The Bhoopali

The genesis

A friend heard the Asawari and said he'd like me to build something for him. He said two magic sentences which made me light up.

  • He would like me to experiment, and didn't mind taking a few risks, where the financial risk would be just his.
  • He was not in a hurry.

So I embarked on another project. This too is unfinished.

This is work in progress, unfinished.

My friend has one constraint. He does not want floor standers, though he wants deep bass. Therefore, I'll build a pair of stand-mounts, and a separate subwoofer. Those of you who have read my note on sat-sub systems know my views on good sat-subs. The Bhoopali will therefore have fairly large standmount speakers, each being a TM. There will be a separate sealed subwoofer enclosure with two large side-firing woofers. I am considering using one of the locally available cast-frame 12" pro woofers, and using one pair of them in twin-opposed configuration, each facing outwards from one side of an enclosure. They will be crossed over quite low with the stand-mount units, probably at 80-100Hz. I am not too worried about the driver T/S parameters because I expect that with suitable measurement and Linkwitz Transform, I'll get them to behave well enough.

The standmount units will use the Peerless India SR10DT fabric-dome tweeter, and the old Bolton 16SJW22 6.5" poly-cone midbass drivers. These drivers are often used in two-way systems, and can comfortably reach below 50Hz. Therefore they will be able to reach 80Hz in a sealed enclosure without any problem. I will use the Linkwitz Transform to make them deliver a Qtc of 0.7 at the lower cut-off point.

Why these drivers? I want to use drivers which I either have or can procure easily, and these drivers will be easy to work with. They have benign characteristics, and can mate well at about 2.5KHz, fourth order.

I am thinking of an active-passive crossover for this three-way setup. The subwoofer will of course have an active low-pass (I'm thinking LR4 electrical) and LT, and probably two power amps for the two drivers. The standmount units will have an active high-pass and an LT to feed the power amps, and the outputs of these power amps will feed a passive crossover for the midbass-to-tweeter split. Therefore, I'll be able to use two pairs of power amps for the entire setup.

Like any other active speaker system, this will be a longish project because there is so much electronics involved.

This too will be a project accessible only to Indian builders, because these drivers are not available outside India.

Next: Enclosure

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