My first proper design of a speaker was the original Asawari. (What would I have said if you’d told me, in 2005, that I would build Asawari after Asawari? “Sure. Right. Another chai?”)
I wanted to build a 2-way design, it keeps things simple. A 3-way design is 10 times more complex. So I was looking at 2-way designs, and it was clear that you get two choices here: you either build a simple, smaller box, with one tweeter above and one midbass below (we call this a TM configuration), or you build a bigger box with two midbass drivers and one tweeter (we call this an MTM configuration, because there’s one midbass at the top, then a tweeter below, then the second midbass). If you build the smaller TM design, you need to make stands to keep the speakers on, so that they sit at the right height for your ears. This means the tweeter centre needs to be about 40” to 45” above the floor. I realised that the floor space would be eaten up by either config, the TM + stand, or the bigger MTM box standing by itself. And two midbass drivers will give me better, cleaner, more powerful bass. So, the MTM it was.
That was how the Asawari started. The two midbass drivers are of 6.5” diameter, and the tweeter is, well, a standard one-inch dome tweeter.
How the journey turned out
That first Asawari was the hardest. It’s like deciding “I’m driving to Goa for my vacation”, and then learning to drive on the trip. Every milestone took weeks or months to cross. (How much worse it would have been if this was a 3-way, I do not want to think.) My speaker guru practically guided me through baby steps most of the way.
The enclosure building itself was a journey of so many lessons learned. But what turned out at the end was a far more rigid, far more inert enclosure than the Wharfedale Pacific Pi-40. It was also twice as heavy. In the process, I learned what it feels like to work with a carpenter who thinks you’re a fool and he has 30 years of experience in woodworking.
Then came the measurements of the acoustic properties of the midbass and tweeter. (This stage has to be done after the enclosure is ready and you mount the drivers on the enclosure.) These acoustic measurements needed a mic, and I had no money to import an expensive calibrated mic at that time, so I made one with Angshu’s help using $2 Panasonic mic capsules. When the measurements were done, I tried dropping them into the crossover design software (we all used Speaker Workshop at that time) and realised that the crossover was not falling into place. So, I went hunting for help from forum members on DIYaudio, and Roman Bednarek, an ace designer in the US, helped me out with an asymmetrical crossover topology.
With a prayer and a lot of doubts, I made the crossover, and wired the speaker together, and the sound which hit me in the very first minute told me that I could leave the Wharfedales behind. I had to tune the sound to get the treble just right, which took a few weeks of listening and experimenting, but it was done. It went to a friend’s home and he used it for a decade.
Looking Back
The Asawari became my favourite configuration for a whole range of subsequent designs. The MTM design has some inherent positives. It is a sweet spot of high performance from a relatively simple design. As long as the owner does not mind a floorstander about four feet tall, he gets a beautiful speaker with the dynamics and impact no small TM standmount design can deliver. And with careful choice of drivers, you can get a sweet midrange which glues the listener to his chair. What is more, the Asawaris have less room echo, because they project their sound in a relatively narrow vertical beam, which means less sound reflected off the floor and ceiling, making the sound you hear cleaner.
I have realised that the choice of tweeter is critical in the Asawaris, because they need to be crossed over low, at 2,000 Hz or lower most of the time. Only some tweeters are sufficiently well built to take this punishment and still deliver clean sound.
It is only now that really good midbass drivers are becoming available which are tailored for 2-way designs, and yet are relatively easy to mate with a good tweeter. It was always easy to make Asawaris with poly cone and paper cone drivers, but then the clean, sharp, clarity of metal cones, specially on complex musical passages (heavy metal, symphony orchestra) was always a fatal attraction – and metal cones which can easily fit into a 2-way like the Asawari are a recent development. Watch this space.