they're totally different sounding mics.
anyone owning both or having used both will have easy answers here.
bluebird is a scooped, hifi sounding mic. in other words, mids are lower level than highs and lows. can work on vocals of course but not the typical goto mic eq you want for lead vocal recording. that being said, some people shine on a mic like this when singing.... not my choice though.
spark is a vocally tuned mic. it has a subtle increase in the presence area and HF area but a really nicely placed narrow dip right in the area that causes a lot of sibilance issues in many singers. it doesn't have a ton of LF body to it but as a result sits really well in a commercial mix. targeted particularly well to female pop singing imho. I used to hate the filter switch (wahtever the hell they call it) in use but now I prefer it on vocal recording. it solves numerous eq problems that I typically eq out when mixing, so just use that silly filter, record your voice and don't freak out about it sounding a little bit lacking in warmth... it's just sounding more "mixed" right from the mic.
the spark is one of the ONLY truly vocally eq'd mics you can get for under $200. the general consensus is that it's capsule is the same one in blue's top of the line handheld vocal condensor mic, the model 300. but in the spark imho it sounds a little nicer. I don't think it's an AMAZING vocal mic, but for it's money it's arguably the best bet.
excellent mic though for stupid cheap "sunday night dinner with the family" money.
bluebird is a really well designed and made utility or instrumental mic. it can work great on the right vocals but inherently is better suited to bg vocals since it's such a hifi scooped sound rather than in your face present middy sound like a typical lead vocal mic. I've always treated the bluebird as an instrumental mic for pop music and acoustic guitars.
Think about it this way - some of the greatest lead vocal studio mics (like the blue kiwi) have a frequency response plot that is vaguely similar to that of the blue spark. it's not nearly as magical as the expensive ones, but compared to a much more neutral affordable mic or a too-bright cheap mic the spark is a far superior choice for vocals and acoustic guitar.
the two together are a perfect low budget pair for recording group vocals with a lead singer on the spark.
all of them are way too cheap for the cool factor of such sexy looking mics, well made products, and good sounding audio devices.
here's a youtube example of a good female singer doing a brittney spears cover with a blue spark:
https://www.youtube.com/watch?v=U9Jvt6kjiAc
I think but could be wrong that the guitar was tracked with the spark as well... dont' recall for sure. prob says in the video.
youtube has lots of examples of hte blue spark in use. you'll notice a VERY consistent sound from recording to recording.... the spark has quite the signature high frequency tone to it. plenty of S sound without being sibilant. almost like a subtle deesser and exciter were used simultaneously. hence why it's so cool on pop and commercial vocals.
That's funny!
