Too much generous, Septi.
Sure, a full and punchy sound is generally what i am looking for and i admit i get such result more or less with any tapes (the last fine touches to the calibration made only by ears are a must here, IMO).
With some tapes i get my usual sound without the need to use dolby but, as you noticed on that "basic" RX cassette, the "trick" i use to get a full-clear-punchy sound on a (good) basic ferric tape like the RX (or the Sony HF and BASF FE-I) needs the use of the dolby B (and, possibly, HX Pro too).
In this situation, not only the dolby B reduces the hiss of these tapes effectively, but if you (manually) calibrate the bias a tiny bit higher than the usual and, at the same time, you raise the sensitivity knob some 0,5dB (or so) over the 'exact' value then the dolby B will decode the sound with a small boost on treble, then you will get back the treble you lost by overbiasing a tiny bit but you will also get a slightly more full and punchy sound on the bass.
It needs a 3-head deck (with tape monitoring) and manual bias fine and cal. rec level to do the trick easily (as you must evaluate the sound by ears AND with the music, of course) but, with some try and error tries, you could do the same even with a 2-heads deck and the internal tuning pots. (i guess that if the deck has also HX Pro it helps a bit more in this as you're working only with basic ferric tapes, after all)
I would like to put in evidence that, most times, i hear people complaining about the dolby B because it cuts the treble so that the sound is muffled... this happens when there is a mistracking to the "negative" side (i.e. the frequency response is off and/or the playback level is off)... but if you misalign the deck to the opposite side (even a boost to the playback level is sufficient to make a marked difference) then the dolby B will decode the sound by boosting the treble... and this is quite what i try to "force" in a controlled way with my trick.
Guys, please, try it... you may begin to really love the way those basic ferrics can sound.
CHEERS,
Vince.
PS: the same trick doesn't work with dolby C (as it's a more complex process) then, when using dolby C, my advice is to calibrate the things just exactly.
PPS: the upper type1 tapes (the "superferrics") may not work equally good with this trick as, generally, these are tapes with some kind of "boosted" response by themselves... then they may easily "over-react" to this trick... but, tweaking them with more care, they can sound wonderful... but, the trick as described above is very good in giving the basic ferrics a noticeable improvement, IMO, and the ones where i had the best results are the basic ferrics with most "IEC standard" bias and response like the Sony HF, BASF FE-I and That's RX.