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Author Topic: LDC vs SDC vs dynamic Why?  (Read 4458 times)

Stephen Swaffer

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LDC vs SDC vs dynamic Why?
« on: May 18, 2020, 12:37:42 PM »

As the topic suggests, when and why would you choose an LDC, SDC, or dynamic mic?

My application specifically is ambient/room sound for a livestream-specifically geared more towards a congregation singing-but on a larger scale I am curious where the different mic types shine and why you would choose them?  I have all three available and have been experimenting with mics and placement trying to find something that I like.  With our very live room, getting primarily the congregation is proving challenging.
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Chris Grimshaw

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Re: LDC vs SDC vs dynamic Why?
« Reply #1 on: May 19, 2020, 08:35:43 AM »

In my experience, a good small-diaphragm condenser is about as good as it gets in terms of fidelity and directivity control. I like my Beyer MC930s for when I need a neutral sound with a cardioid pattern.

However, the other mics do have advantages:
- Large-diaphragm condensers will typically have lower electrical noise figures. The broad reason is that a bigger diaphragm means more sound becomes electricity, so needs less amplification. It's more complex than that, though. A larger diaphragm does mean the off-axis response typically doesn't hold up as well as it might with a small-diaphragm model, so there's a tradeoff there.

- Dynamic mics have negligible electrical noise, but often 10-20dB less sensitivity*. You can still use them for distant pickup, but you'll need very low-noise mic preamps to do it well. Dynamics typically have a more, er, colourful response than a condenser mic - check the frequency response curves of an SM57, for example. Their big advantage is that they can handle very high SPLs without much/any distortion, so they're often the first pick for live sound where everything tends to be close-mic'd.

- Ribbon mics are a sub-type of dynamic mics. They don't like large air movements (the ribbon tends to stretch out), and they almost always have a figure-of-8 pickup pattern. Vintage ribbons had a very dark/smooth sound, but modern ones can tend towards condenser-like clarity. The fig-8 pickup is due to the mechanical layout of the device, and tends to be very consistent across the frequency range. I like to use them for mid-side work.


*It's important to note that, by "sensitivity", I refer to the output in mV/Pa. Not a subjective measure of sound quality.


In all, they each do roughly the same job - convert sound to electricity. Each type of mic can vary wildly in how well or badly it does that job. If I was recording a choir, for instance, my choice of mics would typically be a Beyer MC930 and an SE VR1 (a modern ribbon) in an M/S array. They're both decent, neutral mics.

If I was given a box of random mics to work with, I'd be looking for the good mics instead of a mic that happens to use a particular technology.

For instance, I'd pick a Beyer M201 instead of an EV Cardinal for literally any job. I've worked with both a lot and I don't care that the EV is a condenser - the Beyer is a better mic.

Chris
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Caleb Dueck

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Re: LDC vs SDC vs dynamic Why?
« Reply #2 on: May 19, 2020, 11:23:46 AM »

Chris summed it up very well.

As a general rule, I prefer non-cheap-quality condensers over dynamics.  Especially outdated dynamics (SM57/58/etc). 

Try this - have a single speaker play back speech or fairly open, uncompressed music into a large room.  Speaker on a tripod on stage type of thing.  Set up a number of mics a ways away, just not too close to a wall.  Multitrack record the mics, level matched, as they pick up the speaker.

One by one, listen to the audio clip of each mic vs the "live" sound of the speaker, to see how accurate each one is.  Try EQ on each mic track you play back, to really hear the time domain issues and weaknesses of each mic. 

In a church setting, I like to have a few options for small diaphragm condensers for this application, and most other non-standard application (IE, everything in addition to drums, close-miced vocals, guitar cabs, etc). 

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Chris Grimshaw

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Re: LDC vs SDC vs dynamic Why?
« Reply #3 on: May 19, 2020, 12:05:01 PM »

Playing sound into a room with mics at varying distances is an interesting idea - you're not only varying the direct-to-reverb sound, but also the weighting of the direction from which the mic is receiving signal. English is weird sometimes. What I mean is that the more distant mics will have more sound hitting them from the sides and rear, while a mic close to the speaker will receive most/all of its signal from the front.

The mics with a well-controlled polar pattern should sound pretty natural at any distance, but as you move away from the source, you'll simply hear more "room". Listening to omni mics makes this obvious, but omni patterns are pretty easy to do well.

If a mic is directional, chances are the polar pattern will vary with frequency. I can't think of a mic that's consistent across the entire range, but the good ones get close.

Here's one for an e935:


We can see that the pickup at 90 degrees is pretty consistently -6dB compared to on-axis, except for at 16kHz where the pickup area is considerably narrower.
Not bad, overall, at 90 degrees - reflections from the side walls will be missing a bit of treble, but should sound pretty natural.

Sound hitting the rear of the mic after bouncing off the wall would be another story, though. It's all attenuated a bit, but there'll be 10dB more at 125Hz compared to 1kHz. There'll be some colouration to that sound, for sure.


I think I might give this a try in practice - seems like an interesting investigation.

Chris
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Brian Jojade

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Re: LDC vs SDC vs dynamic Why?
« Reply #4 on: June 02, 2020, 07:15:30 PM »

Another thing to consider is durability of the mic.  Condenser mics by design can be more fragile.  They also do not like humidity or extreme temperatures.

I've done plenty of shows where there's unexpected rainfall and the show must go on.  My Sure handhelds have Beta 58 or SM58 heads on them.  SM58's keep working through the rain.  Beta 58's, not so much.  In extreme cases such as that, I'll ALWAYS use the dynamic mic, regardless of the difference in sound quality.  Because some sound is better than no sound!
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Luke Geis

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Re: LDC vs SDC vs dynamic Why?
« Reply #5 on: June 03, 2020, 03:45:00 AM »

A short, quick, and simple list of why and why not for each type:

SDC:

1. Probably the most accurate and articulate mic option. Its small low-mass diaphragm helps in that regard. A must-have in every mic locker.

2. For a phantom-powered mic, it will likely have the highest self-noise. The packaging space is small and this limits the ability to utilize intricate and sophisticated circuits to run them which is also limited by cost. Most SDC's are fairly affordable.

3. Not a great choice for high SPL instruments usually. Toms and snare are usually out of bounds, so they get stuck on hats, perc, and overheads. They also get employed for anything acoustic in nature.

LDC:

1. Typically employed for low output acoustic instruments and things that need great detail with high output and low noise.

2. Very costly, sensitive to abuse, and obtrusive with cumbersome mounting.

3. Typically lower self-noise because cost and packaging allow for the circuit to do so. Also more efficient at converting acoustic energy into electrical energy.

4. Also a must-have in every mic locker. I have a pair of AKG C214's and looking to get more.

5. Also the most versatile for studio work because most have multiple pickup patterns that aid in efficiency and function or need. 

Dynamic:

1. The #1 workhorse in every mic locker. It provides the greatest performance to dollar value in most situations.

2. Very robust and capable of handling very high SPL levels.

3. The mass of the mic element means that they are not as accurate or as efficient as condenser mics.

4. Generally the most practical tool to use in any situation. They are good enough that you can make them work on anything.

In the end, it comes down to what you have in your inventory. You can use any mic type to do just about anything, but some do work better for certain situations. Very loud instruments like toms and snare typically employ dynamic mics because they are loud enough that efficiency isn't an issue and sonic detail isn't as important. Many SDC and LDC's can't handle the SPL that toms and snare can produce and will distort or damage the mic element when used for that application. SDC's are great for things that need great detail and accuracy that also need to be picked up with something that can fit in the space. Perfect for hi-hats, overheads, acoustic guitars, and percussion, or other fine detail instruments. LDC's are really not a required tool for most live sound. While they are great for certain things such as overhead or choir mics, you can use SDC's and dynamics with similar results in comparison. Where LDC's really excel is versatility in capturing the acoustic space or getting very low energy instruments into the recording or pa. Because many have multiple polar patterns, they can be used for certain things to acquire a result that a typical SDC or dynamic couldn't dream of.

What ultimately determines my selection is dependent upon the client, the circumstances, or the ultimate need. For band showcases with several changeovers, I tend towards as many dynamic mics as I can. If there are only a couple of bands and the client is higher end, I will go with all the best I have to offer. If I have a difficult venue and or acoustical challenges, I will reduce my mic count and rely on dynamics to reduce bleed. If I have an instrument that simply needs X mic to get what is desired, I will employ it. Wheather is a factor too. I don't like having high-dollar mics sitting out in the sun or rain unless it is a must.

I go by the rule of getting the sound right from the source. If the source is the way it is, then I need to adjust my way of capturing it to get a certain result. So if it isn't right, and a small EQ adjustment doesn't fix it, then you must move the mic, switch the mic out with another, or both.
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Chris Grimshaw

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Re: LDC vs SDC vs dynamic Why?
« Reply #6 on: June 03, 2020, 06:10:52 AM »

While they [LDCs] are great for certain things such as overhead or choir mics

Just a quick FWIW that LDCs are typically avoided for choir use. SDCs usually offer a smoother off-axis response, which makes them better suited for picking up physically large sources.


The bit about SPL handling is also misleading. IIRC the Sennheiser e914 will handle 157dB before clipping, while the Beyer MC930s (which I use a lot) top out at 140dB. Both are SDCs I have some LDCs around here that also top out at 140dB.

Condenser mics have finite headroom because the circuitry they have runs on a finite voltage. The capsule itself will mechanically handle pretty much anything, but the circuitry can be driven to clipping if the capsule puts out too much signal.

Dynamic mics don't really have that issue, although I guess the transformer-coupled ones might be able to hit core saturation if you really did something silly.

Chris
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Stephen Swaffer

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Re: LDC vs SDC vs dynamic Why?
« Reply #7 on: June 03, 2020, 01:14:50 PM »

Thanks Luke and Chris-that's what I was looking for-I know there are differences in specific mics.  I ended up getting good results with an inexpensive Peavy SDC (can't remember the exact mic) I had on hand-mounted just above the choir rail on the side away from the piano-seems to do a good job of picking up the sound of the congregation singing and makes sense that that would work best given your parameters

Also explains the mixed results I get-I have several singers that want to sing in a group around an "area" mic (their terminology)-really an LDC because they think it will pick up the group from a distance.  I think they have used them in studios where GBF is not an issue.

I was questioned if the mic I am using for the congregation was too far away-but it only goes to the livestream feed to I don't have to fight GBF.  I do notice more noise because of that (again given your characteristics of the mic, to be expected)-but given the use and that it is only live when the congregation is singing, noise isn't noticeable in use.
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Steve Swaffer

Luke Geis

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Re: LDC vs SDC vs dynamic Why?
« Reply #8 on: June 03, 2020, 02:26:19 PM »

As with all mics, the loudest source wins. When used with a PA system you are limited to GBF regardless of the mic type. Condenser mics are generally more sensitive to feedback because they are more sensitive. When you are distance mic'ing, you run into the critical distance problem. At some point, the mic begins to hear more of the space and soon you just have what you want to hear washed within the space its in. Imagine being in a church hall; pretty quickly you will hear more of the room than you will the direct sound of the singer. SDC's tend to have a higher self-noise than LDC's and dynamic mics. This just comes down to cost and space. So as you need more gain on a particular instrument, the self-noise will come up with it. Higher dollar mics just tend to have lower self-noise and electronics that are just better all around. This, as Chris mentioned, increases SPL capability among other things. LDC's also have the benefit of having a couple of polar pattern options when enough money is spent. These polar patterns can really help in different scenarios' making off-axis coloring and room noise less problematic. Again, as you spend more money, the smaller issues tend to be less problematic. SDC's I feel are the king of accuracy and detail at the cost of fewer options, and generally more self-noise. They don't typically have multiple polar patterns to switch between and their smaller package limits the circuitry to some degree. Spend enough money and you van have anything you want, basically.
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Chris Grimshaw

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Re: LDC vs SDC vs dynamic Why?
« Reply #9 on: June 04, 2020, 05:54:47 AM »

Condenser mics are generally more sensitive to feedback because they are more sensitive.

Surely if there's more voltage sensitivity, you should just turn the mic preamp down in order to get the signal levels to be the same. A condenser mic putting out 10x the voltage is certainly more likely to give feedback trouble if the only adjustment made is to engage +48v.

GBF is a function of the mic's polar pattern, and how well it holds up over the frequency range. There are other factors, too, such as how the sound sources are positioned with respect to the mic. How the sound is made into electricity is irrelevant, though.
Even though they all have the same rated pattern, I have dynamics that are feedback nightmares (a cheap 555 knockoff), and condensers that behave extremely well (TG-X930). I also have dynamics that behave well (e935), and condensers that are nightmares (NX8.8 ).

A good mic will have a consistent pickup pattern over a wide frequency range, regardless of the transducer type. The only correlation I've found is that a good dynamic mic is cheaper than a good condenser. So, if you're on a budget, stick with the dynamic mics unless you can get a real bargain.

Chris
« Last Edit: June 05, 2020, 03:15:46 AM by Chris Grimshaw »
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Re: LDC vs SDC vs dynamic Why?
« Reply #9 on: June 04, 2020, 05:54:47 AM »


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