Step By Step: One Guy’s Path To Building A Pro Audio Rig

[Sydney]

One approach to a 1 man PA rig

http://www.prosoundweb.com/article/step_by_step_one_guys_path_to_building_a_pro_audio_rig/P1/

[Brian Steele]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

I like those 3x12 subwoofers. I wonder what SPL they are really capable of though, particularly if they are capable of output down to the mid 30's as the author suggests.

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Max SPL is rated @127 dB per cab. They're also rated to go down to 35 Hz. That guy ran 2 cabs per side, meaning 12 12 in subs for bass. That's got my curiosity peaked.... Found cabs @ http://www.hkel.com/speaker2.html. I like the quick set up and tear down too.

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

I just modeled a speaker with 3 Dayton 12 inchers for kicks. The subs he had are approx 8.25 cu ft, so using that sized cabinet (tuned to 40 Hz), you can get approx 125 dB @ 50 Hz & 118 dB at 35 Hz. The only downside is that even though the speakers are rated to handle 1350 watts, with that configuration you can only push 750 watts into it before you hit Xmax. Still, that's pretty impressive.

[Brian Steele]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

I just modeled a speaker with 3 Dayton 12 inchers for kicks. The subs he had are approx 8.25 cu ft, so using that sized cabinet (tuned to 40 Hz), you can get approx 125 dB @ 50 Hz & 118 dB at 35 Hz. The only downside is that even though the speakers are rated to handle 1350 watts, with that configuration you can only push 750 watts into it before you hit Xmax. Still, that's pretty impressive.

How did you determine the net volume of the subwoofer boxes? I'd estimated it to be a bit less, somewhere just north of 6 cu.ft, once the volume of the drivers and the vents was taken into consideration.

Then there's the issue of venting a cabinet that small with vent that suitably-sized to give you 35 Hz (-6dB as claimed) and not suffer from compression effects at higher volumes. Note that the subwoofer unit is rated at 93dB/1W/1M (they gave the sensitivity as 96dB, and it's a 4-ohm system), which is pretty low by pro-audio standards. Using 4 of them helps I guess .

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

The original cabinet measures 49H X 16.5W X 23.5D external, so I adjusted it to 47.5H X 15W X 20D for wood thickness and baffle inset. I also modeled it with (4) 4 in diameter ports. I believe BassBox 6 set them up to be 4.6 in long.

[Brian Steele]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

The original cabinet measures 49H X 16.5W X 23.5D external, so I adjusted it to 47.5H X 15W X 20D for wood thickness and baffle inset. I also modeled it with (4) 4 in diameter ports. I believe BassBox 6 set them up to be 4.6 in long.

Did you take into account that it's a trapezoid cabinet? That should reduce the calculated volume significantly when compared to a simple rectangular one.

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Actually, I just went off the manufacturer's published measurements. You have a very valid point on the trapezoidal shape. Next time I get the opportunity, I will see what BassBox will ask for in cu ft. I smell a small project in the making...

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Well, just got home from work and decided to give it a second go at modeling that cabinet. Using BassBox's suggestion for the cabinet size vs dimensions given I came up with needing a cabinet that is 6.657 cu ft. It still looks like it could deliver some good SPL (128 dB @ 50 Hz). To keep the excursion below Xmax, you now need to keep it to below 650 watts. I still used 4 vents that should be 5.76 in long for this configuration. The dimensions could be easily finagled to make it a trapezoidal shape. The only concern is the amp needed to drive it being it is a 2 ohm load, or have 2 cabinets per side like the gentleman in the article for a 1300 watt, 4 ohm load. At that point, it models 131 dB @ 50 Hz.

[Sydney]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Hadn't really examined the cabs in detail - Until the discussion arose:
Frankly the author set criteria and made a decision to buy them that I wouldn't have: I would insist on hearing them extensively first.

[Brian Steele]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Well, just got home from work and decided to give it a second go at modeling that cabinet. Using BassBox's suggestion for the cabinet size vs dimensions given I came up with needing a cabinet that is 6.657 cu ft. It still looks like it could deliver some good SPL (128 dB @ 50 Hz). To keep the excursion below Xmax, you now need to keep it to below 650 watts. I still used 4 vents that should be 5.76 in long for this configuration. The dimensions could be easily finagled to make it a trapezoidal shape. The only concern is the amp needed to drive it being it is a 2 ohm load, or have 2 cabinets per side like the gentleman in the article for a 1300 watt, 4 ohm load. At that point, it models 131 dB @ 50 Hz.


[ATTACH=CONFIG]48077[/ATTACH] [ATTACH=CONFIG]48078[/ATTACH]

The model looks good.

But it doesn't go down to 35 Hz as claimed by the manufacturer at least not in the +/- 3dB claimed window .

A possible driver candidate may be something like the Dayton Audio Series II driver- http://www.parts-express.com/dayton-...oofer--295-120. I did some quick calcs with it though, and three of them I na 6.5 cu.ft. vented cabinet will top out around 124dB. Not too bad, but not 127dB either...

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Much better choice in woofers. I did not consider that woofer as it was not in the pro section.
This cabinet is 6.87 cu ft with 3 4 in ports. It models out at 119.1 dB @ 30 Hz, 123 dB @ 40 Hz, & 124 dB @ 50 Hz. It can also take the full power to the woofers without overexcursion.

[Sydney]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Some things noted:

All of the drivers are Eminence, meaning re-cone parts are easy to find, which was a good thing,

( Once had a band manager cancel a contract that proposed using Eminence drivers )

Couldn't find 12's from their standard inventory that matched the advertised specs ( post #3 )
( Dubious of the accuracy/legitimacy :rolleyes: )

The system has been in constant operation for more than three years now, and I’ve only managed to burn up one of the 12-inch drivers in a main. (At an outdoor gig for a motorcycle rally.)

Considering that the 01V96 has compressors - in all likelihood that burn up could have been avoided:
A friend's system ran for over 8 years for crowds of up to 10,000 with ZERO driver failures.

[Brian Steele]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Interesting. I came up with something slightly different in HornResp. See what your s/w has to say about this alignment using a trio of ST305s wired in parallel - 195 litres tuned to 39 Hz with a 506.7 cm^2 vent that's 38 cm long (which I'd implement this as two separate bifurcated shelf vents to add some rigidity to the box).

Note: HornResp suggests that the response above 180 Hz can be smoothed and the impact of "organ-pipe" resonances from the vent minimized by front-loading the box with a planar horn that's 11 cm long (with the vents terminating at the end of the horn), but that does make the box a bit bigger.

[kblackmore]

Re: Step By Step: One Guy’s Path To Building A Pro Audio Rig

Here is the drawing per the specs you specified. I told the program how deep you wanted the (rectangular) ports and the frequency you wanted to tune it to. I let the program decide the height X width.