I used to prefer grills off, now I prefer grills on. I don't think the speakers have changed, it's my taste that has changed. I also like simpler music. I am more interested in precise notes than how many notes can be played. I want the speaker to let me explore the music not force it on me and if a speaker comes with a grill I believe it is designed to be listened to that way.
When I remove the grill the speaker has more detail, but the speaker also sounds more mechanical, less like music the way some audiophiles describe the difference between analog and digital.
The grill cloth has to affect more than just detail. It must also affect dispersion characteristics and if it affects dispersion characteristics it must affect how the speaker reacts with the room. As Roy explained, with the grill on, air is always stuck around the woofer and there must be some affect on other drivers too, but could this be perceived as a positive affect or do manufacturers take this into consideration and use it to their advantage?
Stan, Raul is a GURU, he is also one of the nicest and helpful folks you will ever meet. Raul, Shadrone, Albert Porter and a few others are an asset to this forum and hobby as a whole.
About that 'softening the attack of a kick drum'-- You are right about what makes up the attack, which indeed are high-frequency tones that follow the impact of the beater striking the tightly-stretched skin. I should have been more clear, but this does describe the impression.
In as small of a nutshell I can find, here is why:
Any drum-sound takes a few cycles to build-up to its main resonant waveform. That resonance could be at a low frequency from a kick drum or in the middle-range from a conga.
Resonance means taking time to build up to an even louder sound, called magnification. Resonance also means taking a while to stop.
At the very first moment though, what we see on the `scope is a near vertical rise in air pressure. This is the beater pushing the drumhead out towards the mic instantly and then holding it out there for a moment. The side of this rise can be thought of as the fastest (high-frequency) risetime. The 'risetime' for the low-frequency portion to fully build up is several far-longer cycles.
In between these two extremes are all the other resonances which come and go with particular timings and loudness'. These are determined by the resonances in the drumhead and drumshell which impulsive 'thrusts', such as from the beater, always trigger.
All together, these make up the sound of "whats-his-name on a maple Pearl 22" kick drum, with Remo heads and a beater from Drum Workshop, an AKG mic placed right there, run into a Neve mixer, Pulltech EQ, Altec compressor, and onto 1" tape at high speed on a Studer. Oh yeah, with some reverb added. And he was having a good day."
The presence of the grille alters the LF-relationship to all of those other tones/events, by delaying the maximum rise of the low-frequency waveform and its subsequent decay.
What we hear and feel can be described as a less-defined impact, perhaps a more-rounded sound depending on the drum and how it was played and recorded. We can often feel the pace is delayed- less 'drive'. The arrival of the LF-portion of that drum's sound has been blurred, and then told to hang on an extra moment.
This is a dynamic issue, not a steady test-tone issue, because the cloth's resistance to air motion changes non-linearly with the stroke of the woofer: Twice the cone velocity (=2x stoke) creates roughly four times the air drag. FYI, this drag can be translated into a total moving mass (cone + air) that is apparently changing with loudness = 'variable mass'.
If you can somehow put an accurate value for that change into the standard equation of motion for the air molecules, watch how fast a computer can choke! As a side note, a rocket loses moving mass as it burns its fuel. So it speeds up more rapidly each moment, from the same amount of thrust. But the increased speed increases the air's drag on the rocket by a lot more, a drag which also lessens with altitude, but then changes again when the speed of sound is first exceeded... Much computer-time for NASA before going to the moon.
When the grille reaches anything close to a steady back-and-forth motion, its resistive loss is then a) steady, and b) small compared to the cone's stroke. Therefore, its effect is not readily measurable on steady test tones, by MLS, or on pink-noise, but can be seen in an impedance curve.
Thanks for pointing this out. I appreciate the opportunity to clarify.
I would add that the baffle step is usually somewhere around 400 to 800 Hz and edge diffraction is something that affects imaging mostly in the midrange and treble. Neither of these frequencies are terribly important for a high quality subwoofer that should not output high amounts of harmonic distortion.
We find it easy to hear cloth soften the attack of a kick-drum and reduce the percussiveness of a string bass. It is best described as hearing a 'mumble' or a 'stumble' in the 50-70Hz range.
Huh? The "attack" on a kick drum is around 5 KHz. Most sound engineers can confirm this for you. How this can affect a subwoofer would be a mystery unless it were run full range like a bass guitar amp/speaker.
The main issue (apart from some very slight attenuation in higher frequencies) with grills is the way the baffle is designed. Some baffles have very sharp corners and the grill acts to help reduce the severity of this baffle step and edge diffraction.
Grille cloth behaves differently at each frequency. In the bass, a great deal of air is literally always 'stuck' to a woofer's cone- the larger the woofer, the deeper/thicker that layer.
Therefore, any cloth will act as a drag on that moving mass. This means it inhibits dynamic response (not so much steady-state) with a time lag, as it follows the cone's motion imprecisely.
Cloth also keeps more air molecules trapped next to the cone, and next to itself. This again changes the moving mass (and also varying with the SPL), and therefore changes the cabinet's bass tuning (again, varying with the SPL).
We find it easy to hear cloth soften the attack of a kick-drum and reduce the percussiveness of a string bass. It is best described as hearing a 'mumble' or a 'stumble' in the 50-70Hz range.
However, in that frequency range, most subwoofers have tremendous amounts of time-delay/phase shift built-in, which swamps our ability to hear such a difference.
While we find that the cloth/no cloth difference in the bass is not bothersome to most anyone, we do remove them when evaluating gear and cables, as we can hear them conceal some differences.
Best regards, Roy Johnson Designer Green Mountain Audio
I'm with Johnk on this one. The rational part of my brain thinks the wavelengths of a subwoofer's output would be much longer than the point at which diffraction effects would be audible. However, sub grills can darn sure rattle. I'd get a test tone cd like the ones Rives or Stereophile sells and check to make sure no grill buzzes need attention. I've had to use dabs of Blutack to damp the odd buzz in a sub grill.
You seem to be overly defensive or are puffing yourself, because I didn't see a single post in the thread that questioned your experience in listening to speakers with or without grills. The complaint about the use of the term always referred to the premise of OP's opening question.
You know, before I joined this forum I had no idea of the power other people appear to think I possess. I had previously regarded myself as unquestionably the worlds foremost authority on my own opinion. When I make a statement like " I have never heard a speaker that sounded better with the grills on" I am recounting my own experience, not making existential statements about the nature of the universe. Some of you out there appear to think that such a statement, if uncorrected, will do damage to the tender minds of the less experienced. Raul recently accused me of ignorantly misleading the uninformed by disagreeing with him about the relative merits of two tonearms. Unlike him, I do not consider myself a GURU and feel free to express myself with the expectation that readers will regard such utterances not as expressions of the REVEALED TRUTH but simply as the current thinking of a very fallible audiophile. So chill out , my opinions are mine alone and binding on no one else whatsoever.
I used to think speakers sounded better with the grills off, but I've changed my ways. Now I like the sound better with grills on, but I find it hard to believe it would make a difference on a subwoofer.
Stan some speaker grills have built in tuning material for the tweeter for example. If a grill does in fact attenuate the treble some speakers may infact be made with a hot tweeter to account for the grills. Its matter of opinion and personal choice but it is not fact. I dont like the look of speakers with grills off, reminds me of college kids for some reason but I also dont hear a negative in sound so that works for me, others like them off and thats cool too.
Just which speakers do you have in mind? Are you saying that the ones I have listened to really sound better with them on? What I said was that I had never heard one sound better. I have not heard all speakers and I doubt if you have heard the ones I listen to. My Mini Utopias did not COME with a grill, did Focal screw up their sound? All the grill can do is attenuate the treble, do you want that done? The only really transparent grills ever made were the old foam ones like JBL use to use, effective but looked cheap. Even the Quads were considered to sound better uncovered.
I have never had a pair of full range speakers that sounded better with grills so I never use them. 3 of the 4 pairs of subs I have have no grill over the speaker, being either upward firing or downward firing. I do have grills on my Nelson Reed 1204s. Considering the frequencies involved I doubt that the grills would be audible; usually the problem with grills is treble attenuation, which of course does not apply here.
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