omni lav pickup patterns
I currently use Trams and PSC Millimics, but would like to add an omni lav with a tighter pickup pattern to my arsenal. This would be used in high-noise environments (e.g. when a PA system is blaring nearby) and also for situations where the lav must be placed further away from the mouth than normal. I find that when the lav is placed 12" away rather than 6" away, there is much more room ambiance and the sound doesn't match the mics on other people in the shot.
So, which omni lav has a tighter pickup pattern. From some limited experience, I thought it would be the Sanken. But, I've had one person tell me he thinks the Sanken is one of the most "open" sounding mics? Thanks for your opinions.
There is no such animal as an omni with a tighter pattern. There may be less sensitive omni lavs, but that won't help. What you need is a cardioid lavalier, such as the Sennheiser ME 104. Sony makes some decent cardioid lavs as well, though they're not my faves. A stick mic, such as the EV RE50 would be a great choice for that situation if you don't mind seeing the mic. Also the countryman headworn mics are a great choice, again if you don't mind seeing the mic.
Freelance Sound Technician/Mixer
Actually, the RE50 is an example of an omni mic with a tighter pickup pattern than some other omni stick mics. I'm guessing there are similar differences between omni lavs.
Another way to ask the question: which omni lav has the most "closed" sound, as opposed to the most "open" sound?
Just some nominclature clarifications . . .
"Omni" is short for Omnidirection - meaning the mic is designed to pick up all sound from every direction fairly uniformly. Omni mics are not intended to have a tight pattern.
"lav" is short for lavaliere - which is the intent of the mic to be positioned generally in the upper chest/lower neck area.
"Cardioid" is another type of mic pick-up pattern, that has a definet direction and does not pick up sound from all direction evenly.
I Concur with Rodney's recomendations. If you want to eliminate other sound you need to go to a lavalier mic with a cardioid pick-up pattern, or go to a headset type mic for even better rejection of background noise. A few years back we used a Sennheiser product with good success. I don't think it's made any more, similar to their ME4 product today.
If anyone would like to offer an opinion about which omni lavs sound more "open," and which sound more "closed," I would appreciate it.
Bob, I didn't intend to turn this post into an argument. I tend to think of things in terms of absolutes. To me, omni-directional means that its pickup pattern allows for all frequencies to be reproduced equally and accurately from all axes. So it's impossible to have a tighter pickup pattern on an omni-directional without it becoming either a different polar pattern or a less sensitive omni. To me, it's similar to asking whether or not there are more oval shaped circles. If they are oval shaped, then they can't be circles.
In practice, however, few mics have perfect omni-directional qualities across the entire frequency range. While they might be perfect omnis at say 5KHz, they may be less sensitive at other frequencies.
You are absolutely correct that some mics sound more "open" than others. I own (and use) the Sanken COS-11 and Tram TR-50 mics. I think the TR-50 sounds more "present" and therefore slightly more "closed" compared to the COS-11, due to it's frequency response. The Tram, as you know, has a presence boost starting around 4K and peaking around 9K. The COS-11 has a slightly flatter frequency response compared to the Tram.
In your situation with the blaring PA in the background, an omni lav is simply the wrong mic for the situation, thus my suggestion of a cardioid lav. You can also go in tight (from underneath) with a shotgun. It will isolate the subject a bit better, but it's not a pretty sound. I know, because I used to be in that exact situation quite frequently in my previous staff job. We were a roving crew and were gathering soundbites from concert audiences. We didn't have time to wire someone up with a lav, so the videographer would shoot tight and I would bring the shotgun (Sennheiser MKH-60) in very close and underneath. In that situation, it's impossible to get good sound so you go for the most usable.
All the best to you Bob.
Freelance Sound Technician/Mixer
If anyone is interested in more information on this subject, I have just found this article: "Selection and Use of Lavalier Microphones," by Dr. Fred Ginsburg. http://www.school-video-news.com/index_files/Lavalier_Mics.htm
I think the article must be about ten years old, since it doesn't mention the newest crop of lavs (such as the Sanken). However, it does provide a good discussion of the differences between "open" sounding and "closed" sounding omni lavs. I can vouch for some of what Ginsburg says, since the Sony ECM-50 was the lav of choice when I started in the business and I also remember when Tram revolutionized lav mics with it's new, "open" sound that better matched boom mics.
Most interesting to me: Ginsburg thinks the Sony ECM-55 and ECM-44, the Countryman B3 and B6, and the Voice Technologies lavs are "closed" sounding, or what he calls "proximity" omni lavs.
My experience with lavs is limited but I do have $0.02 to contribute.
One of the largest contributing factors to the level of your subject to the background noise rejection is the volume of the subject and the proximity of the microphone to that subject. The closer or "tighter" the subject is to the sound source, the more inherent background rejection there is.
Unidirectional lavs reject more off-axis background noise but they also have a very small sweet spot. This means if your subject turns his/her head or if you're forced to pin your mic on a jacket or similar garment, the mic can easily be off axis and sound very distant. If your talent knocks the mic off axis, you're hosed. this is very easy to do if they are jestering or contorting their body to turn to address an interviewee or co-host. I've always tried to stay away from unidirectional lavs because of these problems.
Also, as your unidirectional mic gets closer to your sound source there is a tendency for low frequencies from the source to be increased (known as proximity effect). You may want to move your mic closer to the sound source (usually a mouth) but you end up dealing with proximity.
Your description of 'open' or 'closed' is a little ambiguous and so is the description by the author of your article. I'm assuming open and closed has more to do with the frequency response of the microphone than the directional qualities. Frequency response can emphasize certain tonal qualities that can help or hinder any situation. I've added a link to Sony's PDF of their LAV series. You'll find that ALL the omnis have uniform pick-up patterns in 360 degrees, however they have varying frequency response. I've also included a link to Sanken's lav products.
I've also looked up the Sanken line of COS-11 mics. If I'm reading the frequency specs (NOT THE PICKUP PATTERN) right the Sanken has a significantly higher boost around 5kHz-10kHz compared to an ECM-55. This is probably the contributing factor to what you're coining as "open" or "closed" sounding. In the studio we often call this "brighter" and "darker" sounding; but again the choice of adjectives isn't a definitive as FREQUENCY RESPONSE.
I would suggest learning about frequency response (as well as pickup patterns) if you're looking to be knowledgable about predicting the behavior of a microphone. That way you can just look at specs and know what you're getting.
Now about self-noise and transient response...