Suicide Sushi Posted March 14, 2011 Report Share Posted March 14, 2011 (edited) Hello everyone. So i finished my MB6582 and I really love it. I was in the studio recording with it some time ago and the engineer told me that he thought I could reduce a lot of the background noise by unplugging the fan. I had the synth open due to som SID stuffing, and I tested it out. The engineer was right. The background noise (sounded LFO'ish) completely dissapeared and I could now plug it into a PA without annoying everyone around. I then decided to unpower all the SID's except channel four (2*8580) and then unpluck the fan. I have 7 SID's stuffed into my MB6582 and disconnected 5 of them by unplugging the power jumper (i never really used all the SID's at once). Is that safe? Will I damage anything by using my MB682 with all my SID's in it but with 5 of them disconnected from 12v (6581's) via power jumpers? Thank's! Suicide Sushi Love the MIDIBOX! EDIT: Can anyone point me in the right direction to the feedback potentiometer info? I need to know what kind of pot (linear v logarithmic and resistance) i need? Thank's! Edited March 14, 2011 by Suicide Sushi Quote Link to comment Share on other sites More sharing options...
m00dawg Posted March 14, 2011 Report Share Posted March 14, 2011 I don't think you'll hurt anything, but you are still supplying 5V to the SIDs even by disconnecting the jumper. So if you want to be certain, I would remove them. To avoid damaging the pins of your SIDs, consider plugging them into a socket and plugging that socket into the MB6582. That way you can remove the secondary socket (with SID) and only risk bending the pins on the second socket. The fan noise may be unavoidable but you may be able to reduce it by making sure you are powering the fan using a separate supply from the SIDs and COREs. In some of the PSU designs, you can tap off the power input (before the regulators) for the fan. As far as the pots go, I believe logarithmic is what you want since you are dealing with audio, although I haven't tried using feedback pots myself so you might want a second opinion there. Quote Link to comment Share on other sites More sharing options...
rosch Posted March 14, 2011 Report Share Posted March 14, 2011 here's the info on the pots: Quote Link to comment Share on other sites More sharing options...
Suicide Sushi Posted March 14, 2011 Author Report Share Posted March 14, 2011 here's the info on the pots: Sweet. Thank's guys! Quote Link to comment Share on other sites More sharing options...
Janis1279 Posted March 14, 2011 Report Share Posted March 14, 2011 Hi, Hawkeye answered me too : " 100kohm work fine, 500kohm will also work... the value just specifies the max feedback "dampening" which is at maximum for 100kohms already." Regards, Janis Quote Link to comment Share on other sites More sharing options...
Wilba Posted March 14, 2011 Report Share Posted March 14, 2011 Some fans are noisier (on the audio) than others. From experience, fans with LEDs are often noiser. Powering from J25 is best because it's before the regulators of SID audio voltage (i.e. the 12V or 9V supply to SIDs). Also, dropping the voltage to the fan somehow will keep its RPM low and the fan noise down too, but I don't have advice on that... I suppose sticking an 7805 between J25 and the fan would work... it doesn't need smoothing caps IMHO. As for not powering SIDs... I can only guess that it's OK to leave out the 12V/9V supply to SIDs, since this is only powering the filter/amp inside the SID... let's say, I'd do it for my 6582A SIDs without worrying but for 6581 SIDs which spontaneously die on me even when packed in an antistatic tube, I would avoid even looking at them the wrong way, let alone rob them of power. :rolleyes: Quote Link to comment Share on other sites More sharing options...
Suicide Sushi Posted March 15, 2011 Author Report Share Posted March 15, 2011 Some fans are noisier (on the audio) than others. From experience, fans with LEDs are often noiser. Powering from J25 is best because it's before the regulators of SID audio voltage (i.e. the 12V or 9V supply to SIDs). Also, dropping the voltage to the fan somehow will keep its RPM low and the fan noise down too, but I don't have advice on that... I suppose sticking an 7805 between J25 and the fan would work... it doesn't need smoothing caps IMHO. As for not powering SIDs... I can only guess that it's OK to leave out the 12V/9V supply to SIDs, since this is only powering the filter/amp inside the SID... let's say, I'd do it for my 6582A SIDs without worrying but for 6581 SIDs which spontaneously die on me even when packed in an antistatic tube, I would avoid even looking at them the wrong way, let alone rob them of power. :rolleyes: uh... okay. So the SID's would still generate a lot of heat even without the 12v/9v? I think I'll remove the SIDs and then apply some heatsink to the remaining 2 SIDS. By the way I just had my first jam with the MB6582 drum machine - and it is completely awesome! I love it so much... Quote Link to comment Share on other sites More sharing options...
Wilba Posted March 15, 2011 Report Share Posted March 15, 2011 I think the heat comes from both the 5V and the 9V/12V supply. They suck max. 100mA on the 5V, 40mA on the 9V/12V. So... P=IV... 0.5W + 0.36W (if 9V), or 0.5W + 0.48W (if 12V). I'm guessing... I don't really know the physics of this stuff :rolleyes: but that power has to go somewhere, doesn't it? So I guess it goes out as heat. Quote Link to comment Share on other sites More sharing options...
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