BillFitzmaurice.info

Hey all! Been a long time lurker and I’ve finally decided to take the plunge into building my sound. The problem I have right now is that I can’t seem to wrap my head around amps, ohms and power ratings.



Just when I think I’ve got it understood, I read a bit more from various forums and then I have to start from scratch since I feel like I missed something.



For a bit of context: The sound for local shows here aren’t good. They are consistently under powered and distorted. No regards to tuning or speaker placement. 

Additionally, the sound needed for this genre is way more than what people give it credit for. The genre of choice is Drum & Bass (Think heavier techy, rolling, darker sounds I.e. Rizzle, Kasra, Noisia, Waeys, Halogenix, Klinical.)



The goal with this setup is to be able to expand over the course of a few years and the setting would be smaller venues, capable of fitting about 100-200 people. 



I’ve decided on: 



Two T48's, loaded with the 3015LF.



Two DR280's, loaded with the Deltalite 2512.



Here’s where I’m getting out of my league. I tried to watch videos and read up on amps and ohms, but I’m just getting frustrated.



For the T48s, I’d go with the Crown XLi 3500. At 8ohms, this should power both cabinets if I looked at everything correctly.



For the DR280s, I chose the Crown XLi 2500. 



The idea with both of these amps was that if I wanted to double my speaker count, the amps could handle it. Right?

Yeah, I’m lost because apparently, 8 ohms is nominal but you can run at 4 ohms. Now I’m just frustrated because it sounds like I could just use one amp for everything?



For other sound processing, I chose the UltraDrive DCX2496LE as my DSP. Then the Xenyx Q1204 for the main mixer.



Is this correct? Am I in over my head on this? I’m sure it’ll click at some point, but I just need a reality check.

Any help is appreciated. Thanks guys.

JayVacaro wrote: ↑Tue Oct 03, 2023 1:02 am Hey all! Been a long time lurker and I’ve finally decided to take the plunge into building my sound. The problem I have right now is that I can’t seem to wrap my head around amps, ohms and power ratings.



Just when I think I’ve got it understood, I read a bit more from various forums and then I have to start from scratch since I feel like I missed something.



For a bit of context: The sound for local shows here aren’t good. They are consistently under powered and distorted. No regards to tuning or speaker placement. 

Additionally, the sound needed for this genre is way more than what people give it credit for. The genre of choice is Drum & Bass (Think heavier techy, rolling, darker sounds I.e. Rizzle, Kasra, Noisia, Waeys, Halogenix, Klinical.)



The goal with this setup is to be able to expand over the course of a few years and the setting would be smaller venues, capable of fitting about 100-200 people. 



I’ve decided on: 



Two T48's, loaded with the 3015LF.



Two DR280's, loaded with the Deltalite 2512.



Here’s where I’m getting out of my league. I tried to watch videos and read up on amps and ohms, but I’m just getting frustrated.



For the T48s, I’d go with the Crown XLi 3500. At 8ohms, this should power both cabinets if I looked at everything correctly.



For the DR280s, I chose the Crown XLi 2500. 



The idea with both of these amps was that if I wanted to double my speaker count, the amps could handle it. Right?

Yeah, I’m lost because apparently, 8 ohms is nominal but you can run at 4 ohms. Now I’m just frustrated because it sounds like I could just use one amp for everything?



For other sound processing, I chose the UltraDrive DCX2496LE as my DSP. Then the Xenyx Q1204 for the main mixer.



Is this correct? Am I in over my head on this? I’m sure it’ll click at some point, but I just need a reality check.

Any help is appreciated. Thanks guys.

Hi Jay,
Welcome to the forum!
The reason(s) for distorted sound are many, but the 2 usual culprits in the genre you're looking at are;
The PA isn't up to the task.
The content from mixer through the chain to amps and cabs is being pushed so hard the resulting sound can be nothing but distorted.
eg if it was a DJ, they are above redline and into the clipping.

I know you want to think about amps and ohms and stuff right now, but don't for a second.

Concentrate on your builds first. You essentially have one shot at getting your choices right without having to rebuild if it doesn't work out.
My usual recommendation, for subs, is to find the lowest content in the type of songs you are likely to play (eg 30Hz) by loading the songs into Audacity. It has a content assessing function which you can google.
Then you make a choice based on what's required (or what you're prepared to miss out on), not what you think.
T48's will play that low, but you need a heap of them to do 30Hz with authority, because that figure is below the recommended cut off and only gets there due to roll off of the slope in the High pass.

To protect the drivers, high pass brick wall filters are used to prevent overexcursion and damage.
The DCX is one DSP unit that can do that, but Graphic EQ is not in the LE, only parametric I think. Same for RTA.
The DBX driverack does it all in one unit, so it's now my tool of choice for that purpose (I have 2 sets of the Behringer pair and 2 driveracks, so I have some experience with both).

Have you got help? If no, then the DR280 may be to big for one person to handle and stack comfortably.
Don't overlook the DR250 (the Flagship) is all I'm saying.

Back to the amps.
The 3015lf in a T48 is brick wall limited to 60 volts (volts are measurable, Watts have to be calculated which is impossible on the fly), but that equates to 450W/8ohms. but in order to not flog your amp to death, you need a bit more power per channel.

The 280's with a 2512 will be in the order of 40V max, and will distort before that value. Thats 200W at 8 ohms +some extra for comfort.

Amp choice basically means if you want to double your cab count, then you need 4 ohm stable amps. Without looking up the XLI specs I'm pretty sure they will be fine.
Be aware, outdoors, it's best to have subs to tops at a 2 to 1 ratio. You can use walls and corners indoors to help get free output, but that should come after builds too.

Hope this is enough to start and helps...