In this article I will describe how to build a high-fidelity, bass-intensive sound system for under $1000. The secret ingredient of the system is the use of tactile transducers. These transducers effectively eliminate the need for expensive woofers or subwoofers. It’s an efficient method of producing deep, high-fidelity bass for a fraction of the usual cost. Many of the ideas presented here were gleaned from the recommendations of audio enthusiasts, and the book High-Performance Audio Systems by Robert Harley.

For speakers, the first thing to do is to delegate bass and treble to separate system components. My recommendation is to acquire high-quality bookshelf speakers, to cover the treble and midrange. Then, for the bass range, we will use a tactile transducer. Transducers produce tactile sound in a frequency range of 15Hz to 800HZ. Tactile sound is perceived through bone conduction, muscles, and skin sensation. Basically, you feel tactile sound rather than hear it. Note though, that its not just about rumbling — tactile sound can be heard in high fidelity up to midrange frequencies.

The most common technique to produce tactile sound is to attach a transducer to a floor, couch or chair. This means that the sound is perceived only when sitting or standing on the vibrating object, so there’s less chance that you’ll disturb your neighbors.

It’s also a good idea to build your system with modular components. For example, instead of buying an integrated receiver/amplifier, consider getting a separate amplifier and receiver, and even a separate pre-amplifier. By using modular components, it makes it much easier to upgrade your system. You can upgrade your $200 amplifier with a $600 amplifier, when your budget permits. But from the start, all of your components should be of a reasonable quality to get a good final audio result. For example, a pair of $1000 speakers will produce very poor quality sound if you plug them into a substandard amplifier.

Also, when building any kind of audio system, it is best to use non-toxic audio components. Electronics laden with mercury and cadmium are not efficient. To find non-toxic electronics, look for products with Energy Star and RoHS compliance.

Here are the components of this system:

Bookshelf Speakers: ($270)

Tactile Transducer: ($150)

Amplifier ($100)

Stereo Receiver ($210)

Audio Cables ($35)

Desktop Computer (not included in price)

Here’s a summary of how to build the system:

Use an audio source (like a computer), to output to a good-quality stereo receiver. You use the receiver to power two high-quality bookshelf speakers (covering 65-21,000 Hz). That’s pretty straightforward. Now for the tactile sound sub-system. You power a tactile transducer with a separate amplifier. And you connect the amplifier to your stereo receiver’s “Sub Out” connector. The tactile system takes the place of a woofer and subwoofer, and covers the range of 15Hz to 800HZ (deep bass to lower midrange sounds). This give you a nice frequency overlap with the bookshelf speakers, so together your speakers cover the deepest bass all the way to the highest treble.

Let’s look at each element:

Audio Source: A Computer

For this example, we will be playing MP3 files on a $500 Mac Mini desktop computer. For higher fidelity you can use FLAC files (uncompressed CD-quality sound files). Macs and iPods produce reasonably good sound quality through their audio out connection (via a mini-plug). The Mac Mini uses only about 20-32 watts, making it the most energy efficient desktop computer available. It is also Energy Star 5.0 compliant, and it is rated EPEAT Gold (a green rating for computers). To connect the Mac Mini to our stereo receiver, we use a mini-plug to RCA connector.

The Stereo Receiver

Almost all commercially available music is recorded in stereo for stereo listening, so it makes sense to play it on a system tailored for stereo reproduction. For this example, I’m using a Harman Kardon Stereo HK 3390 receiver. This is attractive stereo receiver produces great, crisp sound. At $210, it is a certainly a high-end device at a budget price. The HK 3390 receiver is aimed for stereo sound reproduction. It does support some video capabilities, but it is not intended for home theater use. The 3390 makes use of a high-current power supply for amplification. But the energy consumption is reasonable — this unit drew 30 watts of power on average, during my tests.

You can of course use almost any AV receiver want for this system, including a home theatre receiver, as long as it has subwoofer pre-output.

The Bookshelf Speakers

For this example, I will be using some PSB Alpha B1 Monitor Speakers. These are audiophile-type speakers that can be purchased inexpensively (they sell for about $260). The December 2007 issue of Stereophile gave the Budget Product of the Year to these speakers. They said “The PSB Alpha B1 is exactly the kind of product this hobby needs — one that brings the High End down to earth, makes hi-fi attainable for just about everyone, and, beyond all, reminds us how much fun this hobby should be.”

The Absolute Sound magazine rated the PSB Alpha B1 as the Best Stand-Mounted Speakers in the Winter 08/Spring 09 issue.

So they are nice sounding speakers, and they are also made of non-toxic materials (they are RoHS compliant).

Next, let’s take a look at the bass:

The Tactile Tranducer

For our bass speaker, we will be using a Clark Synthesis Tactile Transducer. Clark Synthesis makes tranducers that cover the full range of tactile sound (from 15Hz to 800HZ). We will use the $150, entry-level Clark Synthesis Silver Edition (TST239) — this will be more than enough bass for our home system. It will produce solid definition to drum hits, or shake your fillings loose if you so desire. The transducer can be installed in less than an hour. It took me about 45 minutes to bolt it to the bottom of my couch, using the parts provided with the transducer. In my test installation, I removed the fabric from the button of a couch, and bolted the transducer to a crossbeam underneath. Once installed, the entire couch functions as a bass speaker.

The Tactile Amplifier

But wait, we need to power the tactile transducer! Clark Synthesis sells a $350 customized tactile amplifier to do this, but you can actually use any amplifier that outputs at least 100 watts (check the Clark Synthesis documentation for more info).

Well, Cambridge Audio makes good amplifiers, but their entry-level models start at $330. For our budget system, we can instead use a AudioSource amplifier. This is a 2-channel 100-watt (50 watts x 2) power amplifier, which can be purchased for under $100. This amplifier is well-reviewed — 111 reviewers on Amazon gave it an average of 4 out of 5 stars.

You attach your amplifier to the tactile transducer using standard speaker cables. You then connect the amplifier to the Sub Out connector on your receiver.

Cables

It’s a good idea to use good quality audio cables to connect everything together. Cheap cables or the “free” cables that come with your electronic devices can degrade your system’s sound.

The Finished System

After turning test system on, I found it to produce impressive sound — clear treble response and exciting, visceral bass. This system is also quite energy efficient — the entire system uses a total of about 75 watts when powered on (100 watts if you count the computer).

Make sure you spend time positioning your speakers in your room for optimal audio performance. See the book High-Performance Audio Systems for all the details on speaker positioning.

Equipment Used: A Mac Mini connected to a Harman Kardon Stereo HK 3390 receiver, a pair of PSB Alpha B1 Monitor Speakers, a Clark Synthesis Silver Edition Tactile Transducer, and a AudioSource amplifier.