User manual MARTIN AUDIO WAVEFRONT COMPACT APPLICATIONS GUIDE

[. . . ] CONTENTS < > ENGLISH ONLY GUIDES PRINT Wavefront Compact Series Applications Guide MARTIN AUDIO LONDON The Martin Experience All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT Wavefront Compact Series Applications Guide Contents Introduction Section 1 Section 2 Section 3 Section 4 Section 5 Wavefront Compact Series Overview W8C 3-way System W8CT & W8CM Line Array System W8CS Flown Subwoofer WSX Folded Horn Subwoofer W8L Series Line Array Systems Appendix A1 A2 W8 3-way System W8S HybridTM Subwoofer MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT Introduction Wavefront Compact Series Overview Thank you for purchasing a Martin Audio Wavefront Compact Series system. Wavefront Compact Series products make up a coherent "toolkit" of compact, live sound enclosures covering a huge range of professional sound projects from high quality club installations to major touring and festival systems. Unpacking Each Martin Audio loudspeaker is built to the highest standard and thoroughly inspected before it leaves the factory. [. . . ] At this frequency the central position remains well covered but the polar pattern has MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT changed dramatically around the sides. There are now strong lobes at the sides because the spacing is now an even number of half-wavelengths at this particular frequency. These lobes could cause low frequency feedback problems on stage with the high microphone gains used for orchestral low string (cello, double bass) sections or for "unplugged" performances. 60Hz At 60Hz the spacing is an odd number of half-wavelengths again so we see side nulls again. 40Hz When the frequency drops to 40Hz, the 8. 6m spacing = 1 wavelength. Again, the central response is maintained but there is a dip in response over wide areas either side of the centre. The spacing is an even number of half-wavelengths again so we see side lobes again. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT 40 Hz reduced spacing The above shows what happens at 40Hz if we reduce the spacing between the subwoofers to 4. 3m. We get better central coverage without 40Hz side lobes - adequate for long, narrow "shoe-box" venues but wider coverage would be required for most arenas. 40Hz close coupled Close coupling would give a wider coverage at that frequency but the spacing could still give coverage irregularities at mid-bass frequencies due to the shorter wavelengths at higher frequencies. The real world Bass notes usually include harmonic components each with a different wavelength. Some will add giving an amplitude peak whilst others will subtract giving an amplitude dip. This will give tonal changes with listening position and emphasise particular notes and timbres. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT In the following example, listeners over a wide central area will hear a warm bass note rich in harmonics whereas those around the sides (in line with the subwoofers at 90º) will hear less of the fundamental but more of the harmonics whose full wavelengths coincide with the subwoofer spacing. Listeners in the 60º zone will hear the note at a reduced level and may be more aware of room reverberation because the direct-to-reverberation ratio would be poorer for that note. Other notes would give different effects. In practice, these peaks and troughs can be smoothed out with additional fill systems. 4. 11 Electronic steering It is possible to "aim" ground-stacks towards distant raked seating or balconies or away from problematic areas by electronically "tilting" the system using multichannel digital delay lines. The illustration below shows the basic schematic plus the staircase effect** (greyed out) produced by the progressive increase in drive delay from bottom to top. **Important Note: The staggered stack (shown greyed out) illustrates the effect of electronic steering. For safety reasons, never try to tilt or stagger a real subwoofer stack. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT Note that it is important to keep the subwoofers tightly packed to avoid polar anomolies caused by spacing. Procedure The normal procedure is to measure the angle from the top of the vertical subwoofer stack to the highest/most distant seats (using an inclinometer) and to calculate the required delay increment with the formula shown. Example We wish to project bass/mid-bass punch to stadium balcony seats 30º higher than the top of our WSX stacks. The WSXs are 572mm wide giving a centre-to-centre spacing of 0. 572m. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT This means that our delay increment (in ms) = tan 30º x 0. 572 x 1000 340 = 0. 577 x 0. 572 x 2. 94 = 0. 97mS or 970uS. The following delay line taps would be required for the above system: t0 t1 t2 t3 t4 t5 t6 = = = = = = = 0ms 0. 97mS 1. 94mS 2. 91mS 3. 88mS 4. 85mS 5. 82mS Going further It is possible to apply electronic shaping to horizontal arrays. For instance, it is common to use curved main clusters for smooth mid and high frequency coverage. Ground-based subwoofer arrays should follow the same curvature to maintain midbass crossover coherence but this is often difficult due to flat-fronted stage structures. The following illustration shows an example of a flat-fronted horizontal array electronically splayed to emulate the greyed-out example shown. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. [. . . ] This will cause a vertical stack to perform as if it were double the length, giving a useful low frequency boost accompanied by a narrower, more complex polar response. MARTIN AUDIO - APPLICATIONS GUIDE, WAVEFRONT COMPACT SERIES All material © 2007. Subject to change without notice. CONTENTS < > ENGLISH ONLY GUIDES PRINT For instance, a 4 high ground-stack of W8S' will act like the top half of an 8 high stack. (Important: see safety note above) Note that flexible floors may actually absorb sound at some frequencies so the situation isn't always so simple in practice. Horizontal - 6dB coverage The following table gives the approximate horizontal coverage angles of typical W8S arrays - ignoring boundary effects. [. . . ]