ODP: diy GM synth

[Roman Sowa]

find my comments below
Roman

> -----Oryginalna wiadomość-----
> Od:	Mikko Helin [SMTP:MHELIN at tne01.ntc.nokia.com]
> Wysłano:	25 marca 1999 11:51
> Do:	synth-diy at mailhost.bpa.nl
> DW:	MHELIN at tne01.ntc.nokia.com
> Temat:	Re: diy GM synth
> 
> 
> Hi there,
> 
> The Crystal chip is quite limited, IMHO. It even lacks the portamento
> switch (though there is the mono mode)
	[Roman Sowa]  
	Yeah, it's simple, but nice

> . More interesting chip is
> the Atmel/Dream SAM9773, which implements Roland's GS mode
> with tweakable filter cutoff etc. (you can use pitch bend midi
> messages for less zippery realtime control of Fc). It's also
> got 20-bit I2S output.
	[Roman Sowa]  
	coooolll!

>  It needs the opto + 9.6 MHz crystal
> or oscillator, which I haven't found yet. Could we design
> our own pc-board for that chip, and order some chips
> from Dream? Could this be the first digital synth-diy list
> project synth? 
	[Roman Sowa]  
	Good idea

> We would need a pcb manufacturer (was there an 
> inexpensive place in Poland?),
	[Roman Sowa]  
	Yes, there is.

>  also some DAC's (see below). 
> You can use two DAC's for 4-channel output in SAM9773, so you 
> can route some MIDI channels to front DAC and some other
> to rear DAC. To get most of the 20 bit DNR it would be
> better to design a two-sided pcb, which is diffcult to
> do at home.
	[Roman Sowa]  
	No, it's nooot...
	Think as those PCBs would be already made, and cheap
	(well, by making PCBs at home I mean designing them,
	since they are made by this cheap manufacturer anyway)

>  The chip itself is in TQFP80 package,
	[Roman Sowa]  
	I'm not gonna solder it. Do you? I once did 0.65 lead pitch TSSOP
	and I felt like it was beyond my limmits, but TQFP could be even
0.5mm

>  and 
> CS4334 in 8-pin 150 mil SOIC case (smaller than CS4331).
> CS4340 is in 16 pin 150 mil SOIC case, it may be better
> choice as we don't have to order 300 chips.
	[Roman Sowa]  
	As for DACs, I wouldn't stick to Crystal if they were too expensive
	or hard-to-get-in-small-qty. No need to deny, I like An*l*g D*v*c*s'
chips.
>  
> I'm going to ask the prices for the Dream chip, let's
> hope it's not too much.
> 
> 
> -Mikko
> 
>