tropicalrips 0 Report post Posted February 26, 2004 the pre-amp is before the cmoy the caps are still on "trial" it does make the sound a little funny, can't really say what is it, just different. what type of caps should i use firefox? i think the ones in the pre-amp are tantalum i hav some Elna Cerafines, will these work? Share this post Link to post Share on other sites
Firefox 0 Report post Posted February 26, 2004 I suggest using polypropylene film caps of 0.22uF and above. Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted February 26, 2004 ok thanks, i hav some left over 2.20uF Solen caps, these will work too rite? Share this post Link to post Share on other sites
Rameish 0 Report post Posted February 26, 2004 hmm...if you intend to use it between your source and amp - ie gain stage - you'll have to be a bit careful with the value of the volume pot as well - esp so if you're making one for the home and using it as a switch box + volume control (ie passive preamp). A 50k ohm pot should be okay but do ask firefox or the guys in audio asylum. Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted February 26, 2004 (edited) its ment to be a passive pre, with only the volume pot & maybe a switch for 2 source. as for the caps i'm not exectly sure what they will do it just seem like a big waste of space on the case, so decided to put in the caps the pot is a 10k alps mini, can't find a 50k log pot at this size made some changes again following Firefox's advise, used polypropylene film caps 0.68uF after the pot , before the output, now it sounds more like what the Cmoy is suppose to sound Edited February 26, 2004 by tropicalrips Share this post Link to post Share on other sites
huangyong 0 Report post Posted February 27, 2004 rameish, 50k pot for the that is ok. i've tried it. tropicalrips, what kind of funny sound you heard in your 1st version of pre-amp, can describe?? firefox, what kind of filter issue you refering to??; put a cap after pot?? Share this post Link to post Share on other sites
Rameish 0 Report post Posted February 27, 2004 (edited) hmm...if you intend to use it between your source and amp - ie gain stage - you'll have to be a bit careful with the value of the volume pot as well - esp so if you're making one for the home and using it as a switch box + volume control (ie passive preamp). A 50k ohm pot should be okay but do ask firefox or the guys in audio asylum. HuangYong, Didn't I just say that - about the value of the pot. Actually a 10K pot should be better (check with audio asylum diy forum or firefox). So tropicalrip, Seems like you'r experimenting/building a pre-power amp for headphones! Would it be 1) easier 2) cheaper and 3) better sounding (shorter signal path and less components in the way) if you but the pot into the cmoy and build in dual inputs. Anyways, nice experiment but do keep it simple in there as the cumulative effect of additional connectors, wires, switches etc is gonna affect sound -vely. Esp since the output from a portable isn't 1) as powerful as from a home CDP 2) isn't as good sounding. In other words, you may end up negating the benefits of an amp for portables. Much prefer your other idea to make several different housings for your Grado LOL. Edited February 27, 2004 by Rameish Share this post Link to post Share on other sites
hacknet 0 Report post Posted February 27, 2004 well, although they will lower the series capacitance, it will act as a 1st order high pass filter. this can be seen with the formula Fo = 2*Pi*R*C = 2*3.142*100k(cmoy`s input impedance)*0.11*10^-6(cap in passive VC in series with cmoy`s input cap) = 14.4hz this isn`t too bad, but why make it worst. i say caps buger up the vocals as caps as not phase linear and the worst part being that they are not linear in freqency responce. i`ve found caps in path screwing up vocals, they take away the air and and the dynamics in the music. asif they are sucking the life out of the track. i`d prefer not have any caps in the path of an audio signal.. Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted February 27, 2004 the original idea for this pre-amp was that so i can use the line out of my source when using my earlier Cmoys, which did not hav a volume pot. it would be easier to built an amp with the pot but after looking at the pre-amp, i got another idea of making it into a modular type setup, like a home system since i already hav a few Cmoys which can make use of the pre-amp the Cmoys are actually more "neat" without volume pots , fewer wires, i think it should be better sounding (in theory at least) without the pre-amp being an external module. i don't intend to use this pre-amp as part of my portable setup, just too many "things" to carry around huangyong: the previous version sounded "lifeless" i think those were tantalum caps, they had very high values, i can't remember what i bought i think they were 330uF 16v, i was going to use them as power bypass caps, thought i try them in the pre-amp first guys, this is suppose to be a "fun" project so don't take it too seriously, i'll try any ideas u can come up with i'll put aside all the theories and just trust my ears Share this post Link to post Share on other sites
