e022012.pdf

ELECTRONICS ONLINE

Valve Amplifier Revival

return of the ‘warm’ sound

By Harry Baggen

Despite semiconductors being all around us, it seems that valves have

never lost their appeal and even enjoy increasing interest from the ‘all solid-

state’ generation. Among audio purists, valves have an excellent record for

natural sound reproduction. The Internet is full of DIY valve amplifier

designs, often complete with extensive description and photographs.

Despite the fact that semiconductors have

been with us for more than 50 years, there is

still a large number of audio lovers who pre-

fer the warm sound of a valve ampliﬁer over

that produced by a transistor rig. Setting

aside the air of nostalgia around valve ampli-

ﬁers and their ﬁne appearance, audio lovers

will insist that valves are winners when it

comes to sound reproduction with character.

Despite the mechanical and electrical pitfalls

encountered in the design and construction

of valve amplifiers, like exotic transformers

and dangerous supply voltages, thousands of

enthusiasts enjoy tinkering with valves. Some

do so with an innovative approach, while oth-

ers focus on constructional aspects and strive

to give their amplifier the best possible

appearance.

On the Internet, a veritable galaxy of pho-

tographs may be found showing home built

valve ampliﬁers. Once you start searching the

net for websites covering valves, the amount

of information is overwhelming. Besides true

hobbyists you will also find companies pro-

fessionally engaged in valve amplifier tech-

nology (still widely used in transmitters).

Other firms specialize in kit, ready-built

amplifiers or components. However these

websites will not be discussed here since our

aim was to see what was going on in the

hobby department!

A great starting point for your explorations

is the World Tube Portal [1], a website spe-

cialized in links to do with valves. Although

these links have been sorted alphabetically,

it is also possible to search in 105 categories.

Two of these links found under the

heading ‘DIY Tube Audio Sites’, DIY

Tube Amplifiers and DIY Tube

Audio Sites [2] are of particular inter-

est to hobbyists. Together these two

links cover about 150 websites.

Once you start visiting a couple of

the websites mentioned on the por-

tal, you soon notice that there is

much more to be discovered. We had

to make a selection from the vast

amount of information on offer, and

have to limit ourselves to a couple of

sites we found either particularly

attractively styled or rich in useful

content.

To begin with, we should recom-

mend Audio Bizarro from tube

‘fanatic’ Ralph Power. On his web-

site Ralph shows a lot of pho-

tographs of valve amplifiers [3],

which are a sight for sore eyes!

Some amplifiers are complemented

by a circuit diagram. However the

feature par excellence of Ralph’s

website is his set of guidelines for

Elektor Electronics

2/2002

ELECTRONICS ONLINE

building valve ampliﬁers. Of particular inter-

est are his extensive descriptions and care-

fully finished photographs that go with the

designs. There are also quite a few tips for

music to play through your valved stereo —

apparently Dick is a great fan of Mobility

Fidelity Soundlab.

Finally, two websites with lots of schemat-

ics of valve amplifiers from the past — an

excellent source of inspiration for new

designs! The British website The Circuit

Archive [13] holds an extensive archive of all

designs by Dynaco and Heathkit, which were

once famous for their kits. The schematics

cover a lot of valve designs.

The company Triode Electronics Online

[14] has a website with an extensive archive

of antique schematics. Most ampliﬁer brands

are found in the archives. If not, a link is given

to another collection of schematics on the net.

(025012-1)

newcomers [4]. On 14 pages, Ralph

tells you all you need to know to get

started with valve amplifiers for

home construction.

The hobby is international, too, as

we soon discovered. Bob Danielek

from the USA [5] designs and builds

valve amplifiers large and small. Of

the latter, the ‘Darling’, a super sim-

ple 1.5-watt stereo design, is fairly

well known. Another, more

unusual, design is a valve amplifier

for use in a car — Bob has actually

succeeded in fitting his sports car

with a small, valved amplifier incor-

porating a power inverter for the

high voltage supply.

The Japanese also have a soft

spot for valves and the relevant web-

sites we came across are often

marked by original ideas. Of the

many websites we came across we

should mention Explore the won-

ders of direct heating [6] which

describes the Sakuma principle.

The Canadian website run by

Rudy Godmaire [7] allows you enjoy

a visual impression of his beautiful

designs of 70-watt power ampliﬁers.

Rudy was obviously inspired by the

designs of Menno van der Veen, an

authority in the field and author of

the book Modern High End Valve

Amplifiers

valves can bring across musical lis-

tening enjoyment. Besides a descrip-

tion of his own audio system (using

a 300B single ended SRPP final

amplifier), his ‘Electronics’ pages

present a wealth of circuit diagrams

employing transistors, valves and

even hybrids. Here you will find

nearly everything you need for a

complete audio system, ranging from

MC preamp to power ampliﬁer.

Of German origin, Roehrenﬁeber

[9] by Ulrich Romanski offers other

valve amplifier constructors an

opportunity to present their design

on his website. Tuning tips are also

discussed, and there is an interac-

tive introduction into the basic oper-

ation of the valve.

The Dutch, too, have a reputation

to keep up when it comes to ‘all

things valved’. Aren’s Attic [10] not

only presents a description of two

ampliﬁers and a line ampliﬁer, it also

provides an excellent link list to

glance through.

For those interested in the

renowned Williamson amplifier

design, the web pages put together

by Bert van der Kerk [11] are worth

visiting. There, the construction of a

Williamson ampliﬁer is described.

Triode Dick’s page [12] is the

third but by no means least Dutch

website we should mention in this

article. On his homepages, Dick

reports on his own ventures in

Internet addresses

[1] World Tube Audio Portal:

www.worldtubeaudio.com/

[2] DIY Tube Ampliﬁers en DIY Tube Audio

Sites:

www.worldtubeaudio.com/

diy_tube_ampliﬁers.htm

www.worldtubeaudio.com/

diy_tube_audio_sites.htm

[3] Audio Bizarro Constructors Page:

www.spiritone.com/~tube/constructor.htm

[4] Building your own tube amp:

www.spiritone.com/~tube/ralphbuild.htm

[5] Bob’s Music/Vacuum Tube Audio/elec-

tronics Page:

www.geocities.com/TimesSquare/1965/

music_etc.html

[6] Explore the wonders of direct heating:

www10.big.or.jp/~dh/index.html

[7]Rudy Godmaire DIYer zone:

www3.sympatico.ca/r.godmaire/rg32e.html

[8] Claudio Bonavolta:

www.infomaniak.ch/~bonavolt/audio.htm

[9] Roehrenﬁeber:

www.roehrenﬁeber.de

[10] Aren’s Attic:

http://members.tripod.lycos.nl/Aren/

index.htm

[11] The Williamson Tube Ampliﬁer:

www.spiritone.com/~tube/constructor.htm

[12] Triode Dick’s Page:

www.triodedick.com/

[13] The Circuit Archive:

www.circuitarchive.co.uk/heath.htm

www.circuitarchive.co.uk/dynaco.htm

[14] Triode Electronics Online:

www.triodeel.com/schindex.htm

published by Elektor

Electronics.

Claudio Bonavolta [8] from

Switzerland is convinced that only

2/2002

Elektor Electronics

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