Kurzweil 900MX Pt. 3
Finally, some progress! I replaced the relay, but this didn’t seem to make any difference. Next, I replaced the nearby capacitors (quite a tricky job on a 30 year old module) but this didn’t help either. So I resorted to my trusty multimeter and determined that there was no power getting to the negative voltage regulator.
Now, I’ll fully admit at this point, I was way beyond the knowledge gained in my Electronics GCSE. But my theory was that the display, navigation, MIDI etc. all used positive voltages but the sound making areas must need negative voltages. So logically, it can’t have been receiving an alternating current (AC).
It was at this point that I found a forum post along the lines of “Do make sure you are using an AC adapter, not a DC adapter, otherwise you’ll get no sound”. So I thought I’d better order a new one to be on the safe side.
It arrived this morning and low and behold, we now have sound! Sort of.
The first issue is that there is only sound in the right channel. Also, the volume knob seems knackered and only works when turned fully clockwise. So I suspect that could be the cause of the left channel problems too.
There is also a lot of background hum, particularly around 50hz. Fortunately, the Izotope RX De-hum seems to get rid of most of and I’m sure with a bit of tweaking should give me an acceptable sound.
But what does it sound like?
As expected, the pianos sound really nice, if a little one dimensional (i.e. Don’t appear to have many velocity layers). In fact, most of the sounds seem to be piano based with varying degrees of brightness, attack and detuning. For want of a better word, they sound ‘Expensive’, but are perhaps a bit too full sounding. Fine for solo piano, but I would guess they might need to be thinned out a bit to fit in a mix.
There are also a selection of growly synth sounds, soft pads, digital bells, harpsichords and a quite usable Acoustic Bass too.
The Electric Piano is an interesting one. It appears to have two velocity layers, but they sound nothing like each other. The lower velocity has an almost FM like quality, but the higher velocity is a lovely Rhodes sample. It does sound a bit unnatural moving from one to the other, so I’ll probably just multisample them into two separate instruments.
Well, I probably will have a go at replacing the volume potentiometer at some point and tracking down the cause of the hum. If the volume pot isn’t the cause of the left channel being silent, I’ll probably try swapping over the Op-Amps as they are mirrored for left and right channels. Otherwise, I don’t think I’m losing too much in Mono and can always widen the sound in my DAW.
But before I do any of that, I think it’s best to multisample the sounds into Kontakt just in case I manage to fry anything.