Guest tew303 Posted July 15, 2004 Report Share Posted July 15, 2004 Hello Midiboxers,I've a question about the optimized PSU of the C64. Is it necessary to use this PSU or will a normal adapter do the job as well? I read that the sound quality improves when using the optimized or can a adapter have the same quality in a core,sid,ain, module setup. kind regardsTew Quote Link to comment Share on other sites More sharing options...
goyousalukis Posted July 16, 2004 Report Share Posted July 16, 2004 It is not necessary to use the C64PSU, but highly recommended. If you don't use it, Either the output of a 15V transformer, or a wall adapter can be used. 100 mA is recommentedI started with a wall wart, but noticed a big improvement in noise levels when I switched to the C64PSU. Justin Quote Link to comment Share on other sites More sharing options...
pay_c Posted July 16, 2004 Report Share Posted July 16, 2004 The problem with one wallwart is that you introduce ground loops if you´re not very aware of what you´re doing and that the high current stuff will modulate your supply voltage for the SIDs (e.g. the LCD and more important the Midi Lines and LEDs in the Modmatrix). You get much noise this way.I also tried both ways (wallwart and PSU). With my setup (using 8580s SIDs) the wallwart had a signal to noise ratio about -40 dB at best case, the PSU (with TK´s schematic) about -65 dB!!! Muuuuuuch better! Quote Link to comment Share on other sites More sharing options...
arumblack Posted July 16, 2004 Report Share Posted July 16, 2004 Pay_C, (Sorry to go off topic) Could you explain to me how you measure the signal to noise ratio?Thank you in Advance. Quote Link to comment Share on other sites More sharing options...
pay_c Posted July 17, 2004 Report Share Posted July 17, 2004 There are different ways, but I always do it like that (you need a mixer for that).I play some sound on the SID (any sound at max volume - saw or whatever) and level it out until it´s @ 0 dB appr. Then you stop playing it. Now you go up with the gain (remember how much you go up) let´s say with 50 dB. There should be a signal now. Let´s say it´s -10 dB loud. So now you know, that you SNR is about (ABOUT!) 50+10=60dB loud. Normally you would have to go up with the gain until the noise signal is also @ 0 dB, but most mixers don´t have so high gains.btw: 0 dB + 0 dB = 3 dB (hehe...)Greetz Quote Link to comment Share on other sites More sharing options...
Guest tew303 Posted July 17, 2004 Report Share Posted July 17, 2004 Thanks for the info. The only problem I have now is that there aren't pcb's for this circuit. Do you have to build whole the schematics as mentioned in the pdf. And if so how did you guys did this (veroboard??)Tnx Quote Link to comment Share on other sites More sharing options...
arumblack Posted July 18, 2004 Report Share Posted July 18, 2004 @pay_c: Thanks Alot! Quote Link to comment Share on other sites More sharing options...
goyousalukis Posted July 18, 2004 Report Share Posted July 18, 2004 Yeah, it's a pretty simple circuit. I just built it on vector board. Of course you could design your own PCB. If you build it using the original C64 case, you can make it fit perfectly where the power switch, power plug and joystick ports are.Justin Quote Link to comment Share on other sites More sharing options...
Guest tew303 Posted July 19, 2004 Report Share Posted July 19, 2004 I just finished my first build vectorboard circuit :D Quote Link to comment Share on other sites More sharing options...
oberg Posted July 26, 2004 Report Share Posted July 26, 2004 I'm currently trying to put together the PSU-circuit on a veroboard. Do you guys have any pictures of yours? It'd be really helpful to see some other designs before soldering my components in place. ;) Quote Link to comment Share on other sites More sharing options...
Guest Zzzz... Posted July 28, 2004 Report Share Posted July 28, 2004 Too late for TEW303....But I've made a PCB for the PSU,which actually fits perfectly inside of the C64-case....Sorry ... I had to put it online... huh?Will do....will do...better: send me PM....Grtz E. Quote Link to comment Share on other sites More sharing options...
Guest tew303 Posted July 28, 2004 Report Share Posted July 28, 2004 Hi Oberg,I don't have a digital cam and no scanner. But as you probably saw, ZZZ.... has a pcb design for it. I would go for that solution since it's more reliable.Actually I'll probably rebuild it on a pcb when ZZZ... has made layout public.BTW I'm working on a simplified surface (1 SID only). When it's finished (probably within a month), I'll post the details, panel and code. No leds are in the design which makes assemble the unit far more easy (no DOUT, only a core, sid and din module). But it's not as good looking as the surface which Thorsten made ;)Greetz Tew Quote Link to comment Share on other sites More sharing options...
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