When to use Small Diaphragm Mics vs Large

Hello and welcome back to this weeks last installment of this months focus on Small Diaphragm Condensers where we’re taking a look at the when, why, and how a Small Diaphragm Condenser is different to its larger counterpart, and the ways you can use that to your advantage when recording. 

There’s actually more in common than you might think, but it’s important to know the reasons why they both exist and have a home in studios literally across the world for a reason! 

Let’s dive in.

What are the differences between both SDC and LDC mics?

Not to call a spade a spade, but we can all agree the biggest difference is going to be the size and form factor of the mics in comparison. Typically, a small diaphragm is considered to be anything under half an inch, and large diaphragm being of course the opposite; but there is some overlap between some SDC mics where they’re still considered to be SDC despite having a capsule larger than the typical cut off point for size. The actual build of the microphones is also a big difference with SDC mics usually referred to as pencil condensers due to the well known brands opting for a slimmer housing with the capsule at the top (although again, that's also not always the case). 

What is the biggest difference then? Well, it actually resides in the polar patterns and the way they capture sound. SDC mics almost always have a much tighter polar pattern response than their LDC counterpart, but it goes even further than that. It’s in fact the way that the polar patterns affect the individual frequencies, in particular the lower end of the spectrum; as you get below around 500hz, the LDC mics become much less linier in the way they pick up frequencies comparatively to a SDC mic which then has further consequences. 

Because we as humans have evolved to actually like those non-linearities (think for example tape distortion, or transformer harmonic distortion), this is what makes the biggest difference to us in the way we perceive the differences between LDC and SDC mics. The non-linearities make it seem as though the LDC mics are warmer, or thicker in their sound when in actuality the SDC is simply just more accurate with how it captures the entire spectrum of frequencies when referring to the polar pattern shift. 

If you've been following the blog for the last few weeks you may recall my comparison of the BT-202 pair being a mix of both the Amethyst and the V12 for the same reasons as I've mentioned above. 

So, how can you use this to your advantage? 

That's the main question of course, and it’s a pretty subjective answer but I’ll do my best to stay bipartisan and neutral as best as possible. The main issue is that both perform admirably on almost the same sources and it’s more the source that will be the determining factor overall. If for example, you have some very bright cymbals and a drum kit that has a large amount of attack then I would likely pick the LDC mics so I can achieve some of that low-end and ‘warmer’ midrange, whereas if the kit and cymbals were much less bright and the overall picture could end up needing some more control then I’d likely pick the SDC mics with the LDC mics as room mics far away so I can rely on proximity effect for the rooms to keep the low frequencies from overcrowding the mix. 

Piano is another good example of how the source is the determining factor, when you have say a large grand piano versus an upright jazz piano as the variants. It’d end up being a case of shooting out each pair against each other and seeing what worked best over the strings and main sound of the piano I was looking to mic up, but then, again, if I was looking for a more mellow recording then I might mic up the back of the piano to taper off the highend naturally from the way I’ve mic'd up the instrument which would then result in the same process of needing to shoot out the mics against each other. 

In the coming weeks, we'll have many more samples of the BT202 pair such as this double bass and more recorded by our community member Alexandros. For now though, you'll have to take me on my word that this sounded incredible.

Where SDC mics do shine without the need for source to determine whether or not you shoot them out against a pair of LDC mics would be on say acoustic guitar, electric guitar cabinets (depending on the speaker), Saxophone, lower brass instruments, cello, violin, basically anything that calls for both a clear image of the instrument but also retain a tight image of the lower frequencies. Another place I think an SDC works is on vocals as well, but because of the form factor of an LDC mic, most vocalists assume that the shape and look of a mic is what is important to it sounding good; but they really do sound oftentimes better in my opinion than a LDC microphone, but again it's a preference! 

Lastly, if you managed to jump on the BT-202 release, I sincerely hope you’ve been enjoying the microphones if they have arrived; I know I’ve been in love with them since they first arrived and can’t stop using them. Let me know what your favorite sources to use them on are and write to me at Harri@jzmic.com