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Driver age


Moh

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1 hour ago, Moh said:

Do drivers "age" with time and does the sound change with age. .. Are drivers good or no good (binary) or they gradually degrade over say 10 years.

I wonder more about how they were used over their life then the age. I have had plenty of woofers and horn drivers of the same type newer and older and they sounded the same unless there was a problem. Now I will say that with a K-55-V driver I had one time it never did sound right. Frequency swept and ohm checked OK but did not sound right. Talking to Crites about this and hating the idea of ordering $$$$ diaphragms for them. He mentioned they had some that acted the same way and all they could figure was there was some degradation they could not measure that did happen at times.

 

 

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On 3/26/2022 at 5:41 PM, Moh said:

Do drivers "age" with time and does the sound change with age. .. Are drivers good or no good (binary) or they gradually degrade over say 10 years.

 

To stay with the K 55 V example, I ordered new diaphragms from Michael Crites a year ago. It was a big difference compared to the 45 year old original ones. The new ones sound smoother and fuller. Bob Crites had reported here on the forum a few years ago that the old diaphragms can have a loss in lower frequency energy. I can confirm it, the new diaphragms just sound much more pleasant and less peaky on the ear. Perhaps the phenolic material becomes brittle over time.

Related to cone speakers, it is often the question of what material the surrounds are made of. The classic K33 from Klipsch should live forever and remain the same sound if they were not badly beaten. My older Tannoy Canterbury have surrounds made of some kind of foam. This dissolves after 20 years, whether they are played or not. Fortunately, the repair has not been too expensive at 120€.

Another reason can be an Alnico magnet. With my old K77, 1.5 dB was recovered by remagnetization.

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15 minutes ago, jcn3 said:

 

magnets shouldn't need remagnetization unless they've been abused.

This is not generally quite right but the wear only affects Alnico magnets. They can lose their magnetic force if they are dropped or roughly bumped, for example. They also lose their magnetic force if they are stored incorrectly and a strong magnet nearby on the shelf cancels out their magnetic force.

But what is also an essential point is that the current flowing through the voice coil builds up an opposing small magnetic field and for this reason weakens the Alnico permanent magnet of the speaker quite a bit. Only...there is the saying "Constant dripping wears away the stone". And as with everything that gradually loses its performance over the years (tubes, record player stylus, compression in the car engine, etc.), you notice the wear directly when compared with the former new condition.

 

For this reason, my K77 after 44 years were 1.5 dB quieter and less bright. An example. In the 70s there were JBL Alnico guitar amp drivers. They weakened the permanent magnet by the magnetic field of the coil, everything became quieter. How does the guitarist react: he compensates by more amp power. In the end, many voice coils burned out.

So it is definitely a factor to be taken seriously, even if nothing burns out so quickly in the hi-fi field.

Ferrite magnets are usually not affected.

 

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From the mechanical aspect, horn drivers should not age as fast as direct radiators, since a horn driver is contained within its own enclosure and the horn. For example, the woofer of a bass horn is going to live a lot longer (barring abuse) than if it was a direct radiator. The Klipsch Heritage line is so efficient that I think it is rare for any of the woofers to fail from normal use. Having said that, suspensions can dry out with age and raise the Fs, but probably not to degree that's noticeable.

 

In the 50s it was common practice to rotate the woofers, especially 12 inch and larger units, every so ofter to prevent "cone sag." I think with modern materials this should no longer be an issue.

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The doped paper surrounds on most Heritage Series woofers should keep them from ever drying out.  In the case of my now 48-year-old La Scala woofers, I haven’t tested them against anything else lately, to get an objective idea of their condition, but subjectively they still sound as good to me as they sounded when I first got them and they were only 32 years old.  At that time, I did do some tests to check their bass response, to help me integrate the subwoofer into the system.  The 1974 La Scalas showed a smoother frequency response than my other speakers, Forte-sized 1980 Audio Logic models, whose woofers had just been re-surrounded, after the surrounds had deteriorated to the point of bits crumbling and falling off.

 

That’s what I’ve seen.

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On 3/26/2022 at 1:50 PM, Dave A said:

... all they could figure was there was some degradation they could not measure that did happen at times.

 

 

 

Ahem, exuse me. Something you can hear but can't measure? :P

 

Old post by Dennis about AlNiCo and mishandling. I'll see if I can find it.

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59 minutes ago, Crankysoldermeister said:

 

Ahem, exuse me. Something you can hear but can't measure? :P

 

Old post by Dennis about AlNiCo and mishandling. I'll see if I can find it.

Well I don't really know nor do I really care about measuring anything that sounds really good!!! If it sounds terrific why measure???

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4 hours ago, Crankysoldermeister said:

 

Ahem, exuse me. Something you can hear but can't measure? :P

 

Old post by Dennis about AlNiCo and mishandling. I'll see if I can find it.

Well something they could hear but could not measure. Of course with proper equipment I am sure they could have.😉

 

3 hours ago, jcmusic said:

Well I don't really know nor do I really care about measuring anything that sounds really good!!! If it sounds terrific why measure???

Why climb Mt Everest too.

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On 3/26/2022 at 12:41 PM, Moh said:

Do drivers "age" with time and does the sound change with age. .. Are drivers good or no good (binary) or they gradually degrade over say 10 years.

Depends on the wear and tear , if drivers are overused , they wear out faster , if they are used gently , they last a lot longer , 10 years on klipsch drivers is not that much , there are tons of 40+ year old klipsch speakers in very good working order with stock drivers .

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On 3/26/2022 at 11:41 AM, Moh said:

Do drivers "age" with time and does the sound change with age. .. Are drivers good or no good (binary) or they gradually degrade over say 10 years.

Driving age in the state of Wisconsin is 18. Probationary driving is allowed at 16 with restrictions. For most, the way they sound remains the same, unless they are very young or very old. Drivers are usually not good until they have some years of experience, but gradually, they do get better. Age is beneficial for most drivers though.

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