I went to a concert Friday night and noticed something I’ve seen before and never quite understood. The opening band had all their normal (grungy) amps hooked up, and then each amp had another microphone pointed at it, that presumably ran to the super-monster theater sound system.
Seems to me that there’s an extra step in there, and that you could run directly from the instruments and mikes to the theater amps. I’m sure there’s a reason for it though. Anyone know?
To add feedback?
First off, it’s simple. The band doesn’t have to worry about having incompatible equipment with the venue. The band brings their instruments with their amps, which they know work. Then, the techies just stick a microphone in front of the band’s equipment to carry it to the house system.
Also, the band may prefer the way their instruments sound through a certain variety of amp. They may have preferences relating to brands or companies.
When I saw Rammstein the other night, they used amps from a German company I have never heard of; they were familiar with these amps. Certainly it would have been cheaper not to bring over their own amps.
Studi
Different amplifiers sound different.
I miss my old tube amp.
As one of my Communications professors said, the band often considers the P.A.s part of the instruments. Rumor has it that the buzz guitar on the single version of “Revolution” was made possible by multiple knife slits made in the speaker cone by John Lennon.
Somewhere or other, I once saw a picture of Eric Clapton in the studio during his early years, with his guitar plugged into a tiny Fender Champ tube amp (I own one and its only 5 watts). There’s a microphone in front of the Champ, and the mic cord runs to a Marshall 100 stack. Obviously you can’t run 100 watts at full volume unless you’re in a huge hall so you can’t overdrive the amp and get that good sound that comes from a tube running on 10. So you have to overdrive a smaller amp and run it to a larger amp that can produce the high-volume sound.
Of course, nowadays many amps have overdrive knobs (even the Marshall amps, what a heresy!!) you can put the overdrive sound into the preamp output before it’s amplified, but it’s just not the same sound.
Precisely Mr2001.
Sound reinforcement systems are completely different from sound production systems. The dynamic range, total harmonic distortion and frequency response of a production speaker is nowhere near the same as your typical PA (Public Address) or stereo speaker.
When you are winding out your distorted and overdriven electric guitar, one iceing on the cake is constructive feedback (yes, there is such a thing) that you get from your guitar amplification rig.
For the nonce, we will dismiss such crucial topics as simple audibility during a performance whose sound system consumes more power than an urban block of flats.
Instead, let us remember that sound has a detectable delay in its transmission over long distances. This delay alone would make the proper use of constructive guitar feedback impracticable in an arena or amphitheater setting. The time of return (not to mention the acoustic dampening) that the ambiently conditioned signal undergoes renders it useless for such an application. In addition, singers and most other performers rely upon their own stage monitors (another type of production speaker) quite heavily to deliver immediate and vitally neccessary cues regarding their pitch and volume in the ongoing mix of the overall sound system.
Just imagine trying to deliver a speech in public to a large audience whilst wearing rather effective earplugs and you barely begin to appreciate the import of this concept.
One of the truly unsung heroes of the music world is the competent soundman. The skill this crucial member of the supporting cast brings to a show can (with disturbing ease) make or break an event. (Performing musicians at the SDMB, please check in with your own confirmation of this important fact.) If you are not able to hear what you are doing onstage because of the total audio background washing out your own perception of what is happening, you are asking for trouble.
In short, if you do not have an active and accurate source of your contributory output signal while performing in an amplified situation, you are courting disaster.
As to amplifiers and their idiosyncratic spectral signatures, eunoia, it is fairly safe to say that nearly every major venue in the entire world uses semiconductor drivers in the final stage of production amplification.
A fundamental characteristic of power transistors is their lack of grace when it comes to what are known as transient signals. Transients are spikes in the normal flow of preamplified input that drive the production amplifier outside of its performance envelope. When this happens for silicon based devices (i.e., transistors), there is a pronounced “clipping” of the signal. High-end inputs that range beyond the response curve of the amplifier are simply flat-topped during replication.
When you use a vacuum tube (or valve, as the Brits are fond of calling them) based amplifier, the high-end transients enjoy a much more benevolent treatment. Extreme excursions in the signal amplitude are not clipped and, instead, undergo what is known as roll-off. During roll-off, a signal’s amplitude gradually diminishes as it approaches its theoretical maximum. This differs wildly from the way a semiconductor amplifier handles such a signal with its usual clipping response.
This was one of the major design concepts involved with ADA brand amplifiers. The top-end guitar amps built by David Tarnowsky and his crew used a combination of semiconductor and vacuum tube technologies. One of the virtues involved was the extremely fast response time of transistors to acoustic transients being folded into the “warm” signal processing capabilities of a tube amplifier.
For the record, there is a distinct reason why vacuum tube amplifiers sound so “warm”. Tubes tend to better reproduce even order (2X, 4X, 8X and so on) harmonics of a fundamental frequency. It is these even order harmonics that are so prevalent in a majority of acoustic musical instruments. The clarinet and its peculiar timbral qualities are a perfect example of how strange odd order (3X, 5X, 7X, etc.) harmonics sound to the human ear. The reinforcement of even order harmonics is yet another specific reason that performing bands mic their own (frequently) tube amplified, production speaker cabinets before their signal is fed into the main public address system.
I hope that this clears things up a bit.