Clip Indicator (LED) for Any Power Amp

Intro: Clip Indicator (LED) for Any Power Amp

A power amplifier cannot deliver an output wave wider than its power supply voltage. When you reach the limit, increasing gain may sound louder but sound will be distorted and can even damage speakers .This simple clipping indicator circuit will announce with an LED that you have reached that limit.

STEP 1: Circuit Diagram & Main Components

Q1 BC547 NPN transistor

Q2 BC557 PNP transistor

D1-D3 1N4148 diode

note: If your amp V+ voltage is higher than 45v use BC546/BC556 (up to 65v) or other higher voltage ones.

also increase R4 for a led current of 30mA. ( R=v/a )

STEP 2: Q1: Emitter Follower

STEP 3: Q2: Led Driver

STEP 4: C1: Peak Hold

For longer "peak hold" time increase R3 up to 100K

STEP 5: D1-D3 Voltage Drop

STEP 6: For More Datails, Watch Video. Thank You!

Comments

[TibiP2]

Hi. i have several volt dc at the input from power amp ?? should not be there . right ?

[nishantkundu18]

im using tda7294 bridge amplifier having 2 x tda7294 ....total supply input is +35 0 -35v dc ....so im getting peak voltage at output is approx 62v maximum.and this circuit blink LED on 48v ....circuit connected with positive and ground ....sensing one of bridge output .please help ....

[jessejanssen94]

This looks very nice, I read all the comments but I'm still wondering if there's some way to create this for a multi-output setup, so the question would be: Is it possible to create this for 3 amplifiers outputting audio to 7 speakers? (1 mono to sub, one 4-channel to 4 speakers and one 2-channel to 2 other speakers)

I'm mostly interested in the way on how it'll be designed around different setups, if it's possible I guess this would give options to create very nice clipping interfaces for people with audio in their vehicle.

Best regards,
Jesse

[bassblaster505]

I made it, I used the KSA992/KSC1845 as thats what i had on hand. seems to work. altho it doesnt react instantly, and is "hit and miss" as i scoped my amps output and it doesnt light on most of the flat tops. and it only lights if the clip is extended or is into a hard clip point, at which point the indicator is useless as you can clearly hear it clipping.

[MatīssB4]

Hello, take my schematics. Works so excelent as never!!!

[someloser]

Could I replace the x3 diodes with a single LED? As the circuit continuously drains several milliamps but putting a power indicator LED in there would put that current drain to good use especially when powered by a battery.

[simpletronic]

Hi! yes you can, but make sure the forward voltage (Vf) drop of the led is close to 2v. Lower Vf, and indicator wont light. Higher Vf, and the indicator will light prematurely.

in this chart you will find the typical Vf´s of different color leds.

Greetings & thanks!

[Filippo1980]

Ciao a tutti! Ho intenzione di costruire questo indicatore a clip ... Mi chiedevo se potevo sostituire i 3 diodi sull'emettitore q2 con uno zener in modo da poter accendere il LED 4-5 Volt prima dell'alimentazione V + Grazie a tutti!

[someloser]

Oh that's handy then, a green LED will drop around 2.1v which is very close to the 2.2v I measured being dropped by the diodes.

[livoto80]

hi guys. i can use this indicator for preamplifiers? thank you.

[Alexander4269]

Hello, I really liked your circuit but I need some help, I put it together and the led stays constantly on no matter what I do I'm connecting +12 to +of battery and +0 to -of battery and the middle (from output of amp) to +of amp output my amp is a Chinese board amp any help will be very appreciated as this project is my first electronics project and I really want it to work :) thanks

[Alexander4269]

The ic is a tpa3116d2 and here's a photo of it

[BobzB1]

Beautiful simplicity! I've integrated 2 of these on each channel of a 16 channel preamp I've made. (One for signal present and one for clip). I wanted low component count, self adjusting, no ic's and easily modded. This ticked all the boxes. Your a very clever man. This scheme is now in my catalog of go to schematics. Thank you so much for your contribution. Thanks to you my preamp is working hard in my band keeping all our mic signals clean and loud!

[codebeat]

Nice tut. Just wondering, in the 80's some speaker cabinets (see photo on the right side) got a overload indicator, any idea's how these work?

[codebeat]

Another one that got this feature, it is a passive speaker (like the other example), not an active one.

[BobzB1]

Zener and led in parralell with the input?

[JustasK1]

How to make amplifier limiter on relay, that turns off speaker then amplifier is overloading?

[BobzB1]

You could replace the led with an optocoupler and use that to drive a relay that switches a resistor in series with the input? Disconnecting the sub or power mid operation is very risky and could cause a lot of damage. I certainly wouldn't recommend it.

[AndrewM491]

Hi, nice work on your circuit design... few questions...

It would appear the LED is only lit while the output is clipping, if that is for fractions of a second then the led may not be visible... would i be correct to say adding a capacitor between the LED anode and the 0v rail will allow the led to stay lit while the capacitor discharges through the LED?

[BobzB1]

It seems to be the purpose of the electrolytic on the emitter of the npn transistor. The led is switched off by shorting it. So a cap added there would be drained instantly by the PNP transistor. My testing indicates a sufficient viewing time with the original values in the original design, but if you wanted the led to stay on longer, reduce the 100k resistor to maybe 47k.