Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 15 hours ago, blakey72 said: Now I thought I knew what clipping was but am now not so sure. 1. So what exactly is clipping? Clipping should be called 'Voltage limiting'. It refers to a point where an amplifier can no longer deliver a clean, undistorted signal to the speaker, because it has reached the Voltage limits of the power supply. 15 hours ago, blakey72 said: 2. How does it occur? See above. 15 hours ago, blakey72 said: 3 Does the wattage of the amp have anything to do with it? Yes. There can be mounted a credible argument to suggest that amplifiers are rated rather poorly, such as: '100 Watts @ 8 Ohms'. A better rating might be: '30 Volts RMS and 10 Amps RMS'. Or something similar. An amplifier rated to deliver 100 Watts @ 8 Ohms, delivers 28.28 Volts RMS. Or 40 Volts peak. If the amplifier is required to deliver (say) 41 Volts peak, then the amplifier will clip (or Voltage limit). 15 hours ago, blakey72 said: 4. Can clipping damage tweeters/woofers or both? Clipping is normally associated with damage to HF drivers, not bass drivers. However, ANY driver will be damaged if it's thermal or excursion limits are exceeded. Clipping or not. 15 hours ago, blakey72 said: 5. I read that clipping is a myth. Is this true Nope. It is a physical limitation of any amplifier. 15 hours ago, blakey72 said: I look forward to your replies. blakey72. I'll post some oscilloscope photos and post later with a longer explanation, because amplifier clipping is not equal amongst all amplifiers. 4
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 Good post ZB
Batty Posted February 3, 2017 Posted February 3, 2017 I remember early NAD amplifiers having 'soft clipping' I am guessing they introduced clipping slightly before running out of volts to soften the plateau. I am only guessing though.
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 6 minutes ago, Batty said: I remember early NAD amplifiers having 'soft clipping' I am guessing they introduced clipping slightly before running out of volts to soften the plateau. I am only guessing though. Correct. The trick with modern, high global NFB amplifiers, is to introduce a system to prevent the output devices from 'saturating'. NAD did so by introducing a 'soft clipping' system, which gently limits the signal before it reaches the output stage. Such systems have been used in pro equipment for a very long time. The downsides with such a system are: * Significantly lower ultimate output Voltage (power) available. Typically, a 100 Watt amplifier with soft clipping, might be capable of (say) 130 Watts with the soft clipping switched off. * NAD's soft clipping system introduces subtle distortion characteristics at much lower levels. Many listeners report that NAD amps sound better with the soft clipping switched off. 1
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 Ok I have a question. If the input signal is clipped (eg due to excessive "loudness" in the mastering), can this damage speakers even if the amp itself is not clipping?
Tasebass Posted February 3, 2017 Posted February 3, 2017 16 minutes ago, Zaphod Beeblebrox said: * NAD's soft clipping system introduces subtle distortion characteristics at much lower levels. Many listeners report that NAD amps sound better with the soft clipping switched off. ...bit like a mysterious hand grabbing the amp by the balls and saying..."now do as you are told"... I had a NAD 2400 amp that always sounded "less restricted" with the soft clipping off!! ....but does save your speakers though.. Tase
Tasebass Posted February 3, 2017 Posted February 3, 2017 5 minutes ago, Sir Sanders Zingmore said: Ok I have a question. If the input signal is clipped (eg due to excessive "loudness" in the mastering), can this damage speakers even if the amp itself is not clipping? Mmm..methinks.. if you crank the amp then i guess yes..but.. if the distortion is in the signal and is being "amplified" by the amp at a low output surely not.. clipping occurs within the amp when its running out of steam... Tase
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 (edited) 19 minutes ago, Tasebass said: ...bit like a mysterious hand grabbing the amp by the balls and saying..."now do as you are told"... I had a NAD 2400 amp that always sounded "less restricted" with the soft clipping off!! ....but does save your speakers though.. Tase Sometimes. Way back when I sold NAD products (the mid-1980s), I also sold KEF. In those days, KEF and NAD were distributed by Falk Electrosound. The KEF 104.2 was released with much fanfare, due to several innovative design features. One of those features (not particularly new, but new to KEF) was the use of ferro-fluid cooling for the tweeters. KEF claimed that the driver was virtually indestructible. It was certainly tough. It was one of the few speaker systems I sold which never came back for tweeter replacement. Right up until a client came in with his KEFs. He had blown BOTH tweeters, using his, then new, NAD 2200 amplifier. The 2200 was the first NAD product to use their 'Power Envelope' system. In reality, this fancy name was a system that allowed the output stage to draw energy from a high Voltage power supply, when the music demanded it. All well and good, as it allowed NAD to claim a 6dB dynamic headroom figure. IOW: A 100 Watt continuously rated amp could deliver 400 Watts on transients. Again, all well and good. Right up 'till the user played the amp VERY hard. At this point, the high Voltage power supply is exhausted and the amp is now clipping VERY, VERY hard. Much harder than one would normally expect. I'm certain alcohol was of enormous assistance. Falk rejected the warranty claim on the basis that the amp was clipped. Right up until I explained that the amp was a NAD. They approved the warranty. I never sold another Power Envelope product. Edited February 3, 2017 by Zaphod Beeblebrox 1
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 1 minute ago, Tasebass said: Mmm..methinks.. if you crank the amp then i guess yes..but.. if the distortion is in the signal and is being "amplified" by the amp at a low output surely not.. clipping occurs within the amp when its running out of steam... Tase I'm specifically interested in the situation where the amp itself is not clipping but the signal being amplified is clipped.
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 11 minutes ago, Sir Sanders Zingmore said: Ok I have a question. If the input signal is clipped (eg due to excessive "loudness" in the mastering), can this damage speakers even if the amp itself is not clipping? Well, it depends on the thermal limits of the drivers and how much power is being delivered. The business of a small amp doing more damage to speakers than a large amp, is slightly over-stated. A large amp is capable of delivering more energy across the frequency range and is thus capable of doing damage as well. 4
Batty Posted February 3, 2017 Posted February 3, 2017 (edited) Sound wars ! for FM radio sounds what you are referring to Sir. Edited February 3, 2017 by Batty
Tasebass Posted February 3, 2017 Posted February 3, 2017 1 minute ago, Zaphod Beeblebrox said: Well, it depends on the thermal limits of the drivers and how much power is being delivered. The business of a small amp doing more damage to speakers than a large amp, is slightly over-stated. A large amp is capable of delivering more energy across the frequency range and is thus capable of doing damage as well. Only if you tax the amp Trevor..??
Tasebass Posted February 3, 2017 Posted February 3, 2017 8 minutes ago, Zaphod Beeblebrox said: . I'm certain alcohol was of enormous assistance. Yes ..well we've all been there methinks.... ( cost me a retip on a Garrott P89 once.... )
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 Just now, Tasebass said: Only if you tax the amp Trevor..?? Nope. A big amp can deliver more power across the entire range. I will attempt to post some oscilloscope shots, along with some FFT shots a bit later if I can. They will explain better than I can. I should say that a small amp, heavily clipped can do damage. No doubt about it. But so can a large amp (unclipped). It just depends on the thermal limits of the drivers. I recall reading about the KEF KM1 speakers. These speakers were internally amplified and used ferro-fluid cooled HF drivers. The magnets used were oversized and employed cooling. Even so, the magnet temperature could reach 100 degrees C safely. 1
Tasebass Posted February 3, 2017 Posted February 3, 2017 3 minutes ago, Zaphod Beeblebrox said: t. But so can a large amp (unclipped). It just depends on the thermal limits of the drivers. When its warm as has been in Sydney just recently all my gear gets turned off... Not worth the risk IMO ...thanks for the confirmation Trevor.. Tase.
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 Just now, Tasebass said: When its warm as has been in Sydney just recently all my gear gets turned off... Not worth the risk IMO ...thanks for the confirmation Trevor.. Tase. LOL! You left out the smiley.
Tasebass Posted February 3, 2017 Posted February 3, 2017 2 minutes ago, Zaphod Beeblebrox said: LOL! You left out the smiley. Yeah....should have said and go the to beach....
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 39 minutes ago, Zaphod Beeblebrox said: Well, it depends on the thermal limits of the drivers and how much power is being delivered. The business of a small amp doing more damage to speakers than a large amp, is slightly over-stated. A large amp is capable of delivering more energy across the frequency range and is thus capable of doing damage as well. But does it make a difference if the signal is clipped ? 1
Full Range Posted February 3, 2017 Posted February 3, 2017 2 minutes ago, Sir Sanders Zingmore said: But does it make a difference if the signal is clipped ? Yes if your speakers can't handle the stress it is subjected to No if your speakers are operating within its design limits And it also depends on the frequency of the corrupt signal I have blown quite a few tweeters in my Sonab speakers due to clipping and overdriving in my high volume teenage years
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 2 minutes ago, Full Range said: Yes if your speakers can't handle the stress it is subjected to No if your speakers are operating within its design limits And it also depends on the frequency of the corrupt signal I have blown quite a few tweeters in my Sonab speakers due to clipping and overdriving in my high volume teenage years Ok I'll try again. Scenario 1 : amp not overdriven, input signal not clipped vs. scenario two: amp not overdriven, input signal is clipped does scenario two present any greater risk to the speakers.
Zaphod Beeblebrox Posted February 3, 2017 Posted February 3, 2017 5 minutes ago, Sir Sanders Zingmore said: But does it make a difference if the signal is clipped ? The best answer I can provide is: 'It can.' Since clipped music skews the spectral balance towards high frequencies, then the answer to your question is: Yes. However, it is generally more damaging to clip an amplifier, because a clipped amplifier can deliver some pretty nasty stuff, which is generally not reproduced due to limitations in the recording chain. IE: 16/44 digital (aka: CD players) are restricted to an absolute maximum frequency of 22.05kHz, whereas a clipped amplifier may deliver frequencies in excess of 200kHz or more. Make sense? 1
Volunteer sir sanders zingmore Posted February 3, 2017 Volunteer Posted February 3, 2017 4 minutes ago, Zaphod Beeblebrox said: The best answer I can provide is: 'It can.' Since clipped music skews the spectral balance towards high frequencies, then the answer to your question is: Yes. However, it is generally more damaging to clip an amplifier, because a clipped amplifier can deliver some pretty nasty stuff, which is generally not reproduced due to limitations in the recording chain. IE: 16/44 digital (aka: CD players) are restricted to an absolute maximum frequency of 22.05kHz, whereas a clipped amplifier may deliver frequencies in excess of 200kHz or more. Make sense? Thanks ZB makes sense and I learned something. Thanks 1
GregWormald Posted February 4, 2017 Posted February 4, 2017 Here's a simple answer for clipping damage (limited by my electronics ignorance). When the power demanded of an amplifier exceeds the capacity of the amplifier, the peaks of the signal are 'clipped--chopped off' resulting in a distorted signal. This distortion can be identified by the flattened/squared off top of the wave when displayed on an oscilloscope. Squared off waves are made up of higher frequency waves 'stacked' to give the new shape. These extra high frequencies can stress the limits of the speaker as the speaker is not designed to reproduce square waves. Hence--possible damage. In my view any driver can be damaged by the squared-off waves produced by clipping (wherever the clipping is produced) although bass and mid-range drivers are more robust and commonly able to handle higher signal power than tweeters. The amplifier power needed to accurately produce a musical signal without clipping is easily underestimated. Simplistically, if the average level of the music in your room is 85 dB and your amp is using 1 watt to get to this level at your listening position, then a 105 dB peak will require 100 watts of power. Even these requirements may not be enough if the bass frequencies are very strong as bass takes more power to reproduce. I hope this helps (and is reasonably accurate!). Greg
almikel Posted February 4, 2017 Posted February 4, 2017 Rod Elliot's article is worth a read on this topic http://sound.whsites.net/tweeters.htm Mike
Guest Sime Posted February 4, 2017 Posted February 4, 2017 Input signal clipping (non amplifier clipping) in my time as a sound guy working primarily with dj's, they would on 90% of the time, excessively clip the signal on their dj console by upto 12db. I used compression to keep this in control on both the main front of house system volume, the signal coming in from the djs and the booth monitors the dj's used. Now i cant say for certain, being as I never lost a driver from input clipping, but if that signal was left uncompressed and went to the speakers without the actual amps clipping, I do believe that that level of distortion would eventually over heat the voice coils. But I'm probably wrong, but I never ever let a dj test that theory for me
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