Correct. 3U 300x330 for the Modulus-686 on ±27 V rails. 2U 200x230 for the Modulus-286 on ±36 V rails.Obviously the chassis is a non-trivial component of the cost. Tom, you're using the Mini Dissipante 3U 300x330, right? If so, note the base price is $179, so over half the cost Tom quoted above is for custom machining. You can save a lot by doing the machining yourself, or, just go with less machining.
I modify all panels except the top, which drives up the cost, especially at QTY = 1. You could easily drill the holes in the bottom plate and front panel of the MOD286 chassis yourself, provided that you have access to a drill press or drill stand and can drill to a certain depth without punching through the panel. If you have ModuShop do the work, I recommend getting them to machine the rear panel and heat sinks. Most people have trouble with the larger cutouts for the XLR and speakON connectors and with cutting the threads in the heat sinks.
I have. I built my first Modulus-86 amp (four channels powered by Power-86 and an Antek AS-3222 power transformer) in a "BZ4309" chassis from eBay. The chassis arrived coated in cutting fluid (oil) and reeked to high heaven from it. Some of the holes were not de-burred. I wasn't impressed. Once cleaned up, the chassis worked just fine. I still had to machine all the holes I needed, which took the better part of a weekend.I haven't looked, but I'd be willing to bet you could get an even cheaper case from China (ebay/aliexpress).
A few months later, I found ModuShop and went "aww...." for $20 more than the eBay chassis, I could have had something that would have been of much better quality. Oh, well.
True that. ModuShop will sell you the heat sinks too. I bet they'll cut threads in them before they ship if you throw a little money at them.Cheaper still would be to simply buy the required heatsinks, then build a wooden chassis around those (somewhere on diyAudio someone did that with a Mod86 build).
Well, there is that. That's in fact why I decided to offer a kit. The chassis is a significant challenge for many. The drawback of having me do the work for you is that I don't work for free...If you have all the tooling and know what you're doing. Otherwise you'll likely spend hundreds on tools, mess it up and have to fork out for more casework to replace the stuff you ruined!
Heatsink USA is your friend there. You can always get the heat sinks anodized after machining. Black heat sinks are more efficient (closer to black body radiators).[...]I want my amps to be 300mm wide by 420mm deep, but unfortunately heatsinks will add another 80-100mm to the width.
I've given a list of posts with build pictures in Post #1 of the Modulus-686 vendor thread on DIY Audio. I'm pretty sure there's a mono build among them.Another option is to build a pair of dual monos, if the heat cannot be managed. I wonder if anyone has shared their mono 686 build images with you?
Tom