kidvybes said:
Marik...are you saying that 2 ribbons aligned side by side as in the RM4 would have absolutely no benefit as opposed to a single ribbon version?...
Oh no, I did not say that. What I meant, from the description it seems they just don't understand benefits themselves.
what was the intended benefit of this particular design in the original versions of this dual-ribbon configuration?...
OK, I will try to outline it the simplest way I could.
With all seemingly simple construction of the ribbon mic, all its design parameters are very tightly tied together. "Improving" one would inevitibly lead to worsening others. That's why it takes A LOT of experimentation to find that "sweet spot", where all the parameters would "sit together" with minimum compromises.
For decades two problems which ribbon mic designers were fighting the most were directivity on HF on vertical plane, and max. output of the mic. The former is directly affected by the later.
There are many ways of increasing the output and the easiest would be increasing the length of the ribbon.
Let's say we have two ribbons placed into magnetic gap of the same strength. One of them is 1" long and another is 2". The second one will have twice of the output of the first one (i.e. 6db higher). The additional benefit is that longer ribbons have much less resonant modes, esp. in lower mid range. Sounds good!... but... as we know, the directivity on HF is directly affected by the physical dimention of the transducer. So, in our example with 2" ribbon directivity in horizontal plane will be the same, but vertical plane will be worsen by an octave.
Now, let's say we don't want to compromise vertical directivity, but still maintain a higher output. Here comes that "magic solution"--DOUBLE RIBBON.
Let's see how magic it is.
What we do, basically we divide the ribbon into two parts, which would give us a similar output as one longer ribbon, but we get better directivity in the vertical plane--very good!
But... now, since the physical dimention in horizontal plane got increased (the width of the structure) we compromize directivity in this plane.
Moreover, we introduce three more problems:
1) Since the shorter ribbon has more resonant modes, we need to effectively dampen them.
2) Since there is a distance between two ribbons, we introduce phase distortions, leading to cancellations on certain frequencies, esp. those on the wavelengths approaching this distance.
3) Such an arrangement disturbes normal pressure-gradient operation, leading to reduced HF output of the mic.
4) The tolerances of the magnetic gap should be very tight and both ribbons should be very carefully tuned and precisely matched to avoid any frequency response/phase anomalies.
I highly doubt in $150 price point all of those are given carefull attention. Normally, only precise tuning of two ribbon elements can take up to maybe 1.5 hr. I am sure, with the volumes they put on the market it takes about 10 minutes to assemble the whole thing.
But don't take me wrong. I am talking about how to do the thing RIGHT and get maximum performance. I am sure it sounds OK for what it is and for the price tag.
Experiment with it and most likely you will find that in some situations you will find single ribbon works the best, and for others you might reach for a double ribbon.
