THE ENGINEER

Andy Johns: “Black Dog is a very powerful track. I’m still very fond of that one. It’s proto-typical Zeppelin. They were really terrific with dynamics. As opposed to a beginning, middle and an end, they’d take you all over the place. I was very proud of the guitar sound. It was something no one had ever done and I don’t think it’s been done since, actually.

“I came up with the triple tracking idea for the electric guitars on Black Dog. I’d been trying to get a guitar sound that they’d gotten with Buffalo Springfield on the Buffalo Springfield Again album.

“I met Bill Halverson, who did those records about a month before I worked with Zeppelin on the fourth album. I asked him: ‘How did you do that?’ And he explained it to me. You just run the guitar direct and use a couple of compressors, and you use them as amplifiers so they distort each other. So I suggested to Jimmy that we try that on Black Dog. It’s very difficult to achieve, but after much ditzing about I got it to work and it sounded great. And we double tracked it. Then I said: ‘Hell, why don’t we triple track this, it sounds so good.’ So we had one more guitar up the middle as well.

“When I was mixing it, normally you’d have all the guitars in the same plane on the faders as the bass and the other instruments. But the apparent level on these things was so hot they were two thirds of the way down on the faders but still loud. Which was great because it means they’re not taking up more space and it leaves room for everything else. It worked rather well.”