Why Do Audio Engineers Use Different Speakers?

I gather that audio engineers generally use different speakers than audiophiles. I hear they tend to use smaller self-powered speakers the majority of the time.

Other than the appearance of the box and the smaller room size they are likely to be in, why wouldn't an audiophiles want to use the same speaker?
Some of us do. Some of us want to. I would if I could sell my Bryston 7B SST amps! :-) Actually, my passive speakers are studio monitors.
Below is a link to Steve Hoffman's equipment. He is (in my opinion) the best engineer in the business today.

Look at the wide range of speakers and equipment he enjoys.

Mix engineers often work at huge consoles, which can be a bad (reflective) listening environment with small near fields (narrow dispersion) placed on the meter bridge. The narrow dispersion reduces reflections but it makes for a very narrow sweetspot - good for one person at work but not the best way to hear music. They don't care what the speakers look like (no WAF issues so exotic shapes or veneers are a waste of money to them). Finally, they care about accuracy and that mixes "translate": self powered speakers tend to suffer less from IMD distortion and phase/crossover issues compared to passive designs and there is one less variable (amp/speaker interaction) to worry about.

Audiophiles listen at home and therefore it often makes sense to choose speakers with a more natural sound with wide dispersion, for an even soundfield and a larger sweetspot. It also makes sense to choose a pretty speaker design rather than a purely functional one, as the environment is domestic. Audiophiles also do not need to worry about whether the speaker presents a precise balanced sound at different listening levels, as they simply adjust volume to suit their taste on the equipment they have.

Mastering Engineers however will use tend to use some designs that are closer to what audiophiles use.

Examples (and you will see that not all are "different" but many are)
Bob Ludwig used ATC's (in the past) and now uses Egglestons at work and ATC's at home. Alan Parsons uses B&W 802D. Doug Sax uses ATC's at work. Elliot Scheiner uses Yamahas. George Massenburg uses ATC and Genelecs. Bob Katz (Chesky) uses Lipinski's. Chuck Ainlay uses ATC. Ed Cherney uses Custom Tannoy SGM 10's/Mastering Lab at home and KRK E-8 at the studio. Michael Bishop uses ATC. Al Scmitt uses custom Tannoy/Mastering Lab design. This is the Mastering Lab custom design by Doug Sax of Sheffield Direct to Disc fame; a mastering engineer with famous credits list almost as long as Bob Ludwig, Incidently Doug Sax bought the last production run of Tannoy's famous SGM10 - so these are a are collectors item. There are many other custom designs by Ausberger with TAD components and perhaps ten other popular makes that I did not mention (Adams, B&W, K+H, Meyer, JBL, PMC, Wilson, Dunlavy, JM Lab, Von Schweikert, Westlake etc. - go to Gearlutz.com to learn more) Not all but several of the custom designs are "in walls" which requires flush mounting the speaker baffle with the front wall in an acoustically designed setting. In walls are rarely used for mixing and most often used for bass checks and to impress clients or discuss the mix with the band (the nice even soundfield means a large sweetspot which makes group discussions practical). Examples of "In walls" can be seen at the final critical LP mastering stage on the link Albert gave and here at Nashville's Blackbird Studio.

So lots of variety, however, there are some common themes in studios. Reliability is very important so you rarely see ribbons or electrostatics. Loud and dynamic is important so you rarely see electrostatics and you may see more horns. You rarely if ever see speakers with "ambience" drivers. You rarely if ever see dipoles. You rarely if ever see a Studio 5.1 system with a different center channel and/or placed at different height from main left and right. Studios tend to use small nearfields for one purpose and much bigger main monitors for another.
Audio Engineers HAVE to use different speakers than audiophiles because they have to mix and master the music to fit the variety of music systems than people buying the music will play it on, be it an audiophile system or an I-pod, and everything else in between. Also, audio engineers have to hear every detail to be able properly place it into the mix. When they listen to music, it's work. Consequently, their speakers have to be good enought TOOLS to assist them with that work. Generally an audiophile would not want to listen to such speakers because the level of detail would be way to intense for musical enjoyment (think clincal and sterile).
It's a very good question and one that comes up often. Let me try to paint a picture for you.

First, all studio control rooms are heavily treated to minimize any acoustic aberrations. Studio monitors are very flat across the frequency range, capable of very high SPL and bullet proof. They are designed to be extremely durable and to provide a consistent sound over a very long time. The intention is to hear every detail of what is on the tracks.

Most control rooms have several systems.

If the room is used for live recording (and not all are), there will be a big pair of monitors mounted up high that can fill the entire room with high, distortion free SPLs. Keep in mind that a big control room can easily be the size of a living room. This is traditionally the province of brands like JBL, Westlake Audio and Tannoy. These are used so that everyone involved in the session can listen as the band lays down tracks, and/or the engineer plays back a mix.

In addition the engineer will have one or two pairs of speakers on or aimed at his position at the mixing console. This is where you typically see small self=powered Tannoys and ATCs, Yamaha NSMs, and even the lowly 3" Auratone (basicallya 3" car speaker in a 5" box finished in vinyl). The BBC engineers used Spendors for this task.

These speakers enable the engineer to do two things. First monitor accurately at low volumes while s/he works out the myriad of details of a mix. Second, these kinds of speakers are used to emulate what the vast majority of people hear on TV and in their car.

In fact for many years the acid test was to make a cassette of the mix to listen to on the drive home. It had to sound good in the car. While I am no longer involved in the business, I wouldn't be surprised to find people making MP3s to listen to on their iPods and Zunes - it has to sound good on ear buds.

Note that a specialized room: say one used for mastering will be set up differently from one used to build sound effects and dialogue. While accuracy is always paramount, as Albert's post demonstrates there are many ways to skin the cat - probably the closest parallel to what an audiophile would want is a mastering room like Steve's.

The best self powered speakers are very accurate, can play very loud and are easy to move around. As an added bonus they work very well where space is at a premium - for instance a mobile truck or a small control room.

As for why (most)audiophiles wouldn't want the same gear: many people would not like the flat voicing, some of it is brutally expensive and requires massive power, a lot of it is either too big or too small, and probably more then anything else, much of it lacks any semblance of WAF.
Yes, I recently was surprised in meeting an audio engineer in New York City who has spent a life time working for Sony, his home speakers were a self made single driver tower pair. Better then some $10,000 speaker pairs I have heard. The drivers were purchased from Radio Shack twenty years ago. This fellows job is to do audio mixes for TV programs. Aside from a grand piano, his audio equipment was a mix of mid fi, but he did have a VPI turntable. Perhaps in doing audio for a living, they want to give their ears a rest in off time.
Steve Hoffman certainly has some fine audio gear.
But are his speaker choices typical for most engineers?

Am I wrong when I write "I hear they tend to use smaller self-powered speakers the majority of the time."?
The same reason nobody drives an F1 car down the interstate. For the engineer the speaker is a precision tool used to to manufacture a product. Unike the audiophile listening pleasure does not enter into the equation.
hoffman is also a collector and an audiophile. the two are very different. the hobby of collecting,swapping,upgrading, downgrading,and arguing about different components has no relationahip to the music or recording industry, or to most music nuts and collectors. one of the most knowlegable music people i know has a 20 to 30 year old system consisting of old series bose 901's/crown gear that looks like a truck ran over it/an old kenwood turntable/and an old first generation phillips cd player. he would rather get a root canal than discuss components. different strokes
Another way of asking your question is: Why aren't powered speakers popular with audiophiles? Simple, they'd be "stuck" with one amplifier. The thing that drives this hobby (and keeps people employed) is the constant changing, upgrading and experimenting.

Recording engineers need speakers that are accurate. They don't place a premium on imaging and soundstage - just that the speaker is flat enough so it's easy to compensate for different frequencies. Also, their speakers have to reside and perform in a cramped environment so they need to minimize wherever possible. Imagine setting up all your seperates in your bathroom - that's about the workspace of a control room.
They don't place a premium on imaging and soundstage - just that the speaker is flat enough so it's easy to compensate for different frequencies.

I think you will find that recording engineers spend a lot of time adjusting the presentation of the soundstage (left/right and forward/back and tight focussed image/distributed or broad image...track(s) for each instrument are treated differently to create a desired presentation. Don't underestimate the imaging capabilities of studio gear as it can be equally good and bear in mind that all conventional box speakers suffer from edge diffraction at the baffle edges whilst "in wall" speakers completely eliminate this detrimental affect to the soundstage...
The answers to my question have been most enlightening. Thank you.
Now let me put a twist on my original question:
Why Don't Audio Engineers Use Expensive Cables?

I suggested to my audiophile friend that Audio Engineers do not use the expensive cables found in so many audiophile systems. His response:
"Au contraire! The high end remastering studios (not the run-of-the-mill giant studios) use high-end cables, power cords and power conditioners."

Does anyone personally know if Audio Engineers use high-end cables, power cords and power conditioners?

Are there any Audio Engineers out there who might be willing to offer an opinion?
There are audio engineers who believe that audio cables make a huge difference just as there are audiophiles who share the same conviction.

Phil Traynor, the guitar engineer and main gear guy for David Gilmour, likes Van Den Hul cable, and has even rewired the ATC's on Astoria using this cable. He used around 23 Km of Van den Hul. Pink Floyd has used this "Astoria" studio for recording as did David on lhis last album and so have many others.

Here is a link to Pink Floyd studio
I use Altec 604-8G studio monitors (1975) with a pair of McIntosh tube monos and to me they reproduce music very well. Very realistic to my ears. I guess that is why there are so many manufacturers of speakers. I believe a great deal of the music from the 50-70s were mastered using Altec 604. Since most of the music I enjoy is from that era, they just sound right to me. I can and do listen for hours.

I am no speaker expert, far from it actually. But I do know what sounds good to me and falls within my budget.

i visited a recording studio in brooklyn, ny, several years ago. i witnessed a recording , and listened to the recording being played through monitor speakers.

the result: irritation without representation. i would not want to own one. i am not convinced of its flat frequency response. possibly the problem wa the rest of the components, or the recording itself.
David Gilmour also uses Shunyata as do many other studios.

=> your friend is wrong about this point.
One question that comes to mind in this discussion is that if the engineer uses such different equipment/speakers (relative to an audiophile) & optimizes the sound based on very different speakers...then is it dumb luck (most likely not) that a recording sounds great on audiophile setups?

I'm in RDE in a different industry...in my world the base references you use for an optimization makes the optimal end-result somewhat unique. I.e. if I apply the optimal end result conditions to another base reference the new end result is less than optimal. I would espect the same to be true in the studio-monitor mix vs audiophile playback case. No?

if the engineer uses such different equipment/speakers (relative to an audiophile) & optimizes the sound based on very different speakers...

Then it will not sound the same...yes this is a big problem. However most engineers know how to "dumb down" the sound to make it work on ordinary systems....this mostly requires judicious use of compression so that the dynamic range is not as great as real music. Engineers will often check that the mix translates by playing it on the way home in a car or on cheap speakers like Yamaha NS10's.
Fishboat - you hit the conundrum on the head. Layers of sound, room ambience, fast transients, rock steady pinpoint imaging.

Many of these "desirable" audiophile characteristics can only exist in a live, one take environment. Anything else is simply an illusion - however convincing - created by a (talented) engineer.

Recording is a craft and IMHO the best craftsmen are those who use the least gear - historically the guys working classical and acoustic.

The development of multi-track decks and multiple take/punch in techniques together with the compression applied to make up for poor musicianship and mike placement does not result in layers of effortless sound...

in fact a lot of what we hear in that kind of work reflects references no one wants to talk about: the saturation levels of audio tape, the sound of recording equipment distorting, the degradation of less then perfectly made dubs.

I think the variety of hardware reflects the inherent dualism of our community. Some of us like gear that reveals every detail because the fun is isolating the details - oh look the back wall; while others listen to immerse themselves in music for catharsis or escape.