Acceptable levels of distortion?

[Affray]

Hi,
I would be grateful if someone could give me a rough guide of what is generally considered an acceptable level of distortion from the speakers for a sub, mid bass, mids and tweeters please?

Unfortunately I damaged my speakers today by briefly sending well over the rated wattage to the speakers in a moment of stupidity, and I only picked it up as a result of the speakers just sounding off. Read a lot about distortion which helped me to find out that I hadn’t been lucky, trouble is, it’s made me all rather nervous about distortion now

Lots of guides saying high distortion is bad, but lots more saying that you will always get distortion from speakers, with very few if any saying what an acceptable level is other than its lower for tweeters and higher for the sub.

Click to read more...

 

[CarAudio.com - Hal AI Bots]

Hi,
I would be grateful if someone could give me a rough guide of what is generally considered an acceptable level of distortion from the speakers for a sub, mid bass, mids and tweeters please?

Unfortunately I damaged my speakers today by briefly sending well over the rated wattage to the speakers in a moment of stupidity, and I only picked it up as a result of the speakers just sounding off. Read a lot about distortion which helped me to find out that I hadn’t been lucky, trouble is, it’s made me all rather nervous about distortion now

Lots of guides saying high distortion is bad, but lots more saying that you will always get distortion from speakers, with very few if any saying what an acceptable level is other than its lower for tweeters and higher for the sub.

It's great that you're seeking to understand distortion levels in your car audio system, especially after experiencing some damage. Distortion is indeed a crucial factor in sound quality, and different speaker types exhibit different tolerance levels for distortion. Here’s a rough guide to acceptable distortion levels for various speakers:

### Subwoofers
- **Acceptable Distortion Level**: Up to 10% THD (Total Harmonic Distortion) can be acceptable, especially at higher volumes.
- **Notes**: Subwoofers are designed to handle low frequencies and can tolerate more distortion compared to other speakers. However, if you notice a significant drop in sound quality or a “farty” sound, it's a sign you might be pushing it too hard.

### Mid Bass Drivers
- **Acceptable Distortion Level**: Ideally under 5% THD, with less than 1% being excellent.
- **Notes**: Mid bass drivers bridge the gap between low and mid frequencies. They should produce clean, punchy sound without noticeable distortion.

### Midrange Drivers
- **Acceptable Distortion Level**: Around 1-3% THD is generally acceptable.
- **Notes**: Midrange drivers handle vocals and instruments and should reproduce sound accurately. Distortion here can lead to a muddy sound, which is undesirable.

### Tweeters
- **Acceptable Distortion Level**: Less than 1% THD is ideal.
- **Notes**: Tweeters are responsible for high frequencies and should produce clear, crisp sound without any harshness. Even small amounts of distortion can be noticeable in the higher frequency range.

### General Tips
1. **Gain Management**: Always set your amplifier gain properly to avoid sending too much power to your speakers.
2. **Listening Tests**: Trust your ears! If something sounds off, it might be worth checking your system settings or speaker integrity.
3. **Use Quality Equipment**: Invest in good quality speakers and amplifiers that are rated for your intended use.

If you're concerned about your current setup, it might be worth consulting with a professional to assess any damage and ensure your system is properly tuned to avoid future issues.

Feel free to ask more questions or for others to chime in with their experiences and advice!

 

[Jimi77 Premium Member]

Clipping distortion is the problematic one. Clipping distortion literally over powers the speakers.

 

[shredder1 10+ year member]

Having a system is a learning process, how far can it be pushed? Clipping is ALWAYS the culprit when finding limits. Trust your nose and intuition when jamming out. Even $700 of Deaf Bonce tweeters and mids and $4K of Apocalypse subs can be killed on less than RMS. You question is kinda nebulous and vague as user error is something that can't be corrected only taught or learned.

Most will tell you to set levels some kinda way but when you get that bug the clipping light is your friend. Learn why its there. I reconed about a driver a week but it came from demoing and Spl runs... or showing off.
I didn't care as a recone was $200 or so. That was then and now I'd be a bit more conservative with the clipping light now.

Clipping a clean signal is bad, amplifying a clipped signal then going full send is bound to cause failure. 6-5 and pick em'... dealers choice... haha. Best you can do is find clipping at the HU then user error becomes a thing...

 

[Affray]

Thanks for all the replies lots for me to read through and think on.

I damaged the speakers because I changed the head unit, and took the volume up to max to work out the 75% rule and to test how clean the unit was with a SMD DD1, but forgot to reduce the volume down again before reconnecting to the amps. As both the old and new output 5v, I wasn’t too worried about setting the amp gains until I had a bit more time and was just going to run things quietly until then.

I don’t know how much volts/watts I put through the amps/speakers, but it was well into clipping area. Thought I had got away with it, but everything just sounded off. Started looking at ways/signs a speaker can be damaged, and looking at old rew readings, and the rest is history. Discovered in old readings that I was hitting 3% on the sub and 5% on the tweets which became 10% after the error, now they need to be treated with a pinch of salt as the reading weren’t taken correctly, but it was enough to explain why the tweets had never sounded right.

More I learn, the less I realise I know, so really appreciate the help

 

[Affray]

Having a system is a learning process, how far can it be pushed? Clipping is ALWAYS the culprit when finding limits. Trust your nose and intuition when jamming out. Even $700 of Deaf Bonce tweeters and mids and $4K of Apocalypse subs can be killed on less than RMS. You question is kinda nebulous and vague as user error is something that can't be corrected only taught or learned.

Most will tell you to set levels some kinda way but when you get that bug the clipping light is your friend. Learn why its there. I reconed about a driver a week but it came from demoing and Spl runs... or showing off.
I didn't care as a recone was $200 or so. That was then and now I'd be a bit more conservative with the clipping light now.

Clipping a clean signal is bad, amplifying a clipped signal then going full send is bound to cause failure. 6-5 and pick em'... dealers choice... haha. Best you can do is find clipping at the HU then user error becomes a thing...

Hi shredder,
fully except that it was vague and nebulous (good word, had to look it up), as I didn't know what to ask.

I have thought of a few questions since, though.
I'm I right in saying that the measurement mic should be pointed directly at the speakers (not pointing to the roof) and should be about 3 to 4 feet away from the speaker or should it be at the listening position or closer?

Should the REW settings be left at default in the distortion window or do I need to change something?

The last question is how can I reduce any distortion?
I have set the amps with a voltmeter and confirmed with SMD DD1 that there is no clipping from the amps, and I now know that the crossovers were set too low on the tweets. I've add so much sound deadening that it's affected the acceleration of the vehicle (its a commercial van so not really an issue vs noise improvements), and I have stuffed polyfil behind the mids and tweets (need to do the same with mid bass) to reduce standing waves. Anything else I can try?