{"id":1591,"date":"2017-08-28T20:28:13","date_gmt":"2017-08-28T19:28:13","guid":{"rendered":"http:\/\/wfs-diy.net\/?p=1591"},"modified":"2017-08-28T20:28:13","modified_gmt":"2017-08-28T19:28:13","slug":"front-fills-on-a-ground-level-stage","status":"publish","type":"post","link":"https:\/\/wfs.pixetbel.org\/index.php\/2017\/08\/28\/front-fills-on-a-ground-level-stage\/","title":{"rendered":"Front-fills on a ground level stage"},"content":{"rendered":"\n
\"imag0506.jpg\"<\/figure>\n\n\n\n

During our summer residency at Th\u00e9\u00e2tre Garonne we have had the occasion to test our front-fills on a ground level stage. These little speakers have a coaxial design with a wide coverage angle of 120\u00b0. When they are put on the ground there are important reflections bouncing on the floor that can colour or interfere with the original signal.<\/span><\/p>\n\n\n\n\n\n\n\n

The speakers used here are KS-Audio CPD04<\/a>; small 15cm cubes with a 4.5 inch and a 1 inch speakers. They are self-powered with class-D biamplification (50W + 25W) and a FIR digital crossover. The coverage angle advertised is 120\u00b0 conical.<\/p>\n\n\n\n

Here is a series of measurements with the reference microphone at different distances from the speaker: 1m, 1st row of seats (roughly 2.5m) and 5th row of seats (5m). Some meeasurements were done with fabric placed on the floor in front of the speaker to absorb some of the first reflections.<\/p>\n\n\n\n

When the speaker was on a microphone stand we only measure without the fabric with the microphone a 1m.<\/p>\n\n\n\n

\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n

Here is to start the impulse response at 1m with and without the fabric.<\/p>\n\n\n\n

\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro \u00e0 1m \/ R\u00e9ponse impulsionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro \u00e0 1m \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro \u00e0 1m \/ R\u00e9ponse implusionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro \u00e0 1m \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro \u00e0 1m rang \/ R\u00e9ponse implusionnelle<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro \u00e0 1m rang \/ Spectre<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

Same with the microphone placed in the 1st row of seats:<\/p>\n\n\n\n

\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro au 1er rang \/ R\u00e9ponse impulsionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro au 1e rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro au 1er rang \/ R\u00e9ponse impulsionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro au 1er rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro au 1er rang \/ R\u00e9ponse implusionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro au 1er rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

And now in the 5th row of seats:<\/p>\n\n\n\n

\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro au 5e rang \/ R\u00e9ponse impulsionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Micro au 5e rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro au 5e rang \/ R\u00e9ponse impulsionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Micro au 5e rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro au 5e rang \/ R\u00e9ponse implusionnelle avec et sans le tapis<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Micro au 5e rang \/ Spectre avec et sans le tapis<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

If we look at the measurements changing the distance for a fixed speaker height, with and without the fabric.<\/p>\n\n\n\n

Speaker laying on the ground (speaker axis at 10cm off the ground):<\/p>\n\n\n\n

\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Sans tapis \/ R\u00e9ponse imulsionnelle en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Sans tapis \/ Spectre en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Avec tapis \/ R\u00e9ponse imulsionnelle en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte pos\u00e9e au sol (axe \u00e0 10cm) \/ Avec tapis \/ Spectre en fonction de la distance<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

Speaker slightly off the ground (axis at 17cm):<\/p>\n\n\n\n

\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Sans tapis \/ R\u00e9ponse imulsionnelle en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Sans tapis \/ Spectre en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Avec tapis \/ R\u00e9ponse imulsionnelle en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte l\u00e9g\u00e8rement sur\u00e9lev\u00e9e (axe \u00e0 17cm) \/ Avec tapis \/ Spectre en fonction de la distance<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

Speaker on a microphone stand (axis at 1.20m):<\/p>\n\n\n\n

\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ R\u00e9ponse imulsionnelle en fonction de la distance<\/figcaption><\/figure>\n\n\n\n
\"\"
Enceinte sur pied (axe \u00e0 120cm) \/ Spectre en fonction de la distance<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

We see the the fabric does indeed absorb some of the first reflections on the floor. Depending on the placement of the speaker in the venue we also get some reflections off the side walls and cieling. We used some fabric on top and on the side of the speaker to track where each reflections in the impulse response bounced.
We can see that the spectrum is more even with the fabric on the floor. The dips also shift depending on the position of the microphone. The extra distance traveled by the reflected wave depends on the angle of incidence.
We can also see that the spectrum changes depending on the height of the speaker for the same reason. Interference is greater when the speaker is a little off the floor than resting on the ground because the first dip is at a lower frequency.<\/p>\n\n\n\n

The best option for a ground level stage (not raised) seems to be when the speaker is resting on the ground with some absorbing fabric in front to dampen some of the reflections.<\/p>\n\n\n\n

\"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

During our summer residency at Th\u00e9\u00e2tre Garonne we have had the occasion to test our front-fills on a ground level stage. These little speakers have a coaxial design with a wide coverage angle of 120\u00b0. When they are put on the ground there are important reflections bouncing on the floor that can colour or interfere […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,6,10,12],"tags":[],"class_list":["post-1591","post","type-post","status-publish","format-standard","hentry","category-english","category-experimentations","category-pa-design-en","category-practical-setup-en"],"_links":{"self":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/posts\/1591","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/comments?post=1591"}],"version-history":[{"count":0,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/posts\/1591\/revisions"}],"wp:attachment":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/media?parent=1591"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/categories?post=1591"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/tags?post=1591"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}