System Test - Merry Ocarina Tony Hart / Vision On

[User211]

Play this loud on your main system. Does it struggle? Be curious to see the general consensus, or indeed any consensus!


https://www.youtube.com/watch?v=VsPZOb_RL6k

[Lodgesound]

Humphrey the tortoise!!!!!!

[User211]

Three pairs of speakers I know of now that cannot cope with it. I bet there are more....

AKG 702 headphones sail through it.

[RichB]

Dont know what I'm supposed to be listening for here but it made me feel a bit sick if thats any good?

[Roy S]

'It's an ocarina sir'

SNjcSF_OKFM

What am I supposed to be listening for?, sounded ok :scratch:

[User211]

What two passes?

You need to play it 85-90DB and if you hear no distortion it is a pass.

It drives the mid/treble ribbon on my Apogees into some sort of visibly strange resonant behaviour, but only at very high volume.

My little Mark & Daniel speakers have a bass cone cap that is loose and it agitates that quite badly. Time for some glue.

The third speaker that goes nuts has a short 6 inch HF ribbon.

[User211]

It is also an annoying tune that lingers in the brain. Look up Ocarina in Wiki it is a strange instrument indeed - works in an unusual way.

[Roy S]

I'll crank it up tomorrow when all the neighbours are out (in case they think I'm losing it :lol:)

[User211]

You should at least hear some minor distortion because it seems to be resident in the recording like it is overloading whatever recorded it. OK that seems at odds with me saying no distortion above but it is quite minor on the AKG 702 headphones I have.

I got curious and below is a temporal FFT of the whole track. The Y axis goes up to 4KHz from 0 Hz. The Ocarina is basically the thick line at the bottom that goes up and down a bit following the tune - pumping out a lot of energy between 170Hz to 500Hz - the stuff higher up is the glock.

https://lh3.googleusercontent.com/q-2WcHu3VcIyYxKjs4EVrFLjOLiIisBuUZL60Py86Ts=w1117-h481-no

[User211]

'It's an ocarina sir'

SNjcSF_OKFM

What am I supposed to be listening for?, sounded ok :scratch:

BTW video clip quite amusing:)

[User211]

Looking at the TFFT I posted above it is easy to see the bulk of the energy is between 170-500Hz when the y-axis scale is measured.

So I did a slow sweep pure tone input into the Apogees. At high volume, the long thin ribbon which handles mid-range and HF freaks out around 380Hz. Look the wavelength up for that frequency and it coincides with the length of the ribbon from the bottom clamp to a pivot about 90cm up that is made of foam. From this pivot the ribbon angles back (and the magnet angle with it) until it hits the top clamp.

So basically when the ribbon sees a wavelength corresponding to its real physical length it freaks out at high volume. This will happen with any genuine ribbon I would imagine. Fortunately it is very narrow band, and the Ocarina track is the only one I have ever come across with enough energy and simplicity of tone (i.e. there isn't too much else going on) to make it noticeable at high volume.

Placing a digital notch filter using JRiver's PEQ at 380Hz +/- 20Hz and a few DB down makes no audible difference when playing real music and calms the ribbon down. Realistically it isn't worth applying. Lest you are into Ocarinas at volume that is. In which case don't by a pair of Apogees!!!

Do high volume frequency sweeps with most speakers and you will find anomalies/resonances. All speakers sin in one way or another and this is one minor flaw with the Apogee/ribbon approach. Experimenting with ribbon tension and pivot material may well be able to help minimise it. The ribbon tension in my current pair is the same as the previous pair and also equal to that used originally by Apogee. Set it too high and the ribbon movement gets restricted by the tension.