Back in 1987 I was given a Yamaha Porta Sound PSS 570 synth.  I
was a kid and had never owned a keyboard so I was beyond
happy.  It had preset sounds that were all very fm/dx sounding stuff
like most of the 80’s style Yamaha keyboards at the time.  It also
had preset beats that could be changed up in real time with a fill
button, and sliders to control the different styles of each part (bass
drum, snare drum, cymbal, & extra percussion).  There was also the
ability to play the drums sounds live by pushing the ‘keyboard
percussion’ button.  This allowed the keys to play the drum sound of
the corresponding picture above the key.  It had 2 built in stereo
speakers that could get real loud.
the broken keys........yea,
ummmm............  let's just say one day
when I was'nt paying attention I sort of
'stepped' on the poor thing.  the keys
came right off. I'm very lucky more of
them have not come off.
But to me, the most powerful/interesting part of this porta synth is the
‘Digital Synthesizer’ button.  This button overrides the preset sound
banks and let’s you create your own sound with 5 different sliders.  As
they move up and down, they lock in 5 different locations.  This was the
best part for me when I played with it as a kid.  I could come up with
some crazy sounds very similar to my dx100 that I got many years
later.  Also, there were 3 keys near the bottom. ‘sustain’ ‘vibrato’ and
‘duet’.  So once you’ve created your sound you could pick one (or all)
of those 3 buttons to spice up the sound.
man.......those sliders sure
are grimy......I gotta clean
that.
This unit still works fine to this day, the connection for the power
supply needs to be fixed up a bit, but nothing major.  These days
with all the new software and other music toys around, I don’t get
to use this keyboard anymore.  But I will say it played one of the
most important roles in learning music and how synths work.
Here is a wav file with all the individual
drum hits from the 1 drum bank.  load
into your sampler and have fun.
Outputs:  headphone out and RCA stereo.  
It runs on ac power supply and batteries.
PSS-570 Rythem Kit - Wav file
Here are 2 examples of me playing a preset rythem/sound
pattern.  After a few seconds I begin to tweak the 'digital synth'
section.  Nothing amzing, but gives you an idea how fun this
was back in 1987 and the fact that it was my first synth.
Example 1
Example 2
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