I think we cant fix problem with this design, did somebody check the spain forum to solve the problem. ?
actually my Quasi NMOS is back and Im enjoy the sound
Nikola!
Why do you want differrent solution if it works?
I don't know. I already told what should be done. Search for the noise source.
Everybody have to know his own system. In mine there is dead silence. But I've seen many noisy systems with at least 5 different noise sources (and different penetration mechanism), therefore at least 5 different solutions.
I can't investigate your problems without cooperation. For example I had a question, but nobody answered:
"How loud is the noise when you set it to zero volume, and what if you set it to maximum?"
Why do you want differrent solution if it works?
I don't know. I already told what should be done. Search for the noise source.
Everybody have to know his own system. In mine there is dead silence. But I've seen many noisy systems with at least 5 different noise sources (and different penetration mechanism), therefore at least 5 different solutions.
I can't investigate your problems without cooperation. For example I had a question, but nobody answered:
"How loud is the noise when you set it to zero volume, and what if you set it to maximum?"
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What's the problem?
But I don't understand it anyway:
Should I translate it? Change it to 5k!
But I don't understand it anyway:
"my question" and the reply:you asked said:
What kind of noise is this? It disappears immediately as soon as I ask anything about it??? Then comes back when I'm away? This is an extremely intelligent noise! A new life form has been discovered!
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I said that about 100 messages ago lol
No one listens to me.
I had a irs2092 with the same problem, just needed a 4k7 pot on input.
We dont understand each other. Right now i dont have volume potenciometar. When on input stage I put 1nF cap from input to GND paralel with 100pF, I have good mids and hights tones but I also have noise. When I make short on input I still have a noise.
With 4.7nF and 100pF I dont have a problem with noice but hights and mid tones are gone and I must to set hights tones on preamplifier on maximum for good tones but music even with that is not good as with 1nF.
Thats my only problem with this amp and i dont have instruments and osciloskope to sersh noise source. That why I ask for help to resolve this problem.
Pafi, sorry for not understanding
With 4.7nF and 100pF I dont have a problem with noice but hights and mid tones are gone and I must to set hights tones on preamplifier on maximum for good tones but music even with that is not good as with 1nF.
Thats my only problem with this amp and i dont have instruments and osciloskope to sersh noise source. That why I ask for help to resolve this problem.
Pafi, sorry for not understanding
Ok, I try 4.7K pot and this is my results:
-With 4.7n no noise and mid/highs tones too, on any position of pot music is the same.
-With 1nF I have noise and good mid.hig tones, but noise is like when I touch with fingers input of amp, something like swishing noise, with very fast pulse tone in speaker. When I set pot on minimum noise is little but its amplify with music how I volume up the pot.
-With 4.7n no noise and mid/highs tones too, on any position of pot music is the same.
-With 1nF I have noise and good mid.hig tones, but noise is like when I touch with fingers input of amp, something like swishing noise, with very fast pulse tone in speaker. When I set pot on minimum noise is little but its amplify with music how I volume up the pot.
Nikola!
You said:
This is a very strange thing:
But if I concentrate only on gone highs, then I must say: you should drive it with maximum 1.2 k source resistance.
You said:
Unfortunately this doesn't seem to be the same problem.
This is a very strange thing:
This is almost unbelievable. Some very important information must be missing, but I can't tell what it is.
But if I concentrate only on gone highs, then I must say: you should drive it with maximum 1.2 k source resistance.
@ Pafi and nigelwright7557
I found out many things, maybe now you can help me:
-4.7K pot was bad,and signal cables too. I change him and when volume is on 0 I dont have a noise
-Testing was with very good and short signal cable and low impedance source
-When I turn on amplifier, I dont have a noise, I don hear nothing long time, but when I play music, after 1 second noise appears, sound of noise is like touching with fingers input of amp
-Same results is with 1nF and 4.7nF, and highs/mids tones are totaly the same on both values of capacitors, without the cap (only 100p) I have big distorsion on highs tones.
-When I volume up the music, on 10W and higher powers I dont hear the noise because music is too loud.
-I have very bad output coil with noname ferite EE core with experimental nuber of turns (I dont know the inductance) but its very hot on very low power (1..3W), swiching freq is 250KHz.
Thats all.
I found out many things, maybe now you can help me:
-4.7K pot was bad,and signal cables too. I change him and when volume is on 0 I dont have a noise
-Testing was with very good and short signal cable and low impedance source
-When I turn on amplifier, I dont have a noise, I don hear nothing long time, but when I play music, after 1 second noise appears, sound of noise is like touching with fingers input of amp
-Same results is with 1nF and 4.7nF, and highs/mids tones are totaly the same on both values of capacitors, without the cap (only 100p) I have big distorsion on highs tones.
-When I volume up the music, on 10W and higher powers I dont hear the noise because music is too loud.
-I have very bad output coil with noname ferite EE core with experimental nuber of turns (I dont know the inductance) but its very hot on very low power (1..3W), swiching freq is 250KHz.
Thats all.
Please state: is there volume potentiometer now or not? General rule: all test results can be understood correctly only if we know the circumstances!
This is a big step ahead! Is this permanent? I mean: after you turned up the volume (with music), and turned down again, does the noise remain, or disappears?
Does the amp continuously work after it started to work?
Do you mean there is 1 second clean music output, and then noise appears, or there is nothing on output for 1 sec, and then the noise and music appears together?
The first case is hard to be explained, but the second one is easy: the amp is always noisy, but it simply doesn't work, doesn't oscillate in the first second.
In all tests you shold make shure the amplifier does work! If you don't have a scope (which is a very unfortunate state), then the supply current can indicate the operation. You must have a multimeter at least!
This is a very important information, and this already told what the source of noise is: power line. We only have to search for the penetration point and mode!
What is the music source? Write (even better if you draw) everything what is connected directly or indirectly to the amplifier! Even if it is switched off! Power supplies too!
And back to a previous test: what if you short input? (1: with all things still connected!, 2: make shure amp is still working!)
Shorting input should be tested on both ends of the input cable!
This is a different error. One thing at once!
-When I volume up the music, on 10W and higher powers I don't hear the noise because music is too loud.
-I have very bad output coil with noname ferite EE core with experimental nuber of turns (I dont know the inductance) but its very hot on very low power (1..3W), swiching freq is 250KHz.
Thats all.
EE ferrites can not be very bad, only if there is not enough air gap. (Or if cores are very small.) Number of turns should be more than 10 (preferably 20), gap should be more than 1-2 mm (depending on max. power), and wire over the gap should be avoided. Half turn also should be avoided!
Why don't you tell the dimensions of your core and the approximate number of turns? More info cant hurt! BTW: supply voltage and load impedance can be also interesting! BTW: is it stereo or single channel? The more info you tell the more hints you can get!
(Maybe you've told these things earlyer, but 1: nobody remembers everything, 2: things can change.)
Bad inductor alone is not likely to cause noise. But a non-working (not oscillating) amplifier surely doesn't produce noise!
To every ClassD builders:
Buy an oscilloscope!
DIY-ing ClassD amp without scope is like climbing to hill with closed eyes! (But climbing to hill with opened eyes can also be hard without experience and map.)
Pafi, thanks for this detailed replay!
- Yes, I have Volume potenciometar, 4.7K lin, its good
- After playing the music, I stop the music, have a noise and set pot on 0 and noise dispaire
- Yes, amp is always nosy, i dont hear anything as long as I play the music then noise appers together with music when amp start to oscilatte, and when I stop the music amp still oscilatting and i have a noise, set pot on 0 and noise disapire.
- I think its immportant to say that after playing the music amp continue to work and oscilatte. Before playing the music, when amp is not osilatte, on output i have 0V DC offset, but after playing the music, I can hear the noise and DC offset is 0.12mV. I think this is the proof that amp continue to work.
- Signal source:
Toshiba lap top--> Numark DM1720SE--> Beringer CX3400 act.crossover--> my amp
When I play directly form PC result is the same.
- When I short the input cable on begin and end, noise disapire.
- Core is EE33 from PC atx swich supply and i dont know nuber of turns, I forgot but I think it has 15-18 turns. Gap is 2mm and its very difficult to wind the wire to avoid the gap. Its very hot
- To understand each other, noise on my amp isnt big and loud. When I come in front of the speaker, very close then I can hear the noise. When I 3 meters away from speaker I dont hear anything, but that annoys me because this amp is good, produse good sound, very powerfull bass and this is the little things that ruins a good amp.
Thank you Pafi, and I draw to you Source and Power Line.
- Yes, I have Volume potenciometar, 4.7K lin, its good
- After playing the music, I stop the music, have a noise and set pot on 0 and noise dispaire
- Yes, amp is always nosy, i dont hear anything as long as I play the music then noise appers together with music when amp start to oscilatte, and when I stop the music amp still oscilatting and i have a noise, set pot on 0 and noise disapire.
- I think its immportant to say that after playing the music amp continue to work and oscilatte. Before playing the music, when amp is not osilatte, on output i have 0V DC offset, but after playing the music, I can hear the noise and DC offset is 0.12mV. I think this is the proof that amp continue to work.
- Signal source:
Toshiba lap top--> Numark DM1720SE--> Beringer CX3400 act.crossover--> my amp
When I play directly form PC result is the same.
- When I short the input cable on begin and end, noise disapire.
- Core is EE33 from PC atx swich supply and i dont know nuber of turns, I forgot but I think it has 15-18 turns. Gap is 2mm and its very difficult to wind the wire to avoid the gap. Its very hot
- To understand each other, noise on my amp isnt big and loud. When I come in front of the speaker, very close then I can hear the noise. When I 3 meters away from speaker I dont hear anything, but that annoys me because this amp is good, produse good sound, very powerfull bass and this is the little things that ruins a good amp.
Thank you Pafi, and I draw to you Source and Power Line.
