I alternate my playing between an Aerodyne Jazz and a Wal Pro 1 (passive).The Jazz is 5 years old and I'm using flatwounds to re-create the sound I had in the '60's with my 1962 Jazz bass. They have replaced roundwound Elites 40-60-80-100. Conversely, the Wal is 28 years old and I'm using Rotosound RS66 Swing Bass Roundwounds, 45 - 65 - 85 - 105. More of this in the future.
The Jazz now possesses a much deeper, solid sound with a pronounced "thump" throughout the range. The feel is smooth, comfortable and easy. My main areas of playing are blues/soul/r'n'b and country and these strings are perfect, they cut through the mix without problems and they are as clear as the proverbial "bell". I'd forgotten how good Fender strings are - after all they were the first for most of us "old school". I shall not be changing back to roundwounds, as good as they are.
