I have a question about the 830668. I'm kind of dumb and I need a few really basic questions answered, namely "Are three things going to be a problem if I actually build this?" I built a bass box in VCAD. Their new tools are awesome. Kimmo just needs to figure out how to integrate all of them at once so I don't have to keep flipping windows and importing data.
I was doing the usual paint-by-numbers sealed enclosure with EQ. I run into an excursion problem, and my first thought is "Can't I get a lot more power handling by throwing a port in there tuned to driver Fs?" Surely the displacement should be massive and solve the excursion problem! So I kept going with this monstrosity that may never fit together, EQ'ing the medium box flat to 30hz. Then I thought I could do better if I ignore the power handling aspect. So here's the three problems with three dumb questions:
1: Can I ignore power handling requirements if the port is moving the air, not the driver? Similarly, does the driver still use the power even though it doesn't move? I imagine it does to reverberate air, not itself.
2: Is the impedance an issue outside of amplifier selection? It hits 3ohm across most of the sub-bass spectrum.
3: Will everything explode in this configuration?
In very stupid terms, I have colored the driver into the lines. The dark blue fits into that light blue shape at 200W, the excursion is just barely passing xmax, and the vent velocity is manageable if I ignore that we only live in three dimensions. The following represents worst case.
View attachment 1205671
View attachment 1205669View attachment 1205672View attachment 1205673View attachment 1205668
The original sealed box was limited to 95dB SPL. Boosting, cutting, and preamping until the response was flat with EQ. Hence the hair-brained idea. The light blue vs dark blue lines highlighting my completely unfounded theory on porting. Both are maximums, the lighter line is following the natural rolloff, the darker line is what I am afraid I would have to flatten it to if I wanted to reach an F3 of ~30hz. The red is my ultra-optimism that I won't blow the voicecoil.
Here's the sealed configuration:View attachment 1205687
I was doing the usual paint-by-numbers sealed enclosure with EQ. I run into an excursion problem, and my first thought is "Can't I get a lot more power handling by throwing a port in there tuned to driver Fs?" Surely the displacement should be massive and solve the excursion problem! So I kept going with this monstrosity that may never fit together, EQ'ing the medium box flat to 30hz. Then I thought I could do better if I ignore the power handling aspect. So here's the three problems with three dumb questions:
1: Can I ignore power handling requirements if the port is moving the air, not the driver? Similarly, does the driver still use the power even though it doesn't move? I imagine it does to reverberate air, not itself.
2: Is the impedance an issue outside of amplifier selection? It hits 3ohm across most of the sub-bass spectrum.
3: Will everything explode in this configuration?
In very stupid terms, I have colored the driver into the lines. The dark blue fits into that light blue shape at 200W, the excursion is just barely passing xmax, and the vent velocity is manageable if I ignore that we only live in three dimensions. The following represents worst case.
View attachment 1205671
View attachment 1205669View attachment 1205672View attachment 1205673View attachment 1205668
The original sealed box was limited to 95dB SPL. Boosting, cutting, and preamping until the response was flat with EQ. Hence the hair-brained idea. The light blue vs dark blue lines highlighting my completely unfounded theory on porting. Both are maximums, the lighter line is following the natural rolloff, the darker line is what I am afraid I would have to flatten it to if I wanted to reach an F3 of ~30hz. The red is my ultra-optimism that I won't blow the voicecoil.
Here's the sealed configuration:View attachment 1205687
Believe the thermal rating is around 70 watts.
So, I wouldn't expect linear to be anywhere near thermal rating.
Sometimes speakers are what they are.
You use a QB3 or SBB4 alignment
and call it a day.
Ports are not self powered of course.
The speaker provides the energy.
At full port resonance the cone moves little.
So that is were the classic transient or accuracy is
very little with reflex.
Little movement but still powered by the speaker.
Impedance curve will show you the load.
Just learned over time not to overthink.
The sim gives you a good idea of the mechanical
properties and what a good volume is for around
.7 to .8 box Q then your all done.
Tune at Fs or slightly below.
That is what the speaker does.
High pass will help with big dynamics
when going loud.
So, I wouldn't expect linear to be anywhere near thermal rating.
Sometimes speakers are what they are.
You use a QB3 or SBB4 alignment
and call it a day.
Ports are not self powered of course.
The speaker provides the energy.
At full port resonance the cone moves little.
So that is were the classic transient or accuracy is
very little with reflex.
Little movement but still powered by the speaker.
Impedance curve will show you the load.
Just learned over time not to overthink.
The sim gives you a good idea of the mechanical
properties and what a good volume is for around
.7 to .8 box Q then your all done.
Tune at Fs or slightly below.
That is what the speaker does.
High pass will help with big dynamics
when going loud.