For old tapes it is IMPERATIVE, i repeat IMPERATIVE to have a deck with PLAY TRIM !!!!!
It adjusts bad biased tapes by amplifiying or lowying treble section (bias related EQ) during playback.
This is done BEFORE Dolby circuits, so Dolby can work properly.
I strongly recommend Yamaha two Heads for playback they are top Highend, bought a Yamaha KX-260 and i can´t tell Type 2 cassetes recorded back in 1993 from CD.
(Some things are better, others are worst, ever slightly less sharpness, detail and accuracy but more pleasing sound more treble with less sheen, like a studio valve master processor.)
This deck changed my thought on cassetes.
Sound stage of the Yamaha is impressive, so many layers, Holografic as all other sources, and detailed micro dynamics,(singer retains dryness and sharpness, monoaural focus and frontness in a background echoing soundtrack, and this is done with razor sharp separation) absolute zero intermodulation distortion.
Just connect it to a digital 24 bit 96Khz portable recorder like Tascam, Sony or Zoom, or a good DAC on a PC, adjust PLAY TRIM by ear, and you're good to go.
P.S. It still records very well, but biasing a tape is a long process, for recording i recommend 3 head with MANUAL bias and rec gain with display assistance, but not all automatic, cause you may need to tweak it by ear for Dolby on some tapes.
(I've high end sytem with valve preamp Audio note M7 copy, QUAD 405 mod 3 with 500VA power supply, Proac studio 125, all with silver cables and russian paper in oil capacitors, and an acoustically treated room.)