Last couple of weeks I was busy with upgrading my acoustical measurement kit. Lot’s of new and interesting (I hope) content. First, there is a main article “Measurement Microphones & Calibration” were I talk about my particulate tools and how I calibrated them. Then I made a separate tear-down of Dayton EMM-6 measurement mic and reverse engineered it’s schematics. DIY section got updated with useful tools for acoustical measurements. These include microphone holder, calibration chamber and 1kHz calibration. All schematics and 3D design files are included if anyone wishes to reproduce them. Happy reading!

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Another story about unfortunate purchase of a friend of mine. It has all the right ingredients for a good novel. Unpretentious beginning, developing suspension, death of the hero and a sudden plot twist with a somewhat happy ending. It unfolded somewhere around year 2014 and took a while to come to a conclusion. I hope you will like it.

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This is the story of one particulate Vifa speaker that means a lot for me. It marked the beginning of my journey to the wonderful world of acoustics. I decided to write this article as a commemoration of a 15 year anniversary. Happy reading!

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Finally. After almost 5 years I managed to find enough time and write this article. It was quite a journey for me personally and I enjoyed every minute of it. Having HPM-100 on my test bench was a very old craving of mine and it finally happened. I included a lot of technical analysis and developed a new cross-over. Hope this benefits those of you looking to buy this legend or just upgrade it. Cheers!

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Another DIY project that I finished recently. This was a really, really long time coming. It took me more time to finish it then I anticipated originally, but after all said and done – I’m pleased with a result. Expect more tube action from now on!

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Although there is still bunch of content to publish in other category’s I decided to make a new one! (I know , I know…) So here it is – DIY.  Why? Because for a lot of what I know and can do today in audio, I’m obliged to numerous DIY communities all over the internet. Sites like diyaudio,  troelsgravesen,  passdiy,  linkwitz etc. are the reason, why I got interested in audio hobby in the first place, so this is my way of giving something back.  Here you will find all kind of projects  and articles (not necessary audio related) that didn’t made to the audio gear sections. Also added first article about Simple Li-Ion battery charger that I made recently.

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And winter is here! Time to crank up those sweet vacuum tubes for heating and get back to audio projects. There was a couple new additions to lab equipment over the summer that deserve at least their own post.  Also there are few diy projects for publishing in the pipeline, and of course my regular programing of restoration write-ups will resume shortly after, so stay tuned :)

This is a second article of the series, and here I will make a small overview of the design and engineering decisions, made by senior NAD engeneer Bjorn Erik Edvardsen, when designing this particular stereo amplifier and their impact on sound quality. There is also some usual measurements included at the end, for factory compliance specs check.

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In this article, I will walk you through another restoration of an classical stereo amplifier. Some small fixes took place as well as upgrade to a new volume resistor attenuator and full blown overhaul, including recap and idle current setting.

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This is a second article about this beautiful Japanese piece of engineering. It has a short model history and brief technical overview of used circuitry and components. Also you’ll find a comparison to it’s little brother – KA-7300 and some basic measurements.

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