Sjöström Audio

http://douglas-self.com/ampins/dipa/dipa.htm
All sorts of distorsion forms are very well discribed here by Doulgas Self. Mr Self has also written a couple of books in the subject but I haven't read any of them. Beware of the huge page. It takes some time to download.
http://waltjung.org
This is Walt Jung's collection of downloadable pdf's. All of them are good reading about electronics and audio.
http://www.kukaudio.com/au/index.asp
Kuk Audio Co., Ltd is highly specialized in supplying a variety of high-quality components for audio amplifiers. They sell many kinds of amp-,audio-,guitar parts and others parts like this, for instance: Vacuum tubes,Tube sockets, Capacitors, Resistors...
http://www.tephrowelt.de/
This site is dedicated the cactus genus Tephrocactus, but also other species. <em>Very</em> narrow subject but if you this special kind of cactus, you can get some information here.
http://www.ezonaudio.se
Urban Erixon from north of the pole cirle in Sweden is a very skilled designer of audio. Power amplifers and DAC's are his thing. He is also very good in mechanics. Check out his enclosures.
http://sjostromaudio.com/pages/index.php/hifi-projects/122-qrv01-headphone-amp
Click on the picture to get a larger view. I designed this amplifier 1986 and I felt like publishing it now. The excellent MOSFETs from Supertex Inc are hard to get these days (not impossible) so therefore the amp needed to be redesigned a little bit...
http://sjostromaudio.com/pages/index.php/hifi-projects/124-qrv03-headphone-amp
This headphone amplifier design is based on a patent by Mark Alexander. It's a patented current feedback design. Design by Per-Anders Sjöström. You may take a look in the application note AN-211 from Analog Devices. Click on the picture to get a larger...
https://lokforaren.wordpress.com
Optimisten ser ljuset i tunneln. Pessimisten ser mörkret. Realisten ser tåget. Lokföraren ser tre idioter på spåret. A Swedish blog about driving trains.
http://sjostromaudio.com/pages/index.php/hifi-projects/129-qrv08-headphone-amp
Click on the picture to see a larger view of the pcb. The performance is outrageous in headphone amp terms. See the technical data! Interesting features: High speed, low distortion current feedback design. All discrete design of the amp itself...
http://sjostromaudio.com/pages/index.php/hifi-projects/187-dct03-the-dc-trap-high-end-style-heavy-duty
Click on the pictures to get a larger view. Do you have an amplifier with a (sometimes) buzzing toroid transformer? This DC trap or DC filter removes or at least lowers the buzzing. Interesting features: Room for up to 6 x 68000 uF snap-in high...
http://sjostromaudio.com/pages/index.php/hifi-projects/121-qrp02-the-smd-gainclone-high-performance-mono-power-amplifier
QRP-02 - The first SMD Gainclone amplifier in the world(?) Click on the picture to get a larger view. The world's frist DIY SMD Gainclone Specifications for the new advanced Gainclone. 50 um pcb with groundplane Fast recovery rectifier diodes...