Omni 12 2-10?...yup.

[Tim A]

Mark, you may want to recheck your numbers. The internal size of an O12Tb is 14 x 33 x 19.

[Mark Coward]

Mark, you may want to recheck your numbers. The internal size of an O12Tb is 14 x 33 x 19.

I gave the external measurements, the internal measurements are 25" x 22" x 16" = 8800.

TB internal measurements are 33" x 19" x 14" = 8778. I mainly wanted the same 17" x 23" footprint, it worked out so close to 25" internal height that I rounded up. I don't think that 22 cubic inches will make much difference. I will have to incorporate a "false wall" like the O15 "Lowboy" which will take up more room than that.

[MYork]

You do such nice work! Would one of these be a viable alternative to the OmniTB15 subs? Mark

[Bill Fitzmaurice]

Would one of these be a viable alternative to the OmniTB15 subs?

Not even close.

[Tim A]

You do such nice work! Would one of these be a viable alternative to the OmniTB15 subs? Mark

Thanks!

This is a case of trading off some volume for a smaller size. For my use it doesn't matter, it's plenty. But you can only ask it to do so much!

[T_Mueller]

Hello there.
First time posting!
This thread has been interesting. I notice that there are very view threads or comments about the 012. Most people talk about the o15TB. The size of the 012TB is perefect for what I am looking for. My question is this...is the 210 option just for "sub" use or can this be built into the full range 012?
Thanks

[Tim A]

Full range too! Options are in the plans.

[bgavin]

The 2x10 option has the 4-ohm drawback, which is only a problem if you use more than one cab. This design is not intended for this anyway. As long as your amp can tolerate a 4 ohm load, it will be fine.

Bass extension and loudness are better with 2x10 instead of the single 12. Add another 3dB to the response plot below 500 Hz, and you will see it smooths out the lower end. The 2x10 adds +6 pounds to the box weight, over the single 12.

[LelandCrooks]

BP102 is available in 4 and 8ohm configuration. You can have either a 4 ohm or 8 ohm cab.

[bgavin]

Do *NOT* do a series-wired pair of 4-ohm drivers. This will severely cut the response off your system by underpowering the pair in relation to the mid-horn.

[Bill Fitzmaurice]

Do *NOT* do a series-wired pair of 4-ohm drivers. This will severely cut the response off your system by underpowering the pair in relation to the mid-horn.

Say what? The result would be the same as with the standard 8 ohm twelve, but would have the advantage of the higher Sd of the two tens.

[bgavin]

Yeah, at 1/2 voltage per driver.

You apply a given voltage to the cab, say 28v (100w). In a series pair, only 14v is applied per driver, while 28v is applied to the mid-horn.

Delta 12LFa sensitivity is 94.6.
BP102-4 sensitivity is 90.5

You gain +3dB from the doubled cone area, and lose -3dB from half-power in the series circuit. The net SPL result is a wash compared to a single driver. Since the 12LF is +4dB more sensitive than BP102, the pair of BP102 in series is a net loss of -4dB at the same voltage.

[Bill Fitzmaurice]

Since the 12LF is +4dB more sensitive than BP102, the pair of BP102 in series is a net loss of -4dB at the same voltage.

I don't have one to measure, but it doesn't model that way. According to McBean 2.83v sensitivity of two 4 ohm BP102 in series versus one Delta 12 LF is similar.

[bgavin]

This is a series driver circuit that is proveable by measurement.
Let's do the math.

Given:
The Eminence data sheets show aggregate SPL levels of 94.6 and 90.5 for the 12LF and BP102-4, respectively.
These values are somewhat unkind to the BP102, so let's restrict our area of interest to the linear 100 ~ 200 Hz range.
This frequency is above the range influenced by the vented cabinet.

From the Eminence data sheets
Delta 12LF
2.83v = 1.0w = 95 SPL at 150 Hz

BP102-4
2.00v = 1.0w = 93 SPL at 150 Hz
2.83v = 2.0w = 96 SPL
1.41v = 0.5w = 90 SPL

Doubling cone area adds +3dB acoustic efficiency
A series circuit is a voltage divider, where each of the pair sees half voltage

Applying 2.83v to the O12 box:
BP102-4 (parallel pair):
99 SPL = 96 + 3; Each Driver at 2.83v + Double Cone Area for pair

BP102-4 (series pair):
93 SPL = 90 + 3; Each Driver at 1.4v + Double Cone Area for pair


BP102-4 pair compared to Delta 12LF at 150 Hz:
-2dB for series pair
+4dB for parallel pair

Using Bill's charts, the Delta 12LF at 150 Hz is already -8dB compared to the mid-horn at 500 Hz.
A series pair of BP102-4 would make this -10dB, which is worse.
A parallel pair of BP102-4 would be -4dB to the mid-horn, which is much flatter response.

The BP102-4 pair has the extra benefit of increased Vd over Delta 12LF.
This makes the 2x10 parallel the ideal solution if one can accept a 4-ohm load.

[Randall Dibble]

What would happen if I USED A Stereo Power amp and dedicate one channel to each speaker with either a 4 or 8 ohms speakers??