Recording - April 2010 - 31

The mount The KSM313 is supplied with what Shure calls a “monocle mount”, which is a fairly long lever arm with the mic on one side and a 5/8"–27 screw for a mic stand on the other side. The good news about this is that it provides a very convenient mount for a singer. The bad news about it is that it provides an arm that bounces up and down and really exaggerates low-frequency noise conducted in from the mic stand. This is a serious problem on stage risers that may not be in good condition, especially with a bass amplifier nearby. It would be good to have a shock mount available in place of the monocle mount for many situations. I took it apart The microphone comes apart very readily, revealing an interesting toroidal transformer that seems to be a smaller version of the one used in the Studio Vocalist. The transformer is really the weak point in any ribbon mic because it takes a very low impedance (well below an ohm) and turns it into a higher impedance the mic preamp can deal with. Typical ribbon transformers have a ratio of 1:100 or more, and it is very difficult to make a transformer with such a high ratio. I didn’t do measurements on this one, but the original measurements on the similar-appearing Studio Vocalist transformer were very impressive. The ribbon assembly itself is quite small and quite solidly and tightly mounted. There’s no internal shockmounting, but everything inside is very tightly supported so that shocks won’t be exaggerated by internal resonances. Consequently, handling noise is actually very good, aside from the problems with vibration pickup from the stand noted above. Some careful thought has gone into dealing with grille problems in a way that wasn’t done on the Studio Vocalist. This is important, and it’s probably much of the reason why the mic works so well in the far field. The aforementioned asymmetry turns out to be the result of a plate mounted behind the ribbon. Not only does this change the response and make it different between the front and the back, but it also may act as a blast filter; if you have a problem with ppopping it might help to try the rear lobe. This isn’t mentioned by Shure but it could be a useful side-benefit of the design. Measurements The measured frequency response looked more or less like the response in the datasheet of the mic, with a few narrow spikes here and there that don’t normally show up on smoothed datasheet plots. The spikes all moved around as the mic position changed, which makes me think they are acoustical things going on rather than mechanical resonances. This is a good thing. The mic response is, as mentioned above, wildly different in front and back. Whether this is an advantage or a disadvantage is up for discussion but it’s clearly deliberate. Conclusion This mic is bright without being shrieky or gritty. It’s good when you want to exaggerate something like a vocal and bring it forward in a dense mix without it being too over the top and piercing. This would also be a really great microphone for voiceover and announcer work, and the fact that it does well with a wide variety of different vocalists makes it a good versatile performer. Crowley and Tripp did a good job with their original microphone designs, and Shure did well to buy them out, finally bringing ribbons back into the Shure catalogue. Some of the improvements in this microphone may be the result of Shure’s engineering folks going over it. [Shure comments that the output level of the mic has been set up to be roughly equal to that of their popular SM58 dynamic design.—Ed.] However—don’t think of the KSM313 as a classic ribbon mic at all, because it’s clearly not designed to sound like a conventional ribbon, and it’s clearly not designed to be flat and neutral; instead, think of it as a deliberately forward-sounding and versatile mic that happens to have a ribbon inside. Price: $1619 More from: Shure Inc., 5800 W. Touhy Ave., Niles, IL 60714. 847/600-2000, www.shure.com. Scott Dorsey (dorsey@recordingmag.com) is a recording engineer, gear designer, and ribbon mic enthusiast working out of Williamsburg, VA. Polar pattern and frequency response plots courtesy Shure Inc. RECORDING APRIL 2010

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Recording - April 2010

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