All three of these retro-styled microphones use the physical build of their construction to modify their frequency response, giving the sound ‘old-world’ retro characteristics.
A resonant chamber is created by setting the capsule toward the back of the unit, so that lower- and higher- frequencies become less pronounced, giving the sound a more mid-range push.
You may have seen studio pics where a guitar cabinet is dual-mic’ed with a Copperphone and an SM57. Mix engineers will blend the two together to get more midrange definition to the track, without resorting to EQing.
By using a physical means to accentuate mid frequencies phasing is less of an issue between tracks. Zoomed up close, the waveform is very different in appearance and behaviour, even though its from the same sound source (Guitar cab, drum).
These microphones suit any source that benefits from detail in the midrange. They’re great on guitar cabinets, snares (particularly snare bottom - see phase issue above), and perfect for getting retro vocal sounds without resorting to long plug-in chains. They make old grainy sounds achievable quickly and effectively.
So what are the differences between the models?
MothMic (Original) - handmade from recycled parts in Spain, the MothMic utilises authentic vintage capsules made in the 40s and 50s. The sound is labelled as ‘retrophonic’ and ‘oldie’ by manufacturer Mothsound, and it falls somewhere between a harmonica microphone (like a Shure Green Bullet, but more rustic) and an old wireless AM radio. It has the lowest output level of the review, mainly due to its 1/4 inch jack output. Its also the most lo-fi of the three in terms of character, and was the noisiest of the bunch (not always a bad thing). Audio examples here.
MothMic Deluxe - In this update of the original, Mothsound have made a quantum leap in the construction of this Mic. The solid steel body is larger, and physically much more solid feeling. The cradle is now sturdy aluminium and the address end is now fronted by a mesh grill rather than the ‘salt shaker’ approach of the predecessor. Output is now via Neutrik XLR, and the sound is noticeably richer and fuller in sound, without losing any of its ‘retrophonic’ characteristics.Of the three mics reviewed it has the most balanced sound when heard in isolation.
Copperphone - Hand built in the USA since 2003, the Copperphone was the first original character microphone on the block. It sports a rugged copper outer housing and ported resonant chamber. Sound-wise it is vintage without sounding boxy or telephone-like. It has the most pronounced treble response of the mics reviewed, and therefore adds the most definition when blended with the ‘normal’ track. The deeper barrel of this mic limits the bandwidth naturally without too much ‘thinning’. It has a Switchcraft XLR connector. Audio examples here.
Overall the MothMic Deluxe had the most rounded vintage sound with build features superior to its predecessor, and the Copperphone had the most definition. Possibly this edgier sound would lend itself better to blending duties in the studio (and you'll see studio pics of Copperphones everywhere!), while the MothMic Deluxe would be preferable for single-mic duties on, say, vocals for effect. Of course there are no hard and fast rules. Check out this pic of Jack White's Copperphone live rig:
They all sound great on acoustic pianos, cabs, horns - any sound source where mids need shaping and defining. Coupled with various pre-amps, these microphones open a huge array of sonic posibilites. Recordings sound more naturally effected, rather than processed to achieve warmer, vintage tones. Due to the physical nature of the microphones, positioning plays a big role in creating the amount of character in the sound. Increasing off-axis positioning can greatly increase the vintage effect - a couple of centimetres can add years to your sound!