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Multi-Way Conventional loudspeakers with crossovers

Cone has a small dent/scratch. Audible?
Cone has a small dent/scratch. Audible?
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Old 21st May 2020, 12:13 PM   #1
Kustomize123 is offline Kustomize123
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Default Cone has a small dent/scratch. Audible?

I was in the process of redoing my boxes. And i noticed about 3 of my mids, have very small dents/scratches. Pictures below can be seen.

I was just wondering if this will be audible?

And how can I test the impact of them to see if they are still working as intended to?

I was thinking of measuring all the mids against the one that I know is in perfect form. Should I do it 1" away like with subwoofers? Or should I do it 1 meter?

Last edited by Kustomize123; 21st May 2020 at 12:18 PM.
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Old 21st May 2020, 03:14 PM   #2
stratus46 is offline stratus46  United States
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Quote:
Originally Posted by Kustomize123 View Post
I was in the process of redoing my boxes. And i noticed about 3 of my mids, have very small dents/scratches. Pictures below can be seen.

I was just wondering if this will be audible?

And how can I test the impact of them to see if they are still working as intended to?

I was thinking of measuring all the mids against the one that I know is in perfect form. Should I do it 1" away like with subwoofers? Or should I do it 1 meter?
OK this will sound silly. When I crush Coke cans, the ones with no dents will support my 180 pounds.
The ones with a minor dent collapse much easier. I expect your speakers will behave similarly. At low
to modest levels no discernable results. At high to very high levels the cone may misbehave. Will it
be audible? I doubt I could hear it.

G
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Old 21st May 2020, 03:36 PM   #3
Galu is offline Galu  Scotland
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Any imperfections in my speaker drive units annoy me, but I am finding it difficult to see the dents/scratches to which you refer.

If they're not particularly visible at the resolution of your photographs, I would be inclined not to worry about them.

By all means do some comparative measurements, one metre out seems reasonable.
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Old 21st May 2020, 06:24 PM   #4
system7 is online now system7  United Kingdom
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I might get in trouble for this, but I have to ask if some of you are BLIND!

Click the image to open in full size.

Clearly a fracture problem with these Zaph ZA14W08 woofers. Also possibly using old worn-out moulds. Does it matter?

Back in the day, de Havilland unveiled the terrifically shiny de Havilland Comet Aeroplane. Unfortunately, "Widowmaker" might have been a better name.

The wings fell off after a few flights. This was not good. We started to understand metal-fatigue.

TBH, a speaker blowing is generally less catastrophic than an aeroplane crashing.

This is where I might offend some of you, I'd generally trust Michael Chua more than Zaph on crossovers: Swift 2.5 (Zaph ZA14W08 with Peerless DQ25SC16-04) – AmpsLab

Onwards and upwards. Or as the RAF say: "Per Ardua, ad Astra."
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Old 21st May 2020, 06:51 PM   #5
Galu is offline Galu  Scotland
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Originally Posted by system7 View Post
I might get in trouble for this, but I have to ask if some of you are BLIND!
As subtle as a brick as usual Steve!

Yes, I CAN see that particular ding, even though I'm currently BLIND DRUNK!
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Old 21st May 2020, 07:51 PM   #6
system7 is online now system7  United Kingdom
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Well, bless you my son. If anybody isn't drinking more, or self-medicating as my niece says, they don't know what is going on!

I can do Science, but right now, we probably need spirit more than anything.

I like Leonard Cohen: YouTube

Anoushka Shankar is ridiculously talented: YouTube

And for you Scots, I always admired yon Dougie MacLean: YouTube

Don't know if Cal Weldon will make me suffer for this post. Personally, I consider him a friend. We'll be alright.
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Old 22nd May 2020, 01:42 AM   #7
Kustomize123 is offline Kustomize123
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Firstly, all of the measurements were done in the same exact conditions. I had it in my enclosure, with one of the mids and tweeter removed from it, so there were 2 big holes. And I wired it to the upper mid on the crossover. Not sure if I got the polarity right as it was supposed to be on the crossover, but I did use the same polarity throughout this test. 10" away, pointed right at the mid.

So basically. You were all right. There was no impact that I could find from the small dent/line/dinged unit based on measurements.


Here is what happened though.

I took my FIRST mid, which was totally okay. Measured it. Got a response.
Took my SECOND mid, which was also totally okay. Got a response, with a 5db dip.
Not knowing which one is correct, I kept going through all of them.

The one with the scratch/dent and all others matched my FIRST measurement.
Now this is totally bothering me. The mid that shows no physical damage or anything upon inspection, shows a 5db drop around 1500hz and has higher distortion too.

Graphs are here.

Distortion graphs are of one of the normal mids and the other with the dip.
Attached Images
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Old 22nd May 2020, 07:43 AM   #8
ErnieM is online now ErnieM  United States
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You know what you need to do....put a dent in it! SB Acoustics does it.

In seriousness, that would trigger my OCD too. Something is obviously different but probably not audible once eq'd the same as the other drivers.
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Old 22nd May 2020, 10:46 AM   #9
system7 is online now system7  United Kingdom
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You'd expect the quality control on a $50 5" metal driver to be quite good.

The dents do look merely cosmetic. But the duff driver is clearly doing something bad. A full frequency response without filter might tell you more.

You've got Michael Chua's measurements to compare:
Swift 2.5 (Zaph ZA14W08 with Peerless DQ25SC16-04) – AmpsLab

1.5kHz is the region where surrounds and corrugated spiders cause distortion. Maybe too much glue? Maybe a rubbing voicecoil.

Rubbing voicecoils are usually easy to feel with a bit of prodding and pushing. The cure is often to rotate the driver. Not unknown for a bit of ferrite or grit to get stuck in the gap too.

Who knows, eh? I expect a reputable supplier will replace/swap if you are unhappy.
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Old 22nd May 2020, 11:06 AM   #10
Kustomize123 is offline Kustomize123
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Its the Zaph ZA5. I purchased it from Madisound 2 years ago. I am not sure they’ll change it for me now. What so you mean rotate the driver?
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