I've got a Basic C2 preamp and love it, especially for its phono preamp. That manual, however, is poorly written/translated, and also contains some errors (e.g. the High filter attenuates frequencies ABOVE 8 KHz, not below).
I suggest you do a little research about preamplifiers in general, so you will understand about tape monitor settings, tone controls, why a phono input is different from other sources, etc. But here are answers to your specific questions:
- Turnover controls set the frequency range that the bass or treble controls will affect. If you set the bass turnover at 200 Hz and turn the bass knob, you will be affecting relatively low frequencies only. If you set the bass turnover to 400 Hz, you're still affecting the bass but the effect will reach higher, affecting the lower midrange as well. Put on some music and just give these settings a try. You will hear the difference. The treble turnover has the same choice: affect just the higher treble, or reach down and affect the upper midrange as well.
The C2's tone controls have a limited range of boost or cut, so you're unlikely to damage anything by playing with them. But keep the volume reasonable and turn things down if you hear any distortion, especially when testing the bass boost.
I almost always have both bass and treble controls set to Off. Once in a while I'll encounter a recording that needs a little fixing to make it listenable (e.g. maybe the top end is shrill so I turn the treble down a bit, just adjusting it by ear).
- The Filter settings are to cut off the lowest or highest sounds.
The Subsonic filter removes sounds so low that you can't hear them, but that can be generated by some records and styli. Those very low frequencies potentially can harm your speakers or at least make your amp work harder than it should. It won't hurt to leave it on, but the more purist approach is to keep the audio signal as unaffected as possible, so I usually leave mine turned off because I don't see that rumble problem in my system.
The Low filter removes the bottom hearable octave or so of sounds. It's like turning the low bass way down. It's rare you'd need to use this, but perhaps for very small speakers that just can't handle much bass signal.
The High filter removes the top octave or so of hearable frequencies. I'd only use that for an old recording with terrible tape hiss, or a badly noisy record. In real life I don't think I've ever used it.
In short, leave all these tone controls off unless there's a specific need to adjust them.
- About source selection: If you're only listening to records, just make sure you have the turntable plugged into the Phono input. Start with the Cartridge control set to MM/47K. You can try the MM/100K setting without hurting anything, too -- that will sound slightly brighter. Use what sounds best to you.
Good luck! Enjoy your C2. It's a fine preamp.
