I am loving the Spirocore Weich strings on my 1/2 size Christopher 102 double bass. They were suggested to he here on TB several times and I listened. Two days ago I took my early 1900s 4/4 German Flatback to a very reputable luthier in Springfield, Missouri. He will have it for about a month because he it taking the top off so he can repair the cracks. He will also plane the fingerboard. It has always been almost unplayable. When I bought it years ago, I put the weedwacker type strings on it to release the tension from the guy-wires it had on. The bass has enjoyed a place of honor in my home ever since. Now I am ready to start playing it. I have absolutely no intention of using a bow. My luthier suggested Mittel and not Weich strings when I get it back. With the 1/2 size bass, I am so glad I went with Weich! He certainly knows more than I do, but I have Talkbass! If you had a true 4/4 bass and were choosing between Spirocore Mittel and Weich, would you have any good reason not to choose the Weich? {}
It looks like a very nice bass which might handle mittels well. Tension-wise it they will be a big outstep from the whackers you have now, but so will the weich's. Either way, a good fingerboard & setup should turn this into a beauty. Slightly higher set weichs might also work well, and allow for turning down when you get tired. BUT: I've never owned a 4/4.
I prefer the stiffer feel of the mittels and on my bass I think the mittels sound bigger and more aggressive also I find playing arco on them isn't impossible... The Weichs are a bit too hard to bow for me also feel too low tension to me, but that's just opinion on my specific bass.
The 4/4 Mittel are more consistent and powerful, but can be a bit hard to play for a longer time. Might depend on the string height. With my 110 cm scale I passed out in the middle of the second set with a medium high action. The 4/4 Weich were much nicer to play, but the E feels a bit weaker than the other strings and you need to be careful not to pizz too hard.
It depends on the top as well as the player. Every bass has a "sweet spot" where you need enough downforce on the bridge to properly drive the top to its optimal tone, but not so much as will "choke" the top by damping it from too much downforce. Adding cleats to repair the top cracks adds mass to the top which may, as a result, require more string oomph to get out of it what it has to give, as well as the top being more massive, anyway, due to its full 4/4 size compared to a smaller bass.
When I get it back it will still have the Barefoot Larry's Hillbilly Bass Strings on it. Believe it or not, they are very nice sounding strings. I still have time to make a good decision even after I play it like it is for a little while. Barefoot Larry strings feel pretty good also. In the long run, they will probably be replaced though.
You may need your luthier to make necessary adjustments after the higher tension strings are installed too.
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