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

[Pearljam5000]

The missing attachment...

8361 as a username
Now that's dedication

 

[JustJones]

The D&D 8C goes lower, at an extra cost. Though they seem to be pretty good speakers, probably they have by design a little less coherence in their spatial abilities than the 8361, they are a 2 way speaker, not a 3 way coaxial point source.

Don't want to derail the thread just clarify a misconception. The Dutch 8c is a 3 way speaker not 2 way.

Specifications​

COMPONENTS
LF: 8″ High Excursion Subwoofer (2x)
MF: 8″ Mid-Range Driver
HF: 1″ Alloy Dome Tweeter
ENCLOSURE TYPE
LF: Sealed
MF: Passive Cardioid
FREQUENCY RESPONSE
30 Hz – 20 kHz ± 1 DB
AMPLIFIER POWER
LF: 500 W
MF: 250 W
HF: 250 W

 

[MAB]

(a) EQing to boost bass at the cost of a flat response (e.g., setting a 2dB shelving filter at 100Hz using GLM's SCP)
(b) EQing to boost bass in line with a flat response (e.g., perhaps setting multiple filters...)
(c) Some combination of (a) and (b)

Yes, conceptually this is what is done to equalize woofers/subs. I do this often, but with sealed subs. I typically use a Linkwitz transform, which specifically equalizes the driver with a 12dB/octave shelf to compliment the driver's natural 12dB/octave mechanical highpass response. I use a steep DSP highpass about one octave lower than Fs to limit the driver excursion and distortion, and most importantly damage. I do this sealed only. Ported systems use the port to assist the woofer's output at the port resonance, they actually help the driver to minimize excursion at resonance, but below resonance the driver rapidly increases excursion (you can see all of that in the excursion vs. frequency graph I posted). Keep that in mind because you misinterpreted what I said:

I hadn't thought about excursion, thank you. It seems that I at least need to be cautious of:

(a) insufficient power being delivered to the driver (causing distortion)
(b) more power being delivered to the driver than the driver can handle (also causing distortion but further potentially damaging the driver)

No, the driver's dramatically increased excursion is the source of distortion. Also, EQ will remove the benefit of lower driver distortion provided by the port. And introduce more port distortion due to the higher wind velocity in the port.
Fortunately, Genelec seem to already thought this out, and use DSP filters to keep the speaker operating only in it's design window:

The speaker rolls off at 48dB/octave below 30Hz! Genelec appear to have thoughtfully provided a filter that will prevent or limit just what you are attempting (among many things). I actually don't think there is a risk of breaking the speaker, they also use limiters to take care of over-excursion, but I don't know if the limiters will work properly with the EQ you would need to overcome the highpass filter and make a difference in the bass.

This is one of the reasons I am asking you to measure the acoustic result (not the excursion or distortion), because it is likely you will try to EQ and the filters will prevent significant extension. So it would be good for you to make sure and measure to make sure you verify that your EQ actually has made a positive change, and wasn't filtered by the internal DSP. GLM or any competent measurement can do this just fine, your ears cannot.

I personally have no idea why someone would want more bass out of their 8361 mains, where mains sound best in a room is usually not a good place for bass reproduction. Subs do allow deeper bass, but they are even more important for getting better bass without nulls and peaks. Adding bass to your mains is a recipe to create larger nulls and peaks. I barely understand why people reject subwoofers. I also have to wonder what type of music you listen to that has significant content below 30Hz.

 

[sigbergaudio]

@8361AM I have no idea why everyone is confused by your query, it seems perfectly understandable and reasonable.

However the 8361 seem to be both a ported design, and one with an high pass filter employed (as @MAB mentions above). So it is unlikely you are able to extend the response much more, as you will be limited by the port tuning (trying to EQ below the port tuning is not advisable).

EDIT: What you can do if you want is to EQ up the bass level within the current extension.

 

[8361AM]

@8361AM AM : You know, this drawing doesn't tell much, we have understood your questions now.

In terms of the drawing, its purpose was to make it easier for readers to understand my point about "pushing up" the bass response above an overall neutral response at the cost of accuracy (e.g., the more often than not recommended 2dB shelving filter at ~100Hz) and/or "pushing left" (towards lower extension) at minimal accuracy cost (something seemingly more complex but also seemingly unaddressed seriously until now). I appreciate the image could have been better and so apologise if it did not offer the additional clarity I hoped it would. Nevertheless, I'm glad the clarifications have helped and thank you for this opportunity to improve my thinking.

@8361AM AM : There is absolutely no reticence among us to answer them, and IMO you've got a lot of answers yet from each of us.

I'm positive about this and very grateful for members to take the time to read my posts and reply. My point was that my initial post was asking for help about how to improve LFE and in many cases, I seem to have been challenged in terms of why I would want to or if it would be valid to do so. Whilst I appreciate that asking why can be helpful at times, I did my best to be clear that I find the question of how more interesting. For example, if we focus on LFE extension alone, only @unpluggged and @EAXAE appeared to address this (apologies if I've missed one or more others) in terms of suggesting that doing so would be challenging due to the extreme roll off and @MAB for offering insight into the potential risk of doing so. However, whilst I find these insights to be valuable, I'm no closer to understanding how. Specifically, my experience of the GLM software is that it may not be sufficiently flexible for this kind of EQing and so I may need some other software that is. I'm not sure what this software is nor how to measure the changes I do make to determine their effect (e.g., is it possible to apply an EQ to a measurement sweep to directly assess the frequency response of the applied EQ?). To these points, I'll continue exploring but if anyone can point me in the right direction, I'd be grateful for my learning to be scaffolded.

@8361AM AM : Don't get too focused on a few Hzs in the low bass ; for 90 % of music, it doesn't matter.

Agreed but I also listen to movies and here, the 8361A is a limiting factor more often than not. If it's possible to get more LFE at the cost of the SPL I do not utilise, I'd like to. However, I also listen to music that extends extremely low (e.g., organ and some electronic music) and so would also benefit from greater LFE here. Lastly, whilst thinking about this today, I realised that the 8351B is effectively a scaled down version of the 8361A aside from the 8361A having substantially greater SPL and extending 2Hz lower (which seems mostly irrelevant given comments here). This, in combination with my comparison with the 8260A, suggests to me that there's plenty of scope to improve the LFE response of the 8361A at the cost of SPL with little to perhaps no risk at reasonable SPL levels. Put another way, it seems that Genelec strongly priotitised SPL with the 8361A and, had they wanted to, could have produced a speaker with lesser SPL but extending deliciously deeper... As someone who likes to tinker with things and who would prefer greater and more accurate LFE at the cost of SPL, I'm excited to explore this! Again, if anyone can help me with the how, I'd be extremely grateful and will share my findings to the hopeful benefit of us all.

 

[8361AM]

@8361AM I have no idea why everyone is confused by your query, it seems perfectly understandable and reasonable.

Thank you.

Really.

I was beginning to doubt my sanity or otherwise...

@8361AM However the 8361 seem to be both a ported design, and one with an high pass filter employed (as @MAB mentions above). So it is unlikely you are able to extend the response much more, as you will be limited by the port tuning (trying to EQ below the port tuning is not advisable).

I am worn out now, but my challenge to this would be to consider how similar the 8361A and 8260A are. Both are ported and both share very similar enclosures. Unless the bass drivers differ meaningfully (or otherwise), should the 8361A not have the potential to behave more like the 8260A? Even if the difference is subtle, it'd make me extremely happy to demonstrate to you all that the 8361A could be EQ'd to extend to 29Hz rather than 36Hz at ± 1.5 dB. Might members be prepared to support me in this?

 

[8361AM]

I was beginning to doubt my sanity or otherwise...

Unless we both lack sanity..?

 

[holdingpants01]

Even if the difference is subtle, it'd make me extremely happy to demonstrate to you all that the 8361A could be EQ'd to extend to 29Hz rather than 36Hz at ± 1.5 dB. Might members be prepared to support me in this?

It's entirely possible that you have that already in your room, but you'll have to measure it first and post it here. My Genelec W371A is rated -6dB at 23Hz, but in reality and in my room it's flat down to 20Hz and I didn't do nothing but automatic GLM calibration

 

[Digby]

What you are after sounds like it might be a bit like the loudness button amplifiers used to come with, that would increase the bass (and treble) at lower listening levels. If you aren't pushing the speakers SPL wise, you could do this or, as someone else said, put them against a wall and do this (even more efficient).

 

[krabapple]

Why wish for the Genelec to do what it is not designed to do?

 

[GXAlan]

Peak SPL and actual SPL are two different things. Empirically, it seems like peak SPL pink noise is roughly 13 dB higher than the clean FR sweep based upon Neumann, Genelec, and Meyer Sound advertisements versus measurements.

So the 118 dB is actually 105 dB give or take at 1m. This is consistent with Amir’s measurements showing clipping at 106 dB.

That’s at 1m. Now we have to account for distance.

Poll: What is your listening distance? (Fall/Winter 2024)

What’s your listening distance? If you have multiple systems, pick all that apply. (Used at least once a week) We have had previous polls in the past but let’s sample the membership again. Feel free to comment with typical SPL or details about your systems. Since many of us have headphones...

www.audiosciencereview.com

If you want reference level, you pretty much don’t have any leeway. On the other hand, if you like 65 dB averages with 85 dB peaks and are listening at 3m or so, you have options.

At 3m, your 105 dB hits 95 dB peaks. That means you have 10 dB to play with. From Amir’s 106 dB curve, you can see that it hits 35 Hz at 95 dB. Amir’s 96 dB curve, shows that you were already rolling off at 60 Hz and it was -10 dB at 35Hz.

So you can boost the bass, limit your peak SPL to 95 dB bursts at 3m and now increase your bass extension.

You can do the math for closer listening distances or lower volumes. So your thought is correct, but the actual swing in SPL is ~13 dB less than you might assume.

 

[Tovarich007]

Holdingpants : of course, the room bass reinforcement can be very effective, but the W371 expends the 8361 FR in the bass, no surprise it goes flat down to 20hz and maybe a little lower (but at which SPL ? and is it really necessary ?)

8361 AM : as for the movies, if you really want realistic very low bass to reproduce, for instance, explosion or battle "big" sounds, you'd rather add one sub (or even better two smaller subs) equipped with a calibration system. That would be a better option, you can't turn the 8361 -or the 8260, the D&D 8C or any midsize monitors- into what they're not intended for.

By the way, tell us more about your room, its dimensions, volume, type. Without knowing your room and the SPL max you need, it's impossible to help you more than we try to do.

 

[8361AM]

Holdingpants : of course, the room bass reinforcement can be very effective, but the W371 expends the 8361 FR in the bass, no surprise it goes flat down to 20hz and maybe a little lower (but is it really necessary ?)

8361 AM : as for the movies, if you really want realistic very low bass to reproduce, for instance, explosion or battle "big" sounds, you'd rather add one sub (or even better two smaller subs) equipped with a calibration system. That would be a better option.

By the way, tell us more about your room, its dimensions, volume, type. Without knowing your room and the SPL max you need, it's impossible to help you more than we try to do.

Perhaps my question needs additional refinement, although perhaps also I'm too tired for this right now...

Nevertheless:

How can the frequency response of the 8361A within an anechoic chamber be EQ'd so that it extends lower whilst maintaining as accurate as possible a frequency response (e.g., 29Hz rather than 36Hz at ± 1.5 dB)?

Re: subs, I've already shared that I do not want to include them and this does not seem unreasonable given this forum's dedication to scientific inquiry. For various reasons, I hope to extract greater value from my 8361As without purchasing additional equipment (whether or not this is inferior to adding one or more subs) and given that all that seems to separate the 8361s from the 8351Bs is SPL (that I do not want) and 2Hz in LFE (which others have said is somewhat meaningless), I do not understand why this is not something to be sought after... However, I also accept that any such outcome may potentially be inferior to other solutions (e.g., adding more subs) and if so, accept this.

In terms of the comment about a manufacturer designing something a certain way, it does not necessarily follow that benefit may not otherwise be gained from following a different way.

 

[ChrisG]

MAB has it correct: if you try to EQ boost below the port tuning frequency, you'll very quickly hit lots of distortion. There's basically zero useful output down there, but there is potential to damage the loudspeaker from over-excursion. The correct term is that it's an acoustic short-circuit: the cabinet is applying basically-zero loading to the cones below the port tuning frequency.

FWIW, the 8260A has a 10" bass driver while the 8361A has a pair of 5"x10" oval woofers. They might be somewhere-near-similar in cone area, but what matters here is that the port tuning frequency represents the lowest frequency a cabinet should be asked to reproduce.

This is why Genelec has put a steep highpass filter in place - it will quickly reduce the level of signals below the port tuning frequency to minimise distortion from the drivers flapping around.


If you seriously wanted to attempt to get more LF extension out of a pair of 8361s, the first thing to do is block the port. This will convert the cabinet to a sealed design. You'll lose some LF output potential in the 35-50Hz range, but the drivers will be able to produce frequencies below 30Hz.
Next, you'll need to apply enough EQ to balance Genelec's HPF and the sealed box rolloff. This will be non-trivial.

Finally, I'd like to note that ports are often used to exchange heat with the outside world. The aluminium cabinet will help, but don't be surprised if you burn out the drivers. +3dB = 2x the power, and you're going to need more like +30dB of boost to get down into the 20-somethingHz range.


Chris

 

[dasdoing]

you could easily make it flat down to 20Hz or even less if you sacrifice a little loudness (you don't need).
But it probably goes down there anyways with room gain?

 

[sigbergaudio]

I am worn out now, but my challenge to this would be to consider how similar the 8361A and 8260A are. Both are ported and both share very similar enclosures. Unless the bass drivers differ meaningfully (or otherwise), should the 8361A not have the potential to behave more like the 8260A? Even if the difference is subtle, it'd make me extremely happy to demonstrate to you all that the 8361A could be EQ'd to extend to 29Hz rather than 36Hz at ± 1.5 dB. Might members be prepared to support me in this?

Based on the data, they are likely tuned differently. So it's not the driver, and also not the DSP, but likely the physical port is tuned differently, giving the 8361A a higher tuning frequency. After this frequency, the speaker will start to roll off quickly (as we also see in the data), and there is not much you can do about that without physically modifying the speaker.

Have you measured your speaker in the room, either at the listening position and/or nearfield? A -6dB point of 30hz might still mean it goes pretty much flat to 20hz in room.

 

[GXAlan]

you could easily make it flat down to 20Hz or even less if you sacrifice a little loudness (you don't need).
But it probably goes down there anyways with room gain?

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).

 

[8361AM]

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).

This will be my final check of my email account (and so forum posts) for the next ~12 hours...

Keen to leave things on a + note.

As such, I'm feeling increasingly understood and so thank you all. But also wish to apologise for not making myself clearer, since being clearer about things should generally result in being more clearly understood.

Obviously, there's much I've to learn but I nevertheless hope that I've demonstrated I'm prepared to put the work in (at least in terms of the effort I've invested into my posts). Whilst I hope to gain from this work, I also hope to share any insights to the benefit of others.

Thank you all for your comments and looking forward to some experimentation!

 

[Tovarich007]

Block the ports ? it seems to me not easy to do it properly.

Some speakers are designed to work without or without ports ou partly with ports (when they have two or more ports). In this case, the manufacturer gives specs, more or less detailed, for the different configurations. The Genelecs are not designed that way..

So i srongly suggest to inform and discuss with Genelec before engaging such a process and ask the company if it's reasonably feasable or not, and what result one could expect from such a transformation. But beware of cancellation of constructor warranty !

I mean, without port, of course the sensitivity and the SPL will decrease, but a closed speaker doesn't go lower, all things equal. The bass rolls off more progressively, which is different. As ChrisG wrote, one will need much more power to get extreme bass from a closed design that's both very low and powerful enough not to sound thin (which is sometimes a sound character associated with not well done closed designs). And this will increase condiderably distortion too. Not sure at all the two relatively small bass drivers of the 8361 and their power amps could accept such an increase in power, distorsion and heat for a long period.

But I maintain that without knowing at all 8361AM listening room nor the desired SPL max he wants, all what we're talking about is vain.
If his room is not large and if he wants, let's say, about 85/90 dB max at 20hz including room gain, maybe it will be OK (this is not loud at all for some for realistic movie soundtracks, but for music OK, there is little extreme bass content in music). But we don't know this two parameters.

P.S. : 8361AM, your quest and questions are quite clear, but once again you can't turn a speaker into what it's not designed for. There are inherent limits to your quest of gain in bass extension. And maybe you don't need it a all, considering the room gain, the possible EQs and the output level you listen to. That's why I asked you several times to give us details about your room, about the max volume you usually listen to music and to movies.

 

[ChrisG]

but a closed speaker doesn't go lower, all things equal.

A sealed loudspeaker will have more output than a ported one, below the port tuning frequency. Since we're looking specifically for increased output down there, sealed is about the only option.

NB - the other option is to extend the length of the port, which will decrease the tuning frequency. This is much more difficult to do well than simply sealing the port. Ideally, you'd increase the cabinet size to maintain a somewhere-near flat response. Playing around in WinISD or Hornresp will be educational for those following along.


Chris