Karaoke Forums

Hi folks,

I'm thinking about getting at least one sub for my setup. Is there some kind of formula of how many watt a sub should have, compared to the tops?

Positioning: Is there any recommendation about where to place a sub?

I'm running EV SX500+ speakers, 800 Watt continued Power.

Thanks!

As a general rule you want a sub to push at least equal-double (preferably double) what your tops are pushing.
As far as positioning, sub frequncies are non-directional so placement isn't as important as your main top cabs. Ideally if you can stick them under your tops is great, but you can stick one in a corner and it will be fine (as long as it isn't all the people hear).

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you are way under powering those speakers. if you put about 600 each to them they will thump plenty for almost any room thats not in a basement. with a small amount of eq work SX 500s will THUMP. I have run mine off of one side of a qsc rmx2450 and 2 single 18 EV driven subs off the other in a really large basement room and had more bass than I could use. I agree with Lonman that double the power in subs is better, but you already have cabs that will kick. crossover frequency will also change how much power your subs need. with the EVs you can set your crossover to 100hz or below and just use subs to make everything shake. IMHO you really don't need subs with those speakers in 90% of rooms that do karaoke.

another contributer to how much amp you need is what type of drivers you have. I have 4 identical 18" scoops. 2 have EV drivers, 2 have Peavey lowriders. it takes about 30% more power to make equal DB out of the peavey driven cabs. the Peaveys are rated for 1000w @8 ohm. the EVs are rated at like 400w @8 ohm. the EV is cleaner sounding and uses far less power. Im not really a fan of the peaveys , but they are less expensive. I bought the cabs with them in already. the dealings Ive had with JBL tell me that they draw about as much as the Peavey stuff, but do sound better. cab design also effects the Db output per watt. A scoop or "W" design can make more Db than a standard front load cab, but don't work as well in smaller rooms

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the voices arent real, but they have some good ideas

Thank you for your answers.

I run the Tops 775 Watts each, with a QSC PLX3602. That was by Forum and QSC recommendation.

Yes, they do have a lot of punch and sound great without sub, no question about that. The reason, why I'm considering a sub is: I read about Top/Sub PA's and I hear all the time, that if you use a sub and a crossover, the tops would even sound better, since they're only reproducing the mid and high range.

I'm just a sound fanatic.

So if I would get one Yorkville LS800PB it would be efficient (1500 Watt)? It says in the description, the LS800PB has a Mono Blend Input, which allows it to function in a stereo system by blending the two sources and creating a single in-phase mono subwoofer.

800 watts continuous is just about right for those speakers. EV's own manual recommends 800-1600 watts per speaker for maximum efficiency. Quote from their spec sheet:
1. To use the Sx500PI+ to full capacity, skilled
experts in sound-system installation and operation
will obtain the best results if the
power amplifier is 2.0 to 4.0 times the longterm
average noise- power rating of the
speaker system. For the Sx500PI+, this is
800 to 1,600 watts.
http://www.fullcompass.com/common/files ... 0specs.pdf

Now determining how skilled one is with their sound engineering may be another thing.

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LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

The York would be a good match. I would actually run the crossover point starting around 75hz (although it looks as though the York only goes as low as 90hz) & work from there. It could sound best anywhere from 75-120 depending on the room.
Ideally you would still want an external crossover so you can adjust your tops matched to the sub. If your top cabs aren't crossed over to match the sub, they will still be trying to reproduce some of the lower frequencies & could cause some phase cancellation in those frequencies.

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I read this as 800 to the pair = 400 each and under powered..775 is great

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the voices arent real, but they have some good ideas

So can anyone tell me, if it would be sufficient to buy 1 LS800PB and feed both Channels to it?

1 sub will be more than likely all you need, start off with one, if you decide you need more, you can always add another later. I have 1 sub going with 1500 watts pushing it & it's all I need.

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I own two of these rascals, they are great. I just did an outside gig the other day and even though I had them both set up I only turned one of them on and it did just fine all by itself. I doubt You will be disappointed in the LS800P. they are also not power hungry like some other powered subs out there. Just for test purposes I ran two LS800P's and two U15P's off from one 15 amp circuit and they worked fine. Please note It was only a test and I didn't run them full out. I was just curious of how friendly they may be if I get in a bind for electricity.

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Quickness of mind will deceive the eye

Thank you guys. I really appreciate. =)