Just another data point - I had one prolific diy builder colleague who informed me that as good as the Jupiters sound, they are also prone to picking up stray hum. He was chasing this in one of his amplifier builds and when he switched to Miflex, the hum disappeared. Take it for FWIW! I have used Jupiter film caps but it has been mostly in fully isolated crossover networks…I did use it in one large phono preamp build without any issues thermally or electrically (the transformer section was also fully isolated).
Best,
Anand.
Best,
Anand.
I believe the lack of hum or hiss is partially due to the grounding scheme as well as the tremendous PS filter design to eliminate the last vestiges of AC hum. This becomes very important in headphone systems since the transducers are literally across your ears! In the last 1-2 pages of the build document the 60Hz component shown on the FFT is fairly low.
Best,
Anand.
Best,
Anand.
Thank you Sir Anand. How about rinsing the pcb after soldering? Do you think that is an important step?
Hey @MarisO.. I didn't see a post where you might have fixed your amp yet... I did look at the pics you posted and I noted two items that might help you out with the issue.... the first item 1) looks like you may have the output transformers wired differently than the build manual... look at the manual at page 89 and notice the wires at pins 13 and 18... then look at page 97 and note that the Red wire goes to the + terminal and the Black wire goes to the - terminal... and it might not even matter... but the spec of the output transformer does indicate polarity... and then 2) I would look closely around the XLR/14 inch output area... one of those wires could be acting like an antenna...
It is because old ELMA switch PCB had reversed polarity. ( https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/page-64#post-17715223 )
I swapped heater wires ( 6SL7 and right channel EL34, at the transformer ) and it helped.
Before that I changed heater wires (replaced with drill twisted wires) and the noise moved from left channel to the right.
What gives? Does it mean my mains transformer LL2758 is defective (noisy)?
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The transformer isn't defective and the issue was fixed. As I already explained, noise was coupled into the cathode via the heater reference for that particular winding. The noisy winding was moved to the 6SL7, whose heaters are referenced to ground. The PCB was modified so the output tubes' heaters are also referenced to ground, so it shouldn't happen again.
There is still a faint noise if I use sensitive, low impedance headphones / IEMs. Mostly from the right channel.
Not a big issue but my amp would be unusable with , for example, Focal Stellia headphones. I like Focal Stellia.
I am not sure what to do to get rid of the noise. I thought the noise is coming from the power amp (heater wires).
Maybe I should replace the PCB with modified PCB?
Not a big issue but my amp would be unusable with , for example, Focal Stellia headphones. I like Focal Stellia.
I am not sure what to do to get rid of the noise. I thought the noise is coming from the power amp (heater wires).
Maybe I should replace the PCB with modified PCB?
Member Algar_emi did measurements here. It can definitely be used as a preamp since most power amps are super easy loads compared to headphones.
Best,
Anand.