member

    I have always had very sensitive ears. So I can usually hear things that are extremely quiet. That being said I will always be protecting myself when recording. Now when recording the canon blast I would more likely be closer than far away. Fireworks, I have had a friend who recorded sounds like I want about 1/2mile away and still had some clipping. I would probably do the same thing. Dragsters and other loud cars I will probably be close. Similar to this guy:
    Post-Mortem: Drag Race Recordings | Dynamic Interference

    But of coarse I wont have the 702.

    And when I say near the Canon it could be around 1/4mile.

    End results are sound clips that are just fun to play for me and my friends. I will eventually try and dabble in some movies so all the sound FX will help. My movies though wont be anything fancy. Probably Kung Fu flicks and clay stopmotion. My Kung Fu would be pretty silly though. I have just loved audio and would like to create some of my own compilations.

    Just have to get the basics down. And the movies would probably be great sound with cheap props. Like a cardboard car with dragster sounds and plastic guns with canon sounds. LOL

    Like I said I am new so I need to learn what I can do and what I will need. My mic I have is calibrated to 5hz but I think it will only take around 130dbs so I need to be careful. Even with the 160db AEA it is still very fragile. Thats why I joined the forum though to learn.
     
  10. dvdhawk

    dvdhawk Well-Known Member

    Using the AEA (or any other ribbon mic) for field recording would be very scary. Most are notoriously fragile and have to handled with kid gloves in a nice dry environment.

    For what you're trying to do, I'd seriously consider starting out with a dynamic kick mic like (AKG D112, Audix D6, Shure Beta52A, Sennheiser MD421 or e902) and augment that with something a little more favorable above 10kHz - which would be just about anything.

    That rig might not spec down to 5Hz, but you'll be making recordings that can played back on more than the few systems with your emphasis on sub-sonic.

    A bit (or a lot) of compression, and/or an inline pad somewhere in the system will be all you need to prevent any clipping problems. A pad would attenuate the entire recording, while the compressor would let you capture more of the background/ambient sounds prior to the loud part. - but I can't think of any battery operated compressors....

    I've been looking this evening and have seen some digital field recorders that spec at 10Hz - 40kHz. [incidentally, all these specs need to be taken with a grain of salt]
     
  11. chrapladm

    chrapladm Active Member

    I only saw the SD 702 specs to 10hz. The shure goes to 20hz and the AKG is only 30hz and the Senn. So your saying that doing these recordings with this equipment most peoples systems could play it?

    But if trying to emphasize on the 7hz rumble of a canon blast do I need to use a EW M50 for sure? And if the recorder is only spec'd to 10hz would the 5-10hz be lost or not recorded?

    Thanks. I know that the dragsters and stuff would be fine with something around 20hz. Then as their rpms go up so usually does their frequencies. When idling they are pretty low in hz. How low I dont know but is more of a shaking than sound. yah there are 40hz-120hz mixed content but I am just saying there isw some low content in there. But either way.

    It looks like the kick drum mics would work best for the most part.
     
  12. dvdhawk

    dvdhawk Well-Known Member

    I don't know if digital recorders would lop off sources out of their freq. range (high or low) or if they'd just slope off. The A-D converter might be mathematically limited to a specific range. (Boswell or one of the other resident genius-types might know the answer to that)

    You're into serious audiophile range. 99.99% of home theater, home stereo speakers would just fart at 7Hz. That would be a good 3 octaves lower than a more accessible 28Hz - which would be pretty respectable in the speaker world. Again, since the majority of us don't really hear down to 20Hz most manufacturers don't devote much effort to producing those low (energy hogging) frequencies.

    And you pay dearly for studio quality monitors that will be flat as far down as 30Hz without dedicated subs. (even the Genelec subs don't go much below 20Hz) It takes so much power to produce true bass it's considered a poor trade-off. BagEnd ELF speakers are the only monitors I can think of that claim to go sub-sonic to single digits.

    So net result, if you make killer sub-sonic recordings it may very well sound like garbage on someone else's system. As is often discussed here regarding quality of one's studio monitor system - being able to create the world's most perfect sound is going to be of limited usefulness if you have to invite 6.8 billion people over to your place 20 at a time so they can hear it. Your goal is to create mixes or sounds that will translate fairly consistently on the best systems and on mediocre systems as well.

    Back in the 70's when the movie "Earthquake" came out, theaters had to be equipped with special Earthquake cabinets to vibrate the whole theater during the quake scenes. They were just big bass reflex cabinets with a single rear-facing Cerwin-Vega 18" in them, but they could shake the rafters and I think they started tapering off below 32Hz. They eventually fell into the hands of rock bands [ we ended up with 2 pairs :) ], so I'm very familiar. You're probably familiar with ButtKickers and other tactile transducers. That's about the only way most people can experience sub-sonic rumble. Most of us can feel it, but can't really differentiate sounds below 20Hz.
     
  13. audiokid

    audiokid Staff

    Our band debating buying those Dave. I had totally forgotten about them. I don't believe its legal to produce something to go that low in Canada. Is it this way in the USA?

    hawk is right, can you image the power it would take lol.
    Better to just get dynamite for a one time party.
     
  14. dvdhawk

    dvdhawk Well-Known Member

    We ended up with 4 Quakes back in the 80s - 90s, fed them well for the time with 750w/. Beasts to move around 48"x48"x20".

    Now BIG arena concert systems use a big box like that, with what amounts to a big mechanical plunger that strikes a soundboard, rather than trying to use a conventional speaker as the driver.

    1Hz = 1 strike of the hammer/sec.
     
  15. chrapladm

    chrapladm Active Member

    Thigpen.
    http://www.eminent-tech.com/RWbrochure.htm
    or enough conventional woofers to push enough air to get down low. I know I am not mass producing stuff that is for everyone. This is just for me and the few others out there. But that being said there is some very low content here which is marketed to everyone.
    The Recordist
    But I fully understand what everyone is saying in regards to above 20hz. That is also why I dont watch movies in the Cinema anymore. There is so much content that is below the Cinemas range that , for me, I will never pay for a ticket again.

    Usually playing with recording I use headphones. nice big soft pair of AKG's. I am not the norm though even my nass guitar has a string on it that is a low B(B00 15.4hz) I am different and I love being that way. But that being said also I have to take money into consideration and what I can do.

    If I am wanting to sell stuff ,boutique-like, I would only go down to 10hz unless others wanted it. But for the masses I would probably just keep it around 20hz. BUT if there is a sound I am recording, not interference, I would like to record it and not limit myself.

    But either way I will have to learn what the portable recorders do as far as slope off or what. And I need to learn what the big audio production engineers are doing to put these 4hz and above sounds in their movies. Thats probably very high on the list for me also.
     
  16. dvdhawk

    dvdhawk Well-Known Member

    I can hear the fundamental of a low B on a 5-string bass which is 30.9 (ish). An octave below that for any sub-harmonics is out of the range of my monitors and my ears. My AKG0 headphones (K240) claim 15Hz, but they neglect to say at how much of a dB loss at 15Hz. (why we can't go solely by specs).
     
  17. TheJackAttack

    TheJackAttack Distinguished Member

    A B string on a guitar vibrating at 15.4 hz is going to sound like a$$. Sorry. That is why a concert Steinway is 9' and why there is a 15' Fazioli out there and why Bosendorfer makes the Imperial with extra unused strings. The guitar string is just too short to be worth anything even if you were to get a custom made double wrapped spinet piano string it would still sound bad just like a spinet piano.

    I hear the trains run all night way across town and often they keep me awake so I understand about low content. I don't know that I understand the loss of it in most movies though. Maybe I've just lived too much life in areas and environments that were too full of bass content-105mm, 155mm, Dragons, M2............
     
  18. chrapladm

    chrapladm Active Member

    I wont be getting i9nto a debate over a good sound or crappy sounding bass string strung with a B00. But there are plenty of people out there and their bass guitars sound fine with them.

    But I think if I understand more about how the audio engineers are adding the sound maybe I could augment what I want past 15/20hz and down. But that being said I still will have to have equipment and mics that can handle some loud noises to begin with. Other than a 702 in the future, what is a good starter portable recording device?
     
  19. RemyRAD

    RemyRAD Well-Known Member

    When you don't quite understand here is that most recording equipment is bandwidth limited on purpose below 20 Hz. You indicated you heard some recordings that were still clipped at quite a distance. This only happens with clueless individuals that have no idea how to record what they want to record. First off, many dynamic microphones such as the Sennheiser 421 are virtually impossible to overload. In fact the Sennheiser 421 was advertised many years ago as being able to record close proximity gun blasts at sound pressure levels that can cause instant & permanent loss of hearing. Then there is that little thing we call a microphone preamp. Professional microphone preamps, particularly old-school design, incorporate built-in resistive pads of 20 to 30 DB that prevents any input overload on the preamp. So you're just talking about crappy recordings & not professional recordings. Unfortunately, condenser microphones will frequently require a " capsule pad" to prevent the capsule from overloading the microphones electronics. Obviously, some of the things you are mentioning are what we call Hollywood sound effects. You're not listening to icebergs cracking. You might actually be listening to breaking glass being crunched on a piece of sheet metal. That's Hollywood baby! I don't care what you think you're listening to based upon manufacturers specifications? Many speakers & amplifiers including my over 30-year-old JBL's & Crown DC 300 A can reproduce 1 Hz! They called it the DC 300 because it's a response is capable of amplifying small DC voltages to larger DC voltages & up. Now even if I can move my JBL's 1 Hz it still can't move enough of the volume of air to feel it. And you don't need to go that low to feel it. So let's be practical here DON'T BE RIDICULOUS. Unfortunately, many quality preamps which feature transformer inputs are limited in their low-frequency response by the transform. This doesn't necessarily happen with transformer less instrumentation laboratory style direct coupled electronics. A good example would be an oscilloscope input which frequently must be able to read and inputs from DC to 100 MHz, from micro voltages to hundreds of voltages! Stick that in your speaker & smoke it! It should be easy. Let's face it, you might want to record those low-frequency sounds but only about .0001% of anybody with any decent audio equipment, other than yourself, will be able to reproduce your recordings. So you're far from realistic & not being very practical and what you think you want to record & how. If you want to feel that explosion perhaps you should blow yourself up? It's easy with a little fertilizer & diesel fuel and you might be able to hear the frequencies you want?

    Low-frequency recordings really shouldn't be equivalent to your IQ
    Mx. Remy Ann David
     
  20. chrapladm

    chrapladm Active Member

    Wow there is always a person on every forum that has to name call to make themselves feel better about themselves. Didn't think there would be any difference here.

    Is that all you got RemyRad. No helpful info at all. Then keep your posts to yourself. Anytime there is change or someone wants to do something different there are always the others that will always say no.

    SO while there are quite a few others out there with subs capable of below 20hz I guess you just dont know any of them. Thats fine no big deal. BUT I should blow myself up.........WOW what are you 12. Have you ever heard ice bergs cracking? No

    I have so keep it to yourself and if you have some info that helps this thread then add if not......have a good day.

    Maybe dvdhawk can share some info on a budget portable recorder? Been helpful so far thanks.
     
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