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Bass

Paul's Posts — 19 August 2012

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Bass

In past posts I have written much about bass and much of what I have written involves the use of subwoofers.  As many of you know I believe you need subwoofers to make your system whole.  I haven’t built a system I listen to without a sub in years.

If you get everything we’ve been discussing setup correctly and then put on a track that should have good, deep low bass – and find that it doesn’t – then you really only have a couple of choices.  You can try moving your listening position around for best bass with the possibility of losing your imaging in the process, you can ignore the low end of the music if it’s not that important to you or you can add a subwoofer.  There aren’t a lot of other options.

It is at this point where I bring my subs back into the system and integrate the pair for best performance with what I have.  I have used many subs in the past but currently I have a pair of Martin Logan Descent servo subs that are great.  There are a few really great subs around, like those from REL, the JL Audio Fathoms and mine if you can manage.

The trick with adding a sub is two fold: use a left and right pair if you can and if not, make sure the one sub goes on the right side of the loudspeaker pair in case you’re going to be listening to classical music.  Secondly, the sub frequency should probably never go above 30 or 40 Hz and on most music you should almost never hear the sub except if there’s a really low fundamental.

A subwoofer is useful to fill in the lower octaves of bass most loudspeakers cannot produce and couple well into the room with.  Even those loudspeaker pairs that can produce true low frequency bass (and there are only a rare few) are probably not being placed in the right area of the room for good bass – that’s the funny thing – the best place for everything but good bass is where we have the speakers.  So it’s not worth sacrificing what we have achieved to better the bass response.

IMHO it’s much better to either leave the low bass off of the radar or add a subwoofer or two to achieve it.

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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.

(10) Readers Comments

  1. hahax

    August 19, 2012 at 6:57 am

    I’m curious why you advise putting a single sub on the right for classical music. I would guess that you would just choose the best spot for it sonically in rspect to deep bass sonics and also into integration with the system. At the frequencies involved bass is totally non-directional. I recall a CES demo of the the Pipedreams speakers as they were playing at a very high level with tons of bass and people were going up to the woofers(crossed about 65 hz) that were feet away from the rest of the system and putting their ears right next to the subs telling the demonstrator they weren’t working. They had to de shown the drivers moving to concince them everything was OK. It sounded like all the bass came from the main boxes as it should. All the directional info was coming from the harmonics and higher tones in the music.

    • August 19, 2012 at 1:50 pm

      It’s because the way most people use a subwoofer is to cross it over higher than it probably should be crossed over – and I am assuming something similar will happen here. I should probably go into a bit mode depth on the subject but at higher frequencies and what is handled completely by the crossover it seems to always become a bit directional despite your best efforts. If, in the case where you really have it set low, like 30Hz or so and given a 12dB/octave crossover, then it probably doesn’t matter.

      • dr.goodears

        August 20, 2012 at 2:23 pm

        I guess if the room is large enough, the woofer is reference calibre in nature and the crossover is set to 40hz perhaps, it’s challenging to get subwoofers to perform seamlessly with the primary speakers and not draw attention to themselves.

        I’ve always found that the investment in higher quality sources, electronics, cables and powerline filtering always yield high returns in terms of enhanced system musicality and low frequency performance.

        Certainly in a 5.1 system it’s an effects channel and therefore becomes fundamental in terms of the sound mix. I love Richard Vandersteens take on subwoofers, buy 4 and place one in each corner!

  2. Soundminded

    August 19, 2012 at 9:43 am

    Once upon a time when you bought what was advertised as a “full range” high fidelity loudspeaker system, that meant full range. No subwoofers, no apologies. Some were of course better than others, much better in fact. Today you spend thousands on a so called high fidelity speaker and hte manufacturer tells you if you want to hear the lowest octave or more that speaker can’t produce you must buy an external subwoofer. He of course will be happy to sell you one or several usually for thousands more. The ubiquitous 2 way 8″ woofer/1″ dome tweeter or 2 1/2 way that adds a second 8″ woofer is a modern gutless wonder. A not too bad variant of it was AR’s low cost entry into cheap-fi in the 1960s with AR4/4x selling for a whopping $57. It evolved later into Snell type K and then to Audio Note type K juiced to sell for up to many thousands. If I were putting together a high end system from scratch today I’d probably look at Parts Express/Dayton RS 1202 (K). It appears to be a knockoff of the Teledyne AR9 dual sideways 12″ design with a built in 950 watt amplifier. As a one hour kit it sells for $850. Two of those should give most brand name subwoofers a good run for their money.

    I don’t see how any sound system can claim to be high fidelity if it cannot reproduce the lowest octave of sound. The Martin Logan Summit that sold for $10,000 a pair was a huge disappointment for many reasons not the least of which was its bass. It was driven by a monster Krell amplifier when I heard it. The first servo subwoofer I recall hearing was Infinity Servo-Static back in the 1970s. It had one subwoofer driven by its own 250 watt servo amplifier. I’m a bit surprised someone hasn’t already figured out that they could build a servo woofer using the second voice coil in a dual voice coil subwoofer as the feedback signal source. Maybe they have?

    • August 19, 2012 at 1:53 pm

      Yes, many subs have tried this trick of using as second voice coil – it isn’t very good as a servo to be honest. To act like a good servo you have to make sure you wind up with a velocity sensor. The second voice coil can act somewhat like a position sensor but in every attempt I’ve seen it really never did anything to lower distortion.

      We used an actual accelerometer in some cases and a makeshift one in others – based on a piezo electric crystal which, when you integrate its out, can give you both acceleration and velocity.

  3. oliver T. Finch

    August 19, 2012 at 9:17 pm

    You had me scratching my head wondering what IMHO meant. Had to go on google to find that it is a internet slang. Thanks for helping me learn a new word even if it is a slang. Regards.

    • August 20, 2012 at 6:32 am

      Oops, sorry Oliver I didn’t mean to use internet slang but sometimes it’s helpful, at least IMHO. :)

  4. bondmanp

    August 27, 2012 at 8:07 am

    Paul – Just a comment. A subwoofer you might consider adding to your short list is the Vandersteen 2Wq. I have a pair of them, and they offer several advantages over many other subs. First, and foremost, they are designed to produce flat, extended bass when placed in a corner. This is a common sense design idea that is rarely applied to subwoofer designs. This sub also uses the speaker level output from your amplifier as the signal source, similar to the REL, but with the addition of an in-line high-pass filter that matches a roll-off below 80Hz (1st order) to a corresponding rise built into the sub’s amplifier. IME, these subs, which also feature an adjustable Q setting, offer extended, tight, tuneful bass, blend extremely well with almost any speaker capable of clean output down to 40Hz, and never make their physical presence known with directional bass or overhang. I have long felt these are one of the real bargains of the hi-fi world.

    • August 27, 2012 at 8:19 am

      Thanks. Actually I had forgotten about Richard’s subwoofer and I know it to be excellent. Appreciate the suggestion.

  5. Pingback: Teledyne subwoofer | Autoworksbiddi

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