How dumb is this? It sounds great! (-15dB "manual preamp gain" in Dirac Live)

[sigbergaudio]

I did a quick 3-way comparison between Dirac off, stock target curve at 0dB, and my custom curve. My target curve seems to be effectively bypassing Dirac's +10dB boost limit? These sweeps were created with MMM and were level matched approximately by ear.
View attachment 441890

So here we see at least a 10-15db boost below 100hz. Every 3dB of boost requires twice the power. So if you're at 50W and boost 30hz by 12dB, that would require 800W. The loudspeaker probably isn't super interested in getting that. In practice, it will be fine at moderate levels, but amplifier and/or speaker will be very unhappy at elevated listening levels.

 

[sheninat0r]

Now you need to check the distortion curves
If they look fine, then I guess you can just feel free to use your pulled-down target curve

Plugs will change the bass, but I don't know how they would do unplugged that close to a wall. If you have not tried it, you might as well give it a shot and see what you think.

Likely super distorted in the low bass, at any significant volume, that's my guess. I would likely roll those off steeply after 60 myself, ported. Or go small sub to get down to 40 cleanly and cross them over at ~90hz with the plugs. I wouldn't need lower for a desk situation.

I did some sweeps at the main listening position, but I can't tell if I did it right? I have only used MMM for frequency response measurements in the past.

Left channel distortion with my dumb curve (top) and stock Dirac (bottom):

And a THD overlay showing left channel THD in all 3 cases, off/stock/dumb:

Finally, these were my sweep settings:

 

[Soniclife]

I did some sweeps at the main listening position, but I can't tell if I did it right? I have only used MMM for frequency response measurements in the past.

Left channel distortion with my dumb curve (top) and stock Dirac (bottom):
View attachment 441918
View attachment 441919

And a THD overlay showing left channel THD in all 3 cases, off/stock/dumb:
View attachment 441920

Finally, these were my sweep settings:
View attachment 441921

It looks like you are measuring at a very low volume, which will reduce distortion massively. What's the maximum volume you listen at?

 

[sigbergaudio]

If you have a calibrated microphone / can calibrate manually with your phone, try the same at 75-80dB. Maybe increase gradually.

EDIT: Also start the sweep at maybe 20hz not 0hz.

 

[sheninat0r]

It looks like you are measuring at a very low volume, which will reduce distortion massively. What's the maximum volume you listen at?

All of the measurements were made with knobs & sliders at my maximum comfortable listening volume, which is indeed quite low. I don't have a calibrated SPL meter, but the NIOSH SLM app on my phone says LAeq 62dB, Lmax 65dB, and LCpeak 83dB with music playing.

So far my takeaway is that if it sounds good, then it is good. In my particular situation with my particular listening habits, I am not running out of amplifier power or overdriving the woofer into heavy distortion.

I'll try some high volume sweeps and see how it looks.

 

[Old_School_Brad]

If you have a calibrated microphone / can calibrate manually with your phone, try the same at 75-80dB. Maybe increase gradually.

EDIT: Also start the sweep at maybe 20hz not 0hz.

Uh oh, I definitely wouldn’t recommend that.

Start at 65 dB and plot the THD -I have a feeling that small speaker (and its amplifier) will begin to struggle from that point upward.

 

[sigbergaudio]

Uh oh, I definitely wouldn’t recommend that.

Start at 65 dB and plot the THD -I have a feeling that small speaker (and its amplifier) will begin to struggle from that point upward.

Yes, so increasing gradually is a good idea.

 

[Old_School_Brad]

If there weren’t such an extreme curve in play, I wouldn’t think twice. But in this case… yeah, I’d proceed slowly..

And the start at 20 Hz instead of 0 is a good idea as well.

 

[sheninat0r]

It went OK at 65dB (top), but the woofer made some fart sounds at 70dB (bottom) as predicted

 

[Mort]

as predicted

Boom!
Science.

 

[sheninat0r]

As an aside, I found Amir's Chane A1.5 review and it seems like my old speaker is quite similar to its successor. The uncorrected response shows the same broad dip near 500 Hz, rising response after 3 kHz, and the 70dB sweep has the midrange distortion spike around 2-3 kHz.

 

[Soniclife]

I don't have a calibrated SPL meter, but the NIOSH SLM app on my phone says LAeq 62dB, Lmax 65dB, and LCpeak 83dB with music playing.

It went OK at 65dB (top), but the woofer made some fart sounds at 70dB (bottom) as predicted

It looks like you are probably getting away with this because of your low listening level, however I would trial how low you go with the correction, you almost certainly cannot hear much below 35Hz, so any boost down there is a waste.

I'd also try with the ports unblocked, that should give free bass, but you will need correction.

 

[holbob]

I'm sure I tried this years ago and it just sounded really, really bland. Your noise floor is strangely low in the first rew pictures on the first page.

 

[Old_School_Brad]

It looks like you are probably getting away with this because of your low listening level, however I would trial how low you go with the correction, you almost certainly cannot hear much below 35Hz, so any boost down there is a waste.

I'd also try with the ports unblocked, that should give free bass, but you will need correction.

It’s definitely due to the low listening levels. I also have a pair of bookshelf speakers in my workshop with a heavy loudness boost (Yamaha loudness contour). They can’t handle high volumes, but for casual listening, they sound great.

I probably wouldn’t unblock the ports while boosting below the tuning frequency -the blocked port is likely contributing to the positive results.

 

[sheninat0r]

I'd also try with the ports unblocked, that should give free bass, but you will need correction.

I probably wouldn’t unblock the ports while boosting below the tuning frequency -the blocked port is likely contributing to the positive results.

My understanding is that you can (more) easily reach dangerous excursion with EQ below the port tuning frequency. Besides that, one subjective hill that I'll die on is that sealed bass sounds "tighter" and better than ported bass

I'm sure I tried this years ago and it just sounded really, really bland. Your noise floor is strangely low in the first rew pictures on the first page.

Do you mean the absolute level, or the distance between the noise floor and the speaker recordings? I thought that absolute SPL in REW is basically meaningless without calibration.

 

[Sokel]

You also have to do something about this rise over 16kHz, like immediately if you continue to do sweeps I see that REW plays it just fine and you don't want that if you want your tweeters to stay in good working condition.

 

[kyuu]

Besides that, one subjective hill that I'll die on is that sealed bass sounds "tighter" and better than ported bass

Someone will probably correct me, but my understanding is that this is correct insomuch as sealed bass response tends to have significantly less energy (read: max SPL) than bass reflex and therefore activates room modes less, which will certainly results in less huge bass peaks that cause bass to sound "muddy" (along with things in the room resonating). With proper EQ/room correction, though, there's no advantage. Which is certainly my experience: my ported sub has no issue with "tightness" with Dirac doing its thing. If anything, it's too "tight"; I kind of miss the rumble that it otherwise provides on certain content.

 

[staticV3]

If there was a notable difference in time domain between sealed and ported, a corresponding trend should be visible in the measured group delay, step response, and ETC in this test of 10 different subs:

I measured 10 subwoofers.

Hi, it's been a while! I would like to thank the people who made this project possible on a scale never before imagined in South Korea. I measured a total of 10 subwoofers, including my own DIY subwoofer(L26RO4Y), and measured them to the CEA-2010 standard using a Klippel TBM module. Below are...

www.audiosciencereview.com

 

[sigbergaudio]

Someone will probably correct me, but my understanding is that this is correct insomuch as sealed bass response tends to have significantly less energy (read: max SPL) than bass reflex and therefore activates room modes less, which will certainly results in less huge bass peaks that cause bass to sound "muddy" (along with things in the room resonating). With proper EQ/room correction, though, there's no advantage. Which is certainly my experience: my ported sub has no issue with "tightness" with Dirac doing its thing. If anything, it's too "tight"; I kind of miss the rumble that it otherwise provides on certain content.

Correcting someone on the internet, my favorite pastime!

I feel like this is sort of the same argument as saying that a bookshelf speaker is better in smaller rooms, because it has less bass, thus exciting less room modes = better bass.

While it's sort of, technically true, it doesn't really say anything about sealed vs ported. As you can find 8" ported subwoofers, and you can find 18" sealed subwoofers. The latter is (very) likely to have more bass / max SPL despite being sealed. So then suddenly the sealed subwoofer is worse if we are to follow this line of reasoning.

 

[kyuu]

While it's sort of, technically true, it doesn't really say anything about sealed vs ported. As you can find 8" ported subwoofers, and you can find 18" sealed subwoofers. The latter is (very) likely to have more bass / max SPL despite being sealed. So then suddenly the sealed subwoofer is worse if we are to follow this line of reasoning.

Well sure, but I think we can reasonably limit this discussion to a system where all else is equal except for sealed vs. bass reflex. In that instance, I think it's fair to say that the bass reflex enclosure will be substantially more efficient (up to the port's tuning frequency, of course) compared to the sealed one. Again, happy to be corrected though.