Genelec 8351B Teardown (2nd Disassembled)

[Pearljam5000]

How surprising that a manufacturer says his product is better than another brand's product

 

[holdingpants01]

Measurements of the old model which had different drivers, is as relevant here as talking about the lack of damping material or having hard edges of the cabinet. BTW those Knif speakers are more like 50k€, I would like to see comparison to 8381A but in a separate thread

 

[test1223]

Oh good grief, that is the impedance plot!!! Right hand scale on the REW plot, 7.3 to 8.3 Ohms.

The frequency axis you posted starts at 920Hz and ends at 1.1kHz. The resonance shifts to lower frequencies when you use damping material.

No, you misinterpreted the plot I posted. And there are no differences in resonances at in the impedance plot or any other plot in those smaller resonances at the other frequencies. The real big resonances like the actual breakup mode are what should be focused on, not the stuffing. Funny you talking about all of this resonance stuff in reference to this particular Genelec speaker. You are running wild!

So where does the "new " resonance in your plot come from?

 

[MAB]

The frequency axis you posted starts at 920Hz and ends at 1.1kHz. The resonance shifts to lower frequencies when you use damping material.

So where does the "new " resonance in your plot come from?
View attachment 370613

That's huge! Not.

Seriously, no idea. I got the mic as close to same position run to run. But no way exact. May be mic position. It's why I included distortion, and more importantly impedance.

Maybe the single layer of Jute (the purple trace that you highlight in your high-mag zoom) is less effective than the single layer of Polyfill. In that case, thanks for pointing out how effective Polyfill is. Let's talk about Polyfill, since that is what Genelec uses in the midrange, and lots of people seem intent on avoiding Polyfill, like many of your comments ('not so effective', etc.) Let's put aside the midrange non-issue and look at the impedance plot of the system resonance with different stuffing compared to no stuffing:

Single layer of Polyfill (green trace) is more effective at changing system resonance than even two layers of Jute. So perhaps that residual resonance with a single layer of Jute is due to the fact that Jute (and many so-called denser/better/costlier) are actually less effective than Polyfill.

It's absurd we are talking about tweaking this Genelec speaker, especially based on so many misstatements of the effects. So you are clear, I am done with the discussion.

 

[Sancus]

It's pistonic over its passband, but apparently the mid has quite the breakup mode around 6k and that shows as a H3 peak around 2k.

So it has a breakup mode at 6K, but then using a steep crossover which would minimize the effect of that on frequencies outside of the driver's band is somehow also bad because of the not-fully understood-audibility of the resulting change to the *step response*???

 

[MAB]

It's pistonic over its passband, but apparently the mid has quite the breakup mode around 6k and that shows as a H3 peak around 2k.

He is referring to this 2kHz harmonic distortion peak, right?

Yeah, it's huge. Once you make a speaker with low distortion, every remaining resonance becomes evident.
Thing is, I don't see any evidence of a 6kHz breakup mode in the composite mid/tweeter data? Maybe if we had measurements of the mid alone, but it doesn't appear in measured response. I do see a resonance at 30kHz (!) in Knif Audio's measurements, with a 3rd HD peak at exactly 10kHz.

Or maybe this is what Amir measured when he pushed the speakers:

Is that the amp limiting causing artifacts that show up as distortion?

 

[YSC]

That's huge! Not.

Seriously, no idea. I got the mic as close to same position run to run. But no way exact. May be mic position. It's why I included distortion, and more importantly impedance.

Maybe the single layer of Jute (the purple trace that you highlight in your high-mag zoom) is less effective than the single layer of Polyfill. In that case, thanks for pointing out how effective Polyfill is. Let's talk about Polyfill, since that is what Genelec uses in the midrange, and lots of people seem intent on avoiding Polyfill, like many of your comments ('not so effective', etc.) Let's put aside the midrange non-issue and look at the impedance plot of the system resonance with different stuffing compared to no stuffing:

Single layer of Polyfill (green trace) is more effective at changing system resonance than even two layers of Jute. So perhaps that residual resonance with a single layer of Jute is due to the fact that Jute (and many so-called denser/better/costlier) are actually less effective than Polyfill.

It's absurd we are talking about tweaking this Genelec speaker, especially based on so many misstatements of the effects. So you are clear, I am done with the discussion.

IIRC Jonte Knif measured this, let me see if I can find it again. I'll edit when I do.

EDIT:

https://www.facebook.com/KnifAudio/posts/1678539092256566

It's pistonic over its passband, but apparently the mid has quite the breakup mode around 6k and that shows as a H3 peak around 2k.

just dug into the Knif post and it sounds funny... apparently he measured the Genelec nearfield (he didn't mentioned, but hinted in his response), and then he measured his speaker far field and gated it, IME that alone would affect the data quite a bit?

 

[holdingpants01]

He is referring to this 2kHz harmonic distortion peak, right?
View attachment 370686
Yeah, it's huge. Once you make a speaker with low distortion, every remaining resonance becomes evident.
Thing is, I don't see any evidence of a 6kHz breakup mode in the composite mid/tweeter data? Maybe if we had measurements of the mid alone, but it doesn't appear in measured response. I do see a resonance at 30kHz (!) in Knif Audio's measurements, with a 3rd HD peak at exactly 10kHz.
View attachment 370689
Or maybe this is what Amir measured when he pushed the speakers:
View attachment 370692
Is that the amp limiting causing artifacts that show up as distortion?

Those are different models, Knif had 8351A and Amir 8351B, all drivers were changed, tweeter is bigger, midrange cone is completely new and woofers uses different cone material (and different amps, and crossover points)

 

[MAB]

Those are different models, Knif had 8351A and Amir 8351B, all drivers were changed, tweeter is bigger, midrange cone is completely new and woofers uses different cone material

OK, thanks. I missed that!

 

[Luca Formentini]

sorry for sneaking in with a truly basic question: can anyone tell me the surface required for the 8351 iso pods?
thank you!

 

[Descartes]

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Second time, I disassembled my 8351B again.

This time, I opened the speaker driver side and took a picture in more detail.

I wanted to disassemble the tweeter, but it was glued so I couldn't remove it.

The woofer looks like paper and the center is filled with solid foam.

The mid-tweeter driver is not directly screwed into the enclosure, but is pressed by the rear panel.

The notes on the amp module are curious.
This is 8351B, why is the amplifier module marked as 8341A? It seems to be a compatible part.

Then, I hope you enjoy it.

The inside looks so cheap and they charge so much money!!

 

[Pearljam5000]

The inside looks so cheap and they charge so much money!!

I think you're paying mostly for the tech and SQ and less for the parts cost

 

[MAB]

sorry for sneaking in with a truly basic question: can anyone tell me the surface required for the 8351 iso pods?
thank you!

The can mount with stand-plates made to fit the Iso-Pods:

8051-408 Stand Plate - Genelec.com

Stand plate to use together with Iso-Pod stands.

www.genelec.com

Or any flat, stable surface that's larger than the Iso-Pod footprint. Horizontal or vertical orientation.

They have some drawings of the speaker, but don't call out the exact footprint of the Iso-Pods.

https://assets.ctfassets.net/4zjnzn055a4v/6c5OgkeEOpYghQ2TwZMi6r/b1b5ec8768fc1867b97442f7fef3075d/8351Bviews.pdf

 

[bumblebee657]

The inside looks so cheap and they charge so much money!!

Nothing looks "cheap" there. As a mechanical engineer I would say it just looks like good engineering. What do you expect? Do you miss veneer or something?

 

[MAB]

The inside looks so cheap and they charge so much money!!

Until you look at the huge magnet and voice coil on the midrange. It's really an impressive driver.
The aluminum castings are beautiful.
The amps look like... circuit boards.
I'm not sure how some other companies charge so much for their speakers.

 

[Descartes]

Nothing looks "cheap" there. As a mechanical engineer I would say it just looks like good engineering. What do you expect? Do you miss veneer or something?

No just saying it is too expensive for such a spartan design! Love the speakers but not the prices especially since the dealer margins are 40 points off the MSRP

 

[AudioJester]

No just saying it is too expensive for such a spartan design! Love the speakers but not the prices especially since the dealer margins are 40 points off the MSRP

There are some cheaper high performance speakers if you look around.

But its not like dacs and amps where perfection costs peanuts. This may be about to change as some of the bigger Chinese based companies are getting into speakers.
Look up Ascilabs from Korea, about to launch a spectacular range of well priced passive and active small speakers.

 

[napfkuchen]

No just saying it is too expensive for such a spartan design! Love the speakers but not the prices especially since the dealer margins are 40 points off the MSRP

This is probably the best coaxial design you can get, also no need for an amp or dac. Room correction is "only" a 300 Euro upgrade (though it should be included in my opinion). I have tried several other room correction options over the years (REW, DiracLive for PC, Audyssey and Dirac on Denon-AVR) and found GLM to be the most accessible solution for me. So besides the speakers the additional equipment needed is actually very cheap compared to traditional hifi-setups. For studio use the pricing is not that important, but you pay for the engineering, reliability and long-time support.
And finally the resale value of Genelec speakers is very good. My 5 year old 8331A speakers are still worth 80% of what I paid for them.
Compare that with consumer products, e.g. from Kef: I was thinking about getting the LS 60s and was offered a pair for 3,500 euros (as new). Mind you, this is for a speaker that hasn't been on the market for long, initially had an RRP of 6,999 euros (now 4,999 euros) and is probably not selling that well. I recently bought myself a pair of LS 50 Meta (6 months old) for 750 euros. When the next product iteration comes out, it regularly "destroys" the prices for Kef products, for example.

 

[tmtomh]

Driver quality, enclosure material and casting, durability, R&D, resale value.

 

[Sancus]

No just saying it is too expensive for such a spartan design! Love the speakers but not the prices especially since the dealer margins are 40 points off the MSRP

In most countries buyers are generally not paying MSRP for Genelecs, FYI.

Regardless of this though, these are not consumer grade speakers. When consumer actives break down, these will still be working 15 years after that. There really isn't anything comparable to the Ones short of paying for Kef Reference/Blade which are far more expensive. Things like the cheaper Kefs, Kalis, etc don't match up, but of course you can always trade off performance for price. (yes there are some niche brands like Geithain that you can't realistically buy in most of the world)

Manufacturers don't care what people on audio forums who aren't even gonna buy their speakers say about their prices, they care about the buyers, and Genelec is one of the most common brands in studios worldwide. If they were truly poor value, that wouldn't be true.