snowparang 0 Report post Posted August 2, 2003 Good luck on that then... Computer PSU's are all switching units and are very noisy. what's the effect of noisy power supply on the sound? I get humming? Just felt that pc psu is more efficient and cheaper than buying and connecting my own core. I also used it to power my car amp.... Share this post Link to post Share on other sites
Northern Oak 0 Report post Posted August 2, 2003 Humming could more likely be due to improper grounding, eg the potentiometer's metal casing, if left floating and not grounded properly may produce an audible hum. Having a clean power supply could give you more depth, better darkness. The results may be varying for everyone. In my case, I have 2 powerpoints in my room, one to my home rig, the other to my PC. Both power points lay parallel in the same electrical circuit. When I turned on the PC and listen to music at the same time, the darkness and depth were lost significantly. When the monitor is turned off, some level of darkness and depth returned and when the entire PC is off, I will be able to hear the usual darkness and depth. The mechanical hum of the PC's power supply fan is out of question here cos' I placed a table-top fan in between the PC and the home rig and it produces a louder mechanical hum than the PC. Yet, I was able to hear the differences. Me and my crazy talk again! Share this post Link to post Share on other sites
jtfoo 0 Report post Posted August 2, 2003 I tried experimenting using the PC supply for a cheapo desktop multimedia speakers, the the noise (not hum) is unbearable.. Switch to external supply, and the problem is gone. YMMV. Share this post Link to post Share on other sites
N@Z 0 Report post Posted August 2, 2003 Please keep the discussion concerning the CMOY amp. Share this post Link to post Share on other sites
Wortel 0 Report post Posted August 2, 2003 We were discussing what power supply to use with CMOY. Share this post Link to post Share on other sites
N@Z 0 Report post Posted August 2, 2003 I was not commenting about you Wortel but the discussions above about computer PSU & PC supply. Share this post Link to post Share on other sites
Firefox 0 Report post Posted August 2, 2003 My new psu is quite quiet. dual fan unit. I don't want to make a PSU powered amp though. Maybe later on. When I said noisy, I meant electrically noisy. As in noise + ripple. You could get a hum using the amp off the PSU. Share this post Link to post Share on other sites
Wortel 0 Report post Posted August 2, 2003 Im not gonna risk it. Also I'd want to use the amp for other things besides my computer. Like when I get a CDP. Share this post Link to post Share on other sites
Northern Oak 0 Report post Posted August 2, 2003 N@Z, point taken Wortel: The metal chassis of your potentiometer has to be grounded properly. For me, I used the signal ground to ground the metal chassis of the potentiometer. This way, you will not get the humming. Share this post Link to post Share on other sites
Wortel 0 Report post Posted August 2, 2003 Ok Nothern Oak Share this post Link to post Share on other sites
jarthel 0 Report post Posted August 2, 2003 Good luck on that then... Computer PSU's are all switching units and are very noisy. what's the effect of noisy power supply on the sound? I get humming? Just felt that pc psu is more efficient and cheaper than buying and connecting my own core. I also used it to power my car amp.... I think you're forgetting that the current powering up the amp is coming from a power supply. A noisy power supply has a big effect on the sound. Share this post Link to post Share on other sites
Wortel 0 Report post Posted August 2, 2003 I dont think anybody has ever used a computer PSU to power an amp. Proberbly just a crazy as using a PC soundcard. Share this post Link to post Share on other sites
Wortel 0 Report post Posted August 4, 2003 I showd my Dad some of the amp designs I got from headwize. He said the CMOY was too simple and would be crap and the Gilmore was over the top. So my dad is gonna help me build an amp that's a CMOY with extra stuff for filtering. I can't really explain much more than that. I gotta have a chat with him about it. Headwize roX - must have net access. Share this post Link to post Share on other sites
Firefox 0 Report post Posted August 4, 2003 I showd my Dad some of the amp designs I got from headwize. He said the CMOY was too simple and would be crap and the Gilmore was over the top. So my dad is gonna help me build an amp that's a CMOY with extra stuff for filtering. I can't really explain much more than that. I gotta have a chat with him about it. Headwize roX - must have net access. Your dad an audiophile? Share this post Link to post Share on other sites
huangyong 0 Report post Posted August 6, 2003 Hey worthel, want to build a Cmoy for AKG K501?? I have a combo of the 2. Cmoy is the basic design of an opamp circuit, so dont expact too much from it.AKG K501 require a lot of power to drive it, it demand grater power than my HD600. however it's quite a nice amp for portable use .i would suggest you build a Gilmore instead. Let me share my experience building my first DIY amp = Cmoy The original circuit is nice and simple. I build one with cheap components but it's not good at all, especially with external power supply. So i mod it again and again. I add a filter to the power in, to reduce the noise, and it does its job quite well. and for the input cap, 0.1uF is too small in the DC filter, changing to 5uF would be better. Think of this, 0.1uF, the cut off frequency is 15Hz, which is quite high. When change it to 5uF, the cutt off- freq drop to 1.5Hz. The gain of typical Cmoy is 10, which is too high for me. considering the output of cdp is already quite high, the gain of 10 will blow your ear away. it sounds loud, but no depth, and aslo lack of something(.... ) At the output, i suggest you put a 120ohm resistor there for AKG K501 for maximum power transfer.( basically the sound remains the same). Anyway, why dont you try out Grado RA-1 replica, the gain is low, but the sound quite nice. i am going to try out new opamp ( op627/637) soon. Share this post Link to post Share on other sites
