here is an interesting subject. for my part I had long ago an audiotechnica "baton", absolutely zero. cold, matte and metallic.
then an omnidirectional sennheiser mkh-20 (equalized in diffuse field unfortunately) not terrible for the guitar in proximity, expensive and unsuitable.
then a U87 Neumann 70s / 80s, excellent on the voice but not for the classical guitar. , rendering mediums twisted, lack of attack, a lot of wheezing, its unrealistic.
then a dpa 4011 tl (high end) cardioid. an excellent condenser microphone that can be used to some extent on stage, (but that feedback anyway) ..
then An oktava capsule cardio + omni, which for a very modest budget can get a result quite close to the DPA. and I am sincere.
then I have a BIV-1 ribbon. not bad .
but I ended up cracking and ordered the kit from artur fisher in Latvia, The RM-6 ... and after some delicate but few welds luckily I had the best surprise of my life. The rendering of the nylon string guitar is of a natural as I had never heard. The recording by tape is different from the others, and on the voices it can be a little dull in the medium, but without too much, on the other hand with voice you have to use an anti-pop filter.
I kept the DPA, the oktava, and of course the RM-6, which although it is not the most expensive, is the best. And besides I even bought a second during a promotional period. he makes specials on his kits regularly. I will keep you informed if necessary (I do not touch money on its sales, I plebiscite its products because they are exceptionally successful without being of a very high price)
no problem of output level on this model, there is enough punch to not have to add a preamp. the output transformer is for many, and the fineness of the ribbon + "motor" too. It's really professional equipment. you can have a look at the bumblebee site.
the microphone is very responsive and very well reproduces the presence of the instrument. the sound is not "dull" quite the contrary. but there is no aggression. a delight.
There is also the rm-5 of the same manufacturer, it is less good for classical guitars and nylon in general by cons, it is better for the covers of amplifiers of electric guitars.
two other people bought this micro RM-6 on the French site. They praise them too. if you want, take a look at the forum, topic: "ribbon microphones"
By Saint Georges !