Skip to main content
Vintage synths & drum machines
Vintage Synthesizers
Yamaha CS-15 monophonic synthesizer, three-quarter view: black case, 37-key keyboard, tall angled black panel with two rows of knobs in boxed sections, envelope sliders at the right and the YAMAHA logo
Representative photo, made by AI from real seller photos. Every listing differs. How we make these →

Yamaha · Analog monosynth · Pre-MIDI classics

Yamaha CS-15

Yamaha's CS-15 dates from 1978 and packs a lot into a small 37-key case. It's monophonic from its own keyboard, but inside it's two synths side by side, each with its own oscillator, multimode filter and ADSR envelope. The filters switch between low-pass, band-pass and high-pass, so every note can blend two differently filtered tones. There's also a noise generator, an LFO with sample and hold, an external input for processing other sounds, and separate CV and gate jacks for each side, which lets an external sequencer play the two halves as two voices. Those jacks use Hz per volt like Korg's, not volt per octave, so most modular gear needs a converter. The Human League used one on Dare, and Marillion, Vince Clarke and early house producer Boyd Jarvis did too. The CS-15D is a different, preset-based model, so check the name. Pick the CS-15 if you want a big analog sound from a small, light synth.

Spec at a glance

Brand
Yamaha
Type
Analog monosynth
Voices
Monophonic
Keys
37 keys
MIDI
No (pre-MIDI)
eBay asks (Oct 5, 2026)
$1,325–$1,650

What to check before you buy

Owner threads on Vintage Synth Explorer mention portamento faults. Its Hz-per-volt CV and gate also confuse buyers, since they won't drive or follow volt-per-octave gear without a converter.

  1. 01Model: Check the name on the panel in the photos. The CS-15D is a different, preset-based model.
  2. 02Both halves: Ask for a video playing each oscillator and filter on its own. Both sides should sound strong and clean.
  3. 03Filter modes: Ask for a clip switching each filter through low-pass, band-pass and high-pass. Each mode should change the tone clearly.
  4. 04Portamento: Ask for a clip with the portamento turned up. The glide should be smooth and land on the right pitch.
  5. 05Keys: Ask for a video playing all 37 keys slowly. Each should trigger one clean note.
  6. 06CV and gate: If you'll use it with other gear, ask whether the CV and gate jacks have been tested. They use Hz per volt, so plan on a converter for volt-per-octave gear.

Buying guide

Which one to buy

§ Oct 5, 2026

For a CS-15 to play, we'd buy the one titled Used Tested at $988 delivered, well under the band, or pay $1,350 for one titled working with a hard case. There are about 20 for sale, nearly all from Japan, and most ask $1,325–1,650 delivered, with the units that include a hard case sitting near the top. Check the panel says CS-15, since the CS-15D is a different preset model, and ask for a clip with the portamento up, because portamento faults are the common complaint. Skip the AS-IS units, which ask about what a tested one does, and check the voltage plate, since a 100V unit needs a step-down transformer on US 120V mains.

Listed now
20
For parts
2
Typical ask
$1,325–$1,650
Full range
$655–$1,748

Delivered prices include shipping as eBay quoted it to a US address on Oct 5, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.

Snapshot

For sale on eBay

8 of 20 listed

Checked . Some may have sold.

Delivered prices include shipping as eBay quoted it to a US address on Oct 5, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.

Prices change daily. The live eBay search shows everything listed now, including anything new since Oct 5, 2026.

See every listing on eBay ↗eBay search

Related models