Bass Questions

Everything in speaker design involves trade-offs. This is most evident when looking at bass extension, sensitivity, and cabinet size / volume. Unfortunately there are speaker manufacturers provide bass specifications that are suspect at best. There's obviously posturing involved in order to increase sales and tell potential buyers what they want to hear.

From time to time I have customers asking if it's possible to have deep bass extension and high sensitivity in a moderate size (or even small) sized cabinet. In some situations they quote numbers given from other speaker companies and the woofers are drivers that I've used in previous designs. This often presents a problem if the information given me doesn't line up with my own personal tests. After having designed 100's of speakers I can pretty much look at specifications and tell you if they are reasonable.

Part of the problem is there are different ways to take and interpret bass measurements. The best two ways are anechoic or nearfield  tests with nearfield primarily being what I use. You can do in-room curves; however, resolution (accuracy) is often skewed by acoustic problems in the room. Some companies don't even measure at all and rely on software simulations or an "optimistic" guess from their sales and marketing people.

My solution is a simple one - just tell the truth and strive to be as accurate as possible. 

Rick Craig, Owner and Designer




The dumbing down of audio...

In an effort to save space (both physical and bandwidth), reduce cost, and increase portability we have what I refer to as the "dumbing down of audio". It's really not a new concept, considering past changes such as the 8-track alternative to reel-to-reel or the cassette to vinyl. Today it's represented by file compression for delivery over the Net, mostly pathetic soundbars, and pill-shaped Bluetooth speakers (the latter mainly just a modern version of the old table radio).

Being an audiophile non-conformist I've rejected most of these ideas, with the exception of cheap compressed streaming - like that I'm listening to right now as I type. Hey, it allows me to hear lots of new music which if I like it enough I purchase a disc!

I guess what prompted me to write this is that I recently read that only about 10% of the 18-35 age group have a component system, with the 90% majority streaming over soundbars and the like. Part of this is the failure of high-end audio companies to provide products at a reasonable cost and communicate the benefits of better audio. We also need to be able to adapt to changes in the market - turntables still can produce great sound but to ignore digital and streaming will only put another nail in the coffin.  

Yes, I've considered designing some soundbars and wireless speakers. We'll see (or hear) what happens!

Format Wars

Speakers obviously come in all sizes and shapes, some are monopoles, others dipoles, or even a combination of the two. If one design was clearly superior then most buyers would gravitate towards it. Maybe not though since marketing and sales have a huge impact (just consider the mediocre headphones that sell in large numbers).

Herein lies the problem. Too many myths exist so I often find audiophiles looking for answers in the wrong places. One of those myths is that a 2-way design will have better integration than a 3-way based on the lower number of parts and greater simplicity. True, a 3-way is more complicated to design; however, the drivers are operating in a more conservative fashion (narrower operating ranges) so when executed properly integration is actually better. All other things being equal the 3-way usually wins because of lower distortion and better dispersion. 

The second myth is that the crossover point locations must be at certain frequencies, or to the extreme that no crossover should be used so that a single wide-range driver is the only alternative. I've found that where the crossover points fall is secondary to what is best for that particular combination of drivers. To answer those that like the single-driver concept, well, the physics weigh heavily against that approach. There are some drivers that can do amazingly well from about 150hz on up to 20K but I've never heard a system that was convincing tonally, had good bass extension, or let alone dynamic enough to compete with conventional lower cost 2-ways.


DSP (digital signal processing) is becoming more  evident in all areas of audio, especially as the cost comes down making it available to a wider audience. Traditionally 2-channel audiophiles have resisted the change to digital; in fact, the home theater people have been embracing the technology to a far greater degree. The pro audio segment first applied DSP techniques, in particular, of the use with speakers (analog active crossovers having been the previous standard for many years).

A little over ten years ago I imported a unit from DEQX in Australia. I still own it and Selah Audio was one of the first companies to use it with a speaker design. Other companies have now launched similar DSP products such as miniDSP. The benefits of a digital crossover and room correction were obvious to me so it was a no-brainer. Passive crossovers certainly can provide great sound but they still have their limitations. In some cases passive designs make more sense (simplicity and cost) but with more complicated designs such as line arrays DSP offers the best performance.

One of the common complaints against DSP crossovers is that the digital-to-analog converters (D/A) compromise the sound. With current D/A chips it's difficult to argue that there are distinct audible differences - yes I know some would argue they do exist. The question is how this compares with the advantages of using DSP, including smoother frequency response, room correction, and the ability to adjust the voicing of the speaker for your listening preferences. In my opinion these far outweigh any D/A issues which seem to mysteriously vanish with blind ABX testing.



Crossover Parts

One of the questions I'm often asked is something like "what crossover parts do you use or what upgrades do you offer"? Before I founded Selah Audio I worked as a component buyer in the electronics industry. Part of my responsibility included working with design engineers to find suitable parts for a variety of products.

Some of the equipment we manufactured worked at very high frequencies way beyond the audio band. Slight deviations in passive components (resistors, inductors, and capacitors) often became critical to circuit performance.

The same can be true for high end audio; however, it seems that the claims made for exotic parts often have no scientific basis and lack the documentation to show that there's an audible difference (let alone if it's even closer to the source material you're listening to). Of course there are many opinions on this subject and if you ask 99 audiophiles you might receive 100 answers. Stay tuned as I discuss my thoughts on this and other subjects in the coming year...