If my speakers were still under warranty there is NO way I would follow their dumbass advice. If removing that little plastic thingy really improved the sound, don't you think the factory would have done that by now?
-RW- |
Most people listen with their grill clothes removed.Why listen through a sock.Warranty concerns considered or poking an issue? |
In front of the tweeters on my big B&W800's and adjacent midrange I did remove the cloth grill.
In front of the tweeters, behind the cloth grill are plastic rings that serve to focus the tweeters, and they should NEVER be removed!
Richard |
OK the speakers are not in warranty and I do not plan on removing the plastic grill attached. Of course I do always remove the cloth grill when playing music. End of story. |
Check this out: The problem is NOT the metal dome. A good metal dome tweeter will sound sweet, open, transparent, and resolved. The problem is that 98% of all metal dome tweeters put a "thing" in front of the dome. Sometimes they call it a "phase plug". Sometimes they call it a "diffusor". But in reality it is neither of these things. Instead it is actually a Helmholtz resonator (think of blowing across the top of a pop bottle), but tuned to 15 or 20 kHz. The Helmoltz resonator rings like a bell at that high frequency, and THAT is what makes the thing sound "metallic".
The larger the structure in front of the dome, the worse the problem is. Most of the time these things are plastic and can be cut off with a pair of diagonal wire cutters ("dikes"). If you are brave enough, you can cut them off in two minutes and your system will sound much sweeter and smoother in the high frequencies.
The only catch is that if you screw up and damage the tweeter you will have to buy replacements. You may want to call Paradigm first to check, but I would guess that they are somewhere between $25 and $60 each.
I'm not just some crackpot on the internet giving "advice". I was the founder of Avalon Acoustics, and we were the first US company to use metal dome tweeters. This tip was given to me by Martin Colloms in '85 or so, and he was right on the money. - Charles Hansen, Ayre Acoustics |
Here is some more from Mr. Hansen as he answers another poster's questions and comments related to Hansen's original post above: Poster: So you believe that designers added those "Helmholz resonators" purposely to degrade tweeter performance?
Hansen: Of course not. But they designed by measuring and not listening.
Adding the Helmholtz resonator makes the *steady-state* frequency response flatter in the top octave, but at the same time audibly degrades the transient response. It's a *resonator*, so it does its job and resonates. But the human ear-brain is *much* more sensitive to time-smear from the resonance than a small rolloff in the top octave. And even that is easily corrected in the crossover during the design phase.
The "phase plug" is also an easy way to protect the relatively fragile metal dome.
Poster: The real purpose was to block the out-of-phase wave emanating from the center of the dome.:
Hansen: This is not true.
A typical 1" metal dome will move as a piston up to somewhere past 25 kHz. The flatter the profile the lower the break-up point, and the higher profiles give a higher break-up point. For example, the metal version of the Scan-Speak Revelator has very high profile that moves the break-up point well beyond 30 kHz.
When the dome "breaks up", the output will exhibit a peak , typically around 10 dB or so. This *cannot* be blocked. You can see this peak in the response of any metal dome tweeter, with or without a "phase plug". Just browse the archives on the Stereophile website.
The problem is that higher profiles create a greater path length difference from the periphery of the dome to the listener and the center of the dome to the listener. At high frequencies this path length difference will cause a partial cancellation in the output. The frequency response will fall off (droop) at high frequencies. (In theory there would be a deep notch when the path length difference reached a half wavelength, but in practice this doesn't happen because the dome is no longer pistonic and all bets are off.)
Poster: Soft domes are less prone to this problem due to internal damping, however, they still radiate out-of-phase from the center of the dome.
Hansen: Sort of.
A typical 1" soft dome breaks up at 5 kHz or so. That means that the top two octaves are being reproduced by a chaotic membrane that is flexing and resonating and adding colorations to the input signal.
Poster: The most radical solution to this problem is to exclude dome center completely by adding mass to it. This is how Scan Speak ring radiator works.
Hansen: No, they don't add mass. They fix the center of the radiating surface. The only part that moves is essentially an oversized surround working in a bending mode (similar to the bending mode of the MBL drivers). It is unclear that this will solve the breakup problems of soft dome tweeters. I suspect not, but have never measured one to see.
Poster: Removing front cup from a metal dome tweeter will sure cause ragged frequency response.
Hansen: Again, this is not true. Instead it will cause the output in the top octave (10 kHz to 20 kHz) to "droop" slightly. For a typical dome profile, the "droop" will reach a few dB by 20 kHz. All of this is easily measurable.
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Mitch2, thanks for an excellent response. I tried this out a few years ago and snipped off the diffusers on a pair of Vifa metal dome tweeters. At first I thought the highs were much smoother, but after an hour or so, I felt that something was missing. Off axis response also seemed messed up. I carefully glued the diffusers back on and chalked it up to a tweak that did not work for me. |
Hmmmm, the plot thickens. I was considering this option for 2 reasons. First the hi's are too bright for me and second I do remember the suggestion from Mapleshade. The kicker is I am still trying to tweak the room and they may solve the brightness problem.
Those Mapleshade guys do know how to make a great recording but, I don't know about their expertise here. I guess the only way to know is to try it and then get out the super glue if they need to be replaced. I have a Dremel that would do the deed and a chainsaw for backup if necessary. Anyone else tried this TGR process? (tweeter grill removal) |
Had you thought about experimenting with different fabrics or materials around the tweeter element? Or raising the height of the speaker to adjust its' balance-more mid/bass less tweeter energy. |
I believe Hansen was responding to a question about Paradigm speakers, but his answer was generic. Personally, I would probably not try it on expensive speakers unless either I was for sure planning to keep the speakers for the long haul, or unless I would be willing to spring for new tweeters which could be necessary if I screwed up the operation, or if I ever wanted to sell the speakers in the future. A different tweak I would consider trying is the thick felt pad around the outside of the tweeter. Haven't heard too much about the results of that one from those who have tried it. |
Sonic: The tweeters are now between the 2 mid range speakers with factory dampening material around them. They should not be raised anymore since they are already above my ear level
when seated. There is a seperate rear firing tweeter that I should try to turn down I guess...forgot about it. hmmmm? |
Blueskiespbd,That can effect the tonal balance.I learned that from the VSA VR-6s.I was told to raise the rear/ambient tweeter until it begabn to effect the stability of the soundstage/ imaging,then reduce slightly.It was a very low level and can be effected by the material/construction of the back-wall. |
I have been told and have read that the "tweeter grill" is more for protection of the tweeter, but clearly such a device placed over a dome must have some sonic impacts. This thread has helped me to understand what those impacts are, and why the grill may (or may not depending on the tweeter type and grill type) improve the response |
Leave grills on if you like muffed sound on the highs. |
You shouldnt remove a tweeter grille or protection. The sensitivity of a tweeter is with the grille on. X-over is designed according to the tweeters sensitivity. The tweeters SPL will be higher without the grille. If you dont have a way to boost the woofer, the speaker will sound brighter.
The tweeter grille is to reduce physical energy of sound which hurt and fatigue your ears. The physical energy is what pushing the sound (sonic energy) away from the speaker. Without the grille you will have more listener fatigue and unbalanced sound between the tweeter and the woofer. |
