BillFitzmaurice.info

Hello all,
Im currently putting together a 12v system which will be mounted on a steel trailer and pulled by bicycle

The plan is to build a Cubo15 (in 15mm ply) housing a 18Sound 15" - https://en.toutlehautparleur.com/18-sou ... -inch.html

For the Mids+tops I want to build an omnitop 12 and place it on top of the sub with the battery behind it.
For the OT12 i will be using the recommended Eminence compression driver ASD1001
And a 4ohm Faital driver - as it is more compatible with the power i have available to amp it: https://faitalpro.com/en/products/LF_Lo ... =101050112

For the Sub i will power it with this
Pioneer GM-D9701 Mono Block @ 500watts RMS https://www.pioneer-car.eu/eur/products ... ifications
And for the OT12 I will use Pioneer GM-D8704 Class-D 1200w 4-Channel bridgeable amplifier - Allocating 1 set of channels bridged @300watts at 4ohms for the 8ohm compression driver and the remaining bridged channel @ another 300 watts RMS for the Faital 4Ohm 12".

My issue is with how to crossover for the OT12?
I thought i wanted to avoid a DSP because the system is going to be used by different people at different events, some of who may have limited knowledge so the fewer buttons and settings to change the better (and the less likely drivers get damaged). But i don't have the time or knowledge to build my own filters in time for this project . I gather i need a high pass at 2khz for the compression driver and that the 12" will require low passing at that and high passing around125Hz?

Firstly does this sound right ? And can anyone recommend me a way to achieve this ?
I am based in the Uk but the system will be built in France so any passive filters/crossovers or other recommendations would need to be available and affordable in either the uk or France.

Otherwise, if anyone can point out any flaws in this plan that'd also be much appreciated.

Many thanks,

Use the 8 ohm version of the driver. Then you don't have to change the crossover specs.

Build an OTop 15, forget about the Cubo. The OTop 15 goes just as low as the Cubo, and you won't need to bi-amp.

Bruce Weldy wrote: ↑Sat Jan 08, 2022 4:31 pm Use the 8 ohm version of the driver. Then you don't have to change the crossover specs.

thanks for the reply,
Will this not be underpowered by the amp channel I have available for it?

Bill Fitzmaurice wrote: ↑Sat Jan 08, 2022 4:48 pm Build an OTop 15, forget about the Cubo. The OTop 15 goes just as low as the Cubo, and you won't need to bi-amp.

Hadn't heard of this one, Ill look into it !

How do you mean no need to Bi-amp?
how would I best go about powering the 3 drivers in the OTOp 15 ?

I have already got these 2 amps to use:
Pioneer GM-D9701 Mono Block @ 500watts RMS at 4ohms
and Pioneer GM-D8704 Class-D 1200w 4-Channel bridgeable amplifier - 4 x bridgeable channels 150watts rms @4Ohms each

Thanks again,

And roughly how much does the O1Top 15 ? weigh?

monekh wrote: ↑Sun Jan 09, 2022 1:54 pm

Bruce Weldy wrote: ↑Sat Jan 08, 2022 4:31 pm Use the 8 ohm version of the driver. Then you don't have to change the crossover specs.

thanks for the reply,
Will this not be underpowered by the amp channel I have available for it?

No, it doesn't work that way. Speakers see voltage, not watts. 40 volts at 8 ohms will measure 200 Watts. 40 Volts at 4 ohms will measure 400 Watts. But either speaker at 40 volts will produce the same volume. The 8 ohm version of the driver you specified will be just as loud, but you won't have to try to change the passive crossover that's in the plans.

And yes, a Jack 15 would most likely give you what you want in a single cab with less expense.

monekh wrote: ↑Sun Jan 09, 2022 2:06 pm How do you mean no need to Bi-amp?
how would I best go about powering the 3 drivers in the OTOp 15 ?

I have already got these 2 amps to use:
Pioneer GM-D9701 Mono Block @ 500watts RMS at 4ohms
and Pioneer GM-D8704 Class-D 1200w 4-Channel bridgeable amplifier - 4 x bridgeable channels 150watts rms @4Ohms each

Thanks again,

The OTop cabs and Jacks have only 2 frequency ranges the highs and the mids(lows). Depending on the configuration, it might have 1 or 2 compression drivers, but since they produce the same frequency range - it's just a two way box.

The same is true for the Jack 15. The Jack 15 will go lower than the OTops. Use the OTops with a sub - the Jacks without.

monekh wrote: ↑Sun Jan 09, 2022 2:15 pm And roughly how much does the O1Top 15 ? weigh?

My suggestion is to use the Jack 15, not the OTop15 if you are just using a single cab.

Bruce Weldy wrote: ↑Sun Jan 09, 2022 3:17 pm My suggestion is to use the Jack 15, not the OTop15 if you are just using a single cab.

Normally I'd agree, but in this case the higher sensitivity of the OTop 15 within its pass band is a better choice than the lower extension with less sensitivity of the Jack 15. Between the battery power and no boundary reinforcement he needs sensitivity more than extension. OTOH either is a better choice than what he proposed.

thanks again for both your replies.

Forgive my ignorance but does this mean that if i was to be building a OT12 i may as well be using the much cheaper eminence driver : Eminence BETA 12 8ohm? I had hunted down the Faital 12" as a (painfully) expensive replacement because i thought the 8ohms at 250watt would be a problem with the power I had available.

Bruce Weldy wrote: ↑Sun Jan 09, 2022 3:12 pm

monekh wrote: ↑Sun Jan 09, 2022 1:54 pm

Bruce Weldy wrote: ↑Sat Jan 08, 2022 4:31 pm Use the 8 ohm version of the driver. Then you don't have to change the crossover specs.

thanks for the reply,
Will this not be underpowered by the amp channel I have available for it?

No, it doesn't work that way. Speakers see voltage, not watts. 40 volts at 8 ohms will measure 200 Watts. 40 Volts at 4 ohms will measure 400 Watts. But either speaker at 40 volts will produce the same volume. The 8 ohm version of the driver you specified will be just as loud, but you won't have to try to change the passive crossover that's in the plans.

And yes, a Jack 15 would most likely give you what you want in a single cab with less expense.

Bill Fitzmaurice wrote: ↑Sun Jan 09, 2022 3:36 pm

Bruce Weldy wrote: ↑Sun Jan 09, 2022 3:17 pm My suggestion is to use the Jack 15, not the OTop15 if you are just using a single cab.

Normally I'd agree, but in this case the higher sensitivity of the OTop 15 within its pass band is a better choice than the lower extension with less sensitivity of the Jack 15. Between the battery power and no boundary reinforcement he needs sensitivity more than extension. OTOH either is a better choice than what he proposed.

Ive already ordered this 15". https://en.toutlehautparleur.com/18-sou ... -inch.html
would it be compatible with the OTop15?

monekh wrote: ↑Sun Jan 09, 2022 6:28 pmIve already ordered this 15". https://en.toutlehautparleur.com/18-sou ... -inch.html
would it be compatible with the OTop15?

Before you order anything you need to figure out what you're gonna build. I know you already had a plan and now it may be changing, but get all your ducks in a row first. If Bill says the OT15 is your best choice, then I'd go with that. Now you need to order plans and read them till you know every step by heart (j/k). Then read through the build threads on here to gain even further knowledge of the design. I won't say what you have will work or not, but Bill's designs have some leniency to them and after reading through build threads, you'll find a pattern with the choice of materials.

monekh wrote: ↑Sun Jan 09, 2022 6:28 pm Ive already ordered this 15". https://en.toutlehautparleur.com/18-sou ... -inch.html
would it be compatible with the OTop15?

It is.