Behringer Solina ensemble mods impossible - possibly digitally generated - paging Maffez ;-)

Dear Behringer Solina fellows, I got one of the Behringer Solinas when they were first released, and always felt like something's missing. I had a vintage Solina two decades ago and its ensemble chorus somehow sounded more warbly and throbbing, there was more movement and a very slow phasing going on, possibly due to the complete analogue construction of the ensemble circuit. That's why I tried to find out if on my Behringer Solina pcbs it'd be possible to mod the two lfo speeds, lfo mix amounts and levels driving the phase clock chips for the bbds.

Well, unfortunately I'm out of luck. As it seems, both lfos, their rates, levels and mix levels for the combined lfo mix of each bbd phase is generated digitally inside the cpu on the left side of the top pcb. In contrast to the Solina product videos and pcbs where 3 seperate bbd clock driver chips, lfo generation and loads of trimmers can be seen, all of those parts are missing from the actual released product pcb.

So I traced signals back from the bbd chips. U27 V3207 is the first bbd. It´s output level is controlled by a pair of smd resistors r38-1k and r32-1k. If you lower r32 the output gets louder. So the resistors form a voltage divider where formerly - in the product video - had been a trimmer. The same goes for U28, r83/r46, both 1k again, and for U29, r243/r105.

For U27, 28, 29 - each two phase clock inputs are driven by several outputs of U8 74HCT244D, so instead of 3 bbd clock drivers this one chip, U8, is being used to distribute 6 phase clock signals.

So far so good I thought, but then I traced back the signals feeding U8 which should have been the analogue lfo generation and mixing by some op amps, resistors, capacitors and trimmers, so some analogue parts that one could have tweaked to one's liking. But, not here. In fact it looks like the three already pre-mixed lfo signals are generated in the cpu and then directly feeding U8.

This is good and bad news at the same time: bad, because as an analogue tinkerer there's nothing one could do to change lfo speeds (tremolo and chorus speed), their mixes and amplitudes to the 3 bbd chips. Pity! Also, just changing the 3 bbd level outputs by tinkering with the 1k resistors mentioned above won't do anything to the modulation depth, as that's already been pre-set in software, generated and put out by the cpu.

The good thing is, if my investigation is correct, it should be possible for Behringer, to implement chorus speed, tremolo speed, chorus/tremolo mix, and bbd1 to 3 lfo intensity as little software trimmers in the Synthtribe software. Maybe we could even have trimmers for the phase relation of the three clock signals. And by that we could vary the ensemble throb, wobble, intensity and even adapt to the most loved old Solina one may have... Please guys or anyone related to Behringer give them a hug or two to make this happen.:thumbsup:

Maybe Maffez or anyone else technically savvy enough would like to have a look at the Solina pcbs too to confirm my findings? But I think this is how it is. I'd have liked seeing analogue lfos and trimmers inside, but there's nothing in there like in the product development videos, so Behringer economized those, unfortunately. I'd have gladly paid a bit more for having seperate trimmers, but I also understand the Behringer approach of keeping costs down as much as possible to make their units affordable to most musicians around the world.

Caveat: if someone finds some analogue lfo generation and mixing on the pcb please let me know, then I´d be clearly wrong. But as of now I don't think so, unfortunately...:hippie:









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