Omni 15 TB -

High power and fidelity from an easy to build cabinet.
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trebulor
Posts: 2
Joined: Wed Feb 28, 2018 1:51 pm
Location: Sweden

Omni 15 TB -

#1 Post by trebulor » Mon Mar 05, 2018 3:43 pm

Hi everyone,

Just recently got the plans for the Omni 15 Tallboy, looking forward to building this cabinet as it will be my first ever DIY speaker project. I'm planning building it with the recommended drivers:
Eminence Kappalite 3015LF
Eminence Alpha-6C - 4 Ohm
Eminence APT150V2

My plan is to mainly use this as a mobile PA speaker running off battery power, which I believe it should handle quite well from what I've read, especially seeing as it's designed to be quite sensitive.
I'm a little bit lost though on what kind of amplifier I should go with. I will most likely at some point in the future build a second cabinet, so an amp with at least two channels is a no-brainer. Reading posts by other users on the forum and by Bill himself, it was said that 50W should provide plenty of SPL for a party and 100W might even be loud enough for the cops to show up :cop: :D
Am I correct to assume then that a 2x250W Class D amplifier should be enough to power this? Amp in question: https://www.ebay.com/itm/Sure-Electroni ... SwVgZZsSN4
Note: It is very unlikely that a guitar will ever be used with this.

After doing research on forums more focused on battery powered systems, a lot of people seem to be using amplifiers from Sure electronics as the one linked above, sometimes together with a miniDSP and other times using Pioneer car amps with built in active crossovers. This brings me to two other questions I have. Since I'm planning on mostly using this on battery power, do I have anything to gain by using an active crossover instead of the passive one (Either by buying an amp with one built in or by using a miniDSP device) or am I better off just following the instructions and building the passive crossover and then using an amplifier that has enough power per channel to drive this?

Thanks in advance!
/Sebastian

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Bill Fitzmaurice
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Re: Omni 15 TB -

#2 Post by Bill Fitzmaurice » Mon Mar 05, 2018 4:53 pm

Why a 4 ohm mid? There's nothing to be gained with an active crossover.

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Tom Smit
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Location: Sarnia, Ont. Canada

Re: Omni 15 TB -

#3 Post by Tom Smit » Tue Mar 06, 2018 1:18 am

Will you be able to provide 60-70 volts with your batteries? That is how much is needed for that amp.
TomS

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bitSmasher
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Location: Sydney, Aus.

Re: Omni 15 TB -

#4 Post by bitSmasher » Tue Mar 06, 2018 1:26 am

The quick and easy way to drive this would be a class D car amp, just a basic stereo model - possibly look for one that can be bridged.
Mono amp might be useful, but many are designed for sub only so have low pass filtering built in around 500hz
Using the gain control on amp you could run a phone/mp3 player straight in to it.
Maybe some mild high pass filtering, ie 60hz, would be useful to increase battery life (bass needs power!)
I use Pioneer GM-Dxxxx amps for portable sound, Alpine PDX is a premium option and there are others out there too...
Where are you located?

Oh and finally, Sure amps are pretty efficient but take a lot more DIY work to get right

trebulor
Posts: 2
Joined: Wed Feb 28, 2018 1:51 pm
Location: Sweden

Re: Omni 15 TB -

#5 Post by trebulor » Tue Mar 06, 2018 1:21 pm

Bill Fitzmaurice wrote:
Mon Mar 05, 2018 4:53 pm
Why a 4 ohm mid? There's nothing to be gained with an active crossover.
Think I stared myself blind at the model name in the instructions and chose the one called 6C. They only have one more Eminence Alpha called 6A, which is an 8 ohm driver, but the specs of that one is way off from the 6CBMRA you recommend. For e.g, the frequency range goes from 85Hz - 6kHz instead of 400Hz - 5kHz and the Fs is way lower at 118Hz instead of 407Hz. So I'm guessing that this model out of the question for this build.

Luckily I was able to find another European retailer that has the correct 6CBMRA model , so I'll order it from them instead. Thanks for pointing that out!

Ok
Tom Smit wrote:
Tue Mar 06, 2018 1:18 am
Will you be able to provide 60-70 volts with your batteries? That is how much is needed for that amp.
Probably not without a boost converter, which is what I've seen others do when running these Sure amps of batteries. As long as the boost converter is efficient and can handle enough power it should be OK. Will do some more research to determine the pros and cons from just using an amp that is rated for lower voltages (Like the Pioneer car amps bitSmasher proposed) compared to the Sure amps. Thanks for your input Tom!

bitSmasher wrote:
Tue Mar 06, 2018 1:26 am
The quick and easy way to drive this would be a class D car amp, just a basic stereo model - possibly look for one that can be bridged.
Mono amp might be useful, but many are designed for sub only so have low pass filtering built in around 500hz
Using the gain control on amp you could run a phone/mp3 player straight in to it.
Maybe some mild high pass filtering, ie 60hz, would be useful to increase battery life (bass needs power!)
I use Pioneer GM-Dxxxx amps for portable sound, Alpine PDX is a premium option and there are others out there too...
Where are you located?

Oh and finally, Sure amps are pretty efficient but take a lot more DIY work to get right
Ok,thanks for all the advice! I'm located in Sweden :)

That's great, I was first considering a preamp of some sorts or a simple portable mixer/dj controller to help with the potential low gain coming from a phone (and to avoid someone plugging in a phone that is cranked up to full volume). The idea is to build a separate box for the battery + amp with mounted RCA connectors for ease of use. I'm guessing adding too much electronics inside the cabinet should be avoided, especially if it starts taking up too much volume which might affect the acoustics. (Or am I overthinking that part?)

Yes that sounds reasonable, I guess I can fine tune this depending on the situation to find a sweet spot between bass performance and battery life. I'm most likely also going to add a mains connected 12V power supply for use when there's power available, in these cases I would probably turn the filter off for some more bass!

Sweet, I've seen those Pioneer car amps being used a lot on a Danish forum that focuses on boomboxes/portable festival speakers,(https://www.festivalanlaeg.dk) even seen some builds there with BFM speakers . Which model are you using for your portable setups? Been looking at the GM-D8604 (https://www.pioneerelectronics.com/PUSA ... -D8604#faq) which looks promising, 4 channels and is bridgeable at 2x300W @4ohm.

Although, after reading the sticky regarding bridging (viewtopic.php?f=10&p=208276#p208276) I'm unsure whether bridging the amp is something I should do or not , what's your thoughts on this? Am I better off finding an amp that has enough power without bridging?

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