Polypropylene Film Coupling Capacitors
The Dyna-70 Ultimate Upgrade uses German-made Audyn Q4 MKP Polypropylene Film Capacitors as the standard film capacitor in the Dyna-70 Ultimate Upgrade. The Q4 MKP caps are rated @ 400V with a 5% tolerance factor. These are excellent capacitors and have performed well in both Manual and Auto Bias versions of the Dyna-70 upgrade. However, we know experimenters and kit builders like to roll more than just vacuum tubes. The Dyna-70 Ultimate Upgrade PCB was designed with this interest in mind. The film coupling caps, C8, C9 & C10 have generous area to accommodate diverse sizes of film caps, see photo. Do not use any film caps with less than a 400V rating, or more than a 5% tolerance factor.
The Dyna-70 Ultimate Upgrade uses 2 sizes of film coupling caps, 0.10uF and 0.22uF; with two 0.10uF caps for C8 and four 0.22uF caps for C9 & C10. For those who want to experiment with film caps and their impact to audio signature, we offer upgrades to the Audyn Q4 MKP caps with Mundorf or Solen film polypropylene capacitors. Rated for 630V, these caps are slightly larger than Audyn caps. Additionally, Mundorf caps have a tighter tolerance of 3% vs. 5% for the Solen. Some of our customers are old school and prefer to use traditional Sprague Orange Drop Polypropylene film caps and that is all right with us because they too will fit fine on the Dyna-70 PCB.
We have used Audyn, Mundorf, and Solen film caps in all versions of the Dyna-70 upgrade and observe that all three brands perform well, sound great and give owners the ability to customize their ST-70 using audio specific film caps.
NOTE: We recommend you avoid use of capacitor voltage ratings above 800-1000 volts; the size of the cap gets larger in length and/or diameter. We provided room for C9 and C10 to accommodate most any film capacitor size however, C8 is bounded by the 6SN7 tube sockets, limiting the physical size of cap that can be used in C8. For an additional cost we can provide matched sets of all film capacitors.