What is the source that is used to drive your headphone amp?
Can you identify the source of hum and hiss?
If they come from the source, you can add a 10K VR to the input of your headphone amp.
By adding a 50 ohm wire-wound VR between the amp and your headphone, you can decrease the output level as well as the noise. But this may somehow affect the output quality.
Can you identify the source of hum and hiss?
If they come from the source, you can add a 10K VR to the input of your headphone amp.
By adding a 50 ohm wire-wound VR between the amp and your headphone, you can decrease the output level as well as the noise. But this may somehow affect the output quality.
The noise is present even without any source connected.
Ok, I will try playing around output a resistor.
Ok, I will try playing around output a resistor.
Even with a 45R resistor at the output, and the noise is still present, somewhat lower but still there.
I tried using just on channel with the following power supply 10.000uf R5.6 10.000uf R5.6 3.300uf, no hum at all but the hiss is still present.
I also tried replacing C3 with a better quality one, Q3 with a 2SC2240 , replacing R16 and R17 with resistors, no difference to the noise what so ever.
So I guess I have hit the noisefloor of this circuit.
Next step build a LU1014D cascode J-fet follower as shown by EUVL, just with lower rails.
Yes yes steenoe, you told me so 😉
I tried using just on channel with the following power supply 10.000uf R5.6 10.000uf R5.6 3.300uf, no hum at all but the hiss is still present.
I also tried replacing C3 with a better quality one, Q3 with a 2SC2240 , replacing R16 and R17 with resistors, no difference to the noise what so ever.
So I guess I have hit the noisefloor of this circuit.
Next step build a LU1014D cascode J-fet follower as shown by EUVL, just with lower rails.
Yes yes steenoe, you told me so 😉
I've just taken these two screenshots from my Agilent analyzer.
The first is the narrow-band noise of Giuseppe's headphone amplifier, build with Zang (Digi01) printed circuit boards.
The load is a 33Ohms resistor, the input is shorted with 1KOhms resistor.
The PSU noise floor is even lower than my layout.
The 100Hz component power is less than 165 sq.uVrms (uV = microVolts!) .
The second s.s. is the wide-band noise floor, above 1KHz you are below -110dBV2rms (about 3 sq.uVrms!!!).
Sorry (...), no hiss neither in my nor in other DIYers layout.
If you have this you have to check your amplifier.
Merry Christmas to everybody!
Marcello
The first is the narrow-band noise of Giuseppe's headphone amplifier, build with Zang (Digi01) printed circuit boards.
The load is a 33Ohms resistor, the input is shorted with 1KOhms resistor.
The PSU noise floor is even lower than my layout.
The 100Hz component power is less than 165 sq.uVrms (uV = microVolts!) .
The second s.s. is the wide-band noise floor, above 1KHz you are below -110dBV2rms (about 3 sq.uVrms!!!).
Sorry (...), no hiss neither in my nor in other DIYers layout.
If you have this you have to check your amplifier.
Merry Christmas to everybody!
Marcello
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I tried switching C2 and C4/C5, increased R5 and R6 to 440 ohm, and changed R15 to 45 ohm. No difference what so ever.
The amp plays nice with my grados, without any hiss, but with my shures with are much more sensitive you can hear the hiss, not alot but enough to get annoyed.
It is properly just my P2P mess the creates the hiss.
The amp plays nice with my grados, without any hiss, but with my shures with are much more sensitive you can hear the hiss, not alot but enough to get annoyed.
It is properly just my P2P mess the creates the hiss.
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