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Custom Rig Build with Pro Audio Speakers

#41
The whole point to these designs are cost, ease of construction and performance at a compromise. These can be built by the average joe using basic construction methods. The cost of some of the currently available 2x12 is ridiculous. These can be built for a couple hundred bucks. I understand better can be built but for most of my work these do very well and if I beat them up I'm not worried about it.
 
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#42
Here are my 2 cents.
The designs of onamission are IMO a great basis for a 112 or 212 with a hard-to-beat price performance ratio. Btw. I would choose the Dayton PA310 over any Eminence 12" in that price range and probably even those twice as expensive. (you may also want to check this thread for the Dayton PA310 DIY 110 & 112 cabs - light, loud, & cheap - inspired by the Duke)
If you want to use either design and you want it to be able to really handle 400 watts (or 800watts for the 212) mechanically I would reduce the internal volume to 1.8 cu ft (or 3.6 for the 212) and tune the port(s) to 50hz. This will make sure the driver can handle 400 watts from 45hz and up before it exceeds xmax (5mm), see also my post #23. The tuning will be low enough for it to project a low B with authority.

Below is the (mechanical) powerhandling of the Dayton PA310 in a 2.5 cu ft enclosure tuned to 41hz. As you can see there's a powerdip around 55-60hz. Compare this to the graph in post #23.

Dayton PA310 69ltr 41hz.png
 
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#43
Arjank said:
Here are my 2 cents.
The designs of onamission are IMO a great basis for a 112 or 212 with a hard-to-beat price performance ratio. Btw. I would choose the Dayton PA310 over any Eminence 12" in that price range and probably even those twice as expensive. (you may also want to check this thread for the Dayton PA310 DIY 110 & 112 cabs - light, loud, & cheap - inspired by the Duke)
If you want to use either design and you want it to be able to really handle 400 watts (or 800watts for the 212) mechanically I would reduce the internal volume to 1.8 cu ft (or 3.6 for the 212) and tune the port(s) to 50hz. This will make sure the driver can handle 400 watts from 45hz and up before it exceeds xmax (5mm), see also my post #23. The tuning will be low enough for it to project a low B with authority.

Below is the (mechanical) powerhandling of the Dayton PA310 in a 2.5 cu ft enclosure tuned to 41hz. As you can see there's a powerdip around 55-60hz. Compare this to the graph in post #23.

View attachment 3111135
Click to expand...

When I have some time I'll change the cabinet depth to allow for 1.8/3.6Cuft. Thanks for the analysis, I really appreciate it!
 
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#44
onamission said:
When I have some time I'll change the cabinet depth to allow for 1.8/3.6Cuft. Thanks for the analysis, I really appreciate it!
Click to expand...

Would you then reduce the internal depth to 11.7" (pretty sure I did my algebra correctly), or are there other things to consider with this change? Would the depth of the ports remain the same? Would the reduced depth create balance issues (easy to tip over), or could I simply set the front panel with the speakers back 1.8", keeping the external dimensions the same?
 
#45
I ran Boxnotes on the 1x12, which gathers bracing, speaker and Port tunnels to come up with a more accurate cabinet volume.

Boxnotes report for project: default
--------------------------------------------------------------------------------------------

Finished size 20.5 inches wide 16 inches high 18in deep - Panel thickness .75in - Single Front Panel

Internal Volume: 1.94 cu.ft Working Vol 1.7 cu.ft Tune 47hz

Component volumes: Ports = .04 cu.ft Bracing = .1 cu.ft Driver = .08 cu.ft Total = .23 cu.ft
 
#46
onamission said:
I ran Boxnotes on the 1x12, which gathers bracing, speaker and Port tunnels to come up with a more accurate cabinet volume.

Boxnotes report for project: default
--------------------------------------------------------------------------------------------

Finished size 20.5 inches wide 16 inches high 18in deep - Panel thickness .75in - Single Front Panel

Internal Volume: 1.94 cu.ft Working Vol 1.7 cu.ft Tune 47hz

Component volumes: Ports = .04 cu.ft Bracing = .1 cu.ft Driver = .08 cu.ft Total = .23 cu.ft
Click to expand...

I can see where making linear assumtions can lead to problems: I'll wait for an update to see how the proportions work out on a 2x12. Thanks for taking the time to nudge me into a sensible path!
 
#47
D.A.R.K. said:
Agreed- I just see this automatic response of "high pass" all the time, without any real specifics. The Fdeck unit is well liked, but only a 12 db per octave cut with no alignment specified. It really is going to depend on what your port tuning is, coupled with what frequencies you will be feeding the cab and the amount of power you will be using. For sub tuned instruments you may want to go as far as a 48db per octave slope around the port tuning frequency. It takes some experimentation based on the specs to get it right, especially if you are using heavy handed eq to bring forth those sub tunings.
Click to expand...

I have a separate thread on this topic, but what device might you use to achieve this kind of control. I too see lots of people really happy with fdeck and Broughton, but the slopes on these (and practically all devices I've seen) are identical at 12db/oct. One suggestion I've heard is putting two filters in series, which would double the slope at wherever the two filters have the same frequency.

For example, the HPF-Pre 3 has a 12db/oct at a selected freq, then another 12db/oct at <35Hz, = 24db/oct <35Hz. Two in series would then (presumably) double each of these values if the freq on each unit is the same, or create a series of "knees" for a progressive slope, ending in 48db/oct <35Hz.

Or is this simply a rabbit hole...?
 
#48
Reuptake said:
I have a separate thread on this topic, but what device might you use to achieve this kind of control. I too see lots of people really happy with fdeck and Broughton, but the slopes on these (and practically all devices I've seen) are identical at 12db/oct. One suggestion I've heard is putting two filters in series, which would double the slope at wherever the two filters have the same frequency.

For example, the HPF-Pre 3 has a 12db/oct at a selected freq, then another 12db/oct at <35Hz, = 24db/oct <35Hz. Two in series would then (presumably) double each of these values if the freq on each unit is the same, or create a series of "knees" for a progressive slope, ending in 48db/oct <35Hz.

Or is this simply a rabbit hole...?
Click to expand...

The calculations are not this simple.

Cascading 2 HP filters of equal slope and frequency will result in the effective -3dB filter point to shift upwards by maybe 1/3 of an octave or higher. The more you cascade, the higher the effective frequency would become. This is accounted for in cascaded filter math.
 
#49
Corrected volume for the 2x12

Boxnotes report for project: default
--------------------------------------------------------------------------------------------

Finished size 28 inches wide 21.5 inches high 18in deep - Panel thickness .75in - Single Front Panel

Internal Volume: 3.88 cu.ft Working Vol 3.49 cu.ft Tune 46.5hz

Component volumes: Ports = .08 cu.ft Bracing = .12 cu.ft Driver = .17 cu.ft Total = .38 cu.ft
 

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