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Pro Audio Technology / Professional Home Cinema

by Nyal Mellor October 03, 2011

Who are Pro Audio Technology / Professional Home Cinema?

PRO, the company formally known as PHC, have been making world class loudspeaker, subwoofer and amplifiers for home theaters since 2004. Their lead designer is Paul Hales who used to design audiophile speakers for his own company - Hales Audio - prior to founding PRO. They are based in Huntingdon Beach, California and manufacture their products in the USA from a combination of domestic and international components. There are a number of things that make PRO systems cool:
  • High efficiency drivers
  • Constant directivity horns
  • Actively driven i.e. direct coupling of amplifier to driver (no passive crossovers)
  • DSP crossovers and speaker correction
In the rest of this article I'll share more about the requirements for home theater, how PRO delivers these requirements and the PRO product lineup.

What are the requirements of a home theater system?

You should not just assume that the right speakers for home theater are the same ones you use for music reproduction. It is important to understand that the requirements for home theater reproduction are different than those for stereo. Here is a good quote from the Audiophiliac blog on CNET.
"A lot of people think good sound is good sound, but music and movies have very different requirements...remember that today's films have nearly unlimited soft-to-loud dynamic range; dialogue is mixed to the center channel; surround effects may be ambient or point-sourced; and deep bass demands can be extreme. How different is music? Let me count the ways: an exceedingly small number of new music recordings are available in multichannel sound; stereo rules in the music world; most, probably 99 percent of all music recordings are dynamically compressed; and deep bass effects are almost nonexistent."
If the requirements are different then it makes sense that the systems engineered to meet those requirements will take a different approach than is usual in the audiophile world. The film industry mixes movie soundtracks to an industry 'standard', or 'Reference Level', of 85dB average playback level with dynamic peaks of 105dB. For playback 'as the director intended' the main system loudspeakers must be capable of 105dB peaks and the subwoofer of 115dB peaks. Loudspeaker sensitivity is properly defined as the SPL generated by an input voltage of 2.83V as measured at a distance of 1m. 2.83V is equivalent to 1W across 8ohms. Typical audiophile loudspeakers have sensitivities of around 88dB. PRO loudspeakers are actively driven which means that there are two sensitivities - one for the low frequency section and one for the high frequency section. The high frequency, horn loaded section, has a sensitivity on the order of 110dB whereas the low frequency section has an efficiency of 93dB for the SCR-12sm and SCR-26ai (see below for more discussion on these particular models). SPL falls off at 6dB per doubling of distance. So the SPL at the listening position will be significantly less than close to the speaker. Taking just the low frequency section let's look at a comparison of SPL output for 1W power input at a typical listening distance of 4m (13ft). Examining the table below you can see that a audiophile loudspeaker rated at 88dB sensitivity will output 76dB at the listening position for 1W of amplifier power input.

Now let's look at how much amplifier power is required to achieve reference level - 105dB - at the listening position. To achieve a +3dB increase in SPL requires double the amplifier input power. Looking at the table below you can see that an audiophile speaker would need over 1000W compared to just over 250W for the PRO speaker. The critical point to realize is that audiophile loudspeakers cannot handle this much power even if you had a 1000W amplifier available - the voice coils would overheat and melt. PRO uses professional drivers that are rated to handle many hundreds of Watts.
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As you can see high efficiency, high power handling speakers are <strong>the only way</strong> to reproduce movie soundtracks as the director intended.
<h3>What loudspeakers choices are there from PRO?</h3>
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PRO make everything from huge three ways capable of 140dB output at 1m to small in-walls. A couple of their key speaker models follow:
  • SCR-12sm, shown above, combines a 12" woofer with a 1" compression driver. This is perhaps the sweet spot in the PRO lineup and comes in a standard 'box' enclosure for which PRO use the terminology 'surface mount'.
  • SCR-26ai, comprising two 6" woofers and a 1" compression driver designed for installation behind drywall or in a baffle wall. The AI designation stands for architectural installation.
  • SCR-5iw, which is a 5" woofer with a 0.75" compression driver. This is a speaker designed for retrofit in-wall installations (hence the IW designation) and comes with a metal back box and paintable perforated grille.
  • SCR-25ic, which combines two 5" woofers with a 1" compression driver in an enclosure designed for in-ceiling installation.
Here is a video from Larry at PRO talking about the SCR-5iw and the SCR-25ic.

What amplifiers models do PRO have?

PRO use DSP to manage crossover between the drivers in an individual speaker and provide for speaker correction. This is a similar to the approach used by DEQX, another brand that we sell. High order crossover slopes (48dB / octave) are used to minimize overlap between drivers and maximize power handling. Each speaker has its own unique set of DSP crossover and speaker correction curves that must be applied for the speaker to function as designed. Some of the smaller models such as the SCR-5iw can be driven in a 'passive' configuration, with one channel of amplification per speaker. Most speakers, however, require one channel per driver and are driven in an 'active' configuration. The DSP required is delivered by the PRO amplifiers like the PMA series.

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The PMA series of amplifiers combine up to four amplifier modules in a single 3.5" high (2 rack mount unit) enclosure. Modules are available with 200W, 450W and 1000W power ratings. Some of the cool features these amps include are correction for the effects of acoustically transparent screens and parametric EQ (no outboard processor required!).

What subwoofers do they make?

PRO have a number of subwoofers including 15", 18" and 21" models. They are designed to keep up with the maximum output capability of their loudspeakers and as such they use high power handling professional subwoofer drivers in ported enclosures. They are all designed to be used with PRO amplification such as the PMA series above.

Where can I get more information?

If you'd like to find out more on PRO loudspeakers, amplifiers and subwoofers please get in touch!

Nyal Mellor
Nyal Mellor


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Nyal Mellor, Founder, Acoustic Frontiers

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  • Serving USA & Canada
  • Fairfax, Northern California, USA

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