Brilliant woofer testing hardware and software

Posted on March 26th, 2016 in Reviews,testing by Julian Edgar

This week I have been having a great time playing with speaker stuff. About a week ago I bought Woofer Tester 2 from the US, and I’ve since been blown away by what you can achieve with it.

But first, a step back.

If you’re into sound systems (either car or home), you’ll be well aware of the famed Thiele Small speaker parameters that are especially important when designing woofers and subwoofers. These parameters are the speaker specs that you plug into software (or an on-line calculator) to allow you to design the speaker box. That box design includes aspects such as internal volume, length and diameter of any ports, and so on.

Without the Thiele Small (abbreviated to TS) specs of the driver, you’re just guessing the box design – and the chances are overwhelming that your guess will be less than optimal!

So to design a good speaker enclosure, the TS specs are needed. Which is fine if you’re buying a new driver or one that is second-hand but still has specs available on it.

But what if you’ve sourced a speaker that is literally an unknown? For example, a quality driver from a late model car being sold off cheaply? Or even the speaker from a salvaged TV or surround sound system? (Don’t laugh: some of these consumer goods speakers are small and high quality – perfect for enclosures built into car doors or under seats. And people just throw these speakers away…)

In those cases, the driver’s specs need to be measured.

And, if you do a search online, you’ll find plenty of DIY techniques for measuring TS parameters. You’ll need a precision resistor, an AC multimeter that measures over a wide frequency range, and a frequency generator. And a lot of time spent doing very finicky measurements and plugging numbers into lots of equations. It’s certainly possible, but who wants to spend the time and effort doing all that? Especially if you’re sorting through a whole bunch of drivers to find one suitable for an application?

Well, now you now longer need to do so – just use Woofer Tester 2.

Woofer Tester 2 is a complete speaker test unit. This incredible piece of hardware plugs into the USB port of a PC or laptop and connects straight to the speaker under test. Open the software, press a button and within literally seconds many of the TS specs are measured. Do some more testing (eg by weighting the cone by a known amount) and the rest of the important specs are there in front of you – it’s that easy!

You can then import those specs into the provided Thiele Small program that will allow you to model sealed, ported and band-pass enclosures.

Build the enclosure, and then you can use Woofer Tester 2 to test it to see if it matches the predicted response. (Woofer Tester doesn’t include a microphone, so you cannot directly measure frequency response – but, indirectly [eg by impedance plots] you can get a good idea of what is happening.)

So does the system work? Does it ever!

So far, I have measured about 15 pairs of salvaged speakers. Picking the best of these, I have built two different types of enclosures to suit.

In one case, using just an 8 litre ported enclosure and a 5-inch woofer, I have clearly audible (and smooth) response down to 50Hz. In the real world, that’s a stunning result from such a small driver in a very small enclosure. Especially when the woofer (bought as a pair of second-hand speakers) cost $5!

In another case, I had some ex-Sony home surround sound drivers that were originally mounted in tiny (200cc!) boxes. For these drivers, I modelled and then built 2 litre ported enclosures, made from short lengths of 125mm heavy-wall plastic pipe, with MDF ends cut to suit. The drivers are just 3 inches in diameter (and have an effective piston diameter of only 2.4 inches) and yet in these easily built enclosures, sound very good indeed. I am thinking of using them as outdoor speakers for a BBQ area – they’d fit nicely under the house eaves.

Using Woofer Tester 2 hardware and software, you can now measure all those speakers for which proper TS specs are not available (and that’s almost all car sound speakers) and then model enclosures to suit. You can even build enclosures that work for individual drivers (useful, because even apparently identical drivers can have different measured specs).

I think that this approach represents a revolution in how bass / midrange speakers can be installed in cars, and how speakers can be sourced.

I paid US$160 for Woofer Tester 2 – and think it’s incredible value for money.

We’ll be covering in much more detail in AutoSpeed how to use the Woofer Tester 2 hardware and software, and what it can achieve in DIY speaker design and installation. But to say I am impressed is a vast understatement….

The Underwhelming Mercedes

Posted on April 2nd, 2012 in Driving Emotion,Reviews by Julian Edgar

While I don’t write new car tests any more, whenever I am interstate and have the opportunity to hire a car, I drive it with rather more than usual interest.

So the Camry Hybrid (by now the previous model) was a great disappointment (surely a 10 year old Prius is better in every real-world respect?); and a Hyundai i45 was scarcely any better (what happened to the great Hyundai promise exemplified by the i30?).

And what about the BlueEFFICIENCY C200 Mercedes?

Perhaps I am getting old, with all the implications in both perspective and experience, but I thought the car had a direction that was at times bizarrely stupid.

I have to start with the tyres. Here is a small – not compact, small – car that has simply enormously wide, low profile tyres. Is that good? Nope – not in 99.9 per cent of road driving conditions… in this country, anyway.

So what was the tyre size?

Try 225/40 on 18 inch rims – and that’s crap for ride, crap for fuel economy… and oh yes, great for absolute grip. Just what you need on lousy roads and in a country with heavily-policed, low speed limits – not!

So what’s this BlueEFFICIENCY tag? A hybrid electric/diesel maybe?

Er, no.

It’s a turbocharged 1.8 litre with heaps of torque down low (270Nm at 1800 – 4600 rpm – excellent) and a reasonable amount of power at 135kW. And all connected to a 7 speed auto trans – one that has such terrible gear-changing logic that a five-year-old Honda craps all over it from a great height.

Reads well on the spec sheet; performs poorly on the road.

But what about fuel economy?



Ten years out of date.

On my gentle country drives, I got between 7 and 8 litres/100km. And that’s just what the official government test specs say I should be getting. But isn’t that good? Nope, not if you’re driven anything with similar room that’s powered by a diesel, or by a hybrid.

Or, and this is where it gets ridiculous, even a 20 year-old small/medium car.

Cos the Mercedes had just Godawful interior space. I banged my head against the roof rail above the door several times (there wasn’t room to turn to look around) and at all times I felt myself to be in this little, squashed car.

More room in a 1980s Holden Camira? I’d think so.

More room in a 1960s Austin 1800? Without a doubt, vastly more so.

And then we go from the sublime to the ridiculous. This squashed little car weighs-in at 1470kg. Yep, just under 1.5 tonnes. No wonder the fuel economy is nothing to write home about…

Good aspects? Build quality, the sound system and….hmmm, I’d imagine safety. And I loved the self-tightening seatbelts.

More bad points? Yep, can think of lots of those – the steering vague around centre, the hard seats, the rebound damping that was so overdone it’s ridiculous, the lack of space… oh did I mention that last one already?

At AUD$65,000, why would you bother?

AutoSpeed in 2009

Posted on January 9th, 2009 in AutoSpeed,Opinion,pedal power,Reviews by Julian Edgar

It’s a new year – so what do we have coming up in AutoSpeed?

In short, it looks to be a great year.

First-up, we’ll be continuing our ‘How to Electronically Modify Your Car’ series. At this stage the series has about 15 parts – it may grow a little. By reading those stories, you can be taken from knowing literally nothing about electronically modifying a car to the stage where you can confidently make changes to analog and digital signals, and understand how car systems can be altered.

In the second half of the year we expect to cover an innovative development in DIY electronics that will put the power of making major, custom electronic modification of cars into the hands of everyone. It’s a development that has been more than 12 months of work in the making, and one that I think is enormously exciting. More on this as we get closer to launch.

What an absolutely crap car

Posted on November 13th, 2008 in AutoSpeed,Opinion,Peugeot,Reviews by Julian Edgar

Look, I’ve tried to like it. I’ve admired its quite brilliant fuel economy, and its generally excellent ride/handling compromise. I mean, I was even very positive in the new car test I did on the car when it was first released back in 2003.


And when this family bought one with our own money, it was with the (stated) intention of making it an AutoSpeed project car, in much the same way that we did with the Peugeot 405 SRDT.



But I need to be honest. I just simply hate the Peugeot 307 HDi – I think it’s a car that in many ways is just rubbish.


Now normally to support such a statement you’d have an extensive list of shortcomings in its driving performance. But in fact, the Peugeot largely drives very well.


One clear negative is its dreadful low rpm management mapping and/or turbo sizing: this is one of the deadest off-boost turbo electronic direct injected diesels you can drive, especially in hot weather.


(I just checked the date of my original new car test – published November so probably tested about September. Just on the edges of the Australian summer – but not into it.)


But otherwise, the steering is largely OK (well, it kicks back when driving really hard); the ride is good; the handling is adequate and the brakes fine.

I am happy to be biased

Posted on October 30th, 2008 in Driving Emotion,Opinion,Reviews by Julian Edgar

Many articles that I write are subjected to accusations of bias. For example, whenever a new car test appears, I will always see in our referrer’s list a discussion where someone calls me biased.

One dictionary defines bias as:

a particular tendency or inclination, esp. one that prevents unprejudiced consideration of a question

which, in the manner of dictionaries, takes us to a definition of ‘prejudice’, that includes:

any preconceived opinion or feeling, either favourable or unfavourable

Now as academic Grant Banfield makes beautifully clear in this piece, the only unbiased person is one who is fundamentally ignorant of the subject: if you know nothing about the subject, how can you be biased regarding it?

But, probably because it is so politically incorrect to say so, the corollary of that idea is not made by Mr Banfield: the more that one knows about a subject, the more one is likely to be biased.

And in my opinion, the more one can justify that bias.

Books to read…

Posted on October 14th, 2008 in Driving Emotion,Opinion,Reviews by Julian Edgar

I’ve done a bit of reading in the last few weeks – most of the books were bought secondhand.

Jet – the story of pioneer Sir Frank Whittle is penned by the man himself.

It’s always fascinated me how a relatively lowly officer in the Royal Air Force could, in the 1930s, invent the concept of the jet engine. After all, where were all the government scientists and private company researchers? 

Well, to cut the story short, and to paraphrase Whittle, they were largely just getting in the way of the engine’s development. I knew that Whittle had had some differences with the private company Rover, but that’s only a tiny part of the story. This book is submerged in the detail of gaining finance, fighting government backstabbers, overcoming ignorance – and trying to stop Rover inventing “improvements” (that never were) to the design.

And all in a time of world war, the country fighting for its life.

It’s an interesting story, told well.

Black dye…

Posted on November 2nd, 2007 in Driving Emotion,Opinion,Reviews by Julian Edgar

forever-black.jpgIf you own – or buy – an Eighties or Nineties car you’ll invariably find it has lots of black plastic exterior bits. Bumpers are the biggest examples but often there’ll also be side protector strips and rear vision mirrors.

And nothing looks worse on these cars than when the rich, deep black turns to a friable grey.

My Peugeot 405 SRDT is one of the breed with lots of exterior black plastic trim. And, especially against the white paint, the black-that-was-now-grey looked terrible. I tried some exterior trim restorer – a good brand of stuff, quite expensive – and it didn’t fix the problem. (But on another car, with rubber strips rather than plastic, it worked well.) So I went back to the auto parts shop and looked again.

What I came home with is pictured above – Forever Black Bumper and Trim Reconditioner. The on-box blurb says: “Permanently recolors and protects all black plastic, vinyl and rubber surfaces on your car without silicone”.

And now, having applied the stuff, that description seems pretty well on the money. Because you see, this liquid is basically a dye! You clean the surface with the provided cleaner (I must say that, having just cleaned the car, I didn’t bother using the cleaner) and then apply the liquid via a foam applicator, a bit like shoe polish. The instructions suggest masking off surfaces you also don’t want black, and I did a combination of this and later using polish to remove the excess that had got past the masking and onto the paint.

Grey, faded surfaces turn to a rich black – and if they don’t, you simply put on a second coat. It’s nothing like the other ‘black surface’ restorers I have used – although over the years I’ve tried only a handful so am certainly no expert.

The rear bumper of the Peugeot clearly needed less, so perhaps it had been replaced during the life of the car. The front bumper needed two coats.

The end result makes the car look vastly better, not just in that it looks less tired, but also in that the original designers’ intentions are now much clearer – the body visually ties together better.

I saw a Euro Barina on the road the other day – perhaps along with the Ford Ka the car most in need of black plastic restorer. But what made me notice the Barina was how good it looked – someone had spent some time with some black dye…

Will the VE Commodore prove me wrong?

Posted on September 26th, 2007 in Driving Emotion,Economy,Holden,Makes & Models,Opinion,Power,Reviews by Julian Edgar

ve-commodore.bmpMost of our Australian readers won’t be old enough to remember the release of the 1978 VB Commodore – and to be honest, at the time I wasn’t taking much notice of cars myself. However, it was common contemporary lore that the VB represented the new, small and modern family Holden while Ford, with the XD Falcon, persisted with the larger, outmoded type of traditional family car.

With the increasing price of fuel, it appeared that Holden was onto a winner with the Commodore.

But in fact they weren’t onto a winner at all: the VN model of a decade later went to a larger – especially wider – body, initially perched on the narrow track of the previous series.

Most pundits would have thought – and in fact did think – that Holden was heading in the right direction with their smaller original Commodore. It seemed the correct car for the times and in comparison, the face-lifted XC that became the XD looked like a big mistake. (In fact, a few years after this, I can remember looking at an open XD wagon and wondering who on earth needed a load area so enormous.)

But new car buyers didn’t agree with the smaller VB-VL Commodore strategy – Holden would have sold more Commodores if they’d stuck with the larger body all the way through.

Trying a new-fangled car wax

Posted on October 22nd, 2006 in Opinion,Reviews by Julian Edgar

Every so often we at AutoSpeed get sent some free items. Recently, book publisher Veloce has been sending books, and a few months ago Valvoline sent a sample of a new car wax called Eagle One Nanowax.

Most media have a ‘news’ or ‘new products’ page where stuff like this can be displayed but we don’t have either of those – all our articles are full length. So while the books have been reviewed either singly or in pairs as articles, I’ve been a bit unsure of what to do with the wax. After all, who is going to read a 1000 word feature article where some wax is applied to a car? Not me, that’s for sure.

The perfect glove box item

Posted on September 10th, 2006 in Opinion,Reviews by Julian Edgar

Over the years I’ve built and written about plenty of hand-cranked LED torches. The articles have appeared in Silicon Chip magazine (see Our Fantastic Human-Powered LED Torches for an example) and in addition to those covered in the articles, I’ve built plenty of other torches for personal use. But now commercial hand-cranked LED torches have become available – and some of them are very good.