It's an older thread, but it made sense to keep the Prestoflex posts together. After sticking with Spiros at my last string change in 2015, I decided to try out the Prestoflex this time.
This is day one with them. My bass is an old solid wood 3/4 flatback likely from Saxony, and I'd just taken off an 8 year old set of 4/4 Spirocore Mittels that were getting too dark and thumpy for my tastes.
Pre-installation impressions; The packaging is very simple and barebones, just the paper envelopes in an open faced cardboard sleeve, not much info on the package. Uninstalled the strings feel very flexible, which must say something about the core design. The ivory and blue silks are a little more subtle than my familiar Spiro reds, and the ball ends are slightly smaller. They look and feel like a quality string, I really can't fault the construction and polishing.
On the bass, the pitch stabilises quickly, and the tension feels a hair lower than the 4/4 Spiro Mittels, but not by much. I'd place the feel between those and 3/4 Spiro Weichs. The pizz tone is also instantly familiar, lots of growl and sustain, good volume. To my ears (and on my bass) they have a touch less midrange push compared to the spiros but a nice crisp, clear quality in the high end - the thumb position pizz tone is great with these. I think I might want the string height just a tiny bit higher than I had it with the Spiro Mitts, so I'll probably try that in the coming days. Definitely not a rootsy, gut-like sound, they're more geared to a modern jazz pizz tone. Which is absolutely my goal, but it should give you an idea of the kind of player they're for.
I only had a quick play with the bow today since my dog was napping! They're quite a bright arco sound, quick to respond, but friendly enough to get a clean tone on. Probably not your first choice for an orchestral section, but fine for a jazzer using the bow for practice, or for some of my free improv uses.
I'll see how they go over time, but if they last like Spirocores I could be pretty happy with these. I can't comment on the Lycon comparison as I'm too young to have encountered them, but it's nice to have another subtly different flavour in this style of string.