Hello.
Yesss 😛 looking good so far now... but still Penny Dreadful through 😱
I can adjust to zero DC approx. and it stay's very near that point. Actually the picture was taking, during trimming and the final result is preamp pendling around 0.00 --> 0.50 mV
So Salas, when i plug in the opamp, can i still adjust DC offset? or do i have to make final adjustment before plugging that in?
Anyway, i think it works! But ofcause i havent tried to actually hook it up with poweramp/speakers yet. -And without opamp yet also.
Jesper.
Yesss 😛 looking good so far now... but still Penny Dreadful through 😱
I can adjust to zero DC approx. and it stay's very near that point. Actually the picture was taking, during trimming and the final result is preamp pendling around 0.00 --> 0.50 mV
So Salas, when i plug in the opamp, can i still adjust DC offset? or do i have to make final adjustment before plugging that in?
Anyway, i think it works! But ofcause i havent tried to actually hook it up with poweramp/speakers yet. -And without opamp yet also.
Jesper.
Attachments
After you will insert the op-amp can't adjust anymore. It takes over. I know it can do very well on its own in offset test but don't be tempted not to use an op-amp because nothing will be there to auto-guard it from drifts. Especially when having a DC coupled power amp.
What are those nice hats you put over the Leds not to shine a big distraction (especially nice for when test/trimming the board)
Interesting. Give us part number if you can find so we see if they fit in our smaller board. Also, why you shorted the HP outputs in the first photo? Or you have some inputs/outputs swapped sitting places on your board vs my board? Or just leads going to meters looking like looped.
LED's :
http://www.mouser.dk/Search/ProductDetail.aspx?R=MV5064MP4Bvirtualkey63810000virtualkey638-MV5064.MP4B
On first picture, i meassure on line out (L+R).
From left to right on my pcb connection goes like this :
L_in L_out L_headphone_out R_headphone_out R_out R_in
Jesper.
Look's like rock-stable (allthrough it was pretty without)
I will hook it up to my amp. soon 😀
Jesper.
It's ALIVE
Yes i swapped Headphone out / Line out; i think it was easier for me to do the layout this way.
Here is what i tested so far :
I have it hooked up for ~30min. with opamp inserted. DC-offset is solid, pendling very near 0.00vdc now. Bias is equal left/righ meassuring on R10 (10ohm) around 1.011vdc (101mA)... I dident check the stability of that through (did not think of that). I just took some meassurements, while it was cooking warm.
I also tried to adjust left channel dc-offset a little, after inserting the opamp. I see as you told me, it has no affect anymore.
When i have tried listning to it, everything ofcause have to be adjusted and set once more in a longer run. Also i will bolt the alubars onto a somewhat thick alu plate...
Unfortunately i have only a 10k potmeter, and an Ipad as source... But HEY
it plays music now
Jesper.
Yes i swapped Headphone out / Line out; i think it was easier for me to do the layout this way.
Here is what i tested so far :
I have it hooked up for ~30min. with opamp inserted. DC-offset is solid, pendling very near 0.00vdc now. Bias is equal left/righ meassuring on R10 (10ohm) around 1.011vdc (101mA)... I dident check the stability of that through (did not think of that). I just took some meassurements, while it was cooking warm.
I also tried to adjust left channel dc-offset a little, after inserting the opamp. I see as you told me, it has no affect anymore.
When i have tried listning to it, everything ofcause have to be adjusted and set once more in a longer run. Also i will bolt the alubars onto a somewhat thick alu plate...
Unfortunately i have only a 10k potmeter, and an Ipad as source... But HEY
it plays music now Jesper.
Attachments
Congrats. All went well. No hum buzz hiss I would also suppose. It will take one hour+ for the electrolytics to come up well for audition in their first run. What rest Hi-Fi set up you have right now?
I have a RaspberryPi, with an USB Dac (Also partly-DIY), but it is build in my preamp, not giving me possiblilty to take that signal right now, without taking it apart.
I am waiting for a new dac to arrive, for another Raspberry Pi! Hopefully it will be here next week..
I will let it warm up, and take a good listning anyway ofcause.
Thanks for youre interest Salas btw. 😛
Speakers are Audiovector, 15+ years old, but very nice Danish speakers, designed by Ole Klifoth.
Poweramp is a to high gained (giving a little hum) LM4780 poweramp (My Pass B1 unitygain buffer also make the poweramp hum). So hum is not youre preamp Salas.
Jesper.
Not having your Aleph-J or F5 anymore? Those would be nice to combine too. With 10K pot this pre could be as fast as with 2MHZ bandwidth BTW. Looks stable, but try with a 20K pot also when able. For slowing down a bit so less sensitive to RFI maybe.
Yes and No... I have an AlephJ and an F5, but it's taking apart right now.
The torrid i am using for testing you're pre, is actually the torrid from this Pass amp. 😀
Later this vinther i will assemble my F5 again.
I am pretty happy right now, after i have tested that it actually is working!
Jesper.
The big toroid is cool I am sure but I hope the little sinks in your single DCSTB will stay tolerable hot too. Having plans for double mono?
Yes... double mono it will be... The first DCSTB i did, is also called LEFT DCSTB 😛
I also have to make an input selector for it.
The DCSTB get warm, but not more than 50C. or soo.
Jesper.