Re2: Digital Synths

Matthew Porth mporth at
Thu Jun 19 17:51:32 CEST 1997

     Hello again,
        I suggest you have a look at the StrongARM system (lots of info on 
     the digital site and at These systems have a lot of 
     really nice features that make them scarely efficient performers.
        I am not looking at x'miting digital data to the PC (although you 
     have just given me a good idea!). It may be that I just use 2 MIDI 
     setups on the DigitalSynth card.
        The advantage of this other using software synths on my PC is
        - don't have to put up with the shit sample / playback quality of 
     PC cards
        - can do MIDI and DAC stuff together RELIABLy
        - can build effects that can be MIDI controllable (e.g. flanging/ 
     delay synced to a multiple of the current music tempo)
        - don't have to have 2 PC's (thats like BIG SPACE)
        - cost of components is about $150, not $2500 ;)
     PS - digital synths are allowed here, Aren't they???
     There is a dated but excellent intro:  Hal Chamberlain's Musical 
     Applications of Microprocessors which goes into great detail about the 
     "classical" digital synth you are talking about including schematics 
     and code stubs.
     What might be of more interest is the new crop of Digital Signal 
     Processor chips ( DSP ) from companies like Texas Instruments and 
     Analog Devices.  There is rumor of an Analog Devices DSP with decent 
     A/D and D/A all on a PCI card for under $200 - I am familiar with 
     their big SHaRC development kits but these cost upwards of $1K-buck 
     and are out of my range...  Anyway, one of these PCI cards, a decent 
     PC clone and a copy of CSound with one of the front end processors 
     would be an excellent place to start experimenting with digital 
     My interest though is Analog synthesis - there is something wonderful 
     about the sound.  I think that a marriage of Analog tone generation 
     and signal processing with digital control and sequencing systems will 
     offer the best of both worlds.
     In terms if I/O - going from the PC to the synthesizer, there is no 
     real need to go for a proprietary connection.  There is a high-speed 
     digital serial connection called FireWire which was initially 
     developed by Apple but has been released into commercial use and is 
     now available on many new motherboards.  The speed of this is such 
     that it can support streaming video, several channels of digital 
     audio, hard disk drives, etc...  There are cheap support chips 
     available so incorporating this into a new design is not a difficult 
     As for schematics, it is pretty much roll your own for now.  There is 
     a wonderful body of traditional analog schematics archived at various 
     sites and the technologies to interface to them are well known, it is 
     just a matter of putting the two of them together with some software 
     > -----Original Message-----
     > From: Matthew Porth [SMTP:mporth at] > Sent: Thursday, 
     June 19, 1997 8:33 AM
     > To: synth-diy at
     > Subject: Digital Synths
     >       Hi all,
     >         After reading the recent postings about PIC / Stamp 
     >      microcontrollers I was wondering if there is any schemtacis and 
     > info 
     >      for digital synths based around ADC / DAC's and CPU's. These > 
     >      systems interest me because I am a software engineer and have > 
     >      coding for a very long time... >      
     >         I am not really interested in Stamp / 8051 designs as I 
     think > they 
     >      are a little long in the tooth now. >      
     >         I am looking to use at least 1Mbyte of SRAM, at least 3 
     serial > 
     >      ports (MIDI In, Midi Out+Thru, Hi Speed serial IO (115200 Baud) 
     > for a 
     >      PC link), ADC/DAC via some kind of DMA device or more probably 
     a > FIFO, 
     >      a programmable clock device (5Khz up to 44.1Khz) and the SA110 
     > CPU 
     >      (StrongARM running at 233Mhz). >      
     >         Of course one could always use an 8 bit parallel port > 
     >      which would allow a stupidly fast PC link (1->6 MBytes Per > 
     >         What it really boils down to I am a software engineer not a 
     >      hardware designer. Are there any schematics of digital CPU
     > controlled 
     >      synths on the net?? Are there any mail lists / news groups that 
     > deal 
     >      with the building of simple computers. I have yet to find > 
     >         TIA
     >                 Matthew.

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