The next thing to be redesigned are the two so-called Driver Circuit Boards (SUPA2590, SUPA2600). But first let’s have a look at the circuit design that this amplifier is built around. ❗ Caution All information is provided “AS IS”, without warranty of any kind, express or implied. ❗ Caution The elevated voltages inside this amplifier can cause damage, severe injury, and death. If you are not authorized or qualified to work on such equipment, do not do it. If you follow along, you do so at your own risk. ...

Most audio power amplifiers are supplied by an unregulated power supply: A transformer with a center tap, a bridge rectifier and then two large filter capacitors. All the ripple/noise rejection happens inside the amplifier circuit itself. The Technics SE-9600 is a fairly rare exception. Let’s have a look. ❗ Caution All information is provided “AS IS”, without warranty of any kind, express or implied. ❗ Caution ...

The Technics SE-9600 is a high end hifi stereo power amplifier build in the mid to late 70’s - a design about 50 years old. This couldn’t be more obvious: Everything is metal, everything is massive - the chassis, the transformer, the heatsinks, all packed nicely into a 19" inch form factor. And of course it has VU meters with three ranges. Worth mentioning is the input on/off switch - I like that - and the utterly pointless output impedance switch that is capable of making your favorite music sound flat and mushy by reducing the effective damping factor. ...

Homelabbing is fun, but can get expensive very quickly. Using somewhat older hardware may significantly reduce cost, and more often than not, platforms from just a few years ago handle all the services you throw at them with ease—unless, of course, you’re planning to deploy local AI workloads and the like. That’s why I came up with a simple plan to repurpose my old Ryzen desktop. Sort of… There’s one catch, though: like all 5000X series chips my Ryzen 5 5600X doesn’t come with an iGPU, and keeping an RTX 3070 in there wastes a ton of power even at idle-while it has way too little VRAM to be actually useful for local AI tasks. Never did a lot of gaming either. So I decided to run an experiment: pick up a relatively cheap Ryzen 7 5700G and later sell off both the Ryzen 5 5600X and the RTX 3070. The motherboard on hand is an ASUS ROG STRIX B550-F Gaming (Wi-Fi), powered by a Seasonic PRIME TX 750W. The power supply now is absolutely overkill, but that is what is in there. In its silent mode it should easily power two of the servers without spinning the fan once. This is made possible by its fairly good efficiency, so that’s a plus… ...

I’ve recently been restoring vintage Hi-Fi equipment, focusing on Technics preamps, integrated amplifiers, and power amps. My first project in this series is a Technics SU-8080 integrated amplifier, which arrived in decent cosmetic condition (and with printed schematics!). However, it was covered in dust like I’d never seen before and suffered from frequent channel dropouts, rendering it unusable. ❗ The elevated voltages inside this amplifier can cause damage, severe injury, and death. If you are not authorized or qualified to work on such equipment, do not do it. If you follow along, you do so at your own risk. ...

I haven’t found that much information about the Agilent 6811B AC Power Source/Anaylzer. So I thought: Why not post a few pictures a made during troubleshooting of a problem where the display stayed mostly dark (except for the shift key indicator if I remember correctly, which likely is processed locally somewhere on the front panel board. The issue went away shortly after opening the unit, so for now I couldn’t reproduce it). ...

There are many advantages of the 1l mini PCs for home server applications: Obviously they are very compact, but more interestingly: The idle power consumption can be almost as low as current Raspberry Pi 5s acchieve, i. e. 5-6W*, all while avoiding many of their limitations**. In many cases the low power consumption is associated with quiet operation, which is especially important if you don’t have access to a dedicated server room in the basement or at least an acoustically isolated closet. Also, used mini PCs are available in large quantities at reasonable prices. This is why there is a ton of information and data out there, covering hardware expandability, compatibility with hardware and software and other aspects of converting mini PCs into capable home servers. ...

For quite some time I was looking for a rack to mount my 19" HP/Agilent gear in. I haven’t found a single rack that meets all my requirements. Most are too big, too small, too flimsy, too heavy, poorly made, too expensive, lack cooling … or are simply made for a different purpose. Since I already used IKEA LACK tables to put some of my 19" gear on - as a dodgy temporary solution - I thought: Why not build a little rack with those tables? A few screws later, two tables are combined into one ~45 EUR rack on four castors (IKEA RILL, 75mm). ...

The Technics SU-VX 700 is an integrated audio amplifier from the early nineties. It delivers 2x 90W into 8 Ohms and is specified with a THD of 0.007% (20Hz .. 20kHz, rated power). In my opinion it is one of the better Technics amplifiers. Whereas the sound of an amp is always subjective to a large degree there are some design aspects that are a bit more objective. What I particularly like about the SU-VX 700 is mostly related to its simplicity and repairability: ...