Power Supply for Gary Galo's  Archival Phono Preamp

Gary Galo's article in Vol 5, "An Archival Phono Preamp" mentioned that a suitable power supply would be posted online - here it is.

It is based on the Jung/Didden regulator published in Audio Amateur in 1995, amended by Walt Jung's article in issue 4/2000 in Audio Xpress. The original articles can be downloaded from Walt's web site.
 

Gerbers and PCB layout for Bruno Putzeys' article in Vol 5

The article from Bruno Putzeys in Vol 5 'The G-word, or, how to get your audio off the ground' is accompanied by a complimentary PCB for the demo project (courtesy Eurocircuits.com). It's a busy PCB and to help with parts placement, a larger version of the stuffing guide, the top layer and the bottom layer is available here. The Gerbers can also be downloaded if you want to make your own.
 

Patrick K. (aka EUVL) wrote an interesting article for Vol 3, "Design Considerations for a Class A Amplifier Enclosure". This is an subject that is very rarely treated at all. The article gives a complete treatment of all involved issues and can be used as a procedure to calculate the required heatsink capacity for a project, as well as selecting a suitable product to mee those requirements. Therefor, Patrick and I have agreed to place it online for further dissemination.
 

Color graphs for Jack Walton's regulator article in Vol 4

Linear Audio Volume 4 has a long-awaited article by Jack Walton, comparing a large number of low power supply regulators. Comparison includes measurements and controlled listening tests by the New Jersey Audio Club.

The article has a several rather busy graphs with curves in various shades of grey. The readability could be better, so I regenerated those graphs in color and posted them here on-line.

Fig 5, positive regulators Line Rejection

Fig 6, negative regulators Line Rejection

Fig 7, positive regulators Output Noise

Fig 8, positive regulators Output Impedance

Fig 9, negative regulator Output Impedance

 
 

MathCad resources for the audio enthousiast

Update 5 July 2012: Mason Green send me some info on an alternative to MathCad/MatLab: Scientific Python. He included a link to an excellent tutorial on Scientific Python. For an example of a practical application of Scientific Python, see Mason's PORC (Python Open Room Correction) project. Thank you Mason!
 
There have been several articles in Linear Audio supported by MathCad calculations and graphs; Burkhard Vogel's articles come to mind. If you are the curious type you probably discovered that a MathCad license can set you back $ 1500 or so. Not really DIY territory. However, here's a well kept secret: the student/educational version of MathCad is available for less than $ 100 and is identical to the expensive version, the only difference being that you don't get on-line support. And you need a professor- or student ID to be able to buy that version.
 
But it gets still better: if you buy Brent Maxfields'book Essential MathCad for Engineering, Science and Math for less than $ 50 you get an included MathCad 15 one-year student license for free. And the book is a great reference to the application so you can do without the on-line support. For beginners, I recommend Stephen P. Tubbs' MathCad for Electrical Engineers and Technologists. This last book takes you in slowly with calculating and graphing things like the current in a C-R circuit, for example. Both books are highly recommended! Note: the Maxfield book was published in 2009 so I don't know how many copies are still on offer.
 

Audio files for Wurcer mic preamp article V1, V3.

The mic preamp Scott Wurcer developed in his articles in Vol 1 (Part I) and Vol 3 (Part II) were used to record a live concert at Stuart Yaniger's residence in Austin, TX in Nov 2011. I have placed two files online, and you can download them to listen to: the song 'An Army of Kittens' (a 15Mb (!) .flac) and a section of the subsequent applause (.wav). These are uncompressed files recorded in 24 bit / 96kHz.
 
These are excellent examples of the incredible realistic recordings that can be made with relatively simple means, with enough attention to detail.
Files are reproduced here with kind permission from the artist, Southpaw Jones.
 

Zen > Cen > Sen - Evolution of a Minimalistic IV Conversion Circuit

This is the online version of Patrick K (alias EUVL) article in Linear Audio Vol 2. This article has generated considerable interest at diyaudio and with the publication of Vol 3 I have decided to place this article online for free download. For further details and building experiences, see the diyaudio thread.
 
 

Everything about record replay characteristics, recording speeds and such.

This is not an article that has been published in Linear Audio, but I believe the data in the linked table is of importance to anyone seriously involved with record replay and reproduction, especially historical records.

The first reference is a comprehensive list of record manufacturers and speed formats and the pre-emphasis that has been used in producing the recording. It is clear that the ubiquitous RIAA pre-emphasis/ de-emphasis standard isn't really a standard, at least not in the early days of records.

The list has been compiled by Katsuyoshi Miguchi, the owner of SoundBox, an Antique Audio shop in Tokyo. It was originally published in Radio Technology magazine in Japan in October 2011. Reproduced here by kind permission of the Author and the Editor of RT magazine. I am indebted to Mr. Nakamura for arranging the permissions and for providing the English language translation.

If you have any additions and/or corrections to this table I would very much like to receive these, and I will update the list as needed. The last update will be noted at the end of the list.

The second reference is an article by Linear Audio author Gary Galo, who taught audio engineering at the Crane School of Music at SUNY, Potsdam. Gary wrote an article for the Association for Recorded Sound Collections (ASRC) on the Columbia replay equalisation curve.

The Association kindly agreed to place this article online. The powerpoint slides Gary uses for his presentations on the subject is also attached.
 

The F-Word - or, why there is no such thing as too much feedback

In Linear Audio Volume 1, Bruno Putzeys wrote  The F-word - or, why there is no such thing as too much feedback. He addresses many issues related to the use of feedback in audio, as well as several misconceptions. The section on 'slow' and 'fast' amplifiers will be an eyeopener for many. He also traces historical events that puts us in the situation we are now. A critical attitude towards negative feedback is certainly healthy, and Bruno gives us the information to base our opinion on.
 

The Arch Nemesis

The first issue of Linear Audio had an article by Nelson Pass inspired by a vintage Western Electric design, later revived by Jean Hiraga in the French journal L'Audiophile. It's a model of minimalistic design and I placed it on-line for you to read and/or build.  Nelson Pass - The Arch Nemesis (Vol 0)