So why are clipping indicators not standard on amplifiers in 2026?

[Keith_W]

Can you suggest (link to?) low cost examples of such units for use per stereo pair? Low cost as in family meal out territory

@dualazmak can talk to you about how his VU Meters work. I'm sure he would be delighted to do so.

 

[john61ct]

@dualazmak can talk to you about how his VU Meters work. I'm sure he would be delighted to do so.

I look forward

So, for calibrating gain to ensure no clipping, for speaker protection with e.g. drunk teens using the system for parties

Is there a line level device to perform this function after the pre-amp?

Or do you need to measure something at speaker outputs?

 

[babadono]

do you mean a limiter? My set up includes a mixer that allows me to set .a max level on the main fader. Someone (any drunk, not just teenagers) can push the fader up as high as they want but the signal will only go as high as programmed. Then a few seconds later the motorized fader will go to that set level. The ghost in the machine. Also the active crossover has limiters but I have never had to use them in a home environment

 

[morethinkingcapacityneede]

I love the clip and temperature indicators on the Extron XPA 1002 that I started out with. Last year, I put some Hypex NC500MP modules into a box with a custom IO board, which breaks out the status signals to LEDs on the front.

The clipping indicator is more like an in/out signal difference detector, if you have signal in and also mute, the clip indicator comes on (see photo below of one of the NC500MP units).

 

[dualazmak]

@dualazmak can talk to you about how his VU Meters work. I'm sure he would be delighted to do so.

Am I called, because of my DIY-built 12-VU-Meter Array? If so...,

I designed/built my 12-VU-Meter Array, all compatible with IEC60268-17 VU ballistic behavior and high impedance (ref. here), indicating/showing total L&R line-level output and each of the multiple amplifiers' actual L&R SP high level outputs (at amplifiers' SP biding posts) in my PC-DSP-based multichannel multi-SP-driver multi-amplifier full-active audio setup.

All the VU meters are located in the end of the signal chains, I mean no through-output signal of VU meter is used for further audio processing, so that completely eliminating any sound degradation.

At least for me, I have little interest in absolute VU values, but I am much interested, and they are actually useful, in visually observing relative VU meter behaviors (which are carefully adjusted to almost proportional to actual room air sound pressure at my listening position) in my multichannel multi-amplifier audio system.

- My nostalgia and preference for large glass-face VU meters: DIY of 12-VU-Meter Array in multichannel multi-driver multi-way multi-amplifier stereo audio system: #535

- NISHIZAWA R-65 VU meter plus ATV205EXT VU amp board is compatible with IEC 60268-17 VU meter specification/standard: #545

- Dancing video of my IEC 60268-17 compatible large glass-face DIY 12-VU-Meter Array
_____Part-1: with "High Frequency Linearity Check Track" of Sony Super audio Check CD: #750
_____Part-2: with typical "Full Orchestra Music"-1: #751
_____Part-3: with typical "Full Orchestra Music"-2: #752
_____Part-4: with typical "Jazz Piano Trio Music": #753

- New video clips of dancing 12-VU-Meter Array (IEC60268-17 compatible) together with all the on-screen Peak Meters of audio software tools while playing reference/sampler music tracks by JRiver MC, ADOBE Audition 3.0.1 and MusicScope 2.1.0:
____Part-1: using a typical reference/sampler music track suitable for high-Fq (treble) transient music sound: #974
____Part-2: using a typical reference/sampler music track suitable for mainly checking and tuning of low Fq (bass) transient music sound as well as total tonality Fq-SPL balance all over 15 Hz to 22 kHz: #975

 

[john61ct]

The blinky lights are nice but I already have a pair non-accurate ones for that purpose.

I was hoping for reco's on a simple OTS cheap & cheerful gadget for occasional calibration purposes.

or a link to a HowTo just use say REW or an SPL meter for that purpose?

> Or do you need to measure something at speaker outputs?

do you mean a limiter?

I do have one I will be testing, picked up an Alesis 3632 cheap on eBay but again

> a mixer that allows me to set a max level on the main fader

Great, belt and suspenders!

If a Wiim is in the chain (not just one source) it includes that function

but in all cases, I am looking for advice on Howto set the level, besides "turn it up until it sounds crunchy then back off a little"

 

[Keith_W]

The blinky lights are nice but I already have a pair non-accurate ones for that purpose.

I was hoping for reco's on a simple OTS cheap & cheerful gadget for occasional calibration purposes.

or a link to a HowTo just use say REW or an SPL meter for that purpose?

REW+SPL meter does not measure clipping. Suppose you play a bass heavy track, your amplifier will clip much earlier and at lower SPL than if you played (say) female vocals obscenely loud. The only way is to measure at amplifier output. To be honest, the easiest way is to train your ears to detect what clipping sounds like. Go borrow a 5W amp and turn the volume all the way up, or go to Youtube and look for examples of amplifier clipping. If you can't hear it, then it doesn't matter*

* with the proviso that you don't melt your tweeters first.

 

[Roland68]

Yes. Seems to me to be the "emperors new clothes" of the hifi world.
I get that it's probably overkill for lifestyle things like Sonos etc, but for proper hifi gear, seems like a no-brainer to me.

Hate to use the dreaded car analogy, but it's kinda like a performance car without a tachometer.
Very odd.

The tachometer in a car isn't a true analogue to the clipping indicator in an amplifier. The point is that the available power isn't sufficient. When an engine reaches its maximum RPM, it doesn't mean the power is insufficient, but rather that the driver was too incompetent to shift into the next gear.

A true analogue would be a gauge in a car that lights up whenever the available power isn't enough for the amount of throttle input.
I've never seen anything like that!

Most clipping indicators don't work well or accurately.
A genuine clipping indicator can only function correctly if the incoming waveform is compared and analyzed against the outgoing waveform.
This would then be independent of impedance and frequency ranges.

 

[Chr1]

Sure, but I guess the analogy with the tachometer is that they are also there to prevent damage to the engine/speakers.

And personally I would rather have some indication that the potential for damage is happening. Better than nothing surely.

 

[Roland68]

Sure, but I guess the analogy with the tachometer is that they are also there to prevent damage to the engine/speakers.

And personally I would rather have some indication that the potential for damage is happening. Better than nothing surely.

That's exactly the point: the tachometer only tells the driver the engine speed; the rev limiter is there for protection.
But as I said, it's about power.

Most amplifiers don't clip anymore; instead, their output power is limited, especially Class D amplifiers.
An amplifier could only protect the speaker by overloading it if the maximum power output were limited.

Most users don't even understand what clipping is.
These days, speakers (drivers) are damaged by three basic processes:
- Excessive DC voltage at the amplifier output, which can affect all drivers. This is usually due to a lack of protection or a poorly designed protection circuit.
- Excessive power for the speaker, which in most cases affects the woofer first, both electrically and mechanically, but can also affect the tweeter, depending on its maximum power handling and crossover network. Midrange drivers are very rarely affected.
- Clipping usually affects the tweeters first, as the flattening of the sine waves results in excessive power being delivered to the voice coil.

In the last 15-20 years, I've rarely heard or read about damage caused by clipping, and damage from DC only really occurs when the amplifier is defective.
Most damage is caused by excessive overloading. This is easily recognizable by mechanical damage to the cone or voice coil, or by broken voice coil wires, even in tweeters. Of course, the voice coils can also burn out.
These days, we have many unsuspecting and inexperienced users who don't even know when or that they are excessively overloading their bookshelf speakers.
I've experienced this myself many times, and the mechanical failures of woofers, for example, KEF speakers, demonstrate this impressively.

Especially when used without subwoofers in AV systems, when watching movies, or in 2.1 systems without a sufficient high-pass filter, such speakers are often damaged by overload.
A built-in subsonic filter, ideally with an adjustable frequency to adapt it to the speakers, e.g. 20-50 Hz with a high slope, would be many times more useful, as it would protect the speaker and also delay clipping considerably.

 

[Chr1]

That's exactly the point: the tachometer only tells the driver the engine speed; the rev limiter is there for protection.
But as I said, it's about power.

Most amplifiers don't clip anymore; instead, their output power is limited, especially Class D amplifiers.
An amplifier could only protect the speaker by overloading it if the maximum power output were limited.

Most users don't even understand what clipping is.
These days, speakers (drivers) are damaged by three basic processes:
- Excessive DC voltage at the amplifier output, which can affect all drivers. This is usually due to a lack of protection or a poorly designed protection circuit.
- Excessive power for the speaker, which in most cases affects the woofer first, both electrically and mechanically, but can also affect the tweeter, depending on its maximum power handling and crossover network. Midrange drivers are very rarely affected.
- Clipping usually affects the tweeters first, as the flattening of the sine waves results in excessive power being delivered to the voice coil.

In the last 15-20 years, I've rarely heard or read about damage caused by clipping, and damage from DC only really occurs when the amplifier is defective.
Most damage is caused by excessive overloading. This is easily recognizable by mechanical damage to the cone or voice coil, or by broken voice coil wires, even in tweeters. Of course, the voice coils can also burn out.
These days, we have many unsuspecting and inexperienced users who don't even know when or that they are excessively overloading their bookshelf speakers.
I've experienced this myself many times, and the mechanical failures of woofers, for example, KEF speakers, demonstrate this impressively.

Especially when used without subwoofers in AV systems, when watching movies, or in 2.1 systems without a sufficient high-pass filter, such speakers are often damaged by overload.
A built-in subsonic filter, ideally with an adjustable frequency to adapt it to the speakers, e.g. 20-50 Hz with a high slope, would be many times more useful, as it would protect the speaker and also delay clipping considerably.

Thanks for the explanation. Does this mean that it should be impossible for me to damage a pair of Tannoy V12s using a Topping Mini 300? The Tannoys have a sensitivity of 97db, and made for 400W Programme, 800W Peak.
Due to their sensitivity, I have never had the Topping higher than about half volume which is plenty loud, but I certainly don't want to damage the speakers. This what got me thinking about the lack of clipping indicators.

Also, presumably this is only the case with modern Class D chip amps etc, and it's still possible to damage speakers by running Class A/Bs into clipping?

 

[DVDdoug]

Not hard to do. AD/DA DSP between preamp and amplifier.

It's easier than that...
It can be done in analog. About the simplest thing you can build with an op-amp is a comparator. The output state changes when the input is higher or lower than the reference. You could compare the output to input (after scaling with a voltage divider) or you can compare to the power supply, allowing for a couple of volts lost in the output stage. {The peak signal will never exactly match the power supply.)

When I built one, I used the power supply for the reference.

It's a little more complicated than a "standard" comparator and you need one for the positive-half of the waveform and one for the negative-half.

And there are "analog" chips that can stretch the pulse for several milliseconds (or a second) so you can see it.

 

[KSTR]

A genuine clipping indicator can only function correctly if the incoming waveform is compared and analyzed against the outgoing waveform.
This would then be independent of impedance and frequency ranges.

One of the simplest things one can do is to monitor the differential voltage on the (explicit or implicit) operational amplifier that most power amps resemble, or in more general terms, monitor the error signal. When it starts to sky-rocket, the amp cannot regulate the output anymore for whatever reason and the feedback loop opens.
Some amps have provisions to always keep the control loop closed even when running into (what looks like) voltage clipping, for these the monitoring is a bit more complex but still very low cost and effort.
And all the modern class-D chips and modules have proper monitoring means as well.

 

[KSTR]

As for human monitoring of speaker overload, the nose is a good sensor too, at least for ported speakers. When the port winds start to smell, it's time to turn the volume down ;-)

 

[john61ct]

REW+SPL meter does not measure clipping

OK, but my scenario is electronics that are capable of physically damaging my speakers long before clipping occurs at any stage in the chain.

So my request is for a HowTo make the judgment call as to what SPL point to limit input, whichever device I use to do so. Just a link would be fine, and from any member...

Given I plan to be able to measure many factors objectively, I hate to "just trust" my ears

 

[john61ct]

A built-in subsonic filter, ideally with an adjustable frequency to adapt it to the speakers, e.g. 20-50 Hz with a high slope, would be many times more useful, as it would protect the speaker and also delay clipping considerably.

I've read from credible sources, in order to get "max safe" SPL from my OG LS50s, the HPF / low end crossover to midbass couplers, should be 170Hz or higher.

 

[Chr1]

Can someone confirm that modern Class D chip amps should have inbuilt protection that prevents clipping?

If so, this is quite great news and quite a game changer for me.
Thanks in advance.

 

[john61ct]

I do not have much DIY skillz in soldering or electronics in general.

Is there really no OTS tool, reasonably priced?

As for human monitoring of speaker overload, the nose is a good sensor too, at least for ported speakers. When the port winds start to smell, it's time to turn the volume down ;-)

Unfortunately after contracting Covid several times I no longer have much sense of taste/smell

In case you were being serious.

 

[tineared]

Can someone confirm that modern Class D chip amps should have inbuilt protection that prevents clipping?

If so, this is quite great news and quite a game changer for me.
Thanks in advance.

It would not be wise to ask or answer such a broad question. Find an amp you're interested in and do the research and find out if the particular model you are looking at has the sort of protection circuit(s) you desire.

 

[DVDdoug]

So my request is for a HowTo make the judgment call as to what SPL point to limit input, whichever device I use to do so. Just a link would be fine, and from any member...

Limiting isn't necessarily better than clipping. As you turn-up the volume the peaks are limited (or clipped) but the overall average power still goes-up and it's the short-term average which overheats voice coils.

Limiting might be worse since the distortion is harder to hear.

Some kind of overall automatic volume reduction when clipping occurs (or when the average exceeds a threshold) could be helpful but I don't know if that exists.

It's all "statistical" and both amplifier power ratings and speaker power ratings are unreliable. And tweeters can't handle as much power as the woofer, etc. there is no "one number" answer.

Can someone confirm that modern Class D chip amps should have inbuilt protection that prevents clipping?

Amir's measurements don't show that. The distortion usually makes a big-jump upwards. You push the amp beyond its limits and it clips. Some amps tend to "soft clip" which is similar to limiting. Tube amps tend to soft-clip.