Here is my diy chassis of my choked 2SK180 follower mono-block amplifier. It is aluminum with one 300mm x 40mm x 210mm modu heatsink available from the diyAudio store. The heatsink dissipates 88W from one 2SK180. The heatsink gets mildly hot, but not hot enough to burn. I can keep my hand on it indefinitely. There are cooling holes in the bottom plate as shown, and also holes in the top plate. There is enough natural air flow that the interior of the chassis gets only a bit warm.
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All of the ancillary products are in place and tested. Next is to spend the weekend double checking polarities , connections and values of the boards. Then hook em up and start cooking.
The fans are surprisingly quiet yet still barely audible from a couple feet off. The noctua voltage dropper is in place for now , may remove it later. Will see what can be heard from the listening position and if it is a non issue.
Sensor for the temp control is mounted to the power supply cap and reads the same as my infrared thermometer. If the controllers survive their placement near the heat sinks, I will at least have gained an easy spot to check temps. A layer of silicone sheet can be placed between the bracket and case if needed. If the controller becomes problematic I will remove them and use the bracket as a stand for a Nelson Pass bobblehead.
The fans are surprisingly quiet yet still barely audible from a couple feet off. The noctua voltage dropper is in place for now , may remove it later. Will see what can be heard from the listening position and if it is a non issue.
Sensor for the temp control is mounted to the power supply cap and reads the same as my infrared thermometer. If the controllers survive their placement near the heat sinks, I will at least have gained an easy spot to check temps. A layer of silicone sheet can be placed between the bracket and case if needed. If the controller becomes problematic I will remove them and use the bracket as a stand for a Nelson Pass bobblehead.
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Its very likely not a bad idea at all, to place the powersupply outside of, and shielded from the amplifier 🙂👍
It should definitely be enclosed - with at least sturdy mesh. Apart from the risk to humans and pets as Ben points out I had a lizard crawl into a similarly exposed test rig I was using some years ago and it managed to incinerate itself and fry several parts on the amp! So there’s also risk to your hard work in exposing those high voltages.
Thinking of a half height enclosure for the rear with a toroidal enclosure . All of the brackets needed to mount said enclosure are present, just need a solid plan. Haven't found the xformer cover yet either. Antek has the CA-400 yet I am not convinced there is enough clearance for the wires (designed for 400va units while these are 500va). The covers somehow have costs compatible to the transformer? I will do something......No Lizards will be harmed in the production of these amps!
Exposed Ac wires are of course a big no-go.
But when you build a single ended common drain THF-51 amp with a negative power supply. Then you end up with the body (drain) on the SIT connected to ground. Could you then skip the insulation between SIT and heatsink and then get the drain connection through the heatsink?
But when you build a single ended common drain THF-51 amp with a negative power supply. Then you end up with the body (drain) on the SIT connected to ground. Could you then skip the insulation between SIT and heatsink and then get the drain connection through the heatsink?
I believe you are confusing chassis/safety earth with audio ground. I'd recommend to keep those somewhat separated from each other to avoid noise pickup or ground loops. The audio ground (SIT body) should therefore not have a direct electronic connection to the chassis.
Yes. totally agree with mbrennwa.
The chassis, including heat sink, should be connected to safety ground. Audio ground is typically connected to safety ground through a CL60 thermistor. So connecting the SIT drain to the heat sink does not connect the SIT drain directly to audio ground.
Even if the audio ground is connected directly to safety ground, using the chassis and heat sink for audio ground is not recommended as the loop area is not minimized, which could result in noise, as mbrennwa mentioned.
This brings up another possible issue, especially with anodized chassis. Anodization can create an electrical barrier between separate pieces of a chassis, resulting in parts of the chassis not connected to safety ground. Metal chassis parts should be checked for electrical connection to safety ground. File or sand off some anodization if necessary at joints to ensure electrical connection between all parts of the chassis.
Hi,
Can you please let me know on where you got the boards from? If JPLCB, gerbers? I would like to get a pair. Tokin 'bout eight THF-51S that I bought from Saint Watanabe San after the gospel (from Mr. Pass) of acquiring some was published long time ago and maybe when I have all the parts necessary, I will get the "push" I have been waiting for to build the amp. Thank you!
I designed the boards and made the Gerber files available to diyAudio members. The Gerber files went out forty or so members so perhaps there are spare boards out there.
I will send you the Gerber files if want to order the boards yourself.
By the way, post #173 was where I started the V- power supply and PCB posts.
I will send you the Gerber files if want to order the boards yourself.
By the way, post #173 was where I started the V- power supply and PCB posts.
Yes, I had stern words with the rest of the lizard’s family. Who pointed out one of their number had sacrificed itself to teach me the error of my ways before a much more consequential torching occurred🙃
The lizards around here are very much smaller than iguanas - around three inches, nose-to-tail. Fuse did go, but not before some damage.
The lizards around here are very much smaller than iguanas - around three inches, nose-to-tail. Fuse did go, but not before some damage.