Originally Posted by Molon_Labe
I have two 24" Deep Sea Sound subs @ 4000 watts each. I don't run any of my speakers at full range. My JBLs are not handling down to 30hz, they are crossed in the receiver at 80hz. Why do you have Seaton's and all that power? Any sub that can produce down to 20hz will meet the THX spec right? It is because the Seaton has larger, better drivers and more power. It can produce its frequency range better than a smaller sub. This is the same principle. Mid bass content extends up to 200hz. Does the 80 to 200 range not matter? Larger, high-efficiency speakers will produce this more dynamically than smaller less efficient speakers. Here is a THX certified system. Will this system sound as good as your system? Oh course not. Why? It has smaller, inferior drivers across the entire freq range from subs to the tweets.
I've resisted getting pulled into this argument because I outgrew "my <whatever> is bigger than your <whatever>" arguments many years ago. However, I disagree with some of the points that you've made, and in the interest of productive discussion, I'm willing to step into the fray...
I would imagine that you used the above example of the Logitech THX-certified computer speakers in the photo above as an absurd example to make your point, but you opened the door. The speaker system is likely the Logitech Z906
, which is intended and designed to be used on a computer, not in a home theater. It is certified per the THX multimedia system specification, which is not the same as the three THX certifications that actually apply to home theater applications.
I haven't heard these speakers, and I would imagine that you haven't either, so all we have to go on is the specifications. My guess is that this is a pretty nice speaker system... for a computer environment, where the listener is probably within 2-3 feet of every speaker. No one here would likely support using this speaker system in anything bigger than a small dorm room for watching movies.
Since we're on the topic of THX certification, let's follow that path. While some may feel that THX is no longer relevant, and a common argument amongst its detractors are the that shiny logo just adds to the cost, and "high end" products can be better and don't have the logo, the fact remains that the certifications were designed to meet minimum standards. Those standards were used to define a level of performance, which began as one certification and grew into the Ultra (the original spec) and Select (intended for smaller rooms) levels, which now appear to have spawned a third (THX I/S Plus Systems) for smaller rooms yet. While people can take issue with the THX approach to speaker design (dipolar surrounds, front speakers with limited vertical dispersion, etc.), I've not ever seen a qualified criticism of the hard specifications that THX uses for performance standards.
One of the most highly regarded home theater speakers for watching movies is the M&K S100B and its generational siblings:
Three tweeters and two 5.25" drivers. Rated at 77 Hz - 20 KHz ± 2 dB. Their S-5000 was used by Dolby Labs to design Dolby Digital (same size drivers I believe, rated at 72 Hz - 20 KHz ± 2 dB). The company followed with the S-150THX and from that design, the Ultra2-certified MK Sound S-300
, which is rated at 60 Hz – 22 kHz ±3dB.
Through all these years, the size of the drivers hasn't changed. These speakers are designed to be used in conjunction with subwoofers that are appropriate for the application. They aren't trying to reach to 30 Hz, and the subs aren't designed to reach to 200 Hz. Why would you want that (in either end of the spectrum)? Let the drivers specialize at what they do best and don't make them perform at too wide a frequency range. As long as the crossovers are handled properly, there isn't a problem with such an approach.
I found several references to what is required by THX Ultra2 certification. Here is a portion of a 2003 interview of Rick Dean, Director of Technical Business Development at THX Digital Works
THX Ultra2 is a 7.1-speaker extension of the original Ultra spec. It’s designed to work well with multi-channel music and movie presentations--and soon, video games--playing up to reference levels in rooms of 3,000 cubic feet or larger. Each certification requires components to produce high volume levels and disperse sound in specific ways with low levels of distortion.
Reference level is defined on the THX web site:
What is Reference Level?
Manufacturing receivers and speakers that can achieve THX Reference Level is no simple task. It requires a tremendous amount of power to drive an audio system effortlessly without clipping or distorting. To ensure the audio products can reach this peak performance, THX developed a set of standards as part of its THX Ultra2
, THX Select2
and I/S Plus
- Experience Studio Clarity: THX Certified Receivers reproduce studio Reference Level, 85dB SPL with 20dB of headroom.
- Reference Level for your Room: THX Ultra2 Plus, THX Select2 Plus and THX I/S Plus certification categories deliver Reference Level performance in your specific room size.
- Distortion-free Playback: THX Certified Receivers and speakers are designed to recreate Reference Level with minimal distortion.
So, all of this begs the question: If all the speakers in your system can achieve reference levels with minimal distortion across the entire frequency range ("THX Certified Subwoofers must extend to 20Hz (-6dB) to handle the very highest bass levels with ease"), why does it matter what size the driver in any particular speaker is?
If the difference between a 5.25" driver and an 8" or 10" driver in an overhead speaker is so incredibly stunning, it must surely be able to be measured, no? As long as each driver is not distorting, and there is a proper subwoofer and crossover to handle the transition between that speaker and the subwoofer, the end result should be the same (performance-wise). I welcome the chance to review such data if it is available.
There's something to be said for "bigger is better" and some might say that size matters in certain situations, but there comes a point when enough is enough, and anything more is just for show. If large drivers makes one feel better about their system, more power to them. But, in a properly configured and tuned system
, I do not agree that larger drivers in floor or overhead speakers will make a difference.