Doing some more listening after a modest upgrade to the shared Universal PS board. Hum was diminished slightly, but is still present. I am still working on the best way to incorporate some motor run caps into the power supply.
The F5m is proving to be a good match for my speakers. The big Vandersteens have an uncanny ability to preserve the physical sense of acoustic instruments and voice. The F5m keeps this realism intact, aided by a well balanced presentation of harmonic frequencies.
The F5m is proving to be a good match for my speakers. The big Vandersteens have an uncanny ability to preserve the physical sense of acoustic instruments and voice. The F5m keeps this realism intact, aided by a well balanced presentation of harmonic frequencies.
Switching back to this thread..
My F5m is having a very fine settling in period with its recent tweaks.
Besides the motor run caps added to support each channel, I also increased the gate stopper resistors. The FQA28N15 parts got 150 Ohms and the IXTQ26P20P got 110 Ohms. This removed the sense of a slight haze that I was noticing from time to time. The amp is wonderfully transparent and evenly balanced across the audio spectrum.
Something about its sound makes acoustic instruments sound more present in my listening space. I haven’t run any FFT analysis, but I suspect that it is simply a really great match with my speakers. Though my most recent Aleph J is also remarkably transparent, the F5m excels at acoustic presence.
My F5m is having a very fine settling in period with its recent tweaks.
Besides the motor run caps added to support each channel, I also increased the gate stopper resistors. The FQA28N15 parts got 150 Ohms and the IXTQ26P20P got 110 Ohms. This removed the sense of a slight haze that I was noticing from time to time. The amp is wonderfully transparent and evenly balanced across the audio spectrum.
Something about its sound makes acoustic instruments sound more present in my listening space. I haven’t run any FFT analysis, but I suspect that it is simply a really great match with my speakers. Though my most recent Aleph J is also remarkably transparent, the F5m excels at acoustic presence.
@TungstenAudio - you had mentioned you were deciding on the appropriate way to integrate the motor run caps. How did you go about doing so? If convenient, would you mind sharing a photo? 🙏
Always stoked to hear about your builds. Appreciate your thoughts - keep up the good work!
Always stoked to hear about your builds. Appreciate your thoughts - keep up the good work!
They look like this..
I didn't have my preferred 80uF caps on hand, so I supplemented a set of 40uF with 120uF organic polymer in parallel. The caps are wired into the channel board power & ground connections. The speaker (-) were relocated to the PSU board GND.
The motor run caps are held in place by double-sided foam tape.
I didn't have my preferred 80uF caps on hand, so I supplemented a set of 40uF with 120uF organic polymer in parallel. The caps are wired into the channel board power & ground connections. The speaker (-) were relocated to the PSU board GND.
The motor run caps are held in place by double-sided foam tape.
Attachments
Mr. Pass,
Thank you for doing this.
Is this power supply similar to the one you did for the F6?
Super helpful! Loving the compact packaging, as well.
Thank you!
Completion Kit Alert,
Thanks to member Oreo382 we have discovered that the insulator pads for the output transistors are
not very insulator:
https://www.diyaudio.com/community/...dio-store-feedback-thread.221467/post-7635232
My reply was:
It's always something...
Thank you for this correct information.
Looking at the BOM I see Digikey part BER1340, and I don't see it when I go to Digikey, but I trust that this is the case.
Fortunately it's not an issue with the anodized sinks from the store, which insulate into the megohms, but it would be
a problem with bare metal.
Also fortunately we have not yet shipped the second batch of these kits.
Of the 100 kits that have shipped, I am happy to mail different insulators to send to anyone with bare metal sinks.
You can send your address to nelson@passlabs.com
Thanks to member Oreo382 we have discovered that the insulator pads for the output transistors are
not very insulator:
https://www.diyaudio.com/community/...dio-store-feedback-thread.221467/post-7635232
My reply was:
It's always something...
Thank you for this correct information.
Looking at the BOM I see Digikey part BER1340, and I don't see it when I go to Digikey, but I trust that this is the case.
Fortunately it's not an issue with the anodized sinks from the store, which insulate into the megohms, but it would be
a problem with bare metal.
Also fortunately we have not yet shipped the second batch of these kits.
Of the 100 kits that have shipped, I am happy to mail different insulators to send to anyone with bare metal sinks.
You can send your address to nelson@passlabs.com
I have some keratherm from the store, I assume they will serve fine.Completion Kit Alert,
Thanks to member Oreo382 we have discovered that the insulator pads for the output transistors are
not very insulator:
https://www.diyaudio.com/community/...dio-store-feedback-thread.221467/post-7635232
My reply was:
It's always something...
Thank you for this correct information.
Looking at the BOM I see Digikey part BER1340, and I don't see it when I go to Digikey, but I trust that this is the case.
Fortunately it's not an issue with the anodized sinks from the store, which insulate into the megohms, but it would be
a problem with bare metal.
Also fortunately we have not yet shipped the second batch of these kits.
Of the 100 kits that have shipped, I am happy to mail different insulators to send to anyone with bare metal sinks.
You can send your address to nelson@passlabs.com
Russellc
Drilling and tapping holes in aluminum can leave a raised edge around the hole. It is possible for this edge to protrude through a thin insulator. If the edge is removed by one of several means, this leaves a ring of bare aluminum that might conduct to the back of the FET.
