DS-1 SEM/Ultra Q

[FuzzAldrin]

Everything seems to work great, but I cant hear any difference when I switch from Ultra to SEM and vice versa. The LED flickers in one position and not the other... should there be a big difference?

[Renegadrian]

My friend gave me one to check... It has D5 as SE (no switch) and D4 with Ultra on  a switch - first the diode to the switch than the led in series in pos.1 and a jumper on pos.2
There is almost no difference when switching...and the SE lights up in one mode and not in the other...I checked several times, it all should be wired correctly...I also tried to hook up another switch but no differences from the original switch (I tried all combinations and directions of diodes with the hooked up switch...)

[Electron Tornado]

I've done these mods to a few DS-1s.

Yes, there is a difference between the SEM and Ultra. The Ultra will have a slight volume boost over the SEM and be less fuzzy. The LED for the SEM will light up in both SEM and Ultra modes. If the LED isn't lighting up and there's no audible difference in sound, then you've got an error somewhere.