[sdiy] Single chip digital delay

[Seb Francis]

(CCing back onto the list in case the info is of interest)


Hi GB,

Thanks for these links.  The 2nd one looks interesting - I hadn't 
thought of making my own 1-bit oversampled ADC/DAC and just stringing 
some FIFO memory in between.  I think your calculations for the memory 
storage are not quite right though: should simply be the sampling rate * 
the time to give the number of bits needed.  But for this kind of 
conversion it probably needs a sampling rate of somewhere near 1MHz is 
needed to get decent quality .. so 10ms delay = ~10kbit (pretty much the 
same result as calculating it based on 'normal' sampling rate and 16bit 
resolution).

The first link mentions the Mitsubishi M65830 IC and that it has been 
discontinued.  I think the replacement would be the M65850 which is now 
sold by Renesas who took over some of Mitsubishi's product line in 
2003.  I've been finding these chips quite difficult to get hold of, but 
hopefully (fingers crossed) a distributor is going to send me some 
samples in a couple of weeks.

Seb



MTG wrote:

>That's an interesting question.  Here are a couple of links
>of possible interest ;-)
>
>http://sound.westhost.com/project26.htm
>
>http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=8056
>
>For a digital storage method, ou need to define your 
>memory requirements.  EX: 
>44.1 kilosamples/sec * .010s * 16 bits = 7kbits
>
>so it wouldn't be too hard to do (memory-wise).
>That being said a one-chip DSP might do it or
>even a fast microcontroller.
>
>GB
>
>
>-----Original Message-----
>  
>
>>From: Seb Francis <seb at burnit.co.uk>
>>Sent: Jan 24, 2006 3:54 AM
>>To: Synth DIY <synth-diy at dropmix.xs4all.nl>
>>Subject: [sdiy] Single chip digital delay
>>
>>On the subject of delays.. I've been wanting to build a simple digital 
>>delay (or two) for the purpose of making a wide stereo image .. e.g. 
>>hard pan the original sound to one side and hard pan a few ms delay of 
>>the sound to the other side.
>>
>>The delay needs to be clean and accurate (so BBDs are out!), and the 
>>delay time doesn't need to be very long.  I guess what I need is 
>>something like a good quality single chip digital delay.  Anybody know 
>>of something suitable?
>>
>>Seb
>>
>>
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