The sink is good for maybe a single channel.
The trafo should be fine for both channels.
If your trafo has two secondaries use one per channel with its corresponding diode bridge and caps.
Use small value 5W series resistors between the caps to reduce ripple. Let's say 0.1 - 0.22 ohm.
The trafo should be fine for both channels.
If your trafo has two secondaries use one per channel with its corresponding diode bridge and caps.
Use small value 5W series resistors between the caps to reduce ripple. Let's say 0.1 - 0.22 ohm.
Yes, the heatsink is for one channel.
Toroid is 2x16vac, dual channel.
15000uF - 0.22R (5W) - 15000uF - 15000uF <-- like this?
Toroid is 2x16vac, dual channel.
15000uF - 0.22R (5W) - 15000uF - 15000uF <-- like this?
wow, thats a big heatsink and only for one channel? How long you need to wait tills the temp settles after a turn on? Should be like 2 hours minimum.😕
It's look big but not too big. The actual size is 140mm x 135mm x 150mm (H). The weather here is hot, I don't think need too long to heat it up. Normal ambient temperature at day time around 28 ~ 29 deg C before noon. Afternoon will be over 30 deg here, that's why I need to find a slightly bigger heatsink. 🙂
Oh, heatsink looks much much bigger in a photo.
It should also be quite warm about 28C in the weekend down here in Sweden. 14C on Saturday an 14C on Sunday 😛
Good luck with the build!
Thanks. I'm still learning.
I have a question regarding the circuit. There's a revision that Z1 has added in to protect the IRFP250.
According to this thread, I found the latest circuit as below picture attached and the pcb too.
Another picture is the pcb taken from the web that someone is doing this Mofo. I have checked and found the Z1 seems not at the correct location. Anyone can confirm this? I'm don't have any electronics background so I wish someone can confirm this.
I have a question regarding the circuit. There's a revision that Z1 has added in to protect the IRFP250.
According to this thread, I found the latest circuit as below picture attached and the pcb too.
Another picture is the pcb taken from the web that someone is doing this Mofo. I have checked and found the Z1 seems not at the correct location. Anyone can confirm this? I'm don't have any electronics background so I wish someone can confirm this.
Attachments
The PCB on the right has the zener connected before R2 unlike the marked-up schematic. Either way. 🙂
So I moved my MoFos to my main system which has Seas A26 speakers, and the bass seems to be a substantial improvement over my ACA. Maybe the damping factor of 40 vs. 10 for the ACA is what I'm hearing? The surplus Nebraska chokes seem to do just fine. This bodes well I think for other follower designs (thinking SIT amps).
Better damping, more power. Plus there’s a certain ineffable positive quality that magnetics (in this case the choke) have on audio reproduction.
oh yes, Iron is good to have in signal chain
Yes to both. This is the second example of magnetics in my system where I've heard something I like but can't really describe. The Electra-Print line-level trafos in one of my preamps seem to "clean up" the sound of digital sources in some way, as well as improving the bass response of my turntable. Here it seems the MoFos do more than just make the bass louder- strings are sharper and tones are purer somehow? I'm still just starting with these and have many more albums to play. The high end seems fuzzier now though with the MoFos.
As a follower the MoFo has much lower harmonic distortion than the ACA. That probably contributes to the sound that you are hearing.
Hi Ben, thank you for that point, it's helpful to my understanding. FWIW I've read avidly your adventures with the Tokin SITs in common drain mode. I've got a pair each of the THF-51S and the 2SK180 devices set aside from Mr. Watanabe and I'm trying to decide what to use them in. I've been holding out to see what Mr. Pass' design (and kit with hopefully a nice chassis!) for the SITs looks like first. Based on this recent experience with the MoFo I hope those designs have a low output Z as that seems to work well with my current speakers.
(Adding a picture of the MoFos just because)
Attachments
Last edited: