Cassette tape type has a small impact on frequency range, with Metal being the best. The range of response of the recorder is limited by a variety of factors, but generally they follow the price point. Nakamichi and Harmon Kardon made their top line home decks in the '80s able to record full range (20hz-20khz) but few portables made had that quality. The Sony TCD5M, a recorder I used from '84 to '92, gave 20hz-19khz as it's best possible response. That was a professional level portable. Unfortunately, even using the best TDK or Maxell metal formulation tape, the model you referenced can't even get close to the range of a D5. Sorry..