Audio Systems: Speakers, jbl speaker systems, frequency numbers

Question
Dear Kevin,

Thanks for your help on those Yamaha and JBL speaker systems I was looking into buying.  I am looking at one of the higher end systems that Yamaha makes, for about $200 on the internet.  It is the NS-P320 system and the biggest difference is the front speakers are a different configuration than the surrounds.   They are also bigger in that they have a 4 3/4" woofer with 1" tweeter.  The surrounds have a full-range 4" driver.  The sub has a 6 5/16" driver.   Why is it that manufacturers insist on making subs with anything less than an 8” driver?  Where will the bass be?  I noticed a lot of Yamaha's packages come with only about a 6 1/2" driver for the sub. The frequency response of the fronts is 70 HZ to 28 kHz.  For the sub 30Hz to 200Hz.  I still don't understand much about frequency response or what the numbers mean.  Can you tell just by numbers how good speakers will sound, meaning you'll hear more highs or lows depending on the frequency numbers?  What do better speaker packages have in terms of frequency response?  In this case what does the 70 Hz mean and what does the 28 kHz mean?  The JBL's I was looking at had a frequency response of 35 Hz to 20 kHz, which someone told me was very good, and they were even skeptical of that spec, but I don't think manufacturers make things up.  I'm trying to stay within a budget of say, no more than $250, preferably less.  Can you recommend any specific systems from $150 on that would be really good?  Have you heard, or know anything about, speakers from KLH or Cerwin Vega?  Also, I was considering buying 2 larger speakers (maybe bookshelf) for my fronts from some manufacturer and then purchasing a cheaper sub, center and surround package from a different manufacturer.  Any suggestions? Do I have to worry about specifications or matching of anything?  One last question, and I apologize if I have asked this similar question before, but I've noticed that in certain satellites, particularly the JBL's I was looking at, they use a 3” midrange and 1/2" tweeter.  Other speakers by different manufacturers use a woofer and tweeter in the satellites.  I guess that having a midrange and tweeter is better than having a woofer and tweeter, because that's what the sub has, a woofer, and that's what puts out the low frequencies.  It seems like a woofer and tweeter in a satellite might not give you the full dynamic range that you would get with a midrange and tweeter.  Are my assumptions correct?  Thanks very much for your help again.


Answer
Dear Dave,

Nice to hear from you again.

First, I'll reiterate my reservation about Japanese speakers. Don't like 'em; don't recommend 'em.

The general rule of speakers is that the larger the radiating area, the lower the frequency response. Conversely, very small radiating areas generate high frequency response. That's why tweeters are small and woofers are large. Midrange drivers are in between, handling everything but the very low and very high.

However, speakers can be tuned to receive almost any frequency. You could, say, tune a tweeter to reproduce signals only from 35Hz to 200Hz--the normal range for a subwoofer. Problem is you wouldn't hear anything because the tweeter's radiating area is so small it can't (literally) push out the big, huge sound waves that low bass requires. But you can direct those frequencies to a smaller driver, like the Yamaha's 6-5/16" jobber, and it will put out what it can--but it won't be deep bass. Again the radiating area physically restricts its ability to do anything but some decent mid-bass. However, IMHO deep bass is overrated and sometimes all you need is decent mid-bass. For instance the PSB Image 2Bs that I recommended have only a 7" midrange driver (in addition to a 1" dome tweeter), but it puts out generous, fairly even upper low bass at around 80Hz. In my review of it, I noted that in some nearfield applications, like a bookshelf or small home office configuration, a subwoofer was unnecessary. So, depending on what your objectives are, a 6"-7" subwoofer, like that in the Yamaha, might be all you need.

When you're talking about speakers with smaller cones (in the 4" to 7" range) being "woofers" it's because they are tuned to and can reach into the mid-bass region, roughly 200-350Hz. Otherwise, they're midrange drivers; sort of sending out a teenager to do a man's job. When you're talking about even smaller drivers (3"-4"), the only difference between a "woofer" and a "midrange" is the spelling.

Okay, now I'm throwing around all those Hz and kHz numbers like the makers. What do they mean? Hz means "Hertz" a unit that measures frequency response, generally by measuring the number of times the wave (tonal sound generates a sine wave, with equivalent peaks and valleys) generated by the sound source repeats or "cycles" (generates a full wave with one peak and one valley) itself in a second. So, a low sound with a huge wave will only repeat itself a few times (50Hz) while a high sound with a teeny, tiny wave form will repeat itself thousands of times, say, 1,000Hz or 1kHz--the "k" standing for "kilo" or in metric terms the number multiplied by a thousand. When you're measuring how many times something repeats itself, you're measuring it's "frequency"--literally the number of repetition patterns per second. So, speakers have rated "frequency responses" that range from 25Hz (tho' some subs go down to 10Hz--a massive generally inaudible wave form) to 20kHz. Yes, some speakers claim to go even higher (I've seen some claim to go to 40kHz!), but remember two things about these figures. First, the range of human hearing is about 50Hz to 12-15kHz; everything above and below those numbers can be sensed as a vibration, but for all intents and purposes, they're inaudible. Second, makers measure frequency response with a microphone sitting about 1/8" from the driver with the driver being driven to its maximum possible volume in an anechoic (acoustically inert) chamber. Yeah, you can get the measurements, but you'll not hear very much reproduced outside of the range of human hearing.

(I once reviewed a speaker which claimed a low of 28Hz, and all I could get from it at even 50Hz was a loud fart. After that, nothing. When I interviewed the engineer, a veddy polite and earnest British chap, how he measured 28Hz, he told me they'd actually nested the microphone in the mouth of a resonance chamber and cranked the sucker up. Here's the kicker: all of this was from a 4" driver. It was a good speaker, but all that bass was pure fiction.)

What's it all add up to? Well, a couple of good satellites and a modest sub, if properly tuned, will produce the full range of audible sound. I'd aim for 50Hz as my very lowest for my sub and whatever you can get for your satellites, but don't be gulled into thinking the higher the frequency response (28kHz vs. a "mere" 20kHz) will give you better sound. Don't worry what they call the bigger driver in the satellites; it doesn't matter.

Yes, you can mix'n'match brands--the key is what frequency you set the subwoofer's crossover to: in other words, with every sub, you'll choose what you want it to reproduce. The rule of thumb is 80Hz, which is where most subs feels comfortable and where most satellites poop out (called "roll off").

Finally, brands. Man, you're looking at all the stuff I can't stand. Cerwin-Vega simply doesn't make a cabinet that doesn't fatally color the sound with a poor design. KLH used to be great. Now they're simply acceptable. Gave you thoughts on JBL and Yamaha last time.

Here's my recommendation for your price range, since the PSBs seem to be out of it. Go to www.hifi.com, the web site for Cambridge SoundWorks, the best "value" vendor around. Go to home theater speaker packages. Their best value system, the Classic Series Ensemble IV, is on sale for $150. Get it. You'll get the whole shebang: two front channel, two surrounds, a center channel, and a sub. It's mail/web order only, and if you hate the sound (you won't), you can send it back for a refund or an upgrade. If you can stretch your budget to $300, the MovieWorks 56 Home Theater System is even better. Don't go with Yamaha, CV, JBL, or KLH in your price range. All you'll get is crap. Trust me on this.

Let me know how it turns out, and don't worry about the numbers.

Kindest regards,

Kevin