The amazing stereo effect that no-one can hear

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of

Monday May 24, 2021


So I received an email the other day from Eventide. That's the company, formally Eventide Clockworks, that in 1976 made the first flanger-in-a-box so you didn't have to mess about with tape recorders to get that swooshy swirly flanging effect.

Did I hear someone say they want me to make a tape flanging demo. I think I might be able to do that. I'll have to see if my tape recorder still runs.

Eventide is also famous for their Harmonizer H910, which wasn't the first pitch changer - that would be the Tempophon, which, like old-fashioned flanging, worked from tape. Pitch changing now is as common as bug fixes in a Pro Tools update. But back in the 1970s and into the 80s it was amazingly new and interesting. And sometimes a bit glitchy, but we accepted that as part and parcel of the effect.

But back to the Instant Flanger. One of its useful tricks was to take a mono source and give it a stereo effect. Yes there are loads of ways to do that now, but not so much back in history. Here's engineer and associate producer William Wittman who in 1984 used the Instant Flanger on Cyndi Lauper's 'Time After Time'. I'll put a link to the whole video in the description.


This is exciting. We need to hear it. I'll play a bit from the beginning of the song and a bit from the end, which are where the cabasa is most prominent. You can of course listen to the whole thing on your favourite streaming service, which will probably be more accurate than what you hear now through YouTube's sound mangling process.


Wow didn't that sound amazing?

I can't hear it. I can hear a cabasa, but I'm damned if I can hear any stereo effect on it. I hear it fixed just off-centre to the right. I suppose I could try isolating it a little with filters. And maybe look at it in a vector scope and see if I can see anything.


Nope. I still can't hear it. And I can't see any movement in the vector scope that I can conclusively link to the cabasa.

So what does this mean?

Well it could mean that I need to visit both an audiologist and an optician. I haven't seen either for years so that would probably be a good idea anyway.

Or it could mean that actually there isn't any movement in the stereo image.

Or, and this is my preferred explanation, you don't get to be the engineer and associate producer of a Grammy Award winning record, which this is, without having an exceptional degree of perception of music and sound. So with my average human perception I can't hear the movement that William Wittman can.

OK, so you can say it's too subtle, and most people won't hear it. But great engineering and great production is all about assembling masses of small details into a complete music and sound experience that people will love, whether they care about the cabasa or not.

So, crank up your favourite search engine and get to know the Eventide Instant Flanger, and take a listen to the whole of Time After Time too - It's 1984 in a bottle.

By the way - just for comparison here's my quick version. It's the LinnDrum cabasa with a little bit of auto pan and a tiny bit of reverb. As you can hear and see, it isn't as rich as the original.



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