Karaoke Forums

I have the opportunity to pick up an older model Carvin Sub, model RL118 for 90 bucks. Seems like a pretty good deal to me. Don't really need it, but it's one of those deals that I don't want to pass up. It's supposed to work just fine, but I have a question on the amp. I use a Behringer EP2500 amp now for my 2 Behringer B1800 subs now, running stereo into the 2 subs now. I believe that it is in 8 ohm mode if I am not mistaken. The Carvin is a 4 ohm load, and there is only one of them. If I run the amp in bridged mono mode, that will put 2400 watts into that sub. The sub is only rated at 800 watts. Is this too much amp for that sub? or is there a better way to configure the amp to match the Carvin? The amp manual isn't really very clear on what I should do. But it does show using the EP1500 for 1 sub instead. Suggestions are welcome. Thanks.

Scott

Oh, by the way, in case you are wondering I want to pick up this sub, simple. It's because I wanna. haha Actually I want to add 2 more subs eventually for a different application, but this is just a good deal. I will be adding more amps later when finances allow.

The Behinger EP2500 is going to put out 650 watts/channel at 4 ohms.

The Carvin RL118 Sub handles 800 watts PEAK at 4 ohms, so it is 400 watts continuous @ 4ohms.

650 watt amp into a 400 watt speaker is pushing the limits.

If you are the kind of KJ that constantly rides the faders and maintains a balanced system that NEVER bumps much above 0 dB on the meter, then you can probably keep the mismatch under control.

HOWEVER, if you are the kind of KJ who boosts low frequencies to push out juuuust a little more bass, and you don't know how to sonically balanced a system, then you are going to blow the drivers in the sub by pushing it with that amp.

That is a great deal on the sub. Maybe find a amp that you can bridge to drive 400 watts into that sub. You should be able to get something in that range for $100-150 second hand.

_________________
C Mc
KJ, FL

Running it in Bridged Mono would not be a good plan. Way too much power for that speaker. You could try to manage the situation by keeping the input sensitivity low but that's not the best plan. The better approach, as Topher kind of alludes to, would be to leave the amp in stereo and only use one channel of it. Keep the input sensitivity turned down on the channel you're not using. That would actually be a pretty good match of Amp to Speaker at that point.

_________________
DJ Tony
Let It Rip Karaoke

Thank Topher for the quick response. Yeah, I think it's a pretty good deal for the sub for sure. As far as what type of KJ I am, yeah, I can honestly say that I DO "bump" things once in awhile. I don't however turn up the bass a whole lot, but I still do it a little. That's why I asked. I think your numbers are off on the EP2500 a bit, but I still had a feeling that it would be too much amp for one sub. My eventual goal is to have 4 subs, ran by 2 Carvin amps (models of amps is still uncertain tho, depends on what subs I can find). If the amps I have now are too much for that sub, I can just let the sub sit around until needed at a later date when I get the matching amps for it (or them, if I'm lucky).

Again, thanks for the input.

I took the Behringer EP2500 numbers directly from their spec sheet. Your amp puts out 650 watts/channel @ 4 ohms at full frequency range:

http://www.behringer.com/EN/downloads/p ... 3_S_EN.pdf

Be careful, these budget companies often overstate their specs in advertising, so it is best to check the official documentation for the "real" numbers.

_________________
C Mc
KJ, FL

Topher, I see where you got it, I am looking at the PDF manual now. 650 watts is correct if using both sides in 4 ohm.. I was looking at bridged mono in 4 ohm at 2400 watts. If I use both sides of the amp as active, then yes, 650 watts. Maybe that is what I actually want to do and just turn one side totally down. Thoughts?

Yup, you DEFINITELY only want to use one side, and even at that, you are still overdriving the sub. See Letitrip's response, he had it right on. You probably want to turn the attenuator on the one side you DO use to about 3 o'clock and be careful to avoid the temptation to boost the bass on your mixer.

_________________
C Mc
KJ, FL

Honestly, turning the attenuators down wouldn't be an issue, they are already at about 1 o'clock. I don't turn them up much farther than that at all. I only run at about 60% most of the time, so as to not heat anything up at all, ever. Just don't want to run the risk of burning anything up if I can help it. When I do bump things up, all I do is turn up the input just a bit and call it good. Most of the time, the inputs from the laptop/players are only at about 40% on the sliders, when I bump them up they might get to about 75%, that's about all.

Suggestions for a better way? I'm all ears.

Do some research on Balancing a PA System. There are some good YouTube videos on this topic as well.

Assuming your speakers are properly matched to your amp, you should be able to run your amp wide open then balance the rest of the system from there (i.e., you wouldn't want to do this with the mismatched amp and sub we were talking about earlier).

Anyway, if you balance the whole system to where everything is inputting/outputting 0 db pre fader, then you will get maximum efficiency out of each component and have the highest quality sound your system is capable of. Basically, you'll optimize everything so that you'll get the same perceived volume at lower energy levels. Every component in your audio chain will work less to create the same output, and the net result is that your amp will be able to produce higher highs and lower lows, so more of those "subtluties" of the music that are often lost. The biggest benefit of a balanced system to karaoke is that when your system is using LESS energy to produce the same perceived volume, then your crowd will find themselves being able to hear the music clearly but still be able to talk AND because there is less energy, that is less energy that can find its way into a feedback loop, so less feedback.

I learned how to balance my system about 4 years ago on advise from this forum, and I think it makes all the difference in the world. HOWEVER, you need to understand the concept, not just follow someone's directions, or else you are not going to be able to keep your system in balance during the changing dynamics of your show, so I urge you to RESEARCH and understand the concept yourself instead of asking for a play by play list.

_________________
C Mc
KJ, FL

Thanks for the input and the suggestions. I will definitely so some research on that. And thanks to both of you for your brain power!!

Curious.
With sound from subs being omni present...
Why run them in stereo?

Oooh Jerry, you're opening a whole 'nother can of worms there. I've seen discussions on pro-audio boards go to 400 posts or more with people arguing this subject. In the end, most subs that we would be dealing with in the venues we work there would be no difference between detectable difference between stereo and mono.

Now when you get into larger venues and using Sub arrays, the whole discussion changes but that's not something I even want to start getting into here.

_________________
DJ Tony
Let It Rip Karaoke