achra Posted January 15, 2010 Report Share Posted January 15, 2010 Hello all, and thank you very much in advance for your help. This is my first midibox project, so please assume firstly that I have simply made some kind of user error. First, my setup: I am using a Midibox CORE & Midibox SID module from smashtv. I programmed the PIC18F4685 with the bootloader that came with MIOS 1.9g, and uploaded MIOS 1.9g via midi. All is good, the LCD display works great. I uploaded the SID test application, I get a nice clean 1khz tone. All so far so good. I erased the PIC, burned the bootloader, uploaded MIOS, and uploaded the midibox sid v2 application, and uploaded the presets patch bank. Everything looks and controls great.. However, this is my problem: When I try to play a note on my midi keyboard, the SID module makes a loud POP and then I hear a brief quiet synth noise. The synth noise I am hearing sounds like it might be the right kind of SID sound, but it is very quiet (I have this sent through a nice amplifier, but still this is very audible), and also it doesn't sustain, it just is a very brief. The upshot is that any notes I play, it just sounds like a bunch of extremely percussive loud popping noises (followed by very quiet brief synth on some of the patches).. I've tried other SID chips, they all sound the same. Any thoughts? My power supply is a pair of matched transformers, one outputting 18vac@500ma and the other outputting 9vac@1a. I'm measuring 22vdc at the rectifier before the 12volt linear regulator for the SID module, and 10vdc at the rectifier before the 5volt linear regulator for the core module. Please let me know if there is anything else I can provide to offer assistance. Thanks for this great project, I can't wait to get it working properly. -Adam Quote Link to comment Share on other sites More sharing options...
nILS Posted January 15, 2010 Report Share Posted January 15, 2010 1) You don't have to erase the PIC. Ever. All you do is upload the new application. 2) Did you use MIOS Studioto upload the app, and did you enable "smart mode"? 3) The voltages you are feeding the regulators are fairly high. Are your vregs getting hot? 4) Is there a ground connection between core and SID module? (There should be) 5) You are using 6581s, right? (6581s need 12V, 8580/6582s need 9V) Quote Link to comment Share on other sites More sharing options...
achra Posted January 15, 2010 Author Report Share Posted January 15, 2010 1) You don't have to erase the PIC. Ever. All you do is upload the new application. 2) Did you use MIOS Studioto upload the app, and did you enable "smart mode"? 3) The voltages you are feeding the regulators are fairly high. Are your vregs getting hot? 4) Is there a ground connection between core and SID module? (There should be) 5) You are using 6581s, right? (6581s need 12V, 8580/6582s need 9V) Thanks for your prompt reply. Below are my answers: 1) Good to know. Any chance that my initial program/bring-up procedure was incorrect somehow? Should default bootloader/mios have been correct for my purposes? 2) Yes, MIOS Studio, in smart mode. 3) The 5v regulator was getting hot until I heatsinked it. This is expected, since I have a nice backlit LCD display on that supply. The 12v regulator is warm, but not hot. (This thing must not draw much current?) 4) Yes, the two grounds are connected, and I verified that there is 0.0v potential difference between the ground on both boards. 5) Yes, 6581's. As an aside: The next one of these that I make, I am thinking it would be better to use a 15vdc wallwart and 12vdc linear regulator for the SID.. But use a bucking switching supply for the 5vdc and avoid all of these heat problems and ugly transformers.. Unless there are good reasons for not using a switching supply on a piece of audio equipment? -Adam Quote Link to comment Share on other sites More sharing options...
nILS Posted January 15, 2010 Report Share Posted January 15, 2010 Correct, there's not much current draw at the 12V rail. How did you upload the presets? A corrupt upload may well lead to what you are describing. The best way of uploading the patches would be using the sid v2 editor found on ucapps.de Also you might just try making a new (simple) patch (try different waveforms, make sure ADSR is 0-0-15-0, no modulation, no filters). About the switchmode supply: Unless you get a nice (= usually relatively pricey) one you'll have audible clicks and pops on the audio out due to noise from the psu. If you find a cheap _and_ quiet one, please let us know :) Quote Link to comment Share on other sites More sharing options...
achra Posted January 15, 2010 Author Report Share Posted January 15, 2010 Correct, there's not much current draw at the 12V rail. How did you upload the presets? A corrupt upload may well lead to what you are describing. The best way of uploading the patches would be using the sid v2 editor found on ucapps.de Also you might just try making a new (simple) patch (try different waveforms, make sure ADSR is 0-0-15-0, no modulation, no filters). About the switchmode supply: Unless you get a nice (= usually relatively pricey) one you'll have audible clicks and pops on the audio out due to noise from the psu. If you find a cheap _and_ quiet one, please let us know :) I uploaded the patches using midi-ox with delay of 750ms after F7, as described in the preset patches readme.. But I'll try the sidv2 editor in the morning. Thanks for the values of a "simple" patch, I'll definitely try that as well. Hm. I was just thinking of following the MC34063 appnote, I have had great luck with that in the past for various projects at a total cost of under $5. I will let you know how that sounds during my next build. Thanks again for your continued help, I'll report back with my findings in about 9 hours. -Adam Quote Link to comment Share on other sites More sharing options...
nILS Posted January 15, 2010 Report Share Posted January 15, 2010 Thanks again for your continued help, I'll report back with my findings in about 9 hours. I'll just wait here till then :) Quote Link to comment Share on other sites More sharing options...
achra Posted January 15, 2010 Author Report Share Posted January 15, 2010 Ok, I attempted to create a "simple patch" with the values you specified.. Same issue as before. Attempting to send the preset bank via MBSidv2_editor, I was not able to get the send to work at all. I can receive the bank OK, though. Would it be worth posting my patch bank & ensemble bank here so that you can look at it? Is it possible that this kind of behavior might be caused by a bad BC547? Quote Link to comment Share on other sites More sharing options...
nILS Posted January 15, 2010 Report Share Posted January 15, 2010 I assumed you checked all the voltages and they were good (and checked as per ucapps.de), is that the case? ;) If you're having a broken component in the output stage that might well cause the issue. And the transistor is pretty much the only part capable of breaking. You can try to get the audio out directly from pin 27 of the SID. Replacing the transistor is definitely worth a shot. Quote Link to comment Share on other sites More sharing options...
achra Posted January 16, 2010 Author Report Share Posted January 16, 2010 Ok, issue resolved. I installed the SID TestTone application and verified that the output amplifier stage works fine. I installed the SID Interconnect application and verified that the shift registers and SID connections are all working perfect. I swapped out a few other SID chips and verified that the issue was unchanged.. I installed the midi-mon application and verified that the midibox was receiving what I thought I was sending.. Still the same behavior (very little actual synth sound, which was always the same note, and extremely loud popping at the beginning and end of each note).. I inspected the boards and connections, carefully verifying that everything looks good. At this point, I decided that it simply had to be a software issue.. and that is where I found my problem, my PIC programmer software was set to PIC18F4680 instead of PIC18F4685. I had wrongly assumed that because everything seemed to be "acting" right, then the bootloader must have been burned correctly. Wrong. Best guess, the fuses are set differently on these two microcontrollers, and I had the PIC fuse settings set to something crazy. (This is my first PIC project, up until now I've been exclusively an Atmel AVR hobbyist). So, anyways, there is my story for posterity, for the next poor idiot to get clued in with the cluebat. Thanks again for your endless patience, Nils. -Adam Quote Link to comment Share on other sites More sharing options...
nILS Posted January 16, 2010 Report Share Posted January 16, 2010 Glad it all works now :) And on a sidenote: Fuses are evil and PICs don't have fuses :yes: Quote Link to comment Share on other sites More sharing options...
achra Posted September 20, 2010 Author Report Share Posted September 20, 2010 About the switchmode supply: Unless you get a nice (= usually relatively pricey) one you'll have audible clicks and pops on the audio out due to noise from the psu. If you find a cheap _and_ quiet one, please let us know :) Sorry to bump an ancient thread, but I thought I would report back that I did a single 6581 midibox-sid build, using a 15vdc Triad transformer, a 7812, and a LM2575. I used the LM2575 according to the appnote with a small additional filter. Looking at the output (Both loaded & unloaded) on my scope, I don't see any indications of noisy power. Also, the final result sounds great. No strange or unpleasant noises, just a rock solid midibox SID. I entered into this idea because I really was hoping to make a small midibox sid that could be powered via a single cheap walwart supply. Attached is the schematic. Please be aware that the LM2575 is only capable of 1amp of output. Also, although switching supplies are far more efficient than linear regulators, they don't work magic. You may need to heatsink, depending on load. I hope that someone gets some use out of this, I really appreciate all of the great help I've received from other people on the forums, and of course I REALLY appreciate all of the great work that has been put into making this project so great. Thanks! Quote Link to comment Share on other sites More sharing options...
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