Building a portable speaker system - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: February 04, 2017, 02:15:51 pm
content: hello everyone..I'm planning to build a small portable speaker system with 2 speaker(3W each) & a mono sub woofer (10w) & all this must be enclosed in a circular plastic container. I'm thinking to use the PAM 8403 (3W stereo) amplifier for the speaker but I don't have any idea about the sub woofer amp. Can anyone suggest me a 10w sub woofer amplifier circuit??, also I want to know that, will the sound from the system be balanced while using a 3W amp for speaker and a higher watt amp for sub woofer ??

author: Brumby
author_rank: Unknown
timestamp: February 04, 2017, 02:44:16 pm
content: Assuming a similar efficiency in the speakers, the lower the frequency, the greater the power required to provide a 'balanced' output - so you are heading in the right direction.A master volume would be used to control the overall volume of everything, but you would have a separate control on the sub volume to vary it and ensure the balance is right.

author: Audioguru
author_rank: Super Contributor
timestamp: February 04, 2017, 06:34:41 pm
content: The PAM8403 datasheet shows 3 Whats (with clipping distortion like crazy) per channel into 4 ohms with a 5V supply or 2 Watts at low distortion.Its maximum allowed supply is 6V but four alkaline cells will produce 6.4V when new. Four Ni-MH cells produce an average of only 4.8V so the max output at low distortion will be maybe 1.6W per channel.One rechargeable lithium cell at 3.7V will produce a low power that you can calculate.30 years ago my sound system for the beach sounded much better than all the boom boxes that were there. It used six C size Ni-Cad rechargeable cells producing an average of 7.2V and amplifier ICs that produced 6.5 low distortion Watts into the 4 ohm 4" woofer and 3.2W into each 8 ohm 3" satellite speaker.Diodes Inc. produce41PAM amplifiers but most are stereo. You might find amplifiers that use Chinese copies on ebay. Texas Instruments also make class-D amplifier ICs.

author: Adhith
author_rank: Frequent Contributor
timestamp: February 10, 2017, 05:31:06 am
content: But what about the sub woofer amplifier circuit?? can anyone help me ?? I have seen a circuit with TDA2030 but , it has higher output power. can anyone suggest me a circuit with 10w output.

author: Ian.M
author_rank: Super Contributor
timestamp: February 10, 2017, 06:32:20 am
content: A circular plastic container will probably sound horrible as it flexes and buzzes due to the bass from the subwoofer, unless ist really thick walled and rigid. By the time you've stuffed enough acoustic wadding into it and glued on random lengths of wood inside it to try to damp the resonances, you'd have probably done better to build a proper ported cabinet design in wood, and a ported cabinet will get more out of your limited subwoofer power.

author: jdraughn
author_rank: Regular Contributor
timestamp: February 10, 2017, 07:23:52 am
content: Have you chosen a specific subwoofer yet? One option for the subwoofer may possibly be to use a dual voice coil subwoofer and two 5w amplifiers. This amplifier module says 30 watts, but if you are only powering it from about 12v then you will probably only get about 10 watts of clean output.http://www.banggood.com/TPA3110-30W-8-26VDC-PBTL-Single-Channel-Mono-Digital-Audio-Amplifier-Board-p-1120350.html?rmmds=searchQuote from: Adhith on February 10, 2017, 05:31:06 am

author: Audioguru
author_rank: Super Contributor
timestamp: February 12, 2017, 01:30:17 am
content: Why would anybody buy a cheap Chinese Banggood audio amplifier that has absolutely NO detailed spec's?Distortion at rated power? Frequency response? Noise level? Hum rejection from its power supply?Banggood does not say or show the IC from Texas Instruments so it might be a poor quality Chinese knock off.Banggood says 30W PBTL and the recommended speaker impedance is 8 ohms. Know why? Because its maximum output into 8 ohms is only 15 Watts but is 30 Watts with a 4 ohm speaker when it over heats.