Building a System

What is the most important component to choose when building a system? This is a question I am often asked in my capacity as an audio system design consultant, so I thought I’d put down my thoughts on the subject for our periodic Audio Concepts Blog.

There is no one-word answer to the question. Users’ needs vary widely. For the mature, settled shopper, finding speakers that suit the long-term environment properly is the obvious place to start…ones that both fit the space available and can deliver the desired level of performance within that space. I then work in the needs of the speaker (its sensitivity, impedance), the room size, and listener’s predilections in music and media and budget in order to narrow the range of amplifiers to those that make the most sense. The physical placement of the electronics and sources to the speakers helps determine appropriate cabling, remote control requirements, etc.

For the shopper who hasn’t arrived in a long-term domicile yet in their life, the approach changes. It’s not so easy to find one-size-fits-all solutions to quality sound reproduction. The good news is that fairly portable, great-sounding products abound in today’s audio market. Medium sized stand-mount speakers (those with 5.5”-7” diameter woofers) are probably the most versatile recommendation for this customer. These speakers have enough bass extension and volume capability to give a good semblance of full range music reproduction, yet can fit in a smaller room without seeming over sized. And almost any quality amplifier on the market will power these speakers adequately. Younger listeners today rely on media delivery from smartphones, tablets, streaming services, and less on traditional sources like CDs, so an amp ought to have facilities for USB, Bluetooth, and other digital media in addition to conventional analog inputs…if it needs any of those at all!

I should point out, however, that based on my own experience, with each move I made, an overhaul of my system was needed. Perhaps my being in the business made this so natural (and affordable) to me, that I just used the move as an excuse to upgrade or experiment with new components to find just the right fit for the environment. I realize most shoppers cannot easily justify this kind of “flipping” through systems, but for the audio hobbyist the reality is the pursuit never ends!

What We Are After…

A great speaker sounds like “nothing”. It disappears…leaving only the illusion of the reproduced sound in the listeners’ imagination. And that illusion is maintained across an area…not limited to one “sweet spot”. A great amplifier is the same…it gets out of the way, imparting no tonal signature, neither narrowing nor widening the stereo perspective, and leaves the sound illusion to “float” in space. Poor amps sound dull or bright…they flatten the listening perspective and deprive the music of tonal nuances that let you distinguish the performers and their instruments’ unique musical identity.

Where to Start…with Speakers

Subjectively, the biggest determinant of the sound you get is established by the speakers. They have the greatest deviation from the ideal of pure and accurate sound reproduction, so that is where the big differences are found. Most speakers are made using a moving coil electro-magnetic “engine” attached to a cone, which creates sound waves by pushing the air molecules in front of it to simulate the sound waves captured by the recording microphone(s). Since musical sound is produced by instruments and voices of various sizes and pitches, a single diameter cone is rarely able to do a credible job with all that variety. Hence we have woofers and tweeters. To achieve accuracy these parts must operate together (cross over) where their ranges intersect. The measure of a speaker’s performance is a composite of the quality of its woofer, its tweeter, and how they blend to create a seamless whole. These parameters are all experienced in three-dimensional space, with the profound influence of the listening room and their placement in it. Research conducted in the 70s and 80s under the guidance of Floyd Toole at the National Research Council of Canada showed that a speaker’s acoustical power output uniformity in 3-D space is the best indicator of its perceived accuracy. This is now the guiding principle for most speaker design worldwide.

When I say a 5.5”- 7” woofer 2-way is a versatile performer for many buyers, it’s because the size of the woofer is in the sweet spot to take a big enough bite of the air to make deep enough bass, yet small enough to create a smooth and seamless transition to the range covered by the tweeter. Larger woofers can produce stronger bass and more volume only at the expense of worse mid-range clarity. In the 60’s speaker designers often matched 9”, 10” or even 12” woofers with their tweeters (these were also larger then than the norm today of 1”) with the result that HiFis had a lot of “boom-tizz” and not a lot of midrange. Since the NRC’s findings were published, the trend has been to avoid the big mismatch in size between the woofer and tweeter. Since the physics of sound waves sets 1” as the optimal maximum for the tweeter, working down the spectrum to the happy place for a smooth transition gets you to the 5”-7” area. But a woofer of that size isn’t going to shake the room with deep bass.

Who needs a subwoofer?

Full scale orchestral classical music has a range that demands reproduction of the lowest frequencies. Audiophiles want to feel the opening organ pedal of “Also Sprach Zarathustra” at 32Hz, and the impact of the large tympani of “Le Sacre du Printemps”.
Amplified rock and hip-hop music has percussion and electric bass guitar with little content in the sub-40Hz spectrum, but synthesizers can output any frequency the musician wants, often of such high intensity that a 7” woofer can be over-taxed.
Movie sound tracks have a lot of deep bass sound effects, and it is the popularity of home theater systems that created the market for subwoofers that we see today. Many of us justify the investment in a sound system by recognizing it serves both to enhance the enjoyment of TV and as a music system. The widespread acceptance of powered subwoofers to augment the lowest end of the music spectrum has effectively removed the need for the speaker’s own woofer to fully extend to the bottom. You can simply add on the bass extension later if you feel you need to.

Where to Start…with AV Electronics

If integrating TV is involved in your thinking, you should know that all home theater receivers are equipped with “bass management” circuitry to assign upper frequencies to smaller “satellite” speakers and lower ones to the subwoofer, but stereo amplifiers usually do not. Since home theater receivers also possess valuable facilities like HDMI switching, room correction, and decoding for surround formats from Dolby Labs and DTS, they are the most practical item to build your system around. It is a testimony to the expertise of the consumer electronics manufacturers that the level of performance is as good as it is, but there is still the feeling that AV receivers lack the musical qualities of better stereo equipment. At Audio Concepts we offer Anthem AV receivers, which we feel offer a sound closer to that of purist stereo systems than the norm.

Where to Start…with 2-Channel Electronics

The differences between amplifiers that can be heard by the attentive listener are rarely found in the specification sheet, and the explanations for this offered over the years are numerous and mostly unproven. My journey through years of experimentation taught me that one brand of amplifiers with exceptionally good distortion measurements (<.0008%!) sounded squeaky clean, but were flat and dimensionless. That was because the low distortion came as a result of the excessive application of negative feedback in the circuit design (I think). Another amp I tried had exceptionally good current delivery (doubled into 4 ohms, and again into 2 ohms!), but sounded dull and boomy. That might have been because the designer was so focused on his power supply’s performance that he paid too little attention to the amplifying circuit. One highly regarded brand I tried did everything right…on paper…but was so lacking in “life” to the reproduced sound that I kept it for only a month. Tube amps and preamps can be wonderfully musical, but can also soften the timbre of instruments and reduce the speakers’ grip on bass notes. Of course, the best tube gear doesn’t do these things, or does them less. At Audio Concepts, we offer affordable quality stereo amplification from Rotel and Pro-Ject, and higher end choices from Bel Canto, McIntosh and Classé. This latter group let you take your system to the top of what’s possible. In Conclusion… My opinion of AV receivers is mixed…I’ve used models from Denon, Pioneer, Onkyo, Marantz, and Yamaha in my system, and each has done a credible job in my TV system when calibrated and dialed in. But none of them made me want to listen to music the way I used to with a great stereo system. It might be simply that life has other demands as I’ve grown older, my ears aren’t as sharp as they were, and my surround speakers aren’t as good as the best floor-standers I’ve had…or it might be that everything is digitally processed now, even the phonograph goes through the digital bass management, and something is lost in translation. Knowing how these factors interact and operate in real-world systems helps to steer the buying process in the right direction. Lewis Dalven, resident audiophile, shares his thoughts on product, trends, industry happenings, and why Steeley Dan is the greatest band ever.

By Lewis Dalven