I can't view it either, good evening Juan.
hey !, hello sir "buenas tardes" = good evening bro
,man, I want to see it, I was really exited Regards
Juan
PSU question
Juan, are your secondary leds on the PSU always lit?
Mine are and I just realized that on the simulation those would light up just when the PSU is sagging or near it's limit ?!
I'm getting (consider though it's spaghetti wires all over) some HF hiss (about 0.6mv AC) that is purely related to the PSU (when powering off music stays for a while but the hiss is immediately gone)
I've managed to decrease it a bit by using a ground lift a la Rod Elliot and using that point as "star" ground, but it's still there...
Juan, are your secondary leds on the PSU always lit?
Mine are and I just realized that on the simulation those would light up just when the PSU is sagging or near it's limit ?!
I'm getting (consider though it's spaghetti wires all over) some HF hiss (about 0.6mv AC) that is purely related to the PSU (when powering off music stays for a while but the hiss is immediately gone)
I've managed to decrease it a bit by using a ground lift a la Rod Elliot and using that point as "star" ground, but it's still there...
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Yes they do, the LED will stay on indicating power there, the hissing noise is because maybe input GND is not well attached it can be that, or, the device you are using is causing that I use my Dx Super A with my PC and I notice that there was a noise that was driving me crazy so after a changing RCA and soldering and making many way to fix the problem I found that the audio card of my PC was not good enough and it was injecting noise to the amp then I try it with and iPod and the noise goes away that was my case probably your is different
let me know if after you use different sources of audio devices you still got the hiss noise Regards
Juan
well, I'm pretty sure this hiss is only the PSU because I've isolated the problem, ie, remove the input... the hiss corresponds to 0.6mV of AC (this old Onkyo speakers are pretty sensitive), also with just a ~90dB fostex speaker connected the hiss is audible too, notice that I'm not talking about 50Hz LF interference nor audio card noise, It's just the PSU/AMP noise floor, I will maybe try another RC Filter after the PSU to test it...
that's my finding too, the only transistors I didn't match were the triplets TIP35/36C's that I've used on this PSU, so maybe the noise coming from there?
I have several other PSU boards (brazilian PSU layout) to test and also some MJL3281/1302 that can replace those TIPs, pretty sure the other parts are on spec...
I have several other PSU boards (brazilian PSU layout) to test and also some MJL3281/1302 that can replace those TIPs, pretty sure the other parts are on spec...
2 amp boards (separately) give almost the same reading ~0.6mvac on the output and the noise is coincident with the voltage going up on the PSU in that it "installs" in just after reaching my desired Vout (~41Vdc)... this proves nothing I know, but without a scope my best try would be for instance to use another amp with this supply or use a different supply with this amp (altough it need to be regulated as my trafo is 35-0-35) and that gives way to much voltage using a simple linear PSU...
Can I use a simple voltage divider on a linear supply just to test it?
Can I use a simple voltage divider on a linear supply just to test it?
I have my Power (cord) earth connected to a Safety Loop Breaker Circuit as in Rod Elliot site, and all my audio GNDs after the PSU to the 0 volt line (star GND). This is only to minimize loop currents and here it's 230V 50Hz, I do NOT however have any 50Hz hum from the speaker or the toroidal. It's just hissing...
you need to find out where the predominant noise is coming from before you can apply a solution.
use a cheap RCA plug with a shorting link across Hot to Return.
Plug this in to simulate a Source with zero Rs and zero noise.
This is the standard test before you attach a speaker. Measure output offset. Measure output noise and hum.
You can also do this at the far end of an interconnect. This way you can measure if the interconnect is adding noise to the system. Might be important if you run cables around the house.
You can also build some dummy test loading plugs. 100r and 10k would be instructive to hear, or measure, what difference there is compared to zero ohm.
Plug this in to simulate a Source with zero Rs and zero noise.
This is the standard test before you attach a speaker. Measure output offset. Measure output noise and hum.
You can also do this at the far end of an interconnect. This way you can measure if the interconnect is adding noise to the system. Might be important if you run cables around the house.
You can also build some dummy test loading plugs. 100r and 10k would be instructive to hear, or measure, what difference there is compared to zero ohm.
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Input Shorted
no Load
Outputs: 0.07mVac / ~8mVdc
Load - nominal 8ohm speaker
Outputs: 0.08mVac / ~5mVdc
Hiss still there, in fact I cannot distinguish between 0.08 now to 0.6mvac (no input and with speaker connected).
Funny that now with the input shorted, I do hear a 50Hz hum, but that could be the wires all over, so what now? Am I hearing too much gain? some kind of HF instability, PSU?
Where do I start?
PS hum is from the toroidal not the speaker
no Load
Outputs: 0.07mVac / ~8mVdc
Load - nominal 8ohm speaker
Outputs: 0.08mVac / ~5mVdc
Hiss still there, in fact I cannot distinguish between 0.08 now to 0.6mvac (no input and with speaker connected).
Funny that now with the input shorted, I do hear a 50Hz hum, but that could be the wires all over, so what now? Am I hearing too much gain? some kind of HF instability, PSU?
Where do I start?
PS hum is from the toroidal not the speaker
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