Chinese Pass amp clone

Thanks @rhthatcher. I have already packed Jeff Young PCB you gifted me during latest @codyt SJEP giveaway with snubbers and CL-60 + main cap PCBs. I have more PCB of your design for myself.

@TheSoundMann, in the pictures below is what you will receive at the address you gave me (small blue PCBs are for front panel LEDs if you wish). FETs seems will land on your laps thanks to Randy. Find heatsinks and toroid and you have hit the point of no return.

Keep in mind that if you do not build it you will end up in the audiophile hell, where all amplification is class B! :devilr:

2023-05-21 11.53.27.jpg
 
TheSoundMann, you lucky dog 😀👍 This hobby is a black hole but don't be afraid to jump in. This will be mostly a paint by numbers project aside from a few details.

It is hard to drill heatsinks. bottom tapping etc If you are going to do your own, a good way to go about it is drill and tap a piece of 3/8" aluminum stock with through holes, tap them and then attach the aluminum piece to your heatsink. M3 holes or 6-32 holes will work for the IRFP240 mosfets. You can drill through holes for the heat spreader to heatsink bolts between the heatsink fins that way.. The aluminum also acts as a heatspreader which is a big plus. Also you can remove it and drill a new pattern etc.

With the PCBs that you have coming to you, if you drill holes for the mosfets being soldered directly to the PCB, the mosfet leads will be more than strong enough to hold the PCB boards. There is no need to drill holes for the PCB mounting holes. Just use a spacer or something to hold the PCB up while you solder the leads to the board.

Here is a great company for buying metal scraps (no custom sizes available):
https://www.ebay.com/str/usametalonline

Another way to go is to purchase a DIY audio store 4U chassis and attach your mosfets to your heatsinks with short wires. One thing that I have learned is that the 4U chassis is an economical solution being that heatsinks by themselves (of a large enough size) are pretty darned expensive. Also, the 4U chassis is predrilled to accept other designs available from the DIYaudio store. Same with the power supply that you are going to build.

You are going to need a 2x18 300va or larger transformer like this one:
https://www.antekinc.com/as-3218-300va-18v-transformer/

Mouser.com and Digikey.com are two places where you can order parts to populate the boards. Randy's UMS page has BOM's which you can use to cross reference to your build. The part location titles will probably be different but will give you an idea. Like R1 R2 C1 C2 etc but the parts in the BOM are a good selection and should help you fill your cart.

If you don't have a solder gun, the Hakko FX888D is a terrific unit. There are cheaper ones as well.

For attaching the mosfets to the heatsink spreader, you can use Keratherm without thermal paste or Mica pads with thermal paste. the DIYaudio store has Keratherm. Also, their fireball solder is excellent and enough for a few projects.

I would assume you are going to have questions. Ask as many as you want!

First picture is a heatspreader with holes drilled and tapped. 2nd picture is wire leads being used to make existing holes work.
 

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