'Whole Lotta Love' - the mysterious pre-echo explained. Sort of.

There's a strange 'echo' in this Led Zeppelin track that comes before the sound that caused it. A mistake? Intentional? A happy accident? The world needs to know...

Take a look at the recent Audio Masterclass Production Review of Led Zeppelin's Whole Lotta Love and listen to the audio examples. Don't forget to read the comments at the bottom of the page, which contain a lot of insights.

There are several possibilities regarding how the strange pre-echo towards the end of the track occurred...

• It was deliberately recorded that way
• It is the guide vocal leaking into the drum overheads
• Print through
• John Bonham's ghost talking directly to us (kidding)

Here is what mix engineer Eddie Kramer has said on the subject...

"Zep II was mixed over a two day period in New York, and at one point there was bleed-through of a previously recorded vocal in the recording of Whole Lotta Love. It was the middle part where Robert (Plant) screams 'Woman. You need it.' Since we couldn't re-record at that point, I just threw some echo on it to see how it would sound and Jimmy (Page) said 'Great! Just leave it.'"

We seem to be getting nearer to a solution, but the quote doesn't explain how the bleed-through occurred.

One thing I would say from the start is that I am a great believer in allowing a few rough edges to show. Perfection is limiting, but excellence has no bounds.

Having said that, if I had been in charge of the session and I had the opportunity to fix this 'problem' then I surely would have. There's an old saying that tape is 'long thin brown stuff for storing engineers' mistakes', and I wouldn't have wanted this mistake, which it surely is, to escape into the big wide world.

Let's look at the three serious contenders for being the correct explanation...

Firstly, could it be a deliberate mistake? I doubt that. If someone had the brilliant idea of deliberately making a pre-echo such as this, they would have made it clearly audible, not hidden in the background. And they would have done it on other tracks.

So was it the guide vocal leaking into the drum overheads? When recording this kind of music, it is common to record basic tracks first, with a guide vocal because the band will usually play better. The guide vocal is replaced later on with an overdub.

If the singer is not in a separate booth, then the guide vocal can indeed leak into the drum overhead mics. If the guide vocal is different in any way to the overdubbed vocal, then it can become audible.

However, in this song, the drums are silent when the guide vocal - if that is what it is - becomes audible. The drum tracks could have been faded.

Now, the interesting phenomenon of print-through. Some commenters have said that the timing makes this impossible. I don't see that - the maximum gap between the original signal and the print-through signal on a 10.5 inch reel of tape is around two seconds at 15 ips. That certainly makes it possible timing-wise.

However, I've heard print through many times, but never as loud as this. And, the pre-delay varies, which I guess rules out this possible explanation.

So we still seem to be searching for an answer. I guess we'll need a time machine to truly know the secret.