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Genelec 8351B Teardown (2nd Disassembled)

Scoox

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My good buddy 'Devil's Advocate' asked me to ask a simpleton question, and not directed to anyone specifically:
What really is the love affair (infatuation?) with powered/active speakers, anyways?
If I must; I can understand 'plug-in' boards, in sum rear access panel.
I fully understand (and respect) that designing a proper speaker is no walk-in-the-park and neither is designing active circuits.
Yet, stuffing a passive and a very reliable component (of the audio chain) with electronics just seems like a NO-OP failure just waiting to happen.
IMHO, AIOs = NFG!
AFAIK many main monitors, which are designed for flush-mounting, use an off-board rack-mount amplifier. Separate cables run between the amp and the monitor for each of the LF, Mid and HF drivers, respectively. I imagine with fully analogue monitors (no DSP calibration) the amp is individually calibrated for and married to a particular monitor.

The advantage of AIOs is that you don't have so many cables hanging off the back (unless the speaker uses a passive crossover which can be located inside the cabinet), and the cables don't need to be thick and expensive like passive speaker cables. Saves copper.

A fully self-contained active monitor also reduces the chances of it blowing up since one cannot hook it up to an incompatible amp and whatnot. Furthermore, AIOs feature all manner of protection mechanisms, which means its very difficult for users to accidentally damage the monitor. This makes warranty claims easier to resolve since any failures are unlikely to be the user's fault.
 

Sancus

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If I must; I can understand 'plug-in' boards, in sum rear access panel.
I fully understand (and respect) that designing a proper speaker is no walk-in-the-park and neither is designing active circuits.
Yet, stuffing a passive and a very reliable component (of the audio chain) with electronics just seems like a NO-OP failure just waiting to happen.
IMHO, AIOs = NFG!

You're in the wrong thread, you want this one.
 

YSC

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My good buddy 'Devil's Advocate' asked me to ask a simpleton question, and not directed to anyone specifically:
What really is the love affair (infatuation?) with powered/active speakers, anyways?
If I must; I can understand 'plug-in' boards, in sum rear access panel.
I fully understand (and respect) that designing a proper speaker is no walk-in-the-park and neither is designing active circuits.
Yet, stuffing a passive and a very reliable component (of the audio chain) with electronics just seems like a NO-OP failure just waiting to happen.
IMHO, AIOs = NFG!
I would sat this is a tunnel vision thing.

If you only focus one the speaker lifetime yes it might be the case, but if you think of a whole system life time I bet its more or less similar, the amp and electronics need to be in some place anyway, a passive and external amp needed to be built to be more generous in power, able to handle different impedance and power requirements to suit most speakers out there, and so on.

A AIO amp board can be built just right for the task, as you can see the complexity of the boards are usually much lower than dedicated amps and usually contains a lot less caps inside. So chances of failure wise I don’t believe it should be any higher.

And for most cases the AIO packages are quite considerably cheaper than a passive system. Say for a good monoblock I can easily buy 2 x 8030C with that cost, so if you need to replace a monoblock I can simply replace the whole speaker⋯

That bulging cap is bad looking but if that audibly affect the speaker is a question mark, but I do sure genelec will be generous in fixing that. If you could recap your amp easily I can’t think of why when outside warranty you can’t recap your active monitor
 

Pearljam5000

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The amp on the 1237A is detachable of I'm not mistaken, and also looks more ventilated than the other Genelecs, but I'm not sure how critical it is, if at all
Screenshot_20211031-062112.jpg
 

YSC

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The amp on the 1237A is detachable of I'm not mistaken, and also looks more ventilated than the other Genelecs, but I'm not sure how critical it is, if at all
View attachment 162319
but this is intended for flush mount which won't have much ventilation also, and yet they survive quite well.

as someone who build own PC for 2 decades, I can say that while choice of materials are important, the temperature and moisture they are more important for prolonged use, if it didn't get hot either with good design or good ventilation I think they likely last a decade or so, afterward I believe genelec will be quite generous in servicing their products. or you will just throw away and as a reason for upgrade.
 

ivity

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As a person who works in post, I have some experience with statistics. We have a lot of old Genelecs 80X0 (early 2000s models) of all sizes and those aged really well. I think we had only two or three faulty units in recent years and most of them had actually faulty tweeters rather then amplifiers. So if Genelec is suspected of unreliability, then I dont know which brand can be called "reliable" at all.
 

dfuller

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The amp on the 1237A is detachable of I'm not mistaken, and also looks more ventilated than the other Genelecs, but I'm not sure how critical it is, if at all
View attachment 162319
It's important if you're soffit mounting the speakers where there's no rear airflow; arguably it's more critical for AB amps that produce a lot more waste heat.

I would sat this is a tunnel vision thing.

If you only focus one the speaker lifetime yes it might be the case, but if you think of a whole system life time I bet its more or less similar, the amp and electronics need to be in some place anyway, a passive and external amp needed to be built to be more generous in power, able to handle different impedance and power requirements to suit most speakers out there, and so on.

A AIO amp board can be built just right for the task, as you can see the complexity of the boards are usually much lower than dedicated amps and usually contains a lot less caps inside. So chances of failure wise I don’t believe it should be any higher.

And for most cases the AIO packages are quite considerably cheaper than a passive system. Say for a good monoblock I can easily buy 2 x 8030C with that cost, so if you need to replace a monoblock I can simply replace the whole speaker⋯

That bulging cap is bad looking but if that audibly affect the speaker is a question mark, but I do sure genelec will be generous in fixing that. If you could recap your amp easily I can’t think of why when outside warranty you can’t recap your active monitor
And really, if you use high temp rated caps, it's not even an issue. Remember that for every 10C below maximum the life of a cap doubles. Even in a sealed box with relatively hot running AB amps like in a KH310, 105C caps will have a much longer lifetime than their stated rating would indicate. 130F/55C ambient is quite warm, but the cap would have 32 times its rated lifespan.
 
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mkt

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Related?
“While I’m on the subject of the bass drivers, not only is their architecture and location unusual in the 8351B, they also display an interesting constructional feature in that their rubber roll surround is corrugated around the curved section of the oval.”
 

YSC

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Related?
“While I’m on the subject of the bass drivers, not only is their architecture and location unusual in the 8351B, they also display an interesting constructional feature in that their rubber roll surround is corrugated around the curved section of the oval.”
Don’t think so though, it sounds to me it’s the rubber surround’s ridges at the curved part
 
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Ilkka Rissanen

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I was considering this monitor but the tears in that bass driver really don't inspire a lot of confidence... You do say that it should look exactly like that, but I ask, look like what? Are the cracks and tears exactly identical in all units? I'll bet not! To me that just looks like some random cracked-ass paper. Are we referring to different things?
Hi,

Not every driver/cone will look exactly identical but the part that you refer as "random cracked-ass paper" is how it should look like after the manufacturing process. There is nothing wrong with it now or 20 years after everyday use. Longevity of our products is most important to us, that is why we test everything possible and sometimes even impossible.
 

Pearljam5000

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Hi,

Not every driver/cone will look exactly identical but the part that you refer as "random cracked-ass paper" is how it should look like after the manufacturing process. There is nothing wrong with it now or 20 years after everyday use. Longevity of our products is most important to us, that is why we test everything possible and sometimes even impossible.
Wow 20 years from now is quite a bold and reassuring statement
Thanks for that.
 

Scoox

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Hi,

Not every driver/cone will look exactly identical but the part that you refer as "random cracked-ass paper" is how it should look like after the manufacturing process. There is nothing wrong with it now or 20 years after everyday use. Longevity of our products is most important to us, that is why we test everything possible and sometimes even impossible.

Ilkka, thanks a bunch for replying. I hope you weren't offended by my using the word "ass" back there. I'm glad to hear that this is part of the design. I assume the cracks are there to confer certain mechanical properties to the LF driver. I hope you can understand why, at first sight, I was slightly alarmed becasue cracks, after all, are inherently random and potentially unpredictable. Some cracks progress and some are stable.

Maybe this is beyond the scope of what you are able to share with us here but I'm sure some of us are curious about the reasoning behind this feature, and whether you have a name for it internally?

Regarding the 20-year test period, what product are you referring to? The 8351B was released about 2 years ago. Other models of the 'The Ones' line haven't been around that long either.

Please find our product Warranty & Lifetime terms here: https://www.genelec.com/product-warranty-lifetime

Regarding the warranty terms, they are objectively not the best out there. For instance, Adam Audio offers a 5-year warranty that covers both spares and labour costs. I actually had to use their warranty with my Adam S1X nearfields literally a week before warranty expiration to address a manufacturing defect that affected early units, and they replaced both amps and cabinets 100% free of charge. They even sent me a bag of replacement screws 10 years after purchase (already well outside the warranty period) totally free of charge, which I thought was as generous as it was impressive. I'll be honest, I've always thought of Genelec products as being better build-quality than Adam. If Adam can do 5 years, why is it that Genelec can't? Excuse me for being cynical, but from my perspective as a customer I read that as "Adam monitors are less likely to fail". Obviously Genelec isn't the only monitor maker offering a 2-year warranty—I'm just saying there is better. ATC, for example, offers a 6-year warranty on registered products. I'm well aware countless Genelec monitor owners have reported great satisfaction with your products and many years of trouble-free operation well past the end of the warranty period, but to me a 5-year warranty speaks louder than a million positive reviews.
 
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Pearljam5000

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as well as I trust your products (which I am very satisfied after a year of ownership), I wonders what are the failing rate for the newer class D amp modules? are the buldged cap issue apparent in the Class D amp module or even older class AB ones?
What could be the cause of it?
 

Ilkka Rissanen

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Ilkka, thanks a bunch for replying. I hope you weren't offended by my using the word "ass" back there. I'm glad to hear that this is part of the design. I assume the cracks are there to confer certain mechanical properties to the LF driver. I hope you can understand why, at first sight, I was slightly alarmed becasue cracks, after all, are inherently random and potentially unpredictable. Some cracks progress and some are stable.

Maybe this is beyond the scope of what you are able to share with us here but I'm sure some of us are curious about the reasoning behind this feature, and whether you have a name for it internally?

I think you are still misunderstanding me. The "cracks" you refer to are not cracks per se, they just look like it, but in the reality that part of the cone/diaphragm is completely stiff and rigid and the required movement comes from the (rubber) surround, as in any conventional round-shaped electrodynamic speaker driver.

1280px-SpkFrontCutawayView.svg.png


Regarding the 20-year test period, what product are you referring to? The 8351B was released about 2 years ago. Other models of the 'The Ones' line haven't been around that long either.
Please see (also applies to Finnish companies ;) ): https://forcetechnology.com/en/articles/accelerated-lifetime-tests-based-on-the-physics-of-failure

"An accelerated lifetime test is basically a way of fast forwarding time so that we do not have to wait 20 years to find out whether a product can actually last 20 years in the real world. In a nutshell, during testing the product is subjected to a higher stress level so failures appear faster than they would in reality, making it then possible to calculate the time it would take for that failure to appear at the lower, actual stress level."

Regarding the warranty terms, they are objectively not the best out there. For instance, Adam Audio offers a 5-year warranty that covers both spares and labour costs. I actually had to use their warranty with my Adam S1X nearfields literally a week before warranty expiration to address a manufacturing defect that affected early units, and they replaced both amps and cabinets 100% free of charge. They even sent me a bag of replacement screws 10 years after purchase (already well outside the warranty period) totally free of charge, which I thought was as generous as it was impressive. I'll be honest, I've always thought of Genelec products as being better build-quality than Adam. If Adam can do 5 years, why is it that Genelec can't? Excuse me for being cynical, but from my perspective as a customer I read that as "Adam monitors are less likely to fail". Obviously Genelec isn't the only monitor maker offering a 2-year warranty—I'm just saying there is better. ATC, for example, offers a 6-year warranty on registered products. I'm well aware countless Genelec monitor owners have reported great satisfaction with your products and many years of trouble-free operation well past the end of the warranty period, but to me a 5-year warranty speaks louder than a million positive reviews.
Unfortunately this is beyond my scope of expertise and responsibility in the company. I suggest you contact our customer support: https://www.genelec.com/support
 

Pearljam5000

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I think you are still misunderstanding me. The "cracks" you refer to are not cracks per se, they just look like it, but in the reality that part of the cone/diaphragm is completely stiff and rigid and the required movement comes from the (rubber) surround, as in any conventional round-shaped electrodynamic speaker driver.

1280px-SpkFrontCutawayView.svg.png



Please see (also applies to Finnish companies ;) ): https://forcetechnology.com/en/articles/accelerated-lifetime-tests-based-on-the-physics-of-failure

"An accelerated lifetime test is basically a way of fast forwarding time so that we do not have to wait 20 years to find out whether a product can actually last 20 years in the real world. In a nutshell, during testing the product is subjected to a higher stress level so failures appear faster than they would in reality, making it then possible to calculate the time it would take for that failure to appear at the lower, actual stress level."


Unfortunately this is beyond my scope of expertise and responsibility in the company. I suggest you contact our customer support: https://www.genelec.com/support
Thanks for the info
What can you say about the difference between the Ones and the 1237A for example? Both are 3-way and cost a about the same so it's not that clear which is better
 

Scoox

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I think you are still misunderstanding me. The "cracks" you refer to are not cracks per se, they just look like it, but in the reality that part of the cone/diaphragm is completely stiff and rigid and the required movement comes from the (rubber) surround, as in any conventional round-shaped electrodynamic speaker driver.

OK so if I understand correctly the LF driver comes off the production line looking exactly like the one in the OP (even before it is installed in a monitor), with the rough ridges in the diaphragm.

I found this video where at 2:58 we get a glimpse of a bunch of what look like 8331A racetrack drivers:

003.png


A few seconds later we see a close-up of a bigger racetrack drive, probably either 8341A or 8351A as it doesn't have the rubber surround with the corrugated sides:

002.png


In both of these images the diaphragm doesn't have the rough area, in fact, it looks perfectly smooth all around, unlike the driver in the original post:

Genelec 8351B LF driver.png


Even with my optimistic hat on, I still see torn paper, sorry. If other parts of the perimeter are perfectly smooth, I really don't see why the top and bottom can't also be smooth. I assume the diaphragm is a wet-pressed moulded pulp component. The defining characteristic and the reason for using a mould is that it is able to produce consistently identical parts, but you said the "roughness" is not exactly the same in every drive, therefore the tearing must have happened later, not at the pressing stage. Furthermore, the mould is almost definitely perfectly smooth at that spot anyway, so I'm pretty sure when the diaphragm comes out of the mould the roughness isn't there. I have seen plenty of wet-pressed moulded pulp packaging that has very intricate details and the finish is exceedingly smooth and detailed. The tears therefore must have appeared afterwards, once the diaphragm starts is put through its paces.

I notice the rough area only affects about 80% of the length of the top and bottom parts (respectively) of the diaphragm "bump". The white lines in the above image show where the smooth/rough areas end and begin. Notice also how the angel of the white lines and the sides of the triangular shadow cast by the diaphragm on itself are basically parallel, which suggests a correlation between the tearing and the geometry of the diaphragm. I understand that the rubber surround is there to absorb most of the cyclic stresses so the diaphragm doesn't have to; however, in this case, it appears the diaphragm is in fact absorbing more of those cyclic stresses than it can take, which leads to tearing.

I get what said about accelerated lifetime testing, and I believe it is a reliable way to test if properly implemented, but it's still an imperfect approximation. I used to work in test development myself, so I know a bit about testing. I just have trouble believing the racetrack drivers leave the assembly line with the tears in the diaphragm.

Anyway, I think the best way to settle this and prove me wrong (which I would be infinitely grateful for) is to show me a picture of several brand-new and unused 8351B racetrack drivers side-by-side from the assembly facility. If they have the micro tears like the one in the OP I will have made an ass of myself but I will also be able to put my mind at rest and order a pair of 8351Bs + subs, which was my original intention and the one I would like to go with. If, on the other hand, the brand-new drivers are smooth, then perhaps the product needs reviewing, which is fine by me because these monitors are out of stock everywhere and I will have to wait until spring 2022 to buy anyway.

Regarding the warranty, I will contact support with my suggestions, thanks :)

Sorry to be such a huge and persistent pain!
 
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