{"id":2523,"date":"2012-09-07T13:47:21","date_gmt":"2012-09-07T13:47:21","guid":{"rendered":"http:\/\/www.audioexcite.com\/?page_id=2523"},"modified":"2012-09-09T14:58:50","modified_gmt":"2012-09-09T14:58:50","slug":"raal-140-15d","status":"publish","type":"page","link":"https:\/\/www.audioexcite.com\/?page_id=2523","title":{"rendered":"RAAL 140-15D"},"content":{"rendered":"

Overview:<\/span><\/h3>\n

\"\"<\/a><\/p>\n

The RAAL 140-15D is a ribbon tweeter made by the RAAL Company in eastern Serbia.<\/p>\n

The RAAL 140-15D ribbon is made of a 21 sq. cm (14×1,5cm) pure aluminium flat foil which weighs 22mg. It has a sturdy build quality with a 2mm metal faceplate and uses a very powerful neodymium motor system. The ribbon provides a linear frequency response up to +40kHz with an outstanding horizontal off-axis dispersion and for a ribbon tweeter, low distortion and great vertical dispersion.<\/p>\n

With special \u201cfoam deflection pads\u201d it\u2019s possible to adjust, control and improve the vertical dispersion and the so called vertical \u201cbeaming\u201d of high frequencies, which is commonly seen among large ribbons.<\/p>\n

The \u201cfoam deflection pads\u201d are working as an acoustic lens, by slowing down the velocity of sound and thus shaping the sound wave front from cylindrical to spherical.<\/p>\n

By using the \u201cdeflection pads\u201d the high frequency response level can be adjusted to personal preferences without the need of additional padding resistors as well as adjusting and controlling both the vertical and horizontal dispersion.<\/p>\n

Even though this ribbon tweeter is expensive, it\u2019s one of the best measuring ribbon tweeters on the market and with innovative design features such as \u201cfoam deflections pads\u201d and specially designed face plates etc.<\/p>\n

To ensure a nice distortion safety margin I recommend using the RAAL 140-15D from 3kHz or higher. However by using steep cross-over filters it can be used from 2-2.5kHz\u00a0 with some elevated distortion and limited max output.
\nRAAL Spec sheet: RAAL Ribbon Tweeter 140-15D<\/a><\/p>\n

T\/S Parameters:<\/span><\/h3>\n

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\"\"<\/a>Nice consistency between the two tweeter samples.<\/p>\n

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 <\/p>\n

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 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

Impedance:<\/span><\/h3>\n

 <\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Free air impedance measurement:<\/strong><\/p>\n

Left:<\/strong> No protection cap<\/p>\n

Right:<\/strong> 44uF protection cap<\/p>\n

Sample 1 = Green<\/p>\n

Sample 2 = Blue<\/p>\n

A perfect match between the two samples.<\/p>\n

 <\/p>\n

Frequency:<\/span><\/h3>\n

 <\/p>\n

Frequency measurement conditions:<\/strong><\/p>\n

The ribbon tweeter is measured mounted on a baffle with the following conditions:<\/p>\n

Baffle size: (WxH):<\/strong> 33\u00d720cm (baffle edge round-over r=19mm)<\/p>\n

Driver position:<\/strong> Mounted on center-line with driver unit centered on the baffle. Flush-mount using felt carpet.<\/p>\n

Mic position:<\/strong> 1m distance, on tweeter-axis (horizontal measurements). 0.75m distance, on tweeter-axis (vertical measurements).<\/p>\n

Smoothing:<\/strong>\u00a0 1\/24 octave smoothing applied.<\/p>\n

Tweeter configuration:<\/strong><\/p>\n

DPN<\/strong> = No \u201cdeflection pads\u201d.
\nDP1<\/strong> = With \u201cdeflection pads\u201d and 7cm visible ribbon.
\nDP2<\/strong> = With \u201cdeflection pads\u201d and 5cm visible ribbon.
\nDP3<\/strong> = With \u201cdeflection pads\u201d and 3cm visible ribbon.
\n<\/strong><\/p>\n

All frequency measurements are made with a 44uF protection cap.<\/p>\n

Horizontal frequency measurements comparing sample 1 and 2:<\/strong><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = Sample 1 on-axis<\/p>\n

Red<\/strong> = Sample 2 on-axis<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 DPN<\/p>\n

Upper Right:<\/strong> DP1<\/p>\n

Lower Left: \u00a0<\/strong> DP2<\/p>\n

Lower Right:<\/strong> DP3<\/p>\n

Virtually the same frequency response between sample 1 and 2. Note the extended frequency response and the possibilty to shape the response with the \u201cfoam deflection pads\u201d<\/p>\n

 <\/p>\n

Horizontal frequency measurements:<\/strong><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = on-axis<\/p>\n

Red<\/strong> = 15deg off-axis<\/p>\n

Green<\/strong> 22.5deg off-axis<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 DPN<\/p>\n

Upper Right:<\/strong> DP1<\/p>\n

Lower Left: \u00a0<\/strong> DP2<\/p>\n

Lower Right:<\/strong> DP3<\/p>\n

 <\/p>\n

 <\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = 30deg off-axis<\/p>\n

Red<\/strong> = 45deg off-axis<\/p>\n

Green<\/strong> = 60deg off-axis<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 DPN<\/p>\n

Upper Right:<\/strong> DP1<\/p>\n

Lower Left: \u00a0<\/strong> DP2<\/p>\n

Lower Right:<\/strong> DP3<\/p>\n

 <\/p>\n

Horizontal frequency measurements:<\/strong> (comparing different “deflection pad” settings”<\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = DP1<\/p>\n

Red<\/strong> = DP2<\/p>\n

Green<\/strong> = DP3<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 On-axis<\/p>\n

Upper Right:<\/strong> 15deg off-axis<\/p>\n

Middle Left: <\/strong>22.5deg off-axis<\/p>\n

Middle Right:<\/strong> 30deg off-axis<\/p>\n

Lower Left: \u00a0<\/strong> 45deg off-axis<\/p>\n

Lower Right:<\/strong> 60deg off-axis<\/p>\n

 <\/p>\n

Vertical frequency measurements:<\/strong><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a><\/strong>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = on-axis<\/p>\n

Red<\/strong> = 5deg off-axis<\/p>\n

Green<\/strong> = 10deg off-axis<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 DPN<\/p>\n

Upper Right:<\/strong> DP1<\/p>\n

Lower Left: \u00a0<\/strong> DP2<\/p>\n

Lower Right:<\/strong> DP3<\/p>\n

 <\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = 15deg off-axis<\/p>\n

Red<\/strong> = 20deg off-axis<\/p>\n

Green<\/strong> = 25deg off-axis<\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 DPN<\/p>\n

Upper Right:<\/strong> DP1<\/p>\n

Lower Left: \u00a0<\/strong> DP2<\/p>\n

Lower Right:<\/strong> DP3<\/p>\n

 <\/p>\n

Vertical frequency measurements:<\/strong> (comparing different “deflection pad” settings”<\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

\"\"<\/a>\"\"<\/a><\/p>\n

(click on picture to zoom)<\/p>\n

Blue<\/strong> = DP1<\/p>\n

Red<\/strong> = DP2<\/p>\n

Green<\/strong> = DP3<\/strong><\/p>\n

Upper Left:\u00a0<\/strong>\u00a0 On-axis<\/p>\n

Upper Right:<\/strong> 5deg off-axis<\/p>\n

Middle Left: <\/strong>10deg off-axis<\/p>\n

Middle Right:<\/strong> 15deg off-axis<\/p>\n

Lower Left: \u00a0<\/strong> 20deg off-axis<\/p>\n

Lower Right:<\/strong> 25deg off-axis<\/p>\n

 <\/p>\n

Frequency measurement summary:<\/strong><\/p>\n

The dip and peaks between 1.5-2.5kHz is the effect of the baffle size and the diffraction associated with it. The dip gets less pronounced when moving off-axis<\/p>\n

By using the supplied \u201cfoam deflection pads\u201d the frequency measurement performance are truly amazing, both horizontally and vertically. By removing the \u201cdeflection pads\u201d (DPN<\/strong>) setting, the measurements shows the common vertical \u201cbeaming\u201d effect of a large ribbon as well as a rising high frequency response.<\/p>\n

The best overall balance and linearity between the horizontal and vertical frequency response is to use the \u201cdeflection pads\u201d in the DP1<\/strong> or DP2<\/strong> setting e.g. 7cm or 5cm visible ribbon.<\/p>\n

 <\/p>\n

Distortion:<\/strong><\/span><\/h3>\n

 <\/p>\n

Measurement setup:<\/strong><\/p>\n