Alesis S4 / S4 Plus

Alesis S4 Image

The QuadraSynth was introduced in 1993 by Alesis, and it was their first major synthesizer. The S4 is the rack-mount version of the QuadraSynth. It's a 64-voice digital synthesizer with a whopping 16 MB of sample ROM, and was the first synth to offer the ADAT Optical Digital interface. It also featured the same multi-effects processor as the QuadraVerb 2, drum kits based on the D4 drum module, 4 assignable control knobs, one PCMCIA card slot, 48kHz clock input, and 4 audio outputs.

The S4 is undoubtedly a powerful and flexible synthesizer capable of creating rich sounds - both acoustic and electronic. It uses digital additive/subtractive sample playback synthesis to create high quality stereo grand pianos, organs, strings, drums/percussion, brass, woodwinds, new and classic synth textures, and more.

Released in 1995/1996 came the new and improved S4 Plus version (pictured). The S4 Plus rack module came with only 20MB ROM, losing the coveted 8MB stereo Grand Piano sample found in the QuadraSynths in favor of 4MB of General MIDI pianos. For an all around versatile modern synthesizer module that isn't focused just on dance or trance, be sure to consider the S4 or S4 Plus.

Lookup Alesis S4 / S4 Plus Prices

The link above will take you to an eBay search for this synth to see active listings with more images, specs and information. If you don't find it there, try looking in our forum marketplace. Our marketplace gets thousands of visits every week so make sure to check back often if you want to buy or sell a synth.

Related forum topics


Are you looking to buy or sell a Alesis S4 / S4 Plus? Post an ad in Gear For Sale or a request in Gear Wanted. For spare parts and repair services check out Gear Services & Other Goods. Our forums also has a Buyer’s Guide section where you can ask for advice on buying synthesizers.

16 Visitor comments
January 31, 2013 @ 12:12 pm
I'm in need of the S4 manual.. Just got one on Ebay but it came without the manual! If anyone can help me I would appreciate it greatly! Namaste!
October 18, 2012 @ 3:53 pm
I have been trying to patch my Alesis S4 Plus with a Novation SL MK II. I want to use the Novation device to control the sounds generated by the Alesis. I record tracks directly into Digital Performer. Digital performer has recognized both items individually, but patching them together using MIDI cables hasn't worked for me. Anyone have any ideas?
Vicious Lee
February 24, 2012 @ 5:51 pm
I have owned one (S4) since 2002 and have had no problems out of it. Got it for $150 in Boston, MA across the street from Berkley School of Music Theater.
February 18, 2012 @ 11:02 am
Swen - I have a new one ( used for one demo session then stored) . Check under MacCorporate in e-bay
you can contact me at
November 11, 2011 @ 5:42 am
As far as I know the Nanosynth is exactly the same as the S4+ minus 3 Effect Processors, ADAT connection, the four knobs and the card slot. I'm out for a S4 for quite a while now, but they are seldom seen on the german used market. But I own a Nano
What I wanted to add is, that the Quadraengine has a very complicated synthesis, definitely superior to Rolands concept, but the filters are really unimpressing and editing a pain, instead you get tons of Env's, LFO's and the really good FX (for its time). I want one because of the ADAT connectors, to get the sounds into my PC.
Big Shot, that one.
Post Comment!
VSE Rating

It’s Good

User Rating

Rated 3.4 (146 Votes)

  • Check Price
  • The link above will take you to an eBay search for this synth to see active listings. If you don't find it there, try looking in our forum marketplace or post a wanted classified.
  • Demos & Media
  • YouTube Thumbnail
    S4 Plus Factory Demo.
    by eonporter1

    Manual - Alesis have made manuals and program charts for many of their products available on-line, for free download as .PDF files.

  • Specifications
  • Polyphony - 64 voices
  • Oscillators - 48kHz Linear samples
    S4: 16MB, expandable to 24MB using PCMCIA ROM and RAM cards
    S4 Plus: 20MB, expandable to 28MB using PCMCIA ROM and RAM cards
  • Multitimbral - 16 parts
  • Effects - 4 On-board effects, based on the Alesis QuadraVerb 2 FX processor
  • Arpeg/Seq - None
  • Keyboard - None
  • Memory - S4: 128 preset 128 user programs, 100 preset, 100 user mixes
    S4 Plus: 512 preset 128 user programs, 400 preset, 100 user mixes
  • Control - MIDI IN/OUT/THRU (16-channels)
  • Date Produced - 1993 (S4)
    1995 (S4 Plus)
  • Resources & Credits
  • Images from

Errors or Corrections? Send them here.