Making sense

May 3, 2022
 by Paul McGowan

When somebody poses an idea that doesn’t make sense, my first reaction is to reject it as wrong. Over the years, I have been working hard to ignore that first impulse, take a breath, and try and discover what our differences are.

Just because it doesn’t make sense to me doesn’t mean it’s wrong. It is simply a challenge to my worldview.

The practice of taking enough time to investigate the differences in people’s thought processes and conclusions has proven to be quite valuable. The last example that comes to mind is when PS Audio speaker designer Chris Brunhaver and analog engineer Darren Myers both teamed up on me to announce servo woofers could be bested by the removal of the servo.

Heresy!

I had been a fan of servo controlling woofers for decades. You can imagine my initial reaction to their radically different idea. But, I took a deep breath and heard them out.

Turns out the woofers we had been used to using weren’t optimized for anything other than their intended purpose, servo control. There’s no need investing money in exotic magnets, spiders, and Faraday rings when the servo handles all that for you. Only…and here’s where the learning comes in…that improved performance wrought by the servo comes at a price (as does everything in engineering). Active feedback systems depend on errors occurring and then catching up to those errors to fix them by using the power amplifier’s grunt.

By not making the errors in the first place the sound is stunningly better. And, of course, there too is a cost for this method: increased expense. It’s a LOT more expensive to build a low distortion, high excursion woofer in the first place (by a factor of nearly 10X).

It’s helpful to sometimes give what doesn’t make sense a chance to fill in the knowledge gaps.

It’s often how we grow.

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15 comments on “Making sense”

  1. Yes I always believed what Chris believed but could it have been that in the past before technology improved there was no way to make a 15 or 18 inch subwoofer behave without the use of a servo? It’s not that you were wrong Paul, just not caught up with the latest technology. Moreover I don’t believe 8 inch woofers ever had the problems of the giant woofers so you probably could have used multiple older 8 inch woofers in the FR30 without a servo. That’s probably why the 8 inch woofer has been so popular even way back in the day instead of using one giant woofer. I always preferred multiple 8 inch woofers to the single larger woofer but now that larger woofers 10 inch and up can be made to behave without the use of a servo I have warmed up to them. Just wondering where the limit is today where you might still need a servo if you go too big? Can modern state of the art 15 or 18 inch woofers behave without a servo? When the IRSV were made was the technology there back then to make them without a servo and behave?

    1. Dynamic drivers such as midranges and tweeters have come a long way and can compete with the exotic drivers out there. Albeit the exotic drivers have also gotten better. But the gap has been significantly closed to where you can use all dynamic drivers and get astonishing results. Such is the same with tubes and solid state to the point where you can choose one or the other and there’s not really a need for hybrids anymore, though some may still prefer them. There’s a lot of great sounding parts out there and there’s really no bad choices unless the speakers or electronics have design flaws that make them sound bad.

  2. Sometimes what is thought to be the latest, & best, technology isn’t all it’s cracked-up to be.
    Some loudspeaker manufacturers are returning to paper-pulp/wood fibre driver cone materials from their excursions into more exotic materials…why?…because it sounds better; more natural.
    I remember Paul also being very big on having a separate driver for the mid/upper bass frequencies, a four-way crossover/driver designed loudspeaker, & unless one of those four 8″ drivers on the front baffle of the Aspen FR30 is dedicated to the mid-bass, I would guess that CB talked Paul out of that firm belief too.

    Finally, here’s a funny 5 minute review from our ASR hero, Amir, about cheap interconnects.
    Funny because, again, it shows that you just can’t measure everything in home-audio.
    I believe that ‘AudioQuest’ is about to be renamed, ‘FraudioQuest’ 😮

    https://www.youtube.com/watch?v=bHw_Te6IbUI

    1. In my audio life I never experienced significant improvements in sound quality by using expensive (short) „audiophile“ RCA cables for line level. RCA cables for phono that‘s another affair. Here the contact quality is most crucial too. And RCA cables for digital signal require a specific impedance. But also cheap optical Toslink cables do the job if the module for transforming the electrical signal into an optical signal is designed correctly. These modules in my old TacT gear could even transmit 24/192 without losses – galvanic isolation as a nice side-effect!!! No rocket science! In contrast to my prejudices power cables and speaker cables can make huge differences. However I still look for scientifically based explanations.

    2. Agree with most of what you said FR but the 8″ woofer drivers in the FR30 are small enough to be considered bass couplers and also large enough to be used for subwoofers when there are enough of them. Should make for a nice effortless sound especially while working in tandem with those well designed passive radiators which beat ports.

    3. FR, The problem is not just that you cannot measure everything, it is you also have to know how to measure. I have seen demonstration showing how a square wave is altered when there is a cable connecting two pieces of gear where there is an impedance miss match. The cables themselves become part of the circuit and different cables have different results. This is especial true of cables connecting phono cartridges to the phono preamp

    4. FR, thanks for the Amir video link. He had me chuckling and scratching my head. While his measurements seem convincing, my ears still tell me Audioquest Fire interconnects sound much better in my system than my other interconnects, except the outrageously expensive Tara Labs Zero that beats the Fire by a tad.

  3. It always puzzled me that Paul didn’t immediately recognize that negative feedback in amplifiers and servos in speakers suffered from the same disease.

  4. Those four 8-inches do the goods.
    Deep enough, fast enough and clean but only when called upon.

    What I found is unusual to me. Though played at a satisfying natural level, still one could comfortably talk over it.
    I first experienced this with Linn Isobariks.

    Theory time: I credit its being unflattened; the louder parts riding easily over the lower. A kind of high slope transfer function.

    We were auditioning them tonight among the small privileged group in Melbourne Australia where Magenta the agents have got hold of one of the five beta version sets circulating in the world.

    Several liked the idea of matching the planned smaller model— fewer 8inch woofers. supplemented by twin sub-woofers. My guess is it could be even better.

  5. The term ‘making sense’ at the start of todays post is what throws / sets me off. The context of those words is based on individual biases.

    In order to be innovative the status quo has to be challenged. New ways new ideas. Some will succeed, some will prove to be ineffective or impractical.

    Of course enter in the impractical or physically impossible and making sense comes into play.

    I think ‘summarily dismissing’ sums up many initial reactions.

  6. I have an interesting semi custom system with 18″ woofers(the same ones used in the last Snell A) crossed over passively at 85 Hz(Their inductance won’t let them go much higher) by 4th order Linkwitz/Reilly. Because the designer was afraid they would overload his room ported(the bass roll off is a Bessel function achieved with passive equalization) he designed the box to work with the port stuffed as well as open.

    I’ve used both formats. Ported it’s excellent with excellent mid bass, no boom). But with the port closed the bass is even tighter with better detail. The second but is the ported box is richer sounding almost surely due to the more extended overhang with the port. Both the designer and I hear the same way and he knows the port is less accurate but he prefers the port for the richness and I prefer the port closed for the extra control.

  7. Sometimes it doesn’t mean it’s “wrong” as in a binary yes or no.
    It may mean there are more efficient ways to achieve highest goal.

  8. My guess is, today’s topic is mainly a question of developing a “worldview” too quickly out of a personal decision (often even without trying out and making experiences with a necessary amount of alternatives).

    Some people tend to do this often and those people often wonder a lot afterwards as soon as they just practically try out what they rejected for so long and what contradicted “their rule”.

    Among those who constantly try out things, also beyond their initial standpoint and after a first decision, we find a lot of openness and rarely extreme opinions. Among those who make up their opinion on a theoretical vs. practical experience, a single or no relevant experience at all, we usually find the most dogmatic and long lasting worldviews.

  9. I have never been disappointed with my older-technology floorstanding loudspeakers with their low-distortion dual 9″ SEAS Excel magnesium cone woofers without internal amplification and without server control. They do the job simply and competently.

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