This is another project made after detailed study of acoustics and dynamics of the sub woofer. The system is a 2.1 sound system intended for use with TV, PC, RADIO or any multimedia device .The motivation behind making this device was the thirst for a system with a deep and good bass and ease of access.
Construction Materials: 19 mm MDF boards (For construction of Sub Woofer) ,1 inch nails, Wood Glue 500 g, Basic Carpentry Tools, One Sony Sub woofer(I managed one from a spare parts store in Lamington Road Mumbai), Two 4 inch Speakers (Sony Xplod Car Speakers two way),Laser Printer for printing PCB on Magazine Paper,FeCl3 Solution for etching PCB, Small Drill Machine for Drilling holes in PCB, Hand Drill.
Construction of SUB WOOFER Enclosure : There were a lot of Choices for making the subwoofer enclosure such as sealed box, ported box, vented box, dual port box, etc.
All enclosures have their pros and cons, so going with the ease of availability of construction materials and entry level woodworking skills, I decided to go with a Ported Box. The first thing required for construction of a subwoofer are the measurements (inner).
The dimensions of the subwoofer enclosure is decided by the Thiele Small Parameters of the sub woofer used. My subwoofer was a Sony Home Theatre Model: Davis 10.
Since there was no available data of TS Parameters for the above Sub , I had to calculate the TS Parameters with the help of a testing Jig .
The detailed tutorial on finding TS Parameters can be found on Sound.Westhost.com an excellent resource by Sir Rod Elliot.
I am sharing the complete TS parameters calculated for the Sony Davis 10 home theatre (in case any body of you might have found the same at Lamington Road market).I do not know the correctness of the TS params, but the sound real and deep punch.
The software for calculating the sub woofer parameters I used is AJVENT.
Using TS Parameters the calculated volume of the Sub Woofer came out to be 55 Ltrs.
The equivalent Dimension of the box for required volume decided was 12″*15″*18″ with a port of Length 9 inch and Diameter 3 inch.
Construction of Circuit: The Circuit required for the 2.1 system needed to be a 3 Channel Amplifier with Bass and Volume Control. For this I used an already available existing circuit on the internet from Mirley. Firlej with some modification in component Values to tune it according to my Amp. The circuit comprised of a complete pre amp circuit with Pre, Buffer ,Control and Gain Stage using 4 NE5532 ICs.
The schematic and circuit for the same can be found out on Mirley.Firlej.org .
I used TDA 2050 instead of the specified TDA 2030 in the above circuit for mods in values of components seen in the Datasheet. The final constructed circuit was somewhat like this.
The above circuit is currently not having the Amplifier IC TDA 2050 and NE5532 , as it was beeing tested. The Satellite speakers were installed on a normal enclosure sealed box .
Some of the Test Bench Pictures of the Assembly are as shown:
Power Supply: The power Supply reqmt for the above circuit as seen from the Datasheet of the TDA 2050 were, 25-0-25 V Dual Voltage Power Supply with a current Rating of 4 Amperes.
The four leg diode was used for the bridge rectifier and a centre tap transformer at a local shop was ordered a 25-0-25 for 4A rating.
BOM:The bill of Materials as made is also shared for your Reference.
The final system looked like this with a bit of brass on it.
For any queries : pl contact me at sulabh@sslabs.in