Yamaha SK15 | A Mysterious Synthesizer 

I miss those days. When even on an entry level synth, you got a sturdy wood and metal body, loads of features, and at least a 4 octave full size key bed.

The best synth channel to have a cup of coffee and a break from life.

I think yamaha's sk series, especially the sk 30, are some of if not the most underrated string synths of all time. I've always felt like they sounded the most like a conventional polyphonic synth all while keeping that vintage string sound.

Zach did a fine job Demonstrating sounds.

I found an SK15 on Craigslist about 3 years ago when I was looking for an inexpensive string synth (my ideal was an ARP Omni 2, but those haven't been inexpensive for a long time). I ended up being really pleased with its sounds, especially the string/synth combined with the chorus/ensemble effect engaged. It definitely scratched my itch for that sound and I ended up using it on most of my recordings/songs. Definitely a great option for vintage 70's strings on a budget. I was eyeing a Korg Delta, but those sound a bit thinner from what I can tell. My friend loves his though, so I'm sure they're also great. Then my buddy ended up scoring an ARP Omni 2, so I have the option of using that next time I record. Yay!

A lot of Yamaha’s keyboards similar to this were hybrid digital-analog. At this point in time, yamaha only had FM synthesis in one or two of their keyboards and they were much higher-end models

Dude you do exactly the content i was looking for. I hope your channel gets the K's it deserves

The organ section is not FM, but divide-down waveforms like the strings and synth section. I've had the SK-50D. If Yamaha would bring out a new Reface, it should be a Reface SK. It might even be a clone of the simple SK-10, if it has at least the fantastic ensemble effect.

One thing that confuses people about "digital" is it has two meanings - logic chips and microprocessing. Logic chips are things like AND gates, OR gates, etc. which are very basic components. However although they're called "digital" chips you can use them in analogue circuits even in the signal path. My Clef B30 Microsynth (I built from a kit in 1985) uses logic chips for a number of things including a couple of dividers to create the square wave sub-octaves. So, for many of these old keyboards "digital" means logic chips (likely dividers in this kind of keyboard) and probably no microprocessors were involved. Edit: the presence of LSI (large scale integration) chips doesn't indicate microprocessing. In the days before CAD some custom ICs would even be developed on table-sized breadboards.

OMG! I had one of those back in the 80’s! The poly synth part died at some point and it was trashed in a rock video we did :P I’ve gone back to loving analogue synths and would love to find another :) thanks for the great videos on some of the more oddball keys of yesteryear!

Surprisingly good vintage strings.

The organ section's just basic additive synthesis like any other drawbar organ, mixing together sine waves of different frequency intervals. No FM technology required. This was one of the options I looked at for my first synth.

Fantastic as always!

I love my Sk15! I like running it through fuzz and univibe I use a DI box with it because it tends to be a bit noisey . But I love the tones I can sculpt with it.

I’ll say this growing up in the 80s we had a DX 7 in the house.. and yes, that Oregon sounds like FM it has that rigidness about. It doesn’t really sound like an analog organ doesn’t have that sweet warm 60s sound at all

The entire SK-line predates any commercially available FM synthesis from Yamaha - and these contain no FM, at all. Yamaha started as an organ company, and these clearly are organs that are evolving into synthesizers (the GX-1 so-called “Dream Machine” was really a fancy organ giving birth to a synthesizer; its first child was the CS80, basically a 260lbs portable GX-1 which weighed in a nearly a ton when you include pedals, stand and speakers) - notice the SK’s rock solid tuning (compare this to other synth in and around 1981). The “symphonic ensemble” thing was perhaps the first time you heard effects in a synth. The “symphonic ensemble” effect was to turn the lonely and dry sounds in to an ensemble sounding section (its like a chorus with six delay taps). A great demo of this would be to play the string engine, dry, then punch in the Symphonic Ensemble- you do so by toggling the button labeled “Tremolo”: first hit applies Tremolo to the current sound, press it again to toggle to Ensemble… this applies this special deep chorusing effect to the current sound. Basically, electronic synths are simple circuits that create a “buzzer” type sound - not very musical if held in a static fashion. When the buzzer sound contains all harmonics (sawtooth) you can start to use filters to alter the harmonic content. Without the Filter, without the movement from Tremolo or Ensemble, like most electronic synths, it’s just a buzzer. The difference between the PolySynth section and the Strings is the factory preset the sawtooth buzzer tone to resemble strings (assuming the role of ‘string machine’ which was a highly desired keyboard sound in the mid-1970s thru the 1980s)… the Arp String Ensemble was a standalone, one-trick pony, that appeared on hundreds of recordings during this era. So having a one-touch string sound was very, very important circa 1981. Laughable, perhaps today, but if you study keyboards from 1970-1983… you could certainly fashion a competitive string ensemble sound using the SK front panel… competitive with other options at the time. In the 1982-83 era, options changed for getting a keyboard string sound (Kurzweil K250 if you had the $14Gs to afford one, and later the Emulator, etc., etc). But for a brief period versatile keyboards, like the SK were useful. You needed a Rhodes, a string solution, a synth pad solution, a synth lead/synth bass solution… the SK + Rhodes filled the multi-keyboardist card for a brief moment in time. At around the same time there was something called the Moog OMNI 3 - a very similar mix of organ, synth, string/brass.

I Have one i bought new when it first came out. It sits on top of my Wurlitzer 200. Played live gigs with it. The only problem I have is the push buttons are very sticky. I have tried cleaning them. but they still are a problem. I liked it a lot but I am not using it in my current mess of syths..

So how is the organ? Can i get something similar with an analog organ built in or to get that do you have to have dedicated separate keyboards?

I've been lusting after an SK30 for a while...

whats the song you played at the end?

I don't know why they don't teach this in history at school.

My SK20 sure sounds like is has FM artifacts at the extreme ends of the filters.

Great Review! They are not awesome, not awful either. I've had many Yamaha keyboards of that series (big wooden casing and ugly beige knobs) and one thing that I HATE is their smell. It's like a chemical and oddly floral smell, like some toxic potpourri.

🤓

7 voices ain't much for a paraphonic, most of them are fully polyphonic

Years is watching analog and retro synth videos I can sum up that nothing is as perfect as a moog or ARP the rest (Yamaha, Korg, Roland ) have a few flashes of brilliance (CS80, Jupiter 8) from time to time.. nothing owned the genre like Moog or ARP did

Spit it out man .. slow down .. use your words. .. think

The entire SK-line predates any commercially available FM synthesis from Yamaha - and these contain no FM, at all. Yamaha started as an organ company, and these clearly are organs that are evolving into synthesizers (the GX-1 so-called “Dream Machine” was really a fancy organ giving birth to a synthesizer; its first child was the CS80, basically a 260lbs portable GX-1 which weighed in a nearly a ton when you include pedals, stand and speakers) - notice the SK’s rock solid tuning (compare this to other synth in and around 1981). The “symphonic ensemble” thing was perhaps the first time you heard effects in a synth. The “symphonic ensemble” effect was to turn the lonely and dry sounds in to an ensemble sounding section (its like a chorus with six delay taps). A great demo of this would be to play the string engine, dry, then punch in the Symphonic Ensemble- you do so by toggling the button labeled “Tremolo”: first hit applies Tremolo to the current sound, press it again to toggle to Ensemble… this applies this special deep chorusing effect to the current sound. Basically, electronic synths are simple circuits that create a “buzzer” type sound - not very musical if held in a static fashion. When the buzzer sound contains all harmonics (sawtooth) you can start to use filters to alter the harmonic content. Without the Filter, without the movement from Tremolo or Ensemble, like most electronic synths, it’s just a buzzer. The difference between the PolySynth section and the Strings is the factory preset the sawtooth buzzer tone to resemble strings (assuming the role of ‘string machine’ which was a highly desired keyboard sound in the mid-1970s thru the 1980s)… the Arp String Ensemble was a standalone, one-trick pony, that appeared on hundreds of recordings during this era. So having a one-touch string sound was very, very important circa 1981. Laughable, perhaps today, but if you study keyboards from 1970-1983… you could certainly fashion a competitive string ensemble sound using the SK front panel… competitive with other options at the time. In the 1982-83 era, options changed for getting a keyboard string sound (Kurzweil K250 if you had the $14Gs to afford one, and later the Emulator, etc., etc). But for a brief period versatile keyboards, like the SK were useful. You needed a Rhodes, a string solution, a synth pad solution, a synth lead/synth bass solution… the SK + Rhodes filled the multi-keyboardist card for a brief moment in time. At around the same time there was something called the Moog OMNI 3 - a very similar mix of synth, organ, and strings, check it out!