Sorry for my wrong assumption.
Nice to hear that, so we are at least two.🙂
You'll unlike my PCB. It was 1st version "low-noise" ZERO. (Noises on 50 and 100 Hz were not bigger, than -110 db).
Attachments
Yes this we can call a heatsink!
I see you mounted BC550/560 face to face which will give a good thermal coupling and therefore low offset drift. I did the same on my just finished pcb and it realy helps.
I see you mounted BC550/560 face to face which will give a good thermal coupling and therefore low offset drift. I did the same on my just finished pcb and it realy helps.
I did it also, and I fixed together the transistors with a small rubber band (o-ring).I using termal compound Arctic MX-2.
Yes, but I already had some beers (it´s friday night). I should do the test again tomorrow with a clear head.
Yes, but I already had some beers (it´s friday night). I should do the test again tomorrow with a clear head.
Oh, you write to me from yesterday.😀😀😀😀 Saturday.
😀😀😀Boy oh boy, I should consult a watch. It´s two o´clock in the morning, so it´s saturday.Oh, you write to me from yesterday.😀😀😀😀 Saturday.
O.k., a last one and then to bed.😀
We are realy going off topic now, to prevent a warningRendering in process...😀 Sleep and dreams - not available.😀😀😀😀
we should stop that way of conversation. So, the last beer for me and then realy to bed (I would swear)😉
We are realy going off topic now, to prevent a warning
And I start watch good old John Carpenter's film: Antarctica, Winter 1982.
🙂
We are realy going off topic now, to prevent a warning
yep.🙄
I did the test now (with clear head). The sound seemed to me a little more open and spatial, but I´m not sure at all. Honestly, I would lie if I said that I can hear any significant difference.
Anyway, I think it can´t be wrong to lower THD and output impedance as well.
Blackdod, try the test for yourself. It´s easy and quick done, solder 10R parallel to each emitter resistor just on the top layer (0.25W for testing purposes is o.k) , check the offset voltage before pluging in the headphones!
Keep in mind the temperature, let the enclosure open and switch off every 15-20mins to cool down the amp a few minutes.
I did the test on my 7 years old BCL and nothing happened to it.
Of course for long-term usage we have to find a solution regarding heatsinks.
Let me know if you did the test.
Anyway, I think it can´t be wrong to lower THD and output impedance as well.
Blackdod, try the test for yourself. It´s easy and quick done, solder 10R parallel to each emitter resistor just on the top layer (0.25W for testing purposes is o.k) , check the offset voltage before pluging in the headphones!
Keep in mind the temperature, let the enclosure open and switch off every 15-20mins to cool down the amp a few minutes.
I did the test on my 7 years old BCL and nothing happened to it.
Of course for long-term usage we have to find a solution regarding heatsinks.
Let me know if you did the test.
OK, I just check the amp with the new BIAS. I have around 80 mA and the offset is stable (7mVolt). After 15 minutes temperature is 75~80º while I use my Sennheiser HD600 (300 Ohm) if you turn up the volume, temperature increases and can exceed 80 ° (without cover)
With Dt990 (600 Ohm) you need turn up the volume more... and the temperature slashing 90 ° at 5 minutes so I turned off immediately the amp.
DB139/140 has a max operation temperature of 150º but the PCB and the other components (regulation caps, Fet, resistors) are experiencing very high temperatures (60~65º)
I don´t feel at ease knowing this.
Really, I've only heard a slight improvement with high impedance headphones. A little more dynamic and better control of the bass with less volumen but this is something very relative because I've only heard five minutes
The original pcb not serve for this mod. You need a big heatsink like the Damon 🙁🙁
With Dt990 (600 Ohm) you need turn up the volume more... and the temperature slashing 90 ° at 5 minutes so I turned off immediately the amp.
DB139/140 has a max operation temperature of 150º but the PCB and the other components (regulation caps, Fet, resistors) are experiencing very high temperatures (60~65º)
I don´t feel at ease knowing this.
Really, I've only heard a slight improvement with high impedance headphones. A little more dynamic and better control of the bass with less volumen but this is something very relative because I've only heard five minutes
The original pcb not serve for this mod. You need a big heatsink like the Damon 🙁🙁
I understand you, if you don´t feel comfortable with this high temperatures you shouldn´t continue.
Like said, I listened about 15 mins. then 5 mins power off and so on.
But I didn´t worry too much because the unit is 7 years old and my new redesigned build is practically finished.
The new PCB was finished last weekend, before the discussion about BIAS started.
So I didn´t plan it for higher BIAS🙁, well the heatsinks are larger than the originals but probably not large enough for 80mA long-term usage😡. If I only had known before I did the layout........ but now too late!
Like said, I listened about 15 mins. then 5 mins power off and so on.
But I didn´t worry too much because the unit is 7 years old and my new redesigned build is practically finished.
The new PCB was finished last weekend, before the discussion about BIAS started.
So I didn´t plan it for higher BIAS🙁, well the heatsinks are larger than the originals but probably not large enough for 80mA long-term usage😡. If I only had known before I did the layout........ but now too late!
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I understand you, if you don´t feel comfortable with this high temperatures you shouldn´t continue.
Like said, I listened about 15 mins. then 5 mins power off and so on.
But I didn´t worry too much because the unit is 7 years old and my new redesigned build is practically finished.
The new PCB was finished last weekend, before the discussion about BIAS started.
So I didn´t plan it for higher BIAS🙁, well the heatsinks are larger than the originals but probably not large enough for 80mA long-term usage😡. If I only had known before I did the layout........ but now too late!
I think, that 100-140 mA BIAS will be enough.🙂