REGISTER NEW USERLOST PASSWORD? WELCOME, Logout

Clever engineering

Paul's Posts — 29 June 2012

By

Clever engineering

A few posts ago we covered the topic of dynamics in loudspeakers and how a small pair of speakers really isn’t capable of moving large volumes of air.  Unfortunate but true for those of us that enjoy listening to realistic sound pressure levels of orchestral music.

I have experienced “the real deal” with large loudspeakers like the Infinity IRS and the Genesis I’s among other large systems, but never with smaller ones.  Is it possible?  Obviously most of us (including me) neither have the space nor the funds to own a massive loudspeaker system.  The answer is yes if we apply a little bit of clever engineering.

I may have written about this before but years ago I figured out a way to trick the ear into believing the soundfield dynamics were linear and uncompressed in a small speaker system.  It’s been my experience that we perceive these compressed dynamics as a limitation of soundstage width with volume.  This means that as an orchestra gets louder – really loud – the apparent width of the soundstage should increase beyond the size of the room – and dramatically so.  Unless you have a large loudspeaker that simply dominates the room you won’t get this impression when the orchestra plays loudly.  That is unless you apply my trick.

What I did was simple.  I took another pair of loudspeakers, a small bookshelf pair, and placed each one next to the outer sides of of the primary speakers – 90 degrees from the front baffle of the primaries so they pointed to the outside side walls of the listening room.   I then connected the new speakers to a power amp whose input had a threshold gate on it and set the threshold so that the speakers started working only when the music was medium loud.

What happened was fairly amazing to any listener.  As the music became loud the soundstage width increased exactly as it would have in real life or with a huge loudspeaker pair.  It did this because the new speakers added the missing volume levels – but the energy was directed specifically at the sidewalls of the room – not the listener.  Some clever speaker manufacturer could easily add side mounted drivers into their designs and make a passive threshold gate using opto couplers so the primary amp could handle everything should anyone want to.

So you see that by using a bit of clever engineering one can overcome the hurdles we encounter if the desire is there.

email Clever engineering Forward to a friend and help us engage more readers

Get new and fresh stories like this each morning by joining the folks reading Paul's Posts. Click here

Related Articles

Get that mole! Treat the cause or the symptoms? Jelly rolls If you have to ask …..

Share

About Author

Paul McGowan

Paul McGowan is the CEO and co-founder of PS Audio Inc. a Boulder Colorado design and manufacturing company of high-end audio products and services. McGowan has been designing and building high-end products for nearly 40 years. Hobbies include skiing, music, hiking, artisan bread baking, kick boxing and cooking. He lives in Boulder Colorado with his wife Terri and his 4 sons.

(7) Readers Comments

  1. alan

    June 29, 2012 at 6:37 am

    Paul, are you saying that within the speaker itself include some sort of sensing device that will redirect additional energy to the side mounted drivers? … Thanks

  2. June 29, 2012 at 6:54 am

    Yup.

  3. Tom

    June 29, 2012 at 7:07 am

    Jim Gala put that sort of engineering into a bunch of musically superior speakers back in the late ’80s. His patent (#4881265) called it an “Apex Loudspeaker.” The flagship production model was the Grand Soliloquy. The one that probably sold the most was the regular Soliloquy.

    His company was Soundwave Fidelity which later was revamped into Vero Research. One or the other was on a high end blogger’s short list of “companies I wish were still in business.”

    The main sonic feature of the line was the 180 degree dispersion pattern and total lack of cabinet diffraction effects.

    Peter Mitchell wrote a short cogent commentary on the Soliloquy after auditioning them at a CES. The Absolute Sound published a very laudatory (but slightly bemused) review. They seemed to be shocked by a speaker system that sounded like real music rather than hi-fi music, explaining the oddity by the fact that Jim is a musician as much as an engineer.

  4. Soundminded

    June 29, 2012 at 8:43 am

    OMG, not you too! You’re halfway there and the bridge is out. Turn back! Turn back before it’s too late! You know the old saying, the road to Bose is paved with good intentions. :-)

  5. oliver T. Finch

    June 29, 2012 at 9:46 pm

    Quite a lot of sound heard at live performances is reflected sound which gives the sense of space. Your suggestion does something similar by increasing the amount of reflected sound. The greater amount of air reaching the listening position gives the impression of largeness yet after a certain loudness dynamics will be compressed because the cones will begin moving out of their comfort zones.with resultant loss of ease and alacrity of movement with resultant strain. Yet your solution will definitely do the trick in case of small speakers in small rooms. Much better than a single set of small speakers.Regards.

  6. July 24, 2012 at 3:01 pm

    Paul,

    Can you help me understand why you would only want these additional drivers to operate after the volume is moderately loud? Why wouldn’t you want them to operate full time? At least to some degree?

    Why should the additional “help” only be required after a certain level of loudness? Wouldn’t the volume assistance actually be vauable at all levels? Maybe of a variable nature instead of a sort-of on/off switch? If not, I wouldn’t likely ever listen to my system after 10pm (when the kids are in bed) due to this sound-stage augmentation (for lack of a better term) threshold.

    One of the Japanese receiver manufacturers applied a similar technique to their loudness circuit back in the late 70′s or early 80′s. Instead of an on/off loudness button, they made their loudness work backwards, reducing the midrange with a knob, instead of boosting the bass and treble with a switch. I assume they were attempting to track the Fletcher/Munson curve.

    Well, anyway, I just wanted to get your thoughts.

    THX, Doc

    • July 24, 2012 at 5:35 pm

      Doc, I can’t tell you exactly – I can only guess – but on most systems I have owned the deprivation of the soundstage only happens over a certain loudness – and below that loudness level the soundstage really neither needs or wants the extra width – it’s probably room dependent.

      I suppose you could view it in car terms with a turbo – why not have the turbo always engaged – but in fact it doesn’t seem to be like that. If it is always engaged (and I’ve tried it) it adds a phoniness to the soundstage that’s immediately identifiable and undesirable. So, when the orchestra plays really loudly, it simply doesn’t follow the same pattern of loudness and your ear picks that up.

      My guess is that below a certain level the room doesn’t interfere with the dynamics, but over a certain level (which is probably room dependent) you start to get compression of the dynamics within the room. This is where you need to kick the turbo on. :)

Leave a Reply