It was thus said that the Great Tony Duell via cctalk once stated:
  On Tue, Feb 28, 2017 at 4:21 PM, allison via cctalk
 <cctalk at classiccmp.org> wrote:
 The tape recorders used had no agc.  They were simple portables and used the
 mic or line input and headphone output. 
 I have to disagree with you there. I have just looked at the documentation for a
 couple of the Radio Shack tape recorders commonly used with TRS80s, and
 both have automatic gain control on recording. 
  I recall using a normal casette tape recorder with my Coco back in the
day.  I don't recall a gain control, but I do recall setting the volumn
control way up.  Never had a problem reading back tapes.
  -spc