Whats considered decent in terms of listed harmonic distortion. Notice some boxes have levels around 10% and others as low as 1 or 2%.

I'm guessing no boombox's has a distortion level below 1% like a home stereo system ?

copied from wiki:

The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the powers of all harmonic components to the power of the Fundamental frequency. Lesser THD allows the components in a loudspeaker, amplifier or microphone or other equipment to produce a more accurate reproduction by reducing harmonics added by electronics and audio media.

Keep in mind that those levels are only achieved at a certain output which manufacturers take liberties on. Typically a spec might be 10% distortion at 10 watts, what they don't tell you is the output at 5 watts might only be producing .1% distortion which our ears won't detect. The 5 watts would be a more useful spec but the manufacturers want to be able to claim 10 watts because it looks better. Yes the amp can produce 10 watts but it's not useable because of the distortion level. I wouldn't put much weight in the output claims on these boomboxes because of this and many other variables such as the speakers. We really have to go by what our ears tell us about the sound, it means a whole lot more than these overstated specs.

PMPO is another rediculous and useless manufacturer claim. Ever seen a boombox that claims 200 PMPO Watts? Yeah they are a joke.

There's a lot more tech talk behind this and I don't know it all anyway. Google is your friend with this question.

i personally find it funny that they even bother making claims about total harmonic distortion. in many cases the harmonic distortion is what gives a lot of these boomboxes there character. i think that the designers have done a very good job figuring out ways to compensate for the inherent problems of making a boombox sound good.
in the end all boomboxes sound inaccurate. some of them sound nicer than others and that is a open debate that goes on and on.
its pretty open to personal choice what sounds the best.
i find it funny how so many boomboxes have functions like biophonic or wide that intentionally add harmonic content to the signal.
i mean when you use the techno button on a dt707 the sound for sure sounds really cool,but if you listen closely there is added noise in the signal. same thing at the biophonic button on a jvc.
i think there is some boomboxes with less volume and bass that sound better than some of the ones with more of those two.
i am willing to bet that if you took some of these out and had them measured independantly none of them would be where the manufactuers claim them to be.

i cannot see how any boombox could have a less than 1 percent thd.
in fact i dont think i would want to hear one that did.
the way these small portables distort is part of there charm.


the best is the manufactuers claims on headphones.
i mean when you read that a pair of headphones that cost ten bucks can reproduce all of spectrum down to 16 hertz you just know that they are full of crap.

Almost booomboxes uses ampchips with 10%THD at max output power. But this %10 appears only at MAX OUTPUT POWER. You will get a 1% or 2% at normal listening volumes that is fine.
The other trick I've seen (M70) is using a 15W per chanel amp chip, but only allow the amp to deliver 7.5W (because the power supply rails).
You see that, even at MAX OUPUT POWER (just before clipping, of course) the THD is far from the awfull number given in the datasheet for full load, because output power is far from the limit.

All of the above is true. THD levels for boomboxes and car stereo are usually reported at 10-20 times that of quality home stereos. This enables the manufacturer to report power outputs that include distortion at unlistenable levels.

Keep in mind though power output and distortion levels are only part of the story. A digital amp might have very low distortion and high power, but it may also have a harsh and unnatural sound. A tube amp might have high THD and low power output but sound very natural and beautiful.

The only way to judge a system is when all componants are together (amp,preamp,source and speakers). And you are listening to the kind of music you like, at the volume you want, in the venue you plan on using.

It ends up being a very personal choice. That is what makes audio so interesting...

See this note ....

http://www.lennartlabs.se/philosophy/greathobby4.htm

quote:

Originally posted by 71spud:
All of the above is true. THD levels for boomboxes and car stereo are usually reported at 10-20 times that of quality home stereos. This enables the manufacturer to report power outputs that include distortion at unlistenable levels.

Keep in mind though power output and distortion levels are only part of the story. A digital amp might have very low distortion and high power, but it may also have a harsh and unnatural sound. A tube amp might have high THD and low power output but sound very natural and beautiful.

The only way to judge a system is when all componants are together (amp,preamp,source and speakers). And you are listening to the kind of music you like, at the volume you want, in the venue you plan on using.

It ends up being a very personal choice. That is what makes audio so interesting...

good read there success thanks for posting that link.

If you start talking about valve amps, then it starts getting more complicated. In the THD measurement it depends on which order harmonics are present.
Valve amps often have a nice "warm" sound, because of the valves producing certain amounts of second order harmonic distortion. Compared for eg to third order harmonics, which are relative harsh for the ears.

Cheers, Roddy