I suspect that many of you like myself are fans of vintage audio equipment, whether we call ourselves collectors or it's a nostalgia thing.
In my case, I love to buy old amplifiers and things that I remember from when I was a kid that I could never afford at the time and refurbish them.
It's just another little hobby of mine, and if like me any of you are into vintage audio equipment and look at sales sites and forums and things like that discussing vintage audio equipment and stuff for sale, you've probably seen something that's today's audio myth topic.
And that simply is that many times you'll see somebody listing a pair of used speakers or vintage speakers for sale and if they have photos accompanying their ad you might see that some of the woofer or mid-range dust caps are pushed in, or in the case of this poor, sad metal dome tweeter, that it's actually been creased, it's been damaged.
And where the audio myth comes in is that these sellers will often say, "Doesn't affect performance at all. The tweeter dome is pushed in but it doesn't impact performance."
Well, that's complete nonsense.
Now, what they may actually be thinking is that, well, it's still working, that tweeter or that woofer or mid-range or whatever that has damage they may think is just cosmetic damage because the drive unit will probably still be functional. And in that case they jump to the conclusion that, well, it doesn't impact performance.
Well, it does so watch out.
The reason that it does is, a tweeter dome is a very thin, very precise piece of material that has to radiate pistonically. You want the whole thing to be radiating in a certain fashion at certain frequencies. A crinkle, a dimple like this will impact a number of things. The dispersion of the tweeter, how it radiates sound is now messed up, frankly.
Also, by deforming that structure, that dome shape, this speaker will not have the same frequency response anymore. The natural resonance point of that dome will be completely changed.
On woofers and mid-ranges, if the drivers operate up into a higher frequency based on their crossover design or if it's a woofer in a two-way system that crosses directly over to a tweeter.
Many people think that a dust cap is just that, it's to keep dust out. Yeah, okay, that's where the name came from and that's one of the purposes that it serves. You don't want to get material foreign objects, dust and things down into the magnetic gap and mess up the motion of the voice coil. But it's also part of the radiating surface of the driver. And, in particular, higher frequencies tend to be radiated, at least in terms of the operating range of a woofer or a mid-range, they tend to radiate from the dust cap.
Now, some dust caps are a very, very pliable, flexible fabric material, and in many cases, you can pull them out with a balled up piece of masking tape or whatever, you can pull them out, and you will not impact anything. But if you've got a heavier fabric that actually it crinkles when it deforms, it's got some, what's called, doping on it, some material to make it stiffer, some coating, or it's a plastic or a metal dust cap like the one on this woofer here, that's going to significantly impact the high frequency amplitude response of the woofer mid-range if that's damaged and dented. And, again, it will also affect the dispersion of the speaker.
So I guess the moral of the story here is, if you're out shopping for a vintage pair of speakers or any used pair of speakers, I would stay away from anything that has a damaged and pushed in tweeter dome or dust cap unless you're sure that you can get your hands still on the original drivers because, unfortunately, while they may still work, they're going to still produce sound, it's not going to be correct.
So I hope that clears up another audio myth that I see regularly hunting for vintage audio equipment.
