NorthernLightX Posted April 15, 2006 Report Share Posted April 15, 2006 Yes, the SSM2044 should do the same, a sound comparison could be interesting.It is for the CEM filters, and as the negative voltage is available, I'm also using it for the AOUT_LC module. The CV inputs (of the *external* CEM3378 circuitry -> see datasheet) are working in a range of ca. 1V-7V (CutOff) and 0V-3V (Resonance). In addition to the gain/offset trimmpots of the AOUT_LC module, I'm using 10k trimmpots against ground at the filter CV input side - all 4 AOUT_LC modules deliver the same voltages when the CVs are swept from min to max, and with the additional 10k pots I'm able to fine-adjust the desired maximum resonance and I equalize the CutOff frequencies of all filters on an easier way, than with the non-linear gain/offset potsBest Regards, Thorsten.Hi Thorsten,Please excuse my ignorance, but I thought the AOUT(_LC) and the CEM filter both used 12v and -12v, The datasheet I have on the CEM3378 isn't too clear on this (the pinout says -5v on pin 9, but it isn't explained why the -5v is needed, it just says the operating voltage is between +4,75v and +12,5v.I ask this because of the PSU I am designing, I never tought of a -5v rail to be necessary, but now this seems useful for the CEM filter option. Will -12v be sufficient, or will an additional 78L12 (or equivalent) be necessary if one would want to connect a CEM3378 filter to a -12v supply?Cheers, Alex. Quote Link to comment Share on other sites More sharing options...
TK. Posted April 15, 2006 Report Share Posted April 15, 2006 Hi Alex,the CEM3378 datasheet says, that +12V/-5V is for best performance. +12V/-12V would produce more heat, whereas +5V/-5V doesn't allow to reach the maximum cutoff frequency.For the AOUT_LC module any voltage can be used within the supported range of the TL072, it's very flexible!I ask this because of the PSU I am designing, I never tought of a -5v rail to be necessary, but now this seems useful for the CEM filter option. Will -12v be sufficient, or will an additional 78L12 (or equivalent) be necessary if one would want to connect a CEM3378 filter to a -12v supply?I don't think that you need to take care about such special cases. If somebody needs -5V instead of -12V, he can just replace the 7912 by a 7905, or he has to adapt his circuit...Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted April 16, 2006 Author Report Share Posted April 16, 2006 the CEM3378 datasheet says, that +12V/-5V is for best performance. +12V/-12V would produce more head, whereas +5V/-5V doesn't allow to reach the maximum cutoff frequency.Great! If -12v procudes more headroom, I'd prefer that over -5v, and -12v is already in the current designI don't think that you need to take care about such special cases. If somebody needs -5V instead of -12V, he can just replace the 7912 by a 7905, or he has to adapt his circuit...Indeed, if -5v is really needed one could branch off from the unregulated -12v, and then regulate it with a few caps and a 7905 off-pcb. Luckily, untill now I haven't seen interesting designs to add to midibox, where -5v was a must.Last question: If you already had -12v available, and the CEM accepts that, why did you opt for -5v instead?Cheers, Alex. Quote Link to comment Share on other sites More sharing options...
TK. Posted April 16, 2006 Report Share Posted April 16, 2006 Sorry, this was a writing error - I meant "heat" and not "head". Hope that this makes clear, why -5V/+12V is the better solution!Last question: If you already had -12v available, and the CEM accepts that, why did you opt for -5v instead?I don't have -12V available, only -15V/+15V from the Behringer PSU, and -5V/+5V/+12V from my own regulators...Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted April 16, 2006 Author Report Share Posted April 16, 2006 Thanks TK, I understand now. The -12v being available was a reading error from my side, I thought the behringer PSU did +12v/-12v.I will not add the -5v rail to my PSU design, I believe it would be better to include the -5v power rail on the CEM filter board instead since it is only used there.Do you plan to release your CEM filter as a midibox module? I definitely would want to build one or more!Cheers, Alex. Quote Link to comment Share on other sites More sharing options...
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