TangBand W3-1364 3" Monitor

This was a side project which turned out to be ok. I had a pair of Tangband W3-1364S 3" full-range speaker and a pair of Dick Smith bookshelf monitor box lying around.  I enlarged the tweeter hole to 7.5mm and closed the woofer with small mdf board.

- Coherent sounding due to no crossovers
- Somewhat acceptably clean due to low distortion above 70Hz
- Midrange, vocal is warm and glorious. Very realistic
- Small size
- Easy to make

- Low efficiency
- Box signature unavoidable
- Box quality is poor
- High-frequency beaming
- High frequency not sounding 'sublime'

It's ok... if I really want to serious playback I go to my living room for the cannons.

I use Dick Smith 5" monitor bought at ebay auction for $10. With the Tangband bamboo driver it was a lucky match! Ignore the magnitude, it's not a 100db efficiency but observe the driver rolloff which is then extended to about 45Hz by the port tuning. In fact this loudspeaker low extension is fine and I don't feel the need for a subwoofer. In my 3x4m room they are loud enough. The TangBand is flat up to a dip at 15khz but my measurement was not ideal as it was taken in front of the grill and there are diffraction effects. Also the drivers are not flush-mounted (yet).

Harmonics distortion measurement at 50Hz shows reasonable H2 and H3 at 100 and 150Hz. Ignore that peak at 5kHz as it is my computer fan noise being picked up by the microphone. First audible signal is heard around 40Hz. There is no audible sound at 20Hz (as it should) and 30Hz.

More comprehensive distortion measurement. At around 70Hz the 2nd and 3rd harmonic distortion drops to about 1% level which explains the average cleanliness of the sound. Most of the time H2 dominates which is normal cellulose cone behaviour and gives somewhat warm sound. H2 or 2nd harmonics is more pleasant than 3rd. I drive them with little Dared MP5 amps.

Photo of the dicksmith box. It is not well-braced and that's next on my to-do list. The measurement is:

Width: 160mm
Height: 330mm
Depth: 230mm
(outside measurement, panel thickness is 12mm)

Port diameter: 50mm
Port length: 110mm, flared on the outside

Closeup of the TangBand W3-1364 3" speaker. The cone is made from bamboo fiber and the chassis is cast metal (!). Very well made. This driver is highly regarded albeit the cost. See full review at ZaphAudio and his measurement results.

The measurement lab. As usual everything here are prototypes, temporary, and utilise anything available in the garden shed :)

Update 23/12/08

- Added Baffle Step compensation (BSC): 1mH parallel with 8.2R and connected in series with the speaker. Theory and design is here.

- Few attempts to add more damping in the box resulted degradation in sound quality. Better left alone and live with the colorations.

Update 25/5/09

- Blocked the port to make them sealed-box speakers. The bass sounds more realistic, albeit less extension.

- I spotted a very nice build of similiar small TangBand family here: http://attlid.eu/p_swift.html

Cheap and accurate speaker measurement

Measuring an oblate-spheroid waveguide, circa 2010

Never embark on a loudspeaker project without decent measuring tool. This is my set of tools to measure speaker performance. My criteria is simplicity and accuracy.

  • Sound Card
    Soundblaster Live! 24 bit - $60
  • Software
    ARTA. The demo is free and fully functional, except you cannot save files
    Alternatives: HOLMImpulse, REW (Room EQ Wizard), Speaker Workshop. All free.
  • Microphone
    DIY Panasonic WM-61A microphone - US$3 (plenty from ebay)
    Alternative: Behringer ECM8000

To utilise the WM-61A is quite easy. Electret mics all needs "phantom power" and the circuit is something like this, just need a 9-volt battery, 2k2 Resistor, and 10uF Capacitor (non polar). Of course if you want the real deal you can create something like SL's measurement mic or something like this.

The output plugs to left channel if USB DAC's "Line-in". On stereo 35mm connector it's the pointy bit. Mic's ground is the one connected to the body.

The finished product! ... I use chopstick to make it more tasty.

Close-up pic of the WM-61A. They're only like $3 a piece but very flat!

Download and install ARTA from this website, it's quite easy to use. For more functionality such as enclosure design etc. You need to use Speaker Workshop which is free, but very difficult to setup. I actually tried and gave up.

What I like to measure using ARTA are:

1. Frequency response. Simply point the mic to the speaker, choose "FR1" and click the play button. There will be pink noise heard and graph should appear. Something like this. In this case there were two measurements - the yellow line shows bass reflex port response.

2. Harmonics distortion - When a speaker is fed a tone, let's say 40Hz it should only sound 40Hz right? Well unfortunately no. There will be other tones heard as well and these are called harmonics. Ideally the harmonics should be none. The harmonics came in multiplies so for 40 Hz. ther will be:

2nd harmonics - 80Hz
3rd harmonics - 120Hz
4th harmonics - 160Hz

People say that 2nd harmonics sounds more pleasant than 3rd and above. To measure these harmonics, choose "SA" or spectrum analyzer then configure the generator to sine wave at the required frequency.

3. Harmonics sweep - this is similiar to the above, only that it is performed in sweeps. To do this quit ARTA and in the start menu there will be a program called "STEPS". Similiar to ARTA, run this and you'd get this diagram. In the example below it is clearly shown that the driver being measured performs best above 70Hz, where its harmonics are low. This is TangBand W3-1364 and with distortion of around 1% like that it's quite impressive.

So when all has been measured will the speaker sound good? NO. I view these measurements as a guide only, a debugging tool. Tranducer performance is much more complex than the above measurements.

But those who do not measure, don't know.

Update 2/7/09

I imported quite a few of these mics, and people have been asking for them. I'm always happy to distribute to fellow diyers, but there is none left now. Please do not ask me to send you the mic. And btw. a group buy at diyAudio or SNA may be the way to go (and do let me know if you organise one!)

Update 27/8/12
The microphone can be easily found in ebay:

Update 4/3/16
In 2015 I was asked to commission a pair of loudspeakers for Princeton University 3D3A project. I thought it was a good opportunity to compare my mic's measurement with purpose-built lab.
Fig 1: Backyard measurement using this microphone
Fig 2: 3D3A anaechoic chamber
Fig 3: Sonogram measurement using this mic
Fig 4: Sonogram measurement by 3D3A

Looking at the comparison it is clear that this seemingly simple microphone is up to the task!