Posted By
MMS
on 2014-12-02
19:45:09
 |  Re: Trackers ?
OFF from trackers 
My aim: cheap and good quality music from Plussy, different from SID style.
Nothing groundbreaking, same as PC Covox ("poor man's sound card"), Speccy or CPC 8bit DAC trackers
Details:
1) C64 Joy input for sound: it is called Covox Voicemaster, and here it is:
http://www.thepyro.com/blog/covox-voice-master/
2) The thing I am talking about is is the SAME as the Covox Speech Thing for PC.
http://en.wikipedia.org/wiki/Covox_Speech_Thing
Definitely I want to build the same for Plussy, but not on Parallel port (Pc) but on User Port.
Same 8bit out at the same time, no bitbanging.
8bit out --> DA converter --> Analog sound on mono RCA out
3) As I know, ACIA (MOS6551) manages the User port in Plus/4.
Theoretically can push out max 19200baud (means 2400byte/second).
I am not pretty good at math, maybe the 2400 byte per second change rate will lead to nowhere.
(On my very old 268 16Mhz, my self made Covox card worth listening at >16KHz sample rate, may translate)
4) I do NOT want to realize a soft synth on plus/4. Too weak for that
And I know how much resource intensive it is; I know it since maybe 10 years 8or more?), due to Yamaha XG softsynthetizer I upgraded my PC to Pentium3.
5) I try a new way of music style on Plus/4. That is seems not utilized yet by C64 or C128 (?).
6) As I understood, Plus/4 has one of the strongest CPU from this MOS range.
I understood badlines, on the other hand you may switch off partly the screen (OK, no NTSC)
ZX Spectrum could manage 16000 Hz sample rate with the similar setup
(certainly via Interface, not via rs232 style (I mean ACIA could be a bandwidth limitation here). )
http://chipmusic.org/forums/topic/10202/sampletracker-on-zx-spectrum/
6) C64 has a certain kind of sound due to SID.
Has great artists, and great musics, but I also see on some recent youtube videos from the original greta artists, that they wanted the music to sound DIFFERENT, but the C64 has it's own limitations.
With an OFFLINE (and Free) Soft synth you may create any kind sounds, differ siginficantly from SID, and due to 8 bit mixing and playback it may sound much better than a C64 digi.
I can save the made sample from analog synth (eg. Moog Emu), downgrade to 8 bit on PC, and map into Plus/4 memory the PCM wav.
The lenght of the sound(s) are very limited by the available memory, but direct programming of the free / mixed waveforms also a possibility. (like the digidrums on TED).
6-8 pieces of 1-2KB samples still fit into memory.
7) I was not aware of the SID Card extra capability, the 8bit DAC extension.
Maybe I did not read the User Manual well enough 
So maybe really no need for Covox.
But it could be much cheaper than the SID Card with the SID chip, certainly with much less knowledge and support. Cost maybe 10€ or even less, together with the connectors.
To be honest, I really liked my covox sound card on my PC, till I had no money for a long time for Adlib or Sound Blaster. It was cheap, and sounds great.
8) There were some commercial 8its, based on the same concept and IC, on CPC
http://www.cpcwiki.eu/index.php/Amdrum
9) No need to build by anyone.
On SW part may need help, but supposely it will be NOT you
I have one I build myself for my PC ~18 years ago , connecting to parallel port. Still working.
I just need to connect the pins to a User Port connector (I also have), the only thing is the power consumption, if the Plussy User Port 5V can provide enough, or should look for external one.
Mine is too expensive for today realization, as based on Ferranti ZN428e and some tantalum condens
The IC alone costs today some 10€ (chinese copy version is only 2€).
TI version DAC may have better result and reliability thana chinese DAC.
Hopefully you got an elaborate answer and could clarified the point.
|
