Genelec 8351B Review (Studio Monitor)

[Theta]

This is a review and detailed measurements of the Genelec 8351B powered monitors (speakers). It was purchased used by a member and kindly drop shipped to me for testing. They cost US $3,995 each.

The 8351 is a thee-way speakers with the bass drivers hidden beyond the front baffle:

View attachment 129922

Naturally the back panel allows for fair bit of configuration changes:
View attachment 129923

I reset the speaker to factory settings and left all the dip switches off as you see. I used analog XLR input for all measurements and listening tests.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 1000 measurement which resulted in error rate of around 1%.

Testing temperature was around 65 degrees F.

Reference axis for measurements was the center of the tweeter (by eye).

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Genelec 8351B Measurements
As usual we start with our spin frequency response measurements:
View attachment 129926

I expected flat on-axis response and we essentially get that. There is a tiny bit of deviation in lower frequencies. I checked with Genelec and they looked up the measurements and they are ± 0.5 dB in that region. They show it a bit flatter than I do but I don't think either one of us know whose measurements are more correct. Regardless, the deviation is tiny and your room would overwhelm it in practice.

Directivity plots show off-axis that is similar to on-axis as it should be with coaxial drivers. This is in turn reflected in early-window response and predicted one:

View attachment 129927

View attachment 129928

I don't have near-field driver responses for you since it was silly to try to measure them on a coaxial driver.

Directivity plots of almost textbook perfect:

View attachment 129929

View attachment 129930

View attachment 129931

Edit: forgot to post the distortion graphs before:
View attachment 129970

View attachment 129971


Finally waterfall shows a few resonances:
View attachment 129932

Genelec 8351B Listening Tests
Given the size of this speaker and interest in membership to use them in high-fi and home theater applications, I decided to listen to them using my main system in far field listening. From the first few seconds I knew the sound was right and in need of no adjustment other dialing out the one room mode I have around 105 Hz. Track after track has excellent sound with image coming out of a circular halo around the driver. This is what you get when the speaker is well designed and relies on decades of research on what good sound is. All of my reference tracks that were curated on another system like it translated and delighted just as well.

Dynamics and Competition with Revel Salon 2
There has been a lot of talk about how these two speakers compare in the forum. I find the conversion odd as we are comparing a bookshelf speaker to a full blown tower. Still, I decided to compare the two since I own the Salon 2.

The Salon 2 quickly showed its difference in taller image that was not so focused and centered as the Genelec. This of course could be an optical illusion of the Genelec pulling your eye toward its tweeter. Still, I stand by this observation. The other thing that stood out was that the highs were more prominent in Salon 2 bringing more realism to high frequency notes. The Genelec sounded subdued in this front. Perhaps there is some peaking in my Salon 2 (have not measured it yet).

Where one could not doubt a difference was the power capability and bass extension. On sub-bass heavy tracks the Genelec held its own at lower volume. As you turned up the level the bass driver started to make this annoying "furrrrring" sound on heavy bass notes. You could easily hear it if you stood on top of the speaker and listened through the slot on top. Turn up the volume a bit more and the red clipping indicator would come on.

The Salon 2 was in entirely different class. Powered with 1000 watts of amplification, it provided a level of belly shaking that the 8351B could not even dream about reproducing. And it would keep getting louder and louder with zero distortion and strain. It simply was not a fair fight even though the 8351B tries hard.

Overall, the Salon 2 provides that large, dynamic sound that a statement speaker needs to provide to fill a large space. The 8351 is for more intimate and more focused listening.

Conclusions
Both objectively and subjectively the Genelec 8351B delivers. Near perfection as far as tonality and dispersion is provided. Its power delivery is the best of any Genelec speaker I have tested so far and is almost beyond what you may need. In my case though, I am used to much larger and powerful systems and there, the 8351B was limiting especially with its bass slot noise. So I would not position it above its class.

Overall, it is my pleasure to put the Genelec 8351B on my recommended list.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150

Glad to finally see the mention "much larger and powerful systems" by a reviewer.
Many audiophiles are not aware, and are often misled.
Even a not so accurate large and powerful system will give much greater satisfaction than the best and fantastically great measuring neutral small or medium size speaker even in a small room.

 

[Purité Audio]

That’s not correct, you must choose your speaker for its application.
A small fine measuring speaker will sound superb within its constraints.
Sadly SPLs, bass extension and really good measurements cost .
Keith

 

[holdingpants01]

I think grade is a phenomenal tool for people who want to learn the basic concepts of room acoustics/speaker room interactions, but doesn't want to dive too deep into it, or are afraid of the steep'ish learning curve of REW + a measuring mic. REW provides a lot more information and useful tools but GLM/Grade is "one click easy".

Sure, but someone who doesn't want to dive too deep into it also probably doesn't really need more than 12 reports, hence the limit. I wonder what's the price for additional ones though, I only used 1 after installing GLM5

 

[tmtomh]

Glad to finally see the mention "much larger and powerful systems" by a reviewer.
Many audiophiles are not aware, and are often misled.
Even a not so accurate large and powerful system will give much greater satisfaction than the best and fantastically great measuring neutral small or medium size speaker even in a small room.

That’s not correct, you must choose your speaker for its application.
A small fine measuring speaker will sound superb within its constraints.
Sadly SPLs, bass extension and really good measurements cost .
Keith

I think you both have valid points, but I think @Purité Audio is ultimately correct, for two main reasons:

1. @Theta claims that a less accurate but larger and more powerful system will "give much greater satisfaction... even in a small room." In my view the last, bolded part of that claim is easily refuted.

By contrast, if we're talking about a room where the size/volume and the logical listening distance are near or beyond the spec'd limits for a small monitor, then yes, in that case I am totally open to the possibility that a larger, less linear/accurate speaker system could provide more satisfaction. Even then, though, it's not a given because the increased SPL and perceived scale of such a system does not rule out actively unpleasant, difficult-to-correct sonic effects that would be produced by the speaker system's on-axis nonlinearities, poor dispersion characteristics, high distortion, or whatever the issues might be.

2. As is often the case with audio arguments, this one seems to be a qualitative, Yes/No question, but in actuality it's also a quantitative question of degree: let's say that the 8351b is indeed too small and underpowered for certain spaces and listening configurations. Keith from Purité would actually agree with that proposition I believe, since he has posted in the past that in his listening experience he felt the 8361a provided more of a sense of envelopment than the 8351b in a large listening space. (Keith, please correct me if I'm misremembering.)

But exactly how large does such a space have to be for the 8351b to be deemed inadequate - not just producing a different effect or a subtly less impactful effect, but producing a "much less satisfying" experience sufficient to categorically rule it out in favor of something larger and more powerful? That's a very subjective question because what gives people satisfaction is very subjective - for example there are lots of people who love what a 12" or 15" woofer can do and feel there is no substitute for the scale and air-moving effect of large, wide-baffle speakers with big drivers, no matter how small of a listening space we're talking about. Fair enough.

But if we're talking about the capability to output sound at sufficient SPL below the "guaranteed hearing damage" threshold, and to project a perceived soundstage width that feels appropriate to the listening space while maintaining a nice strong phantom center, then the size of the room that will be too big for something like the 8351b is larger than Theta is claiming, and IMHO at least somewhat larger than most people who've never heard a stereo pair of them in action would imagine. Same goes for many other models of stand-mount speakers I'm sure.

Finally, keep in mind that Amir listens to a single speaker in his testing. I don't know exactly what he did when testing this particular speaker, but in many reviews he mentions that he wears hearing protection when he runs the 96dB and/or 106dB SPL tests on a speaker - so you're not going to be listening at those sustained SPL levels, even if you're listening at 2-3M. And then remember that the real-world usable SPL produced by a stereo pair will be 3-6dB higher than what is measured for a single speaker.

So yes, perceived scale is a real thing - and it's also a very subjective thing. And room-size/SPL limits are also a real thing - and for whatever reason, a lot of us read "small-ish speaker limited to 103dB SPL at 1M" and imagine a stereo pair of such speakers being more limited in its application than it actually is.

 

[Spocko]

I think you both have valid points, but I think @Purité Audio is ultimately correct, for two main reasons:

1. @Theta claims that a less accurate but larger and more powerful system will "give much greater satisfaction... even in a small room." In my view the last, bolded part of that claim is easily refuted.

By contrast, if we're talking about a room where the size/volume and the logical listening distance are near or beyond the spec'd limits for a small monitor, then yes, in that case I am totally open to the possibility that a larger, less linear/accurate speaker system could provide more satisfaction. Even then, though, it's not a given because the increased SPL and perceived scale of such a system does not rule out actively unpleasant, difficult-to-correct sonic effects that would be produced by the speaker system's on-axis nonlinearities, poor dispersion characteristics, high distortion, or whatever the issues might be.

2. As is often the case with audio arguments, this one seems to be a qualitative, Yes/No question, but in actuality it's also a quantitative question of degree: let's say that the 8351b is indeed too small and underpowered for certain spaces and listening configurations. Keith from Purité would actually agree with that proposition I believe, since he has posted in the past that in his listening experience he felt the 8361a provided more of a sense of envelopment than the 8351b in a large listening space. (Keith, please correct me if I'm misremembering.)

But exactly how large does such a space have to be for the 8351b to be deemed inadequate - not just producing a different effect or a subtly less impactful effect, but producing a "much less satisfying" experience sufficient to categorically rule it out in favor of something larger and more powerful? That's a very subjective question because what gives people satisfaction is very subjective - for example there are lots of people who love what a 12" or 15" woofer can do and feel there is no substitute for the scale and air-moving effect of large, wide-baffle speakers with big drivers, no matter how small of a listening space we're talking about. Fair enough.

But if we're talking about the capability to output sound at sufficient SPL below the "guaranteed hearing damage" threshold, and to project a perceived soundstage width that feels appropriate to the listening space while maintaining a nice strong phantom center, then the size of the room that will be too big for something like the 8351b is larger than Theta is claiming, and IMHO at least somewhat larger than most people who've never heard a stereo pair of them in action would imagine. Same goes for many other models of stand-mount speakers I'm sure.

Finally, keep in mind that Amir listens to a single speaker in his testing. I don't know exactly what he did when testing this particular speaker, but in many reviews he mentions that he wears hearing protection when he runs the 96dB and/or 106dB SPL tests on a speaker - so you're not going to be listening at those sustained SPL levels, even if you're listening at 2-3M. And then remember that the real-world usable SPL produced by a stereo pair will be 3-6dB higher than what is measured for a single speaker.

So yes, perceived scale is a real thing - and it's also a very subjective thing. And room-size/SPL limits are also a real thing - and for whatever reason, a lot of us read "small-ish speaker limited to 103dB SPL at 1M" and imagine a stereo pair of such speakers being more limited in its application than it actually is.

Having witnessed a pair of the 8351B in action in Sony's mixing studio (approximately 12' x 18') during a session with Ben Goldsmith recording more guitar parts and vocals, I asked the producer whether they had a subwoofer because the mix sounded amazingly full - he said "of course, right?" then the sound engineer in the room said, "No, no sub, just the two Genelec speakers) and our jaws just dropped. In the video below I thought it was the BIG speaker playing but it was the Ones that are lit (oh wait, on second thought maybe those were only 8341??)

 

[G|force]

Those are 8341's in the pic.

 

[Theta]

Having witnessed a pair of the 8351B in action in Sony's mixing studio (approximately 12' x 18') during a session with Ben Goldsmith recording more guitar parts and vocals, I asked the producer whether they had a subwoofer because the mix sounded amazingly full - he said "of course, right?" then the sound engineer in the room said, "No, no sub, just the two Genelec speakers) and our jaws just dropped. In the video below I thought it was the BIG speaker playing but it was the Ones that are lit ( oh wait, on second thought maybe those were only 8341??)

View attachment 399396

Maybe I should have defined a small room, the picture you posted is a studio control room probably 10 sq meters. That is very small. I am thinking more along the lines of a 20 sq meter room. A large living room here in Europe is perhaps 100 sq meters, I auditioned very high end powerful system in such a setting, It had 4 12 inch woofers per side that did not seem out of place. If you scale that down to a more traditional living room, you still have a big system. Serious dealer (they exist) in Europe present large Wilsons or Focals in small rooms with good results. The demographics on this forum is probably not that young, which is my case, the children have left so there is often a small unused bedroom available. Since I made the hi fi move from the living room to a small bedroom my setup has improved by miles.

 

[suttondesign]

As Amir has also pointed out in reviewing large speakers, like tall Revels, you end up being constrained in addressing room modes caused by such speakers. The 8351b readily lend themselves to being supplemented with subs to deal with such things, and you end up with large SPL capability that way. Having dealt with room modes from full-range speakers for many years, I much prefer the monitor + sub solution.

 

[AudioJester]

As Amir has also pointed out in reviewing large speakers, like tall Revels, you end up being constrained in addressing room modes caused by such speakers. The 8351b readily lend themselves to being supplemented with subs to deal with such things, and you end up with large SPL capability that way. Having dealt with room modes from full-range speakers for many years, I much prefer the monitor + sub solution.

But only correct to about 80Hz. If you want to correct all the way to the room transition zone them you need W371.
But, yeah subs are great for extending response and spl

 

[AudioJester]

But only correct to about 80Hz. If you want to correct all the way to the room transition zone them you need W371.
But, yeah subs are great for extending response and spl

Lol, quoting myself now.

I forgot about Mitcho's correction filter service, that is using convolution. He/you can correct all the way to transition zone with the compromise being losing approx. 6dB headroom

 

[Spocko]

Maybe I should have defined a small room, the picture you posted is a studio control room probably 10 sq meters. That is very small. I am thinking more along the lines of a 20 sq meter room. A large living room here in Europe is perhaps 100 sq meters, I auditioned very high end powerful system in such a setting, It had 4 12 inch woofers per side that did not seem out of place. If you scale that down to a more traditional living room, you still have a big system. Serious dealer (they exist) in Europe present large Wilsons or Focals in small rooms with good results. The demographics on this forum is probably not that young, which is my case, the children have left so there is often a small unused bedroom available. Since I made the hi fi move from the living room to a small bedroom my setup has improved by miles.

How far from the front wall do you plan to place your speakers based on your expected listening distance? Boundary reinforcement could be to your benefit (or detriment) depending on how low you need to go!

 

[dfuller]

So, I've gotten to listen to these recently. They sound great. But holy crap, they have zero headroom in the low end. They compress so, so fast. Not even "hitting the limiters", they just run out of steam and distort.

 

[Xyrium]

Sounds about right. I believe Amir called this out in his comparison to the Salons. The THD graphs also seem to support this at 96dB.

Does Genelec make a "monitor" used for far field listening? I believe Neumann does. Those would likely be better for high amplitude listening.

 

[Descartes]

So, I've gotten to listen to these recently. They sound great. But holy crap, they have zero headroom in the low end. They compress so, so fast. Not even "hitting the limiters", they just run out of steam and distort.

That’s too bad so they need subwoofers which in a home theater setup shouldn’t be too difficult!

 

[Pearljam5000]

Maybe the 8361 will have enough bass but you disliked them too if I remember correctly

 

[LTig]

Does Genelec make a "monitor" used for far field listening? I believe Neumann does. Those would likely be better for high amplitude listening.

Genelec do lots of them, they are just "somewhat" big with zero WAF.

 

[dfuller]

Does Genelec make a "monitor" used for far field listening?

Tons. See: the mains.

Genelec do lots of them, they are just "somewhat" big with zero WAF.

tbf, Neumann's "long distance at volume" speakers are also "somewhat" big with zero PAF.

Maybe the 8361 will have enough bass but you disliked them too if I remember correctly

It's not about the bass, it's about the volume. The 8361 sure as shit has more volume on tap, I will say that much!

 

[Xyrium]

Yeah, I'm definitely drooling over those 8381s.... I wonder if their 126dB claim applies to the entire FR range they spec, down to 20Hz.

 

[dfuller]

Yeah, I'm definitely drooling over those 8381s.... I wonder if their 126dB claim applies to the entire FR range they spec, down to 20Hz.

hard to know without seeing a distortion spec, but I'd say "doubtful". 126dB is terrifyingly loud - like "near threshold of pain" loud.

 

[Pearljam5000]