A.S. Audio & Akustik

27/05/2026

What do you get when you combine one of the most legendary tube preamplifiers with one of the most legendary compressors and put it in a box? The Universal Audio 6176! 😎

Apart from a mischievous IDC connector, this unit had a pretty weird problem. One of the potentiometers was ever so slightly conductive to the chassis, that it would cause the sidechain to act up from time to time. Relatively easy fix, but pretty tricky to track down....

18/05/2026

The Marshall JCM 2000 has a bad reputation caused by a less than ideally designed ciruit board that causes a few problems. Most notably, the PCB is turning conductive ever so slightly between closely spaced traces. This not only increases hum, but also causes the bias to drift, which can ultimately destroy the power tubes!
It is possible to modify the PCB to eliminate these problems, but there is another possibility: Valvetubeguitaramps.coms has a replacement for the complete main PCB available, that fixes all the problems the original had and even adds a few more improvements. The installation was a breeze and the amp works flawless again!

Apart from the technical issues, I have to say this is a fabulous sounding amp with incredible creamy overdrive sound!

27/03/2026

East German manufacturer Lorenz made some incredible tube amplifiers back in the days and the MV330, also known as V240 is no exception. While the better known ÜV300 was designed as a mic preamp, the MV330 was a universal amplifier used for line signals or after passive filter circuits. The sound is pretty clean, while still adding some nice saturation in the lower mids that works really nice on the mixbus!

I received a pair of these from a client some time ago for maintenance. While they were in pretty good shape, they still needed some work like retensioning and cleaning tube sockets or changing a noisy tube. And since they deserve better than just the usual run-of-the-mill connector panel, I built nice wooden enclosures with leather handles and aluminium backplate for them. 😎

03/03/2026

The Neve 31105 is one of the lesser known modules and was used in their 8078 consoles produced in the late 70s. Neve's naming convention is not the easiest to follow, but these are basically 1081 with some minor differences like indication LEDs or seperate gain controls for the Mic/Line inputs.

This beautiful (but unfortunately pretty crudely racked) pair that landed on my workbench had a very nice modification: the standard class AB output amplifier was replaced with a "Phoenix Class A" which brings the sound a little closer to the "beefier" 1073.
There was some stuff to fix like a few broken solder joints, rewired polarity switch, dried up electrolytics... But the way these modules are laid out and build makes them a pleasure to work on!

12/12/2025

21/11/2025

Here is a simple Telefunken V676a and V672/2 combo-rack that I built according to a specific request of a client. The only additional controls are switches to set gain and input impedance for the V672.

I know both of these modules very well, but this was the perfect oppurtunity to test them side by side. Nothing unexpected here, but I was surprised how close the V672/2 sounds to the V676a when calibrated accordingly!

23/10/2025

Despite being built like a tank and a sound that is beyond any doubt, a lot of Millennia units seem to be developing the same problem over time: bad push-button switch contacts.
This HV-3D 8-channel preamp was no exception in this regard, so I replaced all of the switches with new ones from C&K (which got crazy expensive recently btw...). Furthermore, one of the preamp sub-boards was dead, which required some hot-air soldering to fix. Last but not least, I added D-Sub connectors for the in- and outputs on client's request to simplify cabling in the studio.

03/10/2025

The NTP 179-400 is a Eurocard module from the 1980s originally intended for the use as broadcasting limiter. Based around a proprietary VCA module and with transformer balanced input and output (Lundahl), it was built to the highest standards, just as you would expect from a company like NTP. While there was a stand-alone stereo rack version available (179-470), the use remained somewhat cumbersome with the screwdriver-operated switches and it was still more of a set-and-forget type processor. Nevertheless, there are quite a few engineers using it as mastering or mixing limiter, just because it sounds so nice and offers the perfect balance between "broadcast-clean" and "vintage-vibe".

Ever since I racked the first pair of 179-400 cards a few years ago, I've been thinking about a more flexible and user-friendly version tailored for the use as mastering and mixing processor. And after countless hours of simulating, measuring, testing and of course listening, I'm happy to present the final version.

Similar to the original there are the basic controls for 'Gain' and 'Limiter Level', but with finer increments of 1dB for more precise adjustment. The maximum setting for 'Limiter Level' is much higher at +22dBu, which is more appropriate for mastering duties. The 'Pre-Emphasis' is now adjustable to exactly dial in the increased sensitivity at high-mid to high frequencies, which is very handy for example to tame a harsh snare poking out in a mix. A completely new feature is the 'Style' switch, which can change the limiter characteristic from 'Soft' (with its associated 'Recovery' control) to 'Hard'. While 'Soft' is more or less how the original unit can be described, 'Hard' achieves a more aggressive and snappy sound with increased loudness which is often mandatory for electronic music and the like.

A visual feedback of the actual gain reduction applied by the limiter is provided by a 20-segment LED-meter with peak hold and a switchable range of 5dB or 10dB. Apart from a relay-based true bypass there is an additional 'Limit' switch, which only switches off the gain reduction but keeps the signal chain and the applied pre-gain unaltered. Furthermore, the sidechain signals of the two channels can be linked so that the stereo image remains intact.

The internal virtual ground voltage supply of the original cards is replaced with a dedicated low noise linear power supply to further increase headroom and signal to noise ratio. All rotary controls are stepped using Elma switches for exact recall of settings and decades of trouble-free operation.

[FOR SALE]
I have a small batch of these limiters for sale, if you are interested contact me for pricing or further details.

28/08/2025

The king (or queen?) of mastering EQs: Sontec MES-432D9, as far as I know the most sought after version with switchable frequencies for both shelving bands and 9dB gain range. A straight-forward interface, low distortion through the use of proprietary operational amplifiers and the 'built-like-a-tank' Shallco switches made this EQ a reference that all others are compared to.

Besides overall maintenance, this particular unit arrived in my workshop with some pesky defects. Most notably a non-working bypass circuit on one channel, which was a real headscratcher... But, all is good now and the unit can be put back into service for many years to come!

26/06/2025

The Lorenz ÜV300 (also known as V241) is a tube microphone preamp from the late 50s. It is often considered the East-German equivalent to the better known V76, since it was released around the same time. Circuit-wise they are completely different though, with the ÜV300 bearing some resemblance to the also legendary REDD47. Built to the highest standards it was a studio workhorse back in the days and it still is, provided that it is properly revised.
Guess what, that's exactly what I did to this beautiful pair I received from a client! And since amps like this deserve a proper home, I also built nice lunchbox-style cases for them. Vintage acacia wood, powder coated back panel and a dogbone leather handle are a really nice match. 😍 What do you think?