Feedback, Effects, And Tone

By Frank Zappa

Guitar Player, 1983 July

HOW DO YOU PLAY at the brink of feedback so much without having your guitar and amp break into a nonstop howl?

At the brink of feedback? That's what I used to do; I don't anymore. I go all the way! When I first started playing, I had a hollowbody Gibson ES-5 Switchmaster. They really feed back. I always liked the sound of that guitar, but when we started working larger halls, and the feedback problem got to be bad, people said, "Stuff it with foam and it won't feed back." But I didn't want to destroy the sound of the guitar, so that's when I switched over to a solidbody instrument. Here's one good piece of advice if you're going to be playing at great volumes or using those midrange frequencies that are going to squeak like that: Don't stack your amps. Don't go for the Marshall stack/pile syndrome. It has two bad effects: One, it makes the feedback harder to control, and two, it rips your head off.

I prefer having smaller cabinets closer to the floor so that if I'm going to do some induction, I can just lean back with the guitar and move it close to the amp like that, instead of always being trapped by a tower of speakers behind me. And a lot of guys think that a big amp stack looks cool, and maybe it does look better than having small amps closer to the floor. But I think you can control your sound better if they're lower down. And it doesn't hurt your ears as much.

Do you also change the tone of your guitar to get bursts of feedback?

For the type of feedback that I'm using now, there's a special circuit in my guitar; it's a parametric equalizer. During the soundcheck in the afternoon, I turn my amp on and turn the frequency select knob on the guitar to locate the frequency that's most prone to feedback in that particular room. It's different for every room, even if you leave your amp set exactly with the same tones. So I search for that, and then it's pretty much preset. If anything changes during the show, I just reach down and squeeze that knob.

That type of feedback tends to give you legato performance whether you want it or not. The notes glue themselves together, because the speaker is constantly twitching. If you're going fast, then the speaker's not punching with every note that you're playing. So, it's not advisable to be up there on the brink all the time. There are other ways around that, though. If you're using a multiple amp setup, you can set up a second amp to have a thinner tone with no feedback, which will always be there for the accentuation of the notes. And you can have another amp that's set for auto-destruct, and have the two sounds combined.

Do you sometimes find that the feedback squeals at a different frequency than you had anticipated?

Quite frequently. I can then either go to another note, or say, "Oh, there's a note that I didn't expect to get," and do something with it. It just depends on how I feel at the time. If it's going to be a surprise, then it's going to be a surprise.

Do you use a multiple-amp configuration?

Well, last tour I was using a three-amp setup. I had a Carvin that I kept fairly clean – it was my precise line amplifier – and I use a Marshall 100-watt for squealing high-end, biting fuzz stuff that's in the 2k [2.000 cycles per second frequency range] register. I also had an Acoustic that was centered more between 100 and 500 cycles, with a peak around 300 for the kind of grunty Les Paul-type roaring sound. The three of them together gave a pretty good balance. I was also using an MXR Digital Delay with a small amount of vibrato in it and a short delay. That was responsible for the difference between the Marshall and the other amps, and it gave a good stereo perspective.

Your most prominent effect seems to be a tone enhancement using a wah-wah.

It's a midrange boost. Sometimes it's actually a wah-wah, while in other cases it's a thing called a Systech Harmonic Energizer, which gives you the same type of midrange frequency boost with more peak. A wah-wah pedal sweeps between, say, 300 cycles (per second) and 700 cycles, making a peak right there. And it's movable. The Systech Harmonic Energizer, on the other hand, allows you to select a frequency that you want a peak at, and lets you crank up the juice so that you get a lot of feedback at that particular frequency.

How do you get the doubling effect on your guitar?

I use a device called a Mic-Mix Dyna-flanger. There are actually two of them being used at the same time. You see, the Dyna-flanger has an envelope follower built into it. So if you set one of them up to go sharp when the envelope is hit hard, and the other one to go flat when the envelope is hit hard, then you're going to get this doubling effect wherever there's an actual pitch discrepancy in the notes, and it really sounds like two instruments playing the same thing. I used a Harmonizer on one track, "Pink Napkins" [Shut Up 'A' Play Yer Guitar Some More, Barking Pumpkin, BPR-1112], only because I used to have one in my rack. In every instance, the guitar is recorded in stereo, using two different amps. In some instances the guitar was recorded on four channels, with four different amp sounds, all blended together to
make various textures.

For more shrill timbres, do you use a treble booster?

No, but I do have a preamp and an active tone circuit in my guitar, which allows me to put a lot of squeak in my sound.

Did you use an octave divider on "Return Of The Son Of Shut Up 'N Play Yer Guitar" [from the album of the same name, BPR1113]?

I used a Mu-Tron Octave Divider for a minute. It comes in and goes out.

It sounds really raspy.

It does, but you can change the tone of the octave divider. It doesn't have to be a blare. One of the first octave dividers I ever used was called an Octavia, which was made by some English company: I used it in 1967. The problem with most of the octave dividers is that they don't play as fast as you can pick, and there seems to be some kind of delay before the subsonic note comes out. Also, you have to have a really good speaker to reproduce the low notes. What I was using on some of the Shut Up tapes was a special cabinet that had a low-end section powered by a 200-watt Marshall into an 18" speaker, just to accommodate the octave divider.

What kind of effect did you use on "Ship Ahoy" [Shut Up 'N Play Yer Guitar Some More]?

It's an Oberheim voltage-controlled filter triggered by a sample/hold unit. It sets up a kind of rhythm that makes an accompaniment for you.

How do you record live material on your Shut Up albums without having a lot of crowd noise?

Do you know what signal-to-noise ratio is? If you have one microphone in front of an amp that's very, very loud, the level at which that microphone is set will have to be very low. It's not going to admit any leakage – or at least very little leakage – from audience noise, because your amp is a very loud sound source with a microphone very close to it. With the level of the microphone turned down to accept this kind of power, this brings the sensitivity of the microphone's response to the audience down even further into the noise floor. Therefore, the audience would have to be as loud as the amp and as close to the microphone to compete with it. That didn't happen. There are some audience tracks on the tape that were used for ambience. But people don't usually scream and holler while I play: They just sit there and scratch their heads, so there wasn't much problem with squealing teenage girls covering up the guitar notes.

– Questions by Tom Mulhern

Read by OCR software. If you spot errors, let me know afka (at)