| Last update: 12/05/2016

Contacts and valve related links

These links are external. (mostly)

Checked: 11/05/2016

Contains (in no particular order):

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The Front Line

“Rodney! How goes the battle?”
“The situation is fluid.”
“What's that mean?”
“We're up the creek.”

Telemarketing calls at tea time are nothing compared to the torrent of advertising that sometimes gets thrust at you while browsing the net.

AVG Free anti-virus system is again available and effective.

Blocking ad's and unwanted parasites with a Hosts file. This method requires no software and saves me considerable time preventing unwanted and time-wasting browser-bogging image and animated ad downloads.

More software-related links for Web site building tools at the bottom of this page.

Notify broken or offensive links.
Submit a link.

OH&S Caution: Ingesting silver is not harmless. [offline]


Pickup secrets - an excellent in-detail look at how pickups work and can be tweeked. By Helmuth E.W.Lemme.

AC circuit theory

University of NSW, AC circuits, AC electricity, very clear animated diagrammes.
Educypedia[updated link] - General primer. Electricity: Basic theory, Electric circuit theory, Electrical power systems, Elektrische huisinstallatie, Electrostatics, General, Lightning, Magnetism, Miscelleneous topics, Safety, Tesla coil
MITOpenCourseWare Circuits and Electronics[new]
Sinusoidal_circuits_analysis Alternating Current (AC), Voltage, sinusoidal Waveform.

Excellent electronics theory site by Jim LeSurf, “Scots Guide”.

Complex numbers (R+jX)
Phasor digrammes can be used to represent voltages and currents in AC circuit analysis., and - RCL Series Circuits. We can understand AC circuits in terms of phasor diagrams.

On-line calculators for Acoustics, e.g...

  SPL - Sound Pressure Level	SPL addition	
  Ceiling speaker coverage	Time <--> Distance 	
  Frequency <--> Wavelength 	Air Absorption	
  dBu <--> dBV <--> Volt	Q <--> B/W (bandwidth)	

Valve load lines [updated link] - Vacuum Tube Theory, Tube Characteristics and Operation by LH-electric.
Spelling's a bit quaint in places but the theory's right on;
Valve curves and parameters Ra, gm, and mu defined.

How to “Screw Around” Your Tube Load Line a.k.a. A Day in the Life of the BOGUS “Circuit Designer” - Valve load lines with a thick humor coating for the maths-allergic.

Phase shift oscillators, A Wizard's Electronics Companion

Voltage controlled LFO's. A Single Pot Speed Control for LFO's - Univibe, Trem Face, and others.
The secret life of pots by R.G. Keen. This site is a “must” for any valve guitar amp freak.

Cathode-follower lo-Z drive and bias on 6L6 Push-Pull, circuit for Amplifier & Power Supply.
Phase Splitters - Cathodyne, Long Tailed Pair, Schmidt, Cross-coupled, Paraphase, Isodyne, Transformer.


For data on A+R and Ferguson transformers click here (local page).

Transformer theory at Educypedia

What does the Transformer Inductance do to the Load Line of a tube?
MagneQuest's Mike LaFevre on transformer design.

The M1115 100V line, 15W Speaker Transformer to Valve Push-Pull Output Transformer Application. An inspired observation by Paul Cambie discovered that a cheap 20W line matching transformer can be used as a valve output transformer, ultra-linear even. Suitable for a pair of 6V6's, and others.
Goto AVA page on the same topic (local)

The following links and references are an excellent collection if you really want to know about transformers. Some math is unavoidable for a full understanding, but a few basic concepts satisfy most needs. As a primer you need to have some understanding of the theory of induction - a coil in a moving magnetic field.

From: artyone c/- Yahoo ANZamps group, Date: Sat, 18 Sep 2004
ANZamps - output transformer theory and rewinding

* Transformer Basics, from Lessons in Electric Circuits[updated link]
* OT transformer design, here
* Gabe Velez, Transformers: here
* Pete Millett, Power Transformers for Audio Equipment: here (PDF)
* Rod Elliot, Transformers I, the Basics: here
* Rod Elliot, Transformers II , the Details: here
* Randall Aiken, Output Transformers Explained here

Oscilloscopes and their use Using an Oscilloscope. Understanding & Using Your (analog) Oscilloscope.


Operator Adjustable Equalizers: An Overview. A RaneNote covering Equalizer History, Industry Choices, Terminology & Definitions, Active & Passive, Graphics & Parametrics, Constant-Q & Proportional-Q, Interpolating & Combining, Phase Shift Examples.

R.G Keen on parametric and other tone controls. Simple, Easy Parametric and Graphic EQ's, Plus Peaks and Notches.

Adams Amps tone stacks, DI and attenuator pads, links. Overview, One Knob Tone Controls, Tweed Princeton, Moonlight, Garnet, 18 Watt, Two-Knobs, Fender “Brownface”, Blonde Twin, Baxandall, Three Knobs, Fender/Marshall, Dumble, Other.

Tonestack design normally requires either a lot of hairy maths or a lot of cut-and-try, but the simple concept of scaling can make the process easier.

For tonestack scaling try Guitar Amp Tone, Effects Placement, and Cranked-Amp Tone at Any Volume.

Serious EQ: a very dodgy scan of the circuit of a Marshall JCM900 Series reverb preamp.

Odd waveform power measurement (SMPS's etc), Hall Effect sensors.

Reverb line links

Reverb circuit from an old Anzac amp from Reynolds-Valveart

Note: is offline, however the Delft reverb circuits can still be found on the AVA Reverbs page. (local page)

Spring Reverb Unit For Guitar at ESP logo
Hardware design, PCB's may be available.
This really is a really well organised site by Rod Elliot with lots of content, circuits for amps, effects, test, and lighting; and articles discussing amplifier design points in a sensible and understandable way.
*** Must visit once ***

Building Your Own

Big Stromberg PA amp circuit, lots of big valve circuits multi KT88 etc.
This tube-amplifier is of the push-pull kind (“Williamson”-style). It uses a 12AX7 (ECC83), a 12AU7 (ECC82) and two KT88 tubes per channel. The output-power is about 50 to 60 Watts per channel. The schematic (thanks to Claudio Bonavolta!) of this amp was first published in the book “An Approach to Audio Frequency Amplifier Design” by the General Electric Co. Ltd. of England in 1957, they called it the “88-50” (KT88 / 50 Watts).

More KT88's from Claudio Bonavolta's site.

Plate Reverb. Reverberation plates were used in Ye Olde days. How To Build Your Own Plate Reverb by Bob Buontempo.

MIDI PIC projects. DIY MIDI Controllers using PIC Microcontrollers and Basic Stamps by Ross Bencina.

Discover Circuits, a resource for engineers, hobbyists, inventors & consultants, is a collection of 7000+ electronic circuits or schematics cross-referenced into 500+ categories to find quick solutions for electronic design problems.


Amateur Science by Bill Beatty - lots of great links to the cool and wierd, such as a schoolies DIY drink can Van de Graff generator; shock waves in traffic flow.

High voltage fun, DIY lightning, and other high voltage/current extremism from Aron and Justin's Lab.
Caution: Popups!

If you like doin' stuff then you will be interest in a good toolkit. Adam Savage from the Mythbusters has a very well developed set of toolkits. I like their attitude - a combination of very practical physics, and finding answers to suicidal questions like “Okay, if a gallon of petrol won't shoot a person out of a drainpipe, how much explosive would it take?”. This is how real Amateur Science is done, and in a workshop most of us would die for. I still think their Chinese Rocket Chair launch is one of the most amusing things I've ever seen - truly spectacular failure. Amp freaks should keep a particular eye out for their “Brown Note” and “Shattering Wine Glass” episodes.

500kW transmitter valve pix complete with chorus line.

Lord Kelvin's water-drop high voltage electrostatic generator. Another good science project.
If charge Q = C x V, what happens when you suddenly reduce the capcitance of a charged capacitor?

DogZilla by Fred Nachbaur, a 6 x 807 guitar amp from Germany. A good example of rigorous valve design and good construction techniques (but how does he ever get it to a gig?) Several other amps including tiny and Hi-Fi.

Jori's Home Built Stuff, a Dutch hobby builder of speakers, bass, guitar and Hi-Fi, stomps, and lighting effects stuff. He likes vented enclosures.

Pete Townsend gear history.

Technical data

NJ7P valve datasheets including many collected operating conditions not found in conventional databooks. (except KT88). My first port of call for valve data.

Duncan Amps has another good 'TDSL' Tube Data Sheet Locator. Note this has little actual data itself but presents a number of links to those who have. (including KT88), circuits, links, homebrew. My second port of call for valve data.

Electronic Vacuum Tube Reference Manual and Specifications from the RCA Receiving Tube Manual, some valve theory. The theory chapters are compulsory reading for anybody intending to design with valves (downloadable as images). I have a real copy of this on my bookshelf, in a bag to keep it together. Seriously useful.
Caution: watch out for the circuits on this site, they contain several errors.

Frank's Electron Tube Pages, valve datasheets (European lists). Frank also has vintage test gear manuals and circuits.

EL36/6CM5: Applications in Audio - in-depth information about this valve and its application to audio by Paul Cambie, an in-depth valve freak.

Valve guitar amplifier circuits:

Larry's Schematic Heaven “Where all good designs await resurrection... Schematic Heaven as gone ACROBAT !!!” Dead since 21-Oct-2010. However their are reports that you can still get circuits at the Wayback Archive.

The Fender Amp Field Guide (left hand pull-down menu for models) really is your first choice for Fender circuits; and archive of original circuit scans for almost every amp Fender has made.

Ampage - the original web community for music electronics enthusiasts. Homebrew gallerys, Forums, Reference, Buy/Sell.

Dr Tube - a modest collection of some interesting (bass)guitar tube amplifier schematics.

General advice

I'm a technician. I fix things. I've taught other people how to fix things. I get a charge out of sharing what I have learned. If you want to fix things, then spend some time at Sci.Electronics.Repair FAQ.

Tube Amplifier Debugging pages by R.G. Keen for the fairly non-technical musician. Recommended.

GM Arts - Good looking, well organised, fairly non-technical and straight-talking valve amp site aimed at guitarists.

Philosophy and Theory

ESP logo
Articles discussing some of the hotter guitar amp topics, trying to get some light among the smoke and mirrors.ESP

Doug Self on subjectivism in audio, and other outstanding articles on amplifier design.
Solid state but rigorous and insightful engineering with no crap.
Home of the “Blameless” amplifier. Notable contributor to Electronics World, UK. (a.k.a. Wireless World)

What's wrong with hi-fi reviewing (and hi-fi in general). Applies to electric musicians as Hi-Fi techno-mythology creeps into band equipment via recording studios. A bit long and specific, but contains lots of lessons. Read this for vaccination.

Tone Lizard
Exploring the vintage myths and voodoo legends of tube guitar amplifiers!
Valve and amplifier tutorial. Many mods (concentrating on Fender circuits, but widely applicable).

Sound science you should know

Musical Acoustics - Some Introductory Pages including sections on String, Woodwind, Brass, and Percussion topics. Clear informative graphics.

Educypedia entry on Fletcher-Munson equal loudness contours.

Tone Stack Calculator[update] free from Duncan Amps - a simulation that is both useful and fun to play with.
[New: 3/11/06]


A really good place to learn about magnetics.

Great basic development of B/H curves

Good magnetic circuit theory page at Monash Uni - offline
I've hunted to re-establish this one. Was at;
If you stumble accross it, please let me know.

Art Ludwig's page - Acoustics, room acoustics, cabs and bracing. Rigorous experimental work and an excellent source of information.

Dummyload 'artificial speaker' circuit for design development work

Speaker impedance, Z

Stethoscopic Examination of loudspeaker cabinets.

Reflecting on Echoes and the Cepstrum: A Look at Quefrency Alanysis and Hearing. Not mis-spellings, but a different way to look at signals. A third dimension after the time and frequency domains. The first domain is time and the CRO showing amplitude-time; the second is frequency an the spectrum analyser showing frequency-amplitude; the third cepstrum which is the spectrum of a spectrum. This is also applied in listening to aircraft gearboxes in real time and warning of impending failure, even identifying which tooth on which gear is chipped or the bearing which is chattering or growling.

Time, Frequency, Phase and Delay in speaker systems.

Internal Structure Construction Tips for Speaker Cabinets and other road worthy cases: an interesting muso-run site (Swedish)

Loudspeaker bin plans including some horn designs and a good set of links.

Shavano - Good how to build a normal guitar speaker box.

Dancetech - 2x15 folded horn which should suit some bass players.

“World's most powerful bass cab” - uses a rotary servo drive[offline] motor coupled to two cones.

Since this link has gone off line, here is what I've got;

ServoDrive Bass Tech 7


Manufacturers Take: This loudspeaker system incorporates a unique, patented operating principle involving the substitution of a high-speed rotary servo-motor and belt-drive system for the conventional loudspeaker voice coil/magnet transducer system.

Designed by Tom Danley over a decade ago, the BassTech 7s provide higher SPLs when used in groups (two, four or six) than almost anything else. Features include low harmonic distortion and virtually no output loss due to power compression.

Frequency response is virtually flat to 28Hz. The BassTech 7 is an efficient system that requires comparatively low power for full SPL output.

The servo motor-driven belt design increases linear excursion and handles large LF peaks without damage or sonic compromise. Website and literature specifications are guaranteed to meet product performance.

Our Take: The first serious LF system that didn't simply rely on size and brute power. The manufacturer promises us that the current belt-drive mechanisms don't require extensive user maintenance. If you ever get to a place where these can be heard, you owe it to yourself to feel them.

Speaker boxes at Duncan Amps.

Don Leslie's rotary speaker systems - definitive site from an old hand.


Grouse Guitars - Neil Rote. Previously “Real Note Guitars”. A lovely collection of pictures of many classic amps in stock and previously sold. One of AVA's highest referers and well worth the occasional visit. Many thanks to Sven Langebeck Sven Langebeck
of Warehouse Sound Systems for kindly allowing the use of his system at times to maintain these pages.
PA hire, design, installation and all sound system service.

32 Rokeby Street Collingwood VIC 3066
PO Box 130 Fitzroy VIC 3065
Phone: +61 3 94174866

Ian Rumbold, a respected technician experienced in valve guitar amp repairs is available in-house.
Ph: (03) 9419 3251

A very big thank you to: Brad Coates at MelMusic for the use of many of his fine photos of classic vintage gear, a band equipment historian in his own right.

521-523 North Rd., Ormond. Vic. 3204
Ph.(61-3) 95782426
Fax.(61-3) 95785112
Specialising in value for money NEW Instruments & Equipment for both the beginner and the Pro musician, plus a wide range of Secondhand gear. Vintage Specialists- including Vintage Spare Parts.

RØDE microphones . I've used one of their “low-end” mikes for band recordings and the difference in fidelity compared to even a good “name” dynamic is obvious. Voices sound more like the person, and the noise floor seems to be quite a bit lower. I have reservations about the valved models until I try one, but in these days of mega-hype it's good to be able to honestly say that these are expensive and slightly fragile, but the couple I've used really do deliver obviously better vocal fidelity.

Reynolds amp
Modern reproduction classic guitar amp continues the retro-that-never-was line, but this not only looks great, it looks like it can actually deliver the goods too.

But where do you put your drink? I reckon the top of a gigging amp should be like a hard plastic flight tray with drink holder, ashtray, songlist clip, pen holder, and guttering around the edges for spills. ;)

WES Components - excellent mail order service, repair trade supplier of cheap valves, speakers, and general components. They sell a range of high-power and efficient Chi-1Dai instrumental speakers, 8, 10, 12, and 15-inch. Experience with more than a dozen of the 12's in direct radiators and horns has been very satisfactory, and inexpensive. Valve and speaker data (as PDF's).

WES say they don't exchange faulty valves and semiconductors, which is fair enough. A while back I got a batch of EL34's and one came out of the box with a white getter. Sigh. So I sent it back well packed with a note suggesting Sovtek might like to have a look at it, not expecting to hear any more about it. This week a replacement turned up. I can only assume Sovtek found it leaky somehow. Given the fragility of valves and their terms of trade I think this was more than fair of them.

Jaycar Electronics - excellent mail order service but I've had goods damaged due to insufficient packing. While they are excellent about returns it's still a waste of time and parts. Good range of general components, poor range of valves and fairly expensive (see WES); now stock 9-pin and octal valve sockets and high voltage electros.

Altronics in Perth, WA, and extending into eastern states - similar stock range and prices to Jaycar. Factory and building PA specialists. Carry a range of 100 volt line tranformers that are suitable as valve output transformers. Very quick replacement for one that went AWOL in the mail (a very rare event for Australia Post in my experience). Read my article on this application here (local).

A (rather limited) directory of Australian valve suppliers

Melbourne realspace links

Music Swop Shop

The ever helpful and patient Brian and staff at:

The Music Swop Shop,
145-147 Elgin Street,
Carlton, Melbourne 3053.
Phone: (03) 9348 1194
11am-6pm Monday-Friday
11am-3pm Saturday-Sunday. (musos hours ;-)

...who share my enthusiasm for old valve amps, understand my need to take photographs of them, pull them apart, and generally act like this sort of disruptive stuff happens all the time.

A pre-loved music shop run by musicians for musicians. Going a long time. I've bought stuff from them because they actually do understand about meeting your new instrument or amplifier - zero pressure. As a browser I have always felt welcome and totally un-pressured, and even jammed with other browsers at times. Where I found my Tele.

Friendly and helpful Paul Paul and staff at

Sullivan's Secondhand
296 Smith St.
Collingwood 3066
Ph: 9417 3223

...who also understand musicians, and who dragged out a long forgotten Strauss Mouse for me to photograph and generally pull apart. Where I found my DX-7. Generally have a few selected guitars, and in playable condition. Where I found my $100 knockabout Strat copy.

Harmony Central logo
Harmony Central equipment reviews
one of the few sources with any information about Australian amplifiers. Large database of musical equipment reviews by users, tending to more modern and US gear. [updated: 25/12/10]

Ampwares Fender circuit archive. Fenders were a favorite for homebrewers to copy, particularly the tone stacks.

Vox Amplifiers.

Missing Links

Tandy/Radio Shack/Realistic. The first sign of electronic realism is when you stop shopping at Tandy. Boners include power diodes for zeners, wrong-band TV antennas for the region, VHF-CB antennas for HF-CB use.

In urgent need of some RF coax a fellow tech and I were examining their cables and comparing their merits at a regional store, shield covering, impedance, dialectric, velocity factor &c. Finally the franchise owner who had been quietly attending us said “There are three people in town who know what you are talking about - the two of you, and someone driving through.” And that sums up Tandy.

DSE - Dick Smith Electronics. The second sign of electronic realism is when you stop shopping at DSE. After Tandy, generally the most expensive and poorest quality component stock range. Poor mail-order service; finally had to write to the CEO to get a refund on an unfilled order that had been placed in the “too hard” basket.

Last, and in this case, least...

Cash Converters - If you want to pay over new price for second-hand crud then you can't go past Cash Converters, particularly in Smith St, Collingwood.

Experience 1: bought a rack mount mixer for my keyboard pit for $100 (down from an original $250), but they tried to tell me the AC plugpak they offered was suitable when it would have blown it to hell if I hadn't known better.

Experience 2: browsing the guitar rack with a fellow muso during a rainstorm when we felt splashes of water. Looking up, the roof was leaking and raining on all the guitars (half of which are missing strings, and they won't let you even touch them without a staff member hovering over you - utterly useless and grossly overpriced).

Be warned that other second-hand dealers use Cash Converters as a dumping ground for their dead stock like Savage amps and guitars with warped necks.

They don't know, and they don't care.

If you really want to buy something from a Cash Converters store do your research so you know what a reasonable second-hand price should be before you go back to the store (e.g. The Melbourne Trading Post), and stick to it. At least be sure of what the item is worth to you (as in experience 1), and walk if they won't meet your price.

Caveat emptor - let the buyer beware.

AVA was first found by a human-moderated Search Engine called Varoosh! based in Canada, now sadly defunct; and once listed there quickly spread to the others.

Dogpile is a meta-search engine that searches other search engines. Slow, but provides a good overview of where your site is listed.

I use and recommend Google and Wikipedia. I use Yahoo! mail but I'm unhappy with the general slowness.

If you've got down to this point and you really still haven't found what you are looking for, then try here.

Please let me know when you find
a good site or page
a broken or offensive link
- thanks.

That goes for ad-ware, viruses, pop-ups, and any other unfriendly activity as well.

And for when you're totally bored, some names for your favorite search engine:
Fleming, Lee de Forest, Lodge, Baxandall, Williamson, Linsley-Hood, Nyquist, Gauss, Thevenin, Kirchoff, Fletcher-Munson, Armstrong, Doug Self, Eccles-Jordan, Haas, Sabine, Puckel, Miller, Claud Shannon, Shockley, Blumlein, Butler, Clapp, Colpits.

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