I have been reading this thread you suggested and it's quite interesting.
Thanks.
Eventually, I decided to go with the double trimpots method.
I also got a couple of XICON styroflex for trying in the 100pF caps position.
Could not find any BC560 on Mouser. They are obsolete..
However, I found a few old BC559/549 silver back transistors made by Philips in my stash.
Hopefully they are suitable for the job.
But how is the proper matching procedure for a lower DC offset?
Should I need to match hFE on each pair of 559/549, or to match the two 559s and the two 549s?
I'm waiting for the parts to arrive.
I'll post after I do the work.
Thanks.
Eventually, I decided to go with the double trimpots method.
I also got a couple of XICON styroflex for trying in the 100pF caps position.
Could not find any BC560 on Mouser. They are obsolete..
However, I found a few old BC559/549 silver back transistors made by Philips in my stash.
Hopefully they are suitable for the job.
But how is the proper matching procedure for a lower DC offset?
Should I need to match hFE on each pair of 559/549, or to match the two 559s and the two 549s?
I'm waiting for the parts to arrive.
I'll post after I do the work.
Reconsidering BCL
Hiya,
I've built my version recently because found my PCB bought long time ago.
I used CCS instead of 1.5k ohms in the diamond buffers created "Walt Jung buffers", and changed to global feedback with 150p local feedback cap around the OPA and ferrit beads on the output, outside the global FB loop.
LC filters are applied on supply rails.
Zener mod (remove 1.1k!) and biasing OPA into class-A are also have to be mentioned.
To avoid transformer buzz, DC-Blocker and 12V drop is applied in the primer circuit.
Sound: a completely new category than the original: open and virtually distortion free to human hearing (not just for measurement gears).
To achieve this, sort the input caps or use NP0, and a good OPA!
Hiya,
I've built my version recently because found my PCB bought long time ago.
I used CCS instead of 1.5k ohms in the diamond buffers created "Walt Jung buffers", and changed to global feedback with 150p local feedback cap around the OPA and ferrit beads on the output, outside the global FB loop.
LC filters are applied on supply rails.
Zener mod (remove 1.1k!) and biasing OPA into class-A are also have to be mentioned.
To avoid transformer buzz, DC-Blocker and 12V drop is applied in the primer circuit.
Sound: a completely new category than the original: open and virtually distortion free to human hearing (not just for measurement gears).
To achieve this, sort the input caps or use NP0, and a good OPA!Attachments
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help me please
Hi, I've searching for a while in the forum as I've the orange pcb. To find the parts is a horrible time consuming experience. Do you have a list or something will all the parts you bought? Its my first electronic build and its being harder than i thought as there are million of resistors in mouser to choose from.
I gathered all the pics, pdfs and part lists i found here in this tread so if you used them i already have them. Thanks and congratulations for such an awesome proyects
Hi, I've searching for a while in the forum as I've the orange pcb. To find the parts is a horrible time consuming experience. Do you have a list or something will all the parts you bought? Its my first electronic build and its being harder than i thought as there are million of resistors in mouser to choose from.
I gathered all the pics, pdfs and part lists i found here in this tread so if you used them i already have them. Thanks and congratulations for such an awesome proyects
I can't see clearly at your photo how much space you have left, but it seems you need to replace those larger capacitors to make some space. I used MKT1813 0.33uF axial capacitors by Vishay there.
But i completely removed those input caps since I feed signal from AC coupled devices.
I now have just a wire link there.
For the two 0.022uF caps in front of the opamp, you can install 2 x 0.01uF polysterene capacitor (Xicon 23PS310) in each side.
One on top of each other.
Their width is 10mm, so typically they would fit in between the capacitors, albeit a bit tightly.
Measure the space among the capacitors to make sure they are 20mm or wider.
But i completely removed those input caps since I feed signal from AC coupled devices.
I now have just a wire link there.
For the two 0.022uF caps in front of the opamp, you can install 2 x 0.01uF polysterene capacitor (Xicon 23PS310) in each side.
One on top of each other.
Their width is 10mm, so typically they would fit in between the capacitors, albeit a bit tightly.
Measure the space among the capacitors to make sure they are 20mm or wider.
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