CARA - Room Acoustic Software

Sean, I've been wanting to start a thread on high performance discotheques. There is much to be learned. I learned a lot from one audio salesman who worked for the same company I did back in 1982-83. He was an opera and classical freak, but started his own business setting up incredible high performance discos. His home system consisted of a Linn Sondek w/Monster Alpha, Klyne SK-5A pre, Conrad Johnson tube power amp, Proac super tablettes and a Janis 12" sub. His objective, as he taught me, was to replicate as much as possible that sound in a club. It worked.

To start with, discos are run mono. A good EQ-ing job will be done by EAR with a 31 band EQ, when the club is packed (this guy told me he took acid before doing such a job!)...so much for overemphasizing frequencies. The curves are very gentle, by the way. The EQ-ing is for flatness, man. The sound will be five way, so you will have tweeters, midranges, mid-bass (~250 Hz, for PUNCH), woofers and subwoofers. Yes, you can get great sound. Liberating the drivers an the amps by doing this on a five way system has an unbelievable effect on sound quality. So much for the schools that teach 'start at the source' or 'start with the speakers'. Has to be experienced for anyone to become a convert.

Regards,

Are there any ways of actually defining a custom loudspeaker with its actual SPL diagram?

"Are there any ways of actually defining a custom loudspeaker with its actual SPL diagram?"

Inadequate. You need the spatial information as well. You need to know all the dimensions of the speaker (you can measure them), the frequency bands for each driver, the crossover slopes, and the bass loading.

Thanks for the input.

My question was more along the lines of whether or not the SPL diagrams were editable, given that you actually have the measured frequency response of each driver.

Psychic, i have worked doing pro sound reinforcement for a living, sold pro sound gear for a living, recorded and produced a few local bands, etc... As such, i would consider myself QUITE familiar with all of the aspects that you have mentioned.

If you would take SPL measurements in the clubs that you think sound "great", you would find that the first thing that they did was to "neutralize" peaks and dips in the room due to its' specific acoustics. This WILL vary with how crowded the club is. That's why minor adjustments are needed on a night by night basis. Once the room is somewhat "flattened out", they will administer further equilization to achieve the tonal balance that they are seeking to achieve for that specific group of entertainers.

Most "metal" or "hard rock" will get tweeked at about 80 - 120 hz with a slight emphasis between 200 - 400 hz. This adds "weight" and "body". Depending on the venue and sound that the band was looking for, sinking the 1 Khz slider down will make the vocals sound more distant and "heavier". One might also elevate the 2.5 Khz to 4 Khz range, as this would let the guitars cut through with more "bite". If cymbals were weak, you would play with the 8 - 12 Khz range. Moving this will add or subtract "splash" accordingly.

On the other hand, acts with a lot of vocals would not want the same equilization as it would come across as being muddy at the minimum and possibly even sibilant or "spitty" sounding due to the upper mid boost.

Even with all of the EQ'ing that takes place, it is next to impossible to get even sound coverage in most halls. The speaker arrays are normally not well thought out, their dispersion characteristics are not optimized, the acoustics of the room are rather eratic and the density of the crowd varies drastically. As such, trying to go for a "flat response" would be a waste of time and typically result in HORRIBLE sounding performances as it would only be "flat" in a very few spots. Most folks would rather have it be "coloured" but sound pleasant.

All of that is why home audio and pro sound are so different. We know the venue that we'll be listening in, we know the acoustics, we know where the listener will be seated, we know the appr listening levels, etc... Since most of the variables have been removed, we can then attack the problems more completely and precisely with less side effects than if one was working on a much "grander" scale.

The bottom line is that Pro Sound and home audio have very little in common other than they both use electronics to amplify and reproduce the signal. Sean
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