C9 doesn't go on the PSU board, but will run between the board and the chassis ground. You can see it on the First Watt PSU schematic here. I haven't gotten there in my build yet, so I'm not sure exactly how that hooks up yet. If you're eager to jump ahead, I think I've seen it in photos either in this thread or in 6L6's "illustrated build guide" thread. (Or if someone wants to explain it and show photos, that would also be nice.)
My understanding from 6L6 is you don't need any snubbers if you're using monolithic rectifier bridges. I hope I've got that right, since we didn't order any of those parts.
Yes! My next blog post will be building the PSU boards and explaining the basic functions of the PSU sections. Mains, secondaries, rectifier, filter caps, etc.
Ooops. Sorry about the wrong lead spacing. We'll need to revise and re-order. Or maybe omit? I'm not sure. My understanding is that C6 and C7 are "bypass capacitors." Despite some Googling, I'm still not really sure what that means, but there does seem to be a widespread practice of using a small film capacitor alongside every larger electrolytic capacitor in the audio signal path. Why? Well, try reading this thread and/or Googling "bypass electrolytics with film caps" to experience this rabbit hole. Something about electrolytic capacitors inherently performing more poorly than film capacitors at high frequencies, and thus the use of a film cap in parallel compensates to some degree for this shortcoming of the electrolytic on it own?
Anyhow, the boards will work fine without C6 and C7 (they don't appear in the official Aleph J schematic), but they may work better with bypass film caps in place (which is why they are included in the revised Aleph J schematic that accompanies the DIYAudioStore Aleph J amp board)?
See discussion here. Quoting @DennisHui: "The original schematics actually uses a 1K resistor. I guess the pot was added to the PCB to allow some adjustment of the current to the jfet diff pair."
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After perusing Mouser last night for a while, here's what I came up with as a potentially good part for C6 and C7 (this time with the correct lead spacing):
MKP2F033301M00JSSD WIMA | Mouser
I'm trying to decide whether it's worth doing these bypass caps myself, and for a n00b build generally. 8 fewer solder joints is 8 fewer things that could go wrong!
That little blue cap is a special rated cap, "x" or something like that. I bought a fist full a long time ago.
Russellc
They are called safety capacitors and are specifically rated for across-the-mains service. They are approved for this application by UL, VDE, etc.
Noobs - please do not substitute regular capacitors. They are called "safety" for a reason.
Specific examples are: VY1332M59Y5UQ6TV0 Vishay / BC Components | Mouser (Vishay ceramic) and MKY22W12203D00MSSD WIMA | Mouser (Wima film).
Noobs - please do not substitute regular capacitors. They are called "safety" for a reason.
Specific examples are: VY1332M59Y5UQ6TV0 Vishay / BC Components | Mouser (Vishay ceramic) and MKY22W12203D00MSSD WIMA | Mouser (Wima film).
Question re transformer
I realize this sounds like a stupid question, but I will ask anyway. I just received my two transformers (I am building mono blocks). They are Avel-Lindberg 18-18 volt 250VA. They came in a box, but appear to be wrapped in a plastic covering. I assume I do not remove that covering, or do I? Here are pictures (they keep showing sideways, I tried rotating them but it does not work):
I realize this sounds like a stupid question, but I will ask anyway. I just received my two transformers (I am building mono blocks). They are Avel-Lindberg 18-18 volt 250VA. They came in a box, but appear to be wrapped in a plastic covering. I assume I do not remove that covering, or do I? Here are pictures (they keep showing sideways, I tried rotating them but it does not work):
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