F5 power amplifier

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Ok it turns out that my bias current has been a bit higher than I thought, around .65v. I was still hooked up to the variac and forgot to double check it again plugged straight into mains. Either way, the temps I reported were with the higher current so I pushed things up a tiny bit more (.680v) and I’m still not hitting 50c. Should I be concerned? I’m using a 4U chassis and keratherm insulators.
 
Final Bias Steps

"WOW"

I have had my newly constructed F5 Ver. 3.0 running for 4 days. What an amazing amp. I have all of my CD's ripped to FLAC, playing through an Allo Boss Dac on top of a Raspberry Pi.

Three Dog Night, AC-DC, Robin Trower, Led Zepelin, Steely Dan, Willie Nelson, Johnny Paycheck, Zac Brown, don't forget Areatha, John Lee Hooker, Muddy Waters, Little Richard, and
Holly Catfish Batman "Ella Fitzgerald". I have been listening to MP3's so long I forgot what a good source and a Great Amp sounded like. Thanks Nelson.
Don't try to guess my age by the music I listen too.


Now my question: I biased the amp to 485mv, one channel at a time. I am now ready to to bias the amp to 600mv. Should I do this "One Channel at a time" or can I do this with both
channels connected to power. I will disconnect V+ V- and Grnd if advised to bias one channel at a time. I will also adhere to Nelsons Temp recomedation of "GRIKY"


Time to listen to some "Al Green"
 
What is a safe minimum current rating for a power switch for an F5 with a soft start board? I'm in Europe, so 240V mains. My current fuses are 1.25A, but I'm guessing that since they are slow blow they may actually be handling a higher current during switch on.

The reason I ask is I'm looking for a long (~20mm) flatted toggle switch (DPDT or DPST) for the front panel of my F5 which currently only has the switch on the back. I've found a few candidates, but one is out of stock everywhere I've looked (APEM 5646AB-8), one seems like it might have too low of current rating (C&K 7201P1Y4ZQE, 2A@250VAC).

My best bet at the moment seems to be the NKK M2022E4S1W01, rated for 3A@250VAC:

m2022e4s1g01_DFI_SPL.jpg


I'd prefer not to have to add another transformer to power a relay board, even though I know that would open a lot more options for power switches...
 
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Back when I biased my F5 I had a problem where I needed to set uneven biases on one channel in order to get 0mV at the output (e.g. +543mV and -557mV, where my target was ~550mV). The other channel was almost perfect (+550mV and -551V).

I just recently received another set of parts (M2X boards and matched quad of JFETs), and it made me wonder about the quad matching scheme.

For a matched quad (NP), are they all matched to each other, or in pairs? I guess what I am asking is that if you built the amp, set it up and biased it, and then swapped LSJ74s (leaving the LSK170s in their original positions), would you expect to see a difference at the outputs?

I may try swapping them, or even putting in my new matched quad, just to see if I can minimize the bias spread. I'm assuming it's not actually a problem to have non-matching +/- voltages, but it would be a learning opportunity to see what parts affect what measurements.
 
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Thanks guys. I had a feeling it was ok but the build guide implies they should be the same voltages. Anyway, I just placed a big Mouser order today so I can have some more fun building M2X boards, and a BA2018 preamp with two VRDN PSUs. I also bought a few power switch options to try (NKK 20mm DPDT flat toggle). Now to wait for the BA2018 board to come back in stock...
 
Hello everyone, some time ago I finished the Pearl 2, B1 and F5 chain, I like it a lot. I also implanted Mundorf audiophile condensers in B1. It was worth it! don't believe anyone who says something different.
But I want the helicopter in "The Wall" by Pink Floyd to land IN my room and not outside.
When I think of driving my JBL Ti6K via bi-amping. Before I start getting material, the community would like to ask if F5 and F5Tv2 can play correctly in phases?
I wanted to build the F5 Turbo anyway, it would be the right opportunity.