• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

sync bass with subwoofer

Status
Not open for further replies.

hmrneves

New Member
Hello, I thing this is the right /r/ to ask this. I have a HTiB and I want to make 2 led strips with ~6 meters blink with bass. I have done some tests with my old subwoofer (logitech z5500) and I noticed that as the bass goes deeper, I got distorsions...

I have read that we can use an amp to store energy (? :S) but it could start a fire due the heat. Can someone help me? Obviously I can use the leds directly conected to the subwoofer and dont turn the subwoofer volume to high and everything will be ok, but I really want to make something cool and safe.

Regards and thanks!

The HTiB this an Onkyo HT-S9700THX, and the subwoofer is powered directly to current, the amp just pass signals. I thing this is called a pre-amp subwoofer, correct if Im wrong please.
 

audioguru

Well-Known Member
Most Helpful Member
What is "HTiB"? Home theater in Box? Did you connect the LED strips to the subwoofer speaker terminals? Are the LED strips designed for 12VDC?

The speaker outputs of an amplifier are AC, not DC. LEDs are made to be powered from DC, not AC and are destroyed and act oddly (causing distortion) when powered from AC, especially when its voltage is too high.
The peak output voltage of the amplifier producing 115W into a 6 ohm speaker is 38V which is much higher than the 12V the LED strip is designed for.
You need an LED driver circuit that gives 12VDC to the LED strips.

An amplifier cannot store energy, a capacitor and a battery can store energy.
 

audioguru

Well-Known Member
Most Helpful Member
12V LED strips from superbrightleds.com use 3.7W per foot. 6m= 19.7 feet and you have two strips so the power in the LED strips is 3.7W x 39.4= 145.78W if the volume is turned down. Do you see that all of the amplifier's power is lighting the LEDs and leaving no power for the speakers? Another problem is the audio AC being fed to LEDs that use DC. Then the sound becomes distorted and you are lucky that the amplifier is not destroyed.
You need an LED driver circuit that gives 12VDC to the LED strips. It will have its own 12VDC power supply.
 

hmrneves

New Member
12V LED strips from superbrightleds.com use 3.7W per foot. 6m= 19.7 feet and you have two strips so the power in the LED strips is 3.7W x 39.4= 145.78W if the volume is turned down. Do you see that all of the amplifier's power is lighting the LEDs and leaving no power for the speakers? Another problem is the audio AC being fed to LEDs that use DC. Then the sound becomes distorted and you are lucky that the amplifier is not destroyed.
You need an LED driver circuit that gives 12VDC to the LED strips. It will have its own 12VDC power supply.
Ok, I can use an external power sorce to led strip. After that, how can I catch the low frequencies of sounds that goes to subwoofer?
 

audioguru

Well-Known Member
Most Helpful Member
Ok, I can use an external power source to led strip. After that, how can I catch the low frequencies of sounds that goes to subwoofer?
146W at 12V is a current of 12A. A Mosfet can drive the LED strips but its gate needs +10VDC pulses. The pulses can be made from an attenuator/rectifier circuit made with a transistor or opamp and a diode circuit.
A problem will be that the LEDs will not light properly when the volume level is changed. Maybe the circuit should have an automatic or manual "LED threshold" control.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top