Those cases look really nice, but if you say they are expensive for someone living in Germany, I guess us US or other based folk might find them very pricey!

Yep, these cases are nice!

I use the same heatsinks, Ali has all sizes available. Milling then the front/back panels need to be done anyway and 2x identical top/bottom covers is pretty straight forward. 

Complete cases with those heatsinks are available as well. Here one with the 2U heatsink though.

Hey Alex, how is your KSA-5 going?

Pretty much on hold until the middle of February. The delivery for the case is delayed and I want to make sure that everything will fit before continuing with ordering the PSUs. The manufacturer has problems with their supply chain for the heatsinks...

I will post an update as soon as I receive the case!

Hello everyone,

it's been a while... busy life, covid, work, supply chains, mouser, jlcpcb, etc...

Anyway - the power supplies are finally done and tested: +21,04V and 21,01V. Transformer is a dual 22V/50VA.

The rectified and smoothed voltage to the 7812 and 7912 are at +/- 36V DC, that's a hair too much. Hopefully that will drop a little when the amplifiers are connected. That's the next step.

Cheerio!

Nice! A couple of questions:

1. How do you guys cut the angle brackets so nice and clean?
2. What are those test point pins used in the boards? Do you have a part number/source?

Thanks!

Hey Pars, these are Mill-Max p/n 4275-0-00-80-00-00-08-0. There are different sizes available. For bigger holes check Mill-Max p/n 4357-0-00-15-00-00-03-0, take a look at the catalog, there lots of options.

Something like this will cut you perfect right angles, cost around $20 or so. You can then make a wooden base for it (attach instead of the black plastic parts) and clamp it to a table to make it rock solid.

Edited March 28, 20224 yr by audiostar

^ Thanks! I figured it might be something from Mill-Max, but hard to go thru all their stuff.

Check as well Keystone 5005 and 5006 if you need a test point with a hook attachment. Mouser p/n 534-5005 and 534-5006. Available in different sizes as well. 

Edited March 27, 20224 yr by audiostar

For cutting small things I have this cute saw:

https://www.proxxon.com/en/micromot/27160.php

The soldering pins I source from a German distributor... similar things should be available everywhere:

https://www.reichelt.de/de/en/soldering-pins-1-mm-pack-of-100-rtm-1-100-p15321.html

The corresponding lugs are these here:

https://www.reichelt.de/de/en/solder-lugs-1-mm-tin-plated-pack-of-100-vt-rf-1-100-p231422.html

First testdrive with amps and psus hacked together. Works fine! Input voltage for the 78/7912 dropped to 31V DC. That's great!

Did a few hours of listening - no flaws to be heard. Had some great fun there and quite forgot that I was testing a new amp!

A tiny bit of 50Hz mains voltage hum to be heard, but that's probably because of no shielding at the moment.

Next: integrate the headphone protection board...

 

2 hours ago, AlexS said:

Next: integrate the headphone protection board...

Where would you put that, there is virtually no space left inside the box 🙂

Everything looks very nice so far, congratulations. 

Btw, I am using the same WAGO connectors, they very handy for quickly connecting multiple wires together during tests. Can even put 2mm test leads inside. 

Edited March 29, 20224 yr by audiostar

Looks nice. Interesting chassis!

I've been using the same Wago connectors as well (2- and 3-way). They're pretty slick and apparently are good up to 450V.

After having double checked that the input voltages to the 78/7912 are within limits (max 35V)... measured 31V, I added the remaining 7812 and 7912 to generate the supply voltages for the protection circuit.

And modified my prototype so that it no longer needs a individual power supply.

The audio 50Hz humm also went away after I no longer crossed the audio input lines with the 230V power cord!!

 

Edited April 3, 20224 yr by AlexS

31 minutes ago, AlexS said:

The audio 50Hz humm also went away after I no longer crossed the audio input lines with the 230V power cord!!

Like magic 🙂

Nice pics and congrats, looking good!

Easter update... a friend of mine has a 3D-Printer:

And this is what those parts are for:

There will be an additional PCB mounted on top of the volume pot that will also serve as wiring distribution and protection circuit. I will only need tapped holes to the heatsinks, all PCBs are otherwise held in place by the plastic spacers.

Great work. Is this is for a second build, or are you just floorplanning with spare pcbs?

Hey Alex, need some pics of your final amp! Hope everything is good!