Amp reccomendations? (2) 30" T39 with Delta12LF

[jska]

Hi all,

I've always used powered speakers, so I'm new to the amp/crossover/eq/limiter/rta game.

I'll be picking up a pair of 30" T39's with Delta 12LF drivers, and am looking for an optimal amp to power them with. To my understanding they handle 500W @ 8ohms. I also understand that the BFM cabs are highly efficient.

What sort of power rating should I be looking at from an amp to power these?

I want to upgrade the drivers to 3012LF's in the future, so I want the amp to be suitable for those too. I may build an additional set of (2) 30" T39's down the road, too.

Also -- I'm a bit confused on how to wire the speakers properly. When I think of unpowered subs, I immediately think I should be running them in bridged mono, but I suspect I'm wrong here. I'll be coupling the two T39's and wall or corner loading them.

I'll be pairing the T39's with powered QSC KW153 tops for the time being, as they are all I have. I'll be looking into building BFM tops in the future.

Aside from purchasing an amp, I'll be looking into a Driverack PA, or a crossover and limiter. Sound good?

If there's a good forum post or article online that will sum a lot of this information up for me, please link.

Thanks everyone, wonderful community you have here, and I'm excited to begin a relationship with BFM loudspeakers!

[Bruce Weldy]

To my understanding they handle 500W @ 8ohms.

As per the plans:

The Delta 12LF has a higher rated voice coil, but it’s also displacement limited to 35 volts.

While you should run the subs in mono, that doesn't necessarily mean bridged. If your amp puts out the required power, you should run in stereo parallel. With the Delta 12LF limited to only 35 volts, that equates to 153 watts. I would suggest getting an amp that can handle about 500 watts per side at 8 ohms should you upgrade to the 3012LF.

The driverack is an excellent device to crossover, EQ, and limit.....among other things.

[BrentEvans]

Peavey IPR3000. I have one on a T30/D12LF and it pounds hard. It will also provide enough voltage to do a 3012 loaded cab.

[Bill Fitzmaurice]

To my understanding they handle 500W @ 8ohms.

That's a thermal rating, which is meaningless. D12LF is displacement limited to 35 volts, which is roughly 150 watts. Anything more will not give additional output.

[Gregory East]

At this point you may be thinking you bought a pup. Not so, 150W of BFM sub is louder than 500W of direct radiator.

I don't have a link for you but if you search on setting limiter and crossover you will find lots of good info.

[jska]

To my understanding they handle 500W @ 8ohms.

As per the plans:

The Delta 12LF has a higher rated voice coil, but it’s also displacement limited to 35 volts.

While you should run the subs in mono, that doesn't necessarily mean bridged. If your amp puts out the required power, you should run in stereo parallel. With the Delta 12LF limited to only 35 volts, that equates to 153 watts. I would suggest getting an amp that can handle about 500 watts per side at 8 ohms should you upgrade to the 3012LF.

The driverack is an excellent device to crossover, EQ, and limit.....among other things.

Ah! Stereo parallel. Knew I was missing something.

So... if I'm running two of these 8 ohm cabs in parallel, my load is now 4 ohms, right? Shouldn't I then be looking for an amp that handles 500 watts per side at 4 ohms?

Or... I'm interpreting this wrong, and in stereo parallel, the amp just sends the same signal to each channel. So my setup would be Amp channel A >>> Cab 1, and Amp Channel B >>>> Cab2.

[jska]

To my understanding they handle 500W @ 8ohms.

That's a thermal rating, which is meaningless. D12LF is displacement limited to 35 volts, which is roughly 150 watts. Anything more will not give additional output.

Right on, so that means... (VxV)/R = W

And upgrading to the 3012LF's, I should stick to a 50 volt max. So (50x50) / 8 = 312.5, and my amp should provide ~double the maximum amount handled by the driver? In this case, an amp producing around 500W per side at 8ohms would be ideal, per Bruces recommendation.

Thanks Bill.

[jska]

At this point you may be thinking you bought a pup. Not so, 150W of BFM sub is louder than 500W of direct radiator.

I don't have a link for you but if you search on setting limiter and crossover you will find lots of good info.

I definitely know I didn't buy pup(s)! These two 30" T39's will happily replace my limping JBL JRX118SP.

I bought the plans for the T30, because a good amount of the prerecorded music I play has a lot of sound sitting right around 30hz, but I couldn't pass up the smoking deal on the T39's! I'll just have to build two more 30" T39's, and load them all with 3012LFs, and I think I'll have all the low end I need.

[Bruce Weldy]

To my understanding they handle 500W @ 8ohms.

That's a thermal rating, which is meaningless. D12LF is displacement limited to 35 volts, which is roughly 150 watts. Anything more will not give additional output.

Right on, so that means... (VxV)/R = W

And upgrading to the 3012LF's, I should stick to a 50 volt max. So (50x50) / 8 = 312.5, and my amp should provide ~double the maximum amount handled by the driver? In this case, an amp producing around 500W per side at 8ohms would be ideal, per Bruces recommendation.

Thanks Bill.

The 3012LF can take take the full 60 volts in a T39. That's 450 watts. So, to run two per side - you need an amp that will run 900-1000 watts at 4 ohms.

[jska]

The 3012LF can take take the full 60 volts in a T39. That's 450 watts. So, to run two per side - you need an amp that will run 900-1000 watts at 4 ohms.

I'll only be running (2) T39's total (v-plated, wall loaded), not two per side, however this is good information to plan for an additional two cabinets in the future.

[Melissa Goudeseune]

The 3012LF can take take the full 60 volts in a T39. That's 450 watts. So, to run two per side - you need an amp that will run 900-1000 watts at 4 ohms.

I'm just finishing up a T39, and that sounded off, so I checked the plans:

The displacement limited voltage for the BP102 and Delta 12 LF is 35 volts. The 3012LF and Lab 12 limit is 50 volts. The 12NLW 9300 limit is 60 volts.

I wouldn't want to see someone toast a 3012LF for want of 10 extra volts .

[Bruce Weldy]

The displacement limited voltage for the BP102 and Delta 12 LF is 35 volts. The 3012LF and Lab 12 limit is 50 volts. The 12NLW 9300 limit is 60 volts.

I wouldn't want to see someone toast a 3012LF for want of 10 extra volts .

My plans say 60 volts for the 3012LF.

The 3012LF power rating and displacement limited power in the T39 is 450 watts, so a 60 volt signal is the maximum allowable; running 10 volts lower will give a higher margin of protection,

I haven't seen the new T39 plans, maybe they've changed.

[Melissa Goudeseune]

My plans say 60 volts for the 3012LF.

The 3012LF power rating and displacement limited power in the T39 is 450 watts, so a 60 volt signal is the maximum allowable; running 10 volts lower will give a higher margin of protection,

I haven't seen the new T39 plans, maybe they've changed.

Right you are... the plans have changed. I quoted from the November 2011 plans. Your spec is from the release before that, if I'm not mistaken.

As far as general usage though, if the 10 volts difference from 50 to 60 is really needed, then it's probably a better idea to build two more cabs.

[jska]

Found a good deal on a Driverack PX and a QSX PLX3402 (700W Stereo @ 8Ohms).

So for now, I'll be pairing the (2) 30" T39 with Delta12LF's with the above setup, running the amp in parallel mode.

I need some advice on setting limiters. The Driverack PX works by setting the threshold of signal level (between -40 to 20dbu) where the limiter kicks in. If I want to make sure that no more than 35 volts go to the drivers (limit of the 12LF's), how do I know where to set the limiter on the Driverack? I don't have a volt meter, but can probably borrow one if it is essential.

Thanks for all the help everyone. Can't wait to get these subs rockin', safely.

[DJPhatman]

Found a good deal on a Driverack PX and a QSX PLX3402 (700W Stereo @ 8Ohms).

So for now, I'll be pairing the (2) 30" T39 with Delta12LF's with the above setup, running the amp in parallel mode.

I need some advice on setting limiters. The Driverack PX works by setting the threshold of signal level (between -40 to 20dbu) where the limiter kicks in. If I want to make sure that no more than 35 volts go to the drivers (limit of the 12LF's), how do I know where to set the limiter on the Driverack? I don't have a volt meter, but can probably borrow one if it is essential.

Thanks for all the help everyone. Can't wait to get these subs rockin', safely.

Get a good quality digital VOM. It's worth it's weight in gold.