DIY Vertical 312

[ThisBass]

I wish we could get out of this fussing match.

You are right.

Yet its interesting to talk about the meaning of plots and graphs that are provided by cab modellings.

All of those plots and graphs are based on pure sine sweeps. In real world practice we do have not only one harmonic at just the same time.
In real world we do have a broad set of harmonics simultaneously that are additionally accompanied by transient noise (that is caused due to dynmaical events).
In practice this means, once an amplifier does push out full power, all of the power is distributed to a broad set of harmonics simultaneously and also to broad transient noise.
In real practice an amplifier will rarely, if ever, push all of its full power to only one harmonic, such as it may look alike for modelling plots and graphs

If I was interested to build a 212 bass guitar cab with extended low end and plenty of mechanical power handling, I might think Kappalite 3012LF was a good way to go down the road.

net volume ~4.5 cu ft
Fb ~46 Hz
F3 ~46 Hz

I'd choose two rounded 4" ports with ~2.5" of length.

1st port resonance ~1360Hz

If the woofers are running full range than the woofers might produce unwanted port resonance artefacts.
At the other hand side the good relationship of length vers diameter helps to effectively damp/supress the emerge of port resonance.
Furthermore, if the design was a two way design with woofer LPF crossover at roughly ~800Hz the port resonance consideration was anyway out of concerne.
Just to optimize things a little bit I'd try to align the ports narrow to a bootom corner of the baffle, or one at bottom and the other one narrow to a top corner.

Air vent velocity consideration

I hope you agree that an 900 Watts rms amplifier will rarely distribute 900 watts below ~55Hz and beyond ~55Hz simultaneously. In total this "fictitious" power was equal to 1.800 Watts
It can be suggested that the distributed power below ~55Hz does not exceed 1/2 of full amplifier power.
1/2 of amplifier power distributed to the bandwidth below ~55Hz, simultaneously the second half distributed to the bandwidth above ~55Hz.

The issue of too highish air vent velocity is gone!


Another but different consideration:
If I was trying to use the same cab size and same driver as a design for application as sub.
Bandwidth of use ~40..100Hz
I'd try to enlarge the port area dimension a little bit cause all of amplifier power was distributed to a quite narrow bandwidth that equals roughly one octave.
Larger port length doesn't matter anymore cause port resonance was aligned way beyond the design/target of cab bandwidth response.

 

[swarfrat]

This also includes things like thicker wood (1-1/2” thick was cooler than cool), ridiculous dimensions, etc,

I have been mullling over using 1/8" plywood skins / foam core - both for weight and price of plywood. Being stupid thick though is actually a drawback imo - it complicates joinery. I'm sure it's been done, but I've not seen a lot of it yet.

 

[agedhorse]

I have been mullling over using 1/8" plywood skins / foam core - both for weight and price of plywood. Being stupid thick though is actually a drawback imo - it complicates joinery. I'm sure it's been done, but I've not seen a lot of it yet.

Yes, and it’s hard to bond to, hard to make secure joints, and tends to grow in dimensions without an increase in Vb which might otherwise be a benefit.

 

[swarfrat]

I actually think the current crop of vertical 210's could stand for a bit more baffle width - stability, aesthetics (the PF-500 will hang off the sides of the SVT210AV - which is actually one of the things keeping me from buying that cabinet), and maybe even help with baffle step.

 

[6thplanet]

These speculation threads are such a buzz kill. I really hope this leads to a build of some sort.

 

[NKBassman]

speculation

You spelled "design" wrong.

 

[ThisBass]

I actually think the current crop of vertical 210's could stand for a bit more baffle width - stability, aesthetics (the PF-500 will hang off the sides of the SVT210AV - which is actually one of the things keeping me from buying that cabinet), and maybe even help with baffle step.

Vertical 210's could also be build/designed with a shape similar like a double T-trap profile.
(just joking a little bit)

 

[6thplanet]

You spelled "design" wrong.

I can "design" a bucket to hold water, pure speculation till it does.

 

[5StringPocket]

You are right.

Yet its interesting to talk about the meaning of plots and graphs that are provided by cab modellings.

All of those plots and graphs are based on pure sine sweeps. In real world practice we do have not only one harmonic at just the same time.
In real world we do have a broad set of harmonics simultaneously that are additionally accompanied by transient noise (that is caused due to dynmaical events).
In practice this means, once an amplifier does push out full power, all of the power is distributed to a broad set of harmonics simultaneously and also to broad transient noise.
In real practice an amplifier will rarely, if ever, push all of its full power to only one harmonic, such as it may look alike for modelling plots and graphs

If I was interested to build a 212 bass guitar cab with extended low end and plenty of mechanical power handling, I might think Kappalite 3012LF was a good way to go down the road.

net volume ~4.5 cu ft
Fb ~46 Hz
F3 ~46 Hz

I'd choose two rounded 4" ports with ~2.5" of length.

1st port resonance ~1360Hz

If the woofers are running full range than the woofers might produce unwanted port resonance artefacts.
At the other hand side the good relationship of length vers diameter helps to effectively damp/supress the emerge of port resonance.
Furthermore, if the design was a two way design with woofer LPF crossover at roughly ~800Hz the port resonance consideration was anyway out of concerne.
Just to optimize things a little bit I'd try to align the ports narrow to a bootom corner of the baffle, or one at bottom and the other one narrow to a top corner.

Air vent velocity consideration
View attachment 4778319

I hope you agree that an 900 Watts rms amplifier will rarely distribute 900 watts below ~55Hz and beyond ~55Hz simultaneously. In total this "fictitious" power was equal to 1.800 Watts
It can be suggested that the distributed power below ~55Hz does not exceed 1/2 of full amplifier power.
1/2 of amplifier power distributed to the bandwidth below ~55Hz, simultaneously the second half distributed to the bandwidth above ~55Hz.

View attachment 4778323

The issue of too highish air vent velocity is gone!


Another but different consideration:
If I was trying to use the same cab size and same driver as a design for application as sub.
Bandwidth of use ~40..100Hz
I'd try to enlarge the port area dimension a little bit cause all of amplifier power was distributed to a quite narrow bandwidth that equals roughly one octave.
Larger port length doesn't matter anymore cause port resonance was aligned way beyond the design/target of cab bandwidth response.

You bring up some good points. Agreed that an amplified bass signal is spread over a series of harmonics so the fundamental probably wouldn’t get more than 40-50% of the power. This reduces the design limits for excursion limited max and port size/velocity.

The KL3012LF works well in the application you described. I think the Greenboy fEarful design is pretty close to this. Ports located at both bottom and top provide more convective cooling which keeps the drivers cooler.

I’ve built with KL3012LF, KL3012HO, and KL3012CX drivers and prefer the CX which has both a stout low end like the LF and the more extended response of the HO. It also has a well-behaved full-range frequency response and only requires a 3.5kHz high pass and LPad for the coaxial HF driver which sounds quite smooth. I have a 1.81 cu-ft 112 with a KL3012CX and ASD-1001 which only weighs 29.6 lbs and has a really solid sound. It’s a keeper.

 

[agedhorse]

The whole cooling premise is about 95% fluff. Thermocouple measurements debunk this myth pretty good.

 

[5StringPocket]

The whole cooling premise is about 95% fluff. Thermocouple measurements debunk this myth pretty good.

Good to know, marketing makes it sound legit.

 

[agedhorse]

Good to know, marketing makes it sound legit.

That's their job!

 

[5StringPocket]

That's their job!

Mythbusters on the job - used to love that show…

 

[5StringPocket]

These speculation threads are such a buzz kill. I really hope this leads to a build of some sort.

This is not just speculation. The intent of this thread was to make sure the concept was solid, optimize the design for the chosen drivers, and generate a construction drawing that could be used by anyone interested in building one for themselves. The construction drawing in Post #40 or #45 is at that point. I’d like to build one myself but don’t currently have the need or the place to put it without selling a couple of my existing cabs. Down the road, maybe…

 

[6thplanet]

I get that, but people could do this for every driver / configuration out there. The buzz kill is seeing pages of speculation as to what it might be without it ever actually being. No disrespect to you or anyone else that does this, I'd like to see it actually come to fruition is all.

 

[MarkA]

Not that I think @5StringPocket is obligated to build anything but, for what it's worth, I've followed similar threads he's done that have culminated in his building the cab(s) under discussion, playing them, and giving his impressions on the end result. (You might find his co-ax 212 or 115 builds interesting.)

Because of that, I figured that the same would happen with this thread -- and, sure, I'd be curious to read about how it turned out in real life -- I absolutely get that sentiment -- but I don't consider myself owed that for having read it. Nor do I think there's any harm in bouncing design ideas off of some other knowledgable posters. Meanwhile, the design is there if you -- or, by some miracle, I -- want to build it and see for ourselves.

I do think that anyone who builds this should post their efforts or a link to them in this thread.

 

[MarkA]

Off-topic, but your screen name, @6thplanet, made me think of this:

 

[3rdcurve]

The KL3012LF works well in the application you described. I think the Greenboy fEarful design is pretty close to this. Ports located at both bottom and top provide more convective cooling which keeps the drivers cooler.

I’ve built with KL3012LF, KL3012HO, and KL3012CX drivers and prefer the CX which has both a stout low end like the LF and the more extended response of the HO. It also has a well-behaved full-range frequency response and only requires a 3.5kHz high pass and LPad for the coaxial HF driver which sounds quite smooth. I have a 1.81 cu-ft 112 with a KL3012CX and ASD-1001 which only weighs 29.6 lbs and has a really solid sound. It’s a keeper.

Is there any reason the KL3012CX wouldn’t work for this project?

 

[6thplanet]

Off-topic, but your screen name, @6thplanet, made me think of this:

Ha! Yeah, I have that album.

 

[5StringPocket]

Is there any reason the KL3012CX wouldn’t work for this project?

It could but the cab should be 1/2” deeper to give 1.8 cu-ft/driver and the KL3012CX weighs 7.3 lbs vs 6.1 lbs for the 12PR320. The coax woofer response only extends to 3.5 kHz and either needs an HF driver mounted or an adapter plate with a plug.

IMO, the KL3012CX which handles 400 watts is a top notch driver which works best in a 112 or 212. In a 212, the upper one has a HF driver and 3.5 kHz high pass while the lower one has the rear mounting hole plugged.

The 12PR320 was chosen for this 312 because of its light weight and extended frequency response to 5.0 kHz. It would probably have enough treble extension on its own for many players who don’t care for tweeters and would prefer the reduced cost and weight of a woofer-only build. This driver only handles 300 watts which wouldn’t be as substantial in a 4-ohm 212 build. A 900 watt 2.67-ohm cab wouldn’t be limiting and could make good use of a high powered amp. The 12PR320 was the best fit I could find for a premium 312 cab of reasonable size and weight. I bet it would slam with my Berg Forte HP which could drive it to full power.