Sub harmonics?

[JD0x0]

Is it possible for tube guitar amps to generate significant 'sub harmonics' provided the circuit and speakers are capable of reproducing those frequencies?

When I use my scope app on my phone and play an open 'A' 110hz fundamental, it shows a small spike at 55hz, albeit, much weaker than the fundamental, 2nd, 3rd harmonics, etc. One of my speakers does have a '55hz cone' I'm just curious if this is an actual phenomena. You dont often hear people talking about sub harmonics when designing amps, but maybe that's because most speakers/Output trannies have such a weak low end response that there isn't a very significant effect, most of the time.

[xtian]

Intermodulation distortion creates notes lower than the fundamental.

[Firestorm]

Possible? Yes. Unpleasant? Maybe. There are cone cry artifacts sometimes mistaken for IM distortion, but mostly it's a filtering or ground issue.

[bluesfendermanblues]

Recently I had bad sub-harmonic on my 5f6a, 1x12" with 6v6. I turned out that the 6v6 harmans were a bad match. Swopping to a set of matched JJ6v6's made the unpleasant sub-harmonics go away. So to answer your question: Yes, producing lower than guitar freq's sub harmonics was/were possible.

However, if you look at a spectrum analyzer and play a tone on you guitar (or sing a note) you'll see that the guitar produce a lot of overtone harmonics and subharmonics as well -same with the human voice. I believe that only a sinus generator produced tone produce one tone only.

[Stevem]

What does your phone read for SPL at 110hz @ 3ft, as most guitar drivers have rolled off 55hz by a good 12 db@ 3ft?