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Can the /excessiveness/ of the 8361A be better utilised?

I think ‘why’ is obvious. OP bought a super expensive pair of speakers that are doing little more for him than the smaller pair could have done. He wants to know if he can somehow squeeze a subwoofer out of them so the expense wasn’t a waste.

OP has also received about 20 thoughtful replies explaining this isn’t a good idea, but doesn’t seem to want to acknowledge any of them, considering the points unhelpful.

OP’s idea makes sense, but it is not practical due to the port design of this speaker.
Right, if you don't need such high output levels but would like an LF extension, it would be much more reasonable to get smaller monitors and a matching sub. After I got the KH 750 DSP for my nearfield setup nothing urges me to replace the KH 120s with something bigger anymore, though on their own they lack bass, of course.
 
If we are talking anechoic, when you ask the speaker to deliver 106 dB, it only gives you 75 dB at 20 Hz. So making it it anechoic flat to 20 Hz limits your SPL to 75 dB.

But you are right, room gain can add 6 dB, and then you can now hit 81 dB down to 20 Hz, and a speaker that was -4 dB at 20 Hz isn’t bad, so you could actually say you were trying to hit 85 dB down to 20 Hz instead of the factory tuning of 65 Hz at -4 dB @ 106 dB. (All at 1 meter).

You are right, I read the 30Hz line as 20Hz on the FR.
flat down to 30Hz is perfectly fine though for music, and that would be possible using them with moderate levels (that most audiophiles use anyways)

and yea, with the room gain the probably could do flat down to 20Hz after this procedure.
 
I think ‘why’ is obvious. OP bought a super expensive pair of speakers that are doing little more for him than the smaller pair could have done. He wants to know if he can somehow squeeze a subwoofer out of them so the expense wasn’t a waste.

OP has also received about 20 thoughtful replies explaining this isn’t a good idea, but doesn’t seem to want to acknowledge any of them, considering the points unhelpful.

OP’s idea makes sense, but it is not practical due to the port design of this speaker.
Yes thy shall not overdrive ported speakers below the port resonance frequency.
Thy drivers will flapp helplessly in the wind and be burned . ( they basically work in free air below port tuning and have no box support, that’s just how it works )

Ie the speakers migth have massive overhead above 100 Hz but actually not at all at <30Hz . So the premise of the tread is wrong the overhead above 100Hz can not be exchanged to massive sub bass because the speaker simply can’t do that.


Get subwoofers ffs :)
 
Yes thy shall not overdrive ported speakers below the port resonance frequency.
Thy drivers will flapp helplessly in the wind and be burned . ( they basically work in free air below port tuning and have no box support, that’s just how it works )

Ie the speakers migth have massive overhead above 100 Hz but actually not at all at <30Hz . So the premise of the tread is wrong the overhead above 100Hz can not be exchanged to massive sub bass because the speaker simply can’t do that.


Get subwoofers ffs :)

Or get a pair of Kef ls60 they are basically designed for this they extend to 20Hz played at low levels , but they are ofcourse closed boxes ( no ports ) otherwise such shenanigans would not work .
 
These do have driver protection limit circuits so hopefully they would kick in before a major malfunction.
The problem comes when you are purposefully "Tricking" the DSP/EQ to send gobs more output below what should be a pre-defined rolloff. Unless the DSP is somehow servo-referenced, how would it know that the speaker has reached X-Mech (which WILL happen way below rated power once unloaded).
 
how would it know that the speaker has reached X-Mech (which WILL happen way below rated power once unloaded).
APS Spanily monitors, (like APS AEON, or APS IO) have optical limiter. But Genelec - i dont know. Its better "not tricking" by manual messing around with the settings, if someone doesn't know what they're doing.
 
APS Spanily monitors, (like APS AEON, or APS IO) have optical limiter. But Genelec - i dont know. Its better "not tricking" by manual messing around with the settings, if someone doesn't know what they're doing.
Optical - as in a laser and sensor pointed at the cone (like an optical servo?)? Or optical like an EL-OP based limiter?

If the latter, it still won't be able to track absolute cone movement, and fooling the DSP can/will allow more energy below the designed rolloff (and physical f3 where the cabinet unloads) - causing the woofer to reach X-Mech at very low power levels (basically an infinite baffle 1/2 octave below f3 tuning frequency, and the speaker's useable lower range is already moving towards the low-end of the tuning / approaching unloading even in the designed pass-band). If truly measuring the cone movement, then yes - it would help prevent self-destruction even if the DSP is horribly fooled to create substantial low-frequency EQ below f3...
 
The problem comes when you are purposefully "Tricking" the DSP/EQ to send gobs more output below what should be a pre-defined rolloff. Unless the DSP is somehow servo-referenced, how would it know that the speaker has reached X-Mech (which WILL happen way below rated power once unloaded).

By manipulation of DSP giving an inadequate signal to force the bass amps and in turn the bass drivers to exceed their thermal limits either of which will trigger protection. Maybe it wouldn't kick in doing what the OP is suggesting but hopefully Genelec has tested their speakers with the understanding people will try idiotic things. Perhaps the OP might ask Genelec if what he proposes is safe.
 
Somehow, I think Genelec will frown on this revolutionary concept ;) Some speakers will "bake it in" as an option with a lower max-SPL trade-off for lower extension - but are doing so in a controlled deterministic way...

And their own notes indicate a thermal modeling reference. Unloading the woofer (playing below f3 tuning) will allow mechanical damage well before any thermal/power limits of the coil are reached...
 
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Somehow, I think Genelec will frown on this revolutionary concept ;) Some speakers will "bake it in" as an option with a lower max-SPL trade-off for lower extension - but are doing so in a controlled deterministic way...

And their own notes indicate a thermal modeling reference. Unloading the woofer (playing below f3 tuning) will allow mechanical damage well before any thermal/power limits of the coil are reached...
I'm not an expert here but for speakers two parameters need to be limited: peak excursion and coil temperature.

In an active speaker excursion is (more or less) linear to the output voltage of the feeding amplifier so a simple voltage peak limiter should suffice to protect the driver.

Limiting the temperature is not that easy, but if you know the thermal behaviour of the driver a DSP can calculate it and protect the driver.
 
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Just a passing note that excursion is frequency-dependent. 10Vrms at 10Hz will produce way more excursion than 10Vrms at 1kHz.


Chris
 
I'm not an expert here but for speakers two parameters need to be limited: peak excursion and coil temperature.

In an active speaker excursion is (more or less) linear to the output voltage of the feeding amplifier so a simple voltage peak limiter should suffice to protect the driver.

Limiting the temperature is not that easy, but if you know the thermal behaviour of the driver a DSP can calculate it and protect the driver.
Yes, I think you are 100% correct. Here is the Genelec approach in a block diagram, they don't measure the coil temperature directly but instead have a heat model for each driver derived from the amplifier output.
1733062930552.png


Genelec's heat model is based on the driver working within the design window. I would be willing to bet that if the driver is operated in a non-linear regime, the heat model is no longer valid and the protection no longer works as intended. The voltage protection is also no longer going to work as intended, underestimating excursion. :eek: OP wants to operate the driver in a non-linear regime, with EQ below the system resonance. Maybe the steep high pass on the bass driver will prevent the non-linearity from happening in the first place, I don't know. Maybe OP will be able to overcome the woofers' high pass with large EQ. Smoke and/or the woofer making car-crash sounds may follow.
 
I think ‘why’ is obvious. OP bought a super expensive pair of speakers that are doing little more for him than the smaller pair could have done.

This does not match my experience. I trialled both the 8351B and 8361A and found the 8361A to be vastly superior, even at 1.5m and identical SPL. I did not expect this given that both Genelec and others here have stated that the primary benefit of the 8361A over the smaller 8351B is SPL (but also a slightly improved low end frequency response and slightly longer listening distance). However, I also took into account the feedback of others here, who stated that the speaker sounded much bigger and delivers substantially greater bass response than the 8351B. This was absolutely my experience and so why the 8351B was returned. In terms of actually why, the question of how some of the SPL available to the 8361A could be traded for greater LFE extension interests me. Perhaps I might also add that I'm someone who enjoys the process of tinkering with things to increase knowledge and understanding whilst also exploring the potential of optimising their performance (even if this results in no or minimal gain).

He wants to know if he can somehow squeeze a subwoofer out of them so the expense wasn’t a waste.

As I've done my best to communicate, the speakers are fabulous. I'm always smiling when listening to them... They were absolutely worth the time it took to save for them and I would never this of them as a waste. I have never stated that I wanted to squeeze a subwoofer out of them. I did mention the benefits of a sub as well as not wanting one, but never that I wanted to turn the 8361A into a sub; rather, I wanted to explore safely trading some of its SPL for greater LFE.

OP has also received about 20 thoughtful replies explaining this isn’t a good idea, but doesn’t seem to want to acknowledge any of them, considering the points unhelpful.

Not once have I said that the points raised are unhelpful. Please re-read my comments. In fact, I would have hoped you would have come to the opposite conclusion! I'm expressed my gratitude for the responses I've received several times now and have changed my thinking on multiple occasions and shared this with you all.

Perhaps my determination can be explained by mostly feeling misunderstood, despite repeated attempts to address this, and not being convinced that what has been shared necessarily means that I cannot continue to explore the overarching question I raised. Furthermore, whilst my -18dB example was extreme, I also provided a -10dB example. If -10dB is also extreme, what about something lower? In the absence of evidence to the contrary, I am happy to accept that ported speakers are not ideal for trading SPL for LFE based on the feedback of multiple individuals here. However, this does not necessary mean I cannot to some degree trade SPL to improve LFE in a manner that is safe and brings measurable benefits. It seems more about getting the balance right and thanks to some of the feedback here, I've more of an idea now about how to achieve this than I did before.

I'm going to take a break for now as I'm exhausted from all this. Nevertheless, I am deeply grateful for everyone's feedback. Thank you.
 
@MAB
"Heat" is from power (V x A), so if "heat model" is good ... this should work just fine.
Excursion is another problem ;)
 
@MAB
"Heat" is from power (V x A), so if "heat model" is good ... this should work just fine.
Excursion is another problem ;)
I know this perfectly well, it's assumed in my post that all others know this too. And I specifically separate excursion. Is that not clear? Not sure why you are repeating the obvious. The model for heat and excursion is derived from the amplifier's output, and assumes operating the driver in a regime where the model is applicable. OP is wanting to boost the bass in a region where the driver will not operate in a linear fashion. Hope this is clear, you seem to have missed my point.
 
Just a passing note that excursion is frequency-dependent. 10Vrms at 10Hz will produce way more excursion than 10Vrms at 1kHz.
How's this? Current flows through the coil and creates a force, independently of the frequency, I think. My logic also tells me that if you're right a DC voltage would produce infinite excursion ... ???

Where is the flaw in my reasoning?
 
How's this? Current flows through the coil and creates a force, independently of the frequency, I think. My logic also tells me that if you're right a DC voltage would produce infinite excursion ... ???

Where is the flaw in my reasoning?
Probably a few ways to look at this. By experience, high frequency causes less excursion than low frequency.

The force and therefore the acceleration of a driver is proportional to current. For a similar peak voltage (and current) polarity reverses sooner with higher frequency, therefore driver velocity slows and reverses sooner, so excursion is less.

Driver suspension makes drivers imperfect in their behavior, so they can tolerate a minimal amount of DC. But significant DC does cause a driver to bottom out, which is the reason they don’t reach infinite excursion. But drivers are not meant to handle DC fur this reason.
 
This does not match my experience. I trialled both the 8351B and 8361A and found the 8361A to be vastly superior, even at 1.5m and identical SPL. I did not expect this given that both Genelec and others here have stated that the primary benefit of the 8361A over the smaller 8351B is SPL (but also a slightly improved low end frequency response and slightly longer listening distance). However, I also took into account the feedback of others here, who stated that the speaker sounded much bigger and delivers substantially greater bass response than the 8351B. This was absolutely my experience and so why the 8351B was returned. In terms of actually why, the question of how some of the SPL available to the 8361A could be traded for greater LFE extension interests me. Perhaps I might also add that I'm someone who enjoys the process of tinkering with things to increase knowledge and understanding whilst also exploring the potential of optimising their performance (even if this results in no or minimal gain).



As I've done my best to communicate, the speakers are fabulous. I'm always smiling when listening to them... They were absolutely worth the time it took to save for them and I would never this of them as a waste. I have never stated that I wanted to squeeze a subwoofer out of them. I did mention the benefits of a sub as well as not wanting one, but never that I wanted to turn the 8361A into a sub; rather, I wanted to explore safely trading some of its SPL for greater LFE.



Not once have I said that the points raised are unhelpful. Please re-read my comments. In fact, I would have hoped you would have come to the opposite conclusion! I'm expressed my gratitude for the responses I've received several times now and have changed my thinking on multiple occasions and shared this with you all.

Perhaps my determination can be explained by mostly feeling misunderstood, despite repeated attempts to address this, and not being convinced that what has been shared necessarily means that I cannot continue to explore the overarching question I raised. Furthermore, whilst my -18dB example was extreme, I also provided a -10dB example. If -10dB is also extreme, what about something lower? In the absence of evidence to the contrary, I am happy to accept that ported speakers are not ideal for trading SPL for LFE based on the feedback of multiple individuals here. However, this does not necessary mean I cannot to some degree trade SPL to improve LFE in a manner that is safe and brings measurable benefits. It seems more about getting the balance right and thanks to some of the feedback here, I've more of an idea now about how to achieve this than I did before.

I'm going to take a break for now as I'm exhausted from all this. Nevertheless, I am deeply grateful for everyone's feedback. Thank you.
Enjoy your Genelec’s :) as for why so much fuss from people .
Read up on how bass reflex loudspeakers work ( speakers with a port/hole/tube into the box ) then you get why increasing levels at frequencies below the tuning frequency is futile or possible damaging, for example ported subwoofers has a similar protection scheme as these genelecs for the same reasons.
 
How's this? Current flows through the coil and creates a force, independently of the frequency, I think. My logic also tells me that if you're right a DC voltage would produce infinite excursion ... ???

Where is the flaw in my reasoning?

You've forgotten that the suspension (and cabinet) apply some restoring force. ie, when DC is applied, the cone will exhibit rapid acceleration (due to the limited HF bandwidth, it won't be infinite), and then stop moving when the restoring force matches the motor force.


At low frequencies, the cone will accelerate for longer before changing direction, resulting in larger excursions.

This is trivial to prove in reality: tweeters have tiny cone excursion compared to subwoofers.


Chris
 
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