Congrats on the great find. The 246 is my personal favorite 4-track portastudio of all time.
Yes, you should use Type II high bias tape for best results. TDK SA or Maxell XL-II in 60-minute length is recommended, but 90 minute is ok. Inside the cassette lid is a high/low switch that switches between normal cassette speed (1-7/8 ips) and high speed (3-3/4 ips). Switch it to high for best results.
There are two switches on the back labeled dbx. Make sure they are both in the up position.
Before you use the machine clean the tape heads with rubbing alcohol and a Q-tip. In the future buy 90% or stronger alcohol at a pharmacy for regular maintenance.
TO RECORD:
-Plug a mic into a channel (CH 1) and set the switch on that channel to “Mic/Line”
-Turn the trim control fully counter-clockwise (lowest setting)
-Bring the channel fader (slide control at bottom) up to the shaded area between 7 and 8
-Press down the assign switch labeled L/1 and turn the pan control all the way counterclockwise to the odd position.
-Bring the master fader labeled L/ODD up to the shaded area between 7 and 8.
-Press down the button labeled #1 in the record function section. The LED will blink.
-The above steps set everything up to record on track #1.
-Since the signal will only be traveling through the left buss you will want to engage the MONO button in the MONITOR section, or use the pan control on channel #1 in that section to hear the signal in both sides of your headphones. Still in the MONITOR section, set the track #1 level and the master level to 12 o’clock.
-Engage the Program (PGM) button in the METER section
-Engage the MONITOR button in the PHONES section and set the phones level to about 3 o’clock to start (so you wont break your eardrums just in case).
-Now sing into the mic and bring the TRIM control up on CH 1 until the signal is between –10 and 0 on the VU meter. Now bring up the phones to a comfortable level and hit RECORD and PLAY simultaneously.
After recording a few seconds rewind and set the switch on channel 1 to REMIX. When you press play you should hear your recording. You can also listen by engaging the PGM button in the MONITOR section, and then turn the PAN control on channel #1 to 12 o’clock. Use the slider control on that channel to adjust volume.
Recording guitar plugged directly will sound bad because of impedance mismatch. You will want to use a direct box or mic a guitar amp. The preamps on the 246 have plenty of gain for a mic.
~Tim