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The Best of Audion & Horn speakers design

A couple of very interesting books

[Italian version]

Title: The best of AUDION
Editorial project: Luciano Macrì
Publisher: Demidoff C.P. 47, 50020 Romola (FI)
Tel +39055827292 fax +390558277528 - http://www.audion.net
Language: English

Title: Horn speakers design
Editorial project: Luciano Macrì
Publisher: Demidoff C.P. 47, 50020 Romola (FI)
Tel +39055827292 fax +390558277528 - http://www.audion.net
Language: English/Italian
Web site: www.audiolamp.com

AUDION is an interesting Italian journal edited by Luciano Macrì treating all kind of topics related with tubes and tube amps, including speakers especially suitable for tube amps.
By the way, several designs published by AUDION are also available as DIY kits.
Even the two books we are talking about are strictly connected with these areas. The origin of the two books is rather different though.

The first one (The best of Audion) is an anthology of articles taken from different issues of the magazine. It contains several interesting, original designs, ranging from preamplifiers to speakers.

The first article is a study for the design of a high efficiency, high sensitivity speaker to be used with tube amplifiers. The study leads to a definitely not so common solution, a closed, two ways, 110 litres tower, with two Dynaudio Esotar woofers and a Dynaudio Esotec tweeter. A closed box is perhaps a weird solution for a tube-oriented speaker, but personally I find it a good one, if a high enough efficiency can be achieved.

Next you can find a low cost, simple tube pre-amplifier, named Easy Pre. Here too the solution is not the most common, an active RIAA, actually, is not frequently found these days, but it is a quite classical one. The tubes are the usual ECC83 and ECC82.

Then it follows an analysis of a super-classical tube design, the Loftin-White direct coupled amplifier; various implementations and a proposal for a new one with the 2A3 direct heated triode are described.
Then comes a study about driver stages for direct heated triodes, with an analysis of distortion performances of the different configurations and a possible way to reduce it is described.

A single ended triode amp, named "Russian Panzer", featuring the PT49 and the 6C33 Russian tube can be found next.

To end with, Her Majesty the 300B direct heated triode appears in two implementations, a mono single ended amp with PT8 in gain stage and 311 as driver and a two stage dual mono amp with PT49.

Each article is complete of all required data and schematics. As I said before, most designs can be supplied as DIY kits; often even separate parts are available on request.

What I find specific and typical of Audion is a deep knowledge of good 'ol days designs and the capability of proposing new designs based on this knowledge. Taking into account that a lot of knowledge about tubes and tube systems design has for sure gone and lost, this is a very commendable perspective. The Best of Audion is a good example.

The second book, Horn Loudspeakers Design, is based on an article by Jack Dinsdale published in 1974 on Wireless World.
The author starts from the beginning and studies the evolution of knowledge about horn speakers.
Then there is a rather in depth presentation of the theoretical principles of horn speakers; flare of the horn, ways to "size" the mouth area, wavefronts configurations, efficiency and tuning of the throat cavity are the topics treated in this section.

A section related properly to the design of a horn follows. Here the concepts defined in the first section are treated from the point of view of the designer. Even the effects of the environment and of the folding which in practice is necessary to obtain manageably sized boxes are discussed.

Finally a couple of boxes are proposed; one is a no compromise, very high quality and complexity system; the other is a far simpler "mini-horn", suitable for listening also in small rooms (please note, just to set the correct size scale when talking about horn speakers, that the "mini" one is just 125cm high, 75 cm wide and 48cm deep... the big one actually is 125 cm high, 168cm wide and 100cm deep! That's not my idea of small room, I'm afraid...).

All topics are developed and treated from a strictly technical point of view, with plenty of diagrams and tables.

The book closes with some notes by Paolo Viappiani, a very well known Italian hifi journalist and loudspeaker expert and a good number of horn speaker schematics (mainly Lowther).

A 3" floppy disk is also included, with software by Giampiero Matarazzo that can be used to design one's own horn: even though any horn can be designed by hand, with a computer program things are far easier. The software is really straightforward and easy to use.

The book gives interesting, clear and detailed information, and is highly commendable if not definitely necessary for anyone who wants to design a horn speaker.
Please note anyway that, due to the difficulty of finding any information related to horn speakers, this text is even more important.

Summing up, two books that, given their specialisation, are perhaps not strictly necessary for everyone interested in HiFi systems, but are nearly mandatory for anyone concerned with tube systems.

© Copyright 1999 Giorgio Pozzoli - http://www.tnt-audio.com

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