Newbie question: Amplifiers, Volume, Clipping?

I am the furthest thing from a tube amp expert but with solid state the problem with clipping is that it eventually will let DC through to your speakers; this use to be called hard clipping. I think that tube amps generally exhibit what was called soft clipping, in which they fail to follow the waveform completely but do not let DC through. I am sure Al will roll his eyes if he reads this; I could have explained it much better 40 years ago when I actually used tube amps. Clipping will usually be accompanied by some type of audible distortion but not in every case. I really don't think you will hurt them, why don't you get a Radio Shack sound level meter and see how loud you are playing them? They are not expensive; if you have a hi tech phone it may have an app that does the same thing. I wouldn't know, I am a product of the crank phone era.

No eye-rolling here, Stan, just a good chuckle at your comment :-)

The reason that speakers are commonly damaged by clipping of underpowered amplifiers is essentially as follows: Clipping occurs when the amp is asked to deliver a larger voltage swing at any instant of time than it is capable of delivering. That will usually occur at bass or mid-bass frequencies, where music typically contains its highest energy levels. Clipping means that the positive and negative peaks of what would normally be a smooth sinusoidal waveform will abruptly transition to a flat, essentially constant output level corresponding to the maximum positive and negative voltages that the amp is capable of delivering.

The ABRUPTNESS of those transition points corresponds to high frequency spectral components being present in the output signal that are not present in the original waveform. In other words, the clipped waveform contains excess high frequency energy, which the speaker's crossover will duly route to the tweeter. That can occur even if there is no high frequency energy at all in the original signal, as a result of the clipping of bass frequencies. Tweeters are ordinarily able to handle much less energy than lower frequency drivers, and can therefore be damaged by that excess energy.

Solid state amplifiers will typically clip more abruptly than tube amplifiers, therefore making them more likely to cause that kind of damage. Although if a tube amp is clipped severely enough, the same damage can result.

Severe clipping will be immediately obvious, because the sound will be horribly distorted. The onset of clipping may be characterized by mild distortion or slight popping sounds on musical peaks. I doubt that occasional mild clipping would cause any damage.

The volume control position at which the onset of clipping may occur is, IMO, unpredictable as a practical matter, and will vary very widely depending on the gains and sensitivities of all of the components that are involved, on the output level of the source component, on the power capability of the amplifier, and on the recording.

Best regards,
-- Al

One thing that may be a problem is the age of your speakers. If the voice coils have been warm in the past from loud volume, they may fail quicker than a new pair. The glue in them could be getting weak just from age also.

On the tube amp clipping issue, tube amps do seem to give a better warning with audible distortion more noticeable quicker than SS amps in my past experience. I have never blown a speaker with a tube amp yet. I use a fuse when running low powered SS amps, because they do catch you off guard quicker than tubes do with distortion in my past experience. Yes I have blown speakers with low powered SS amps, that's the reason for the fuse with them. I don't use a fuse with tube amps. If it would blow(with tube amp), it could cause the output transformers to blow, for not having a speaker load.

In the end, anything you hear that sounds wrong, back the volume down to be safe, and save your equipment. And I also agree with the volume position not meaning much, since it can vary so much in some types of gear, and/or matching of gear.

Hi Al and Hifihvn: I had a question about tube amp clipping. In the case where the tube amp uses output trannies, if the signal fed to the primary coils in the output trannies clips, what type of output is induced into the secondaries?

Let me elaborate. Al explained that "[c]lipping means that the positive and negative peaks of what would normally be a smooth sinusoidal waveform will abruptly transition to a flat, essentially constant output level corresponding to the maximum positive and negative voltages that the amp is capable of delivering."

So, if the input to the primary coils transitions to a flat non-alternating voltage, is it possible to induce a voltage in the secondaries?? If the answer is no, I would think that the clipping would be expressed as a distorted output wave form, but not necessarily of a type that would damage speakers. I imagine the distortion would sound terrible though.

Alternatively, if the signal fed into the primary coils wildly oscillates as bursts of positive and negative voltage, wouldn't the output voltage still be limited to some extent by the output trannies? I suppose in this case, while the output trannies wouldn't be passing pure DC to the speakers, the widely oscillating signal fed into the primaries could induce bursts of oscillating DC voltage which perhaps in extreme cases might damage speakers.

I ask because I own a 130 wpc tube amp that drives speakers having a sensitivity 89 db and a nominal impedance of 8 ohms. As you might imagine, my rig can get quite loud without having to push the amp. Hence I am somewhat dubious that I clip the amp because my wife would start screaming bloody murder to turn the da** stereo down way before a clip. She's better than any speaker fuse on the market today. I would say she a hyper fast fuse -- a real live wire.

Thanks for the clarification.

Hopefully Almarg will answer these questions. If I would, my answers might be in error, and confusing.