Karaoke Forums

Hi guys.

I have a QSC 2450 and i want it to hook up to 2 pairs of speakers. what's the best way to do it? Should i do bi wire or bi amp?

First Pair.

http://www.mdesignlife.com/productPage.asp?pin=2243

I don't know how many watts to how many OHM these are.

2nd Pair.

http://www.klipsch.com/na-en/products/k ... fications/

I don't know those speakers, but my gut is that they may not be at all designed for the dynamics of live singing. Many people have blown some very nice (and expensive) speakers by trying to make PA speakers out of them.

I am sure the speaker geeks will be along shortly to confirm or deny.

The Klipsch speakers are 400 watts RMS @ 8 ohms.

I couldn't find specs on the Centa 7200s anywhere, but I did find a reference on the Monster site that recommended on of their amps for those speakers, and it was 250 watts RMS @ 4 ohms.

I personally would never use home theater speakers for live vocals, especially high-end stuff like this. Also, I wouldn't go messing with running speakers with differing resistance (OHMS) in parallel.

You asked a million questions about PA speakers, and said you had a $2000.00 budget. Why are you talking about home theater speakers all of the sudden? You can make a really good home karaoke system for around $1200.00 complete with EVERYTHING you need, and if I remember right, you already have most of the stuff already. Spend a little money on some decent powered speakers and you'll be the envy of home karaoke on your block. I think you are overthinking this, or at least not listening to the hundreds of responces for advise from your other postings!! Just pick one and go with it. 90% of the people on this board are going to give you good advice, even if it is different one to the other!!!

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C Mc
KJ, FL

I have these 2 pairs of speakers for a long time now. These were my initial speakers. They're sitting in my room for movies. I haven't tested them out on my Karaoke rig yet. I was just curious if they would do good for singing.

Using home speakers as PA speakers is like pulling a large trailer with a Honda civic. You can do it, but eventually something bad is going to happen.

I'd just called monster cable and they said the Stream Line 7200 speakers runs 200 Watts @ 4 Ohms.

ya, i am still contemplating that. I got these used 1k for the both pairs. They're excellent Home theater speakers.

Can i hook up a pair of 200w @4ohm speakers with a pair 200 Watts @8 Ohm? What will that create? 2 Ohms or 4 ohms?

The simple answer here is don't connect both sets of speakers in parallel to that amplifier, the likelihood of damage to the speakers and even your amplifier is quite high. To connect speakers with varying impedances and power handling capabilities in parallel requires a great deal of understanding in terms of electrical theory, power amplification and speaker dynamics. The design process required to successfully pull that off is so complex that most audio engineers will simply tell you to not do it.

Given your lack of experience and knowledge in this field, that would be my advice to you as well, don't do it.

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DJ Tony
Let It Rip Karaoke

Let it Rip,


I can't hook these up to 1 Amp? i'll have to hook them up to two separate amps?

To run speakers in parallel, use the following equation..

1 / R = 1 / Ra + 1 / Rb

Where R is your total impedance (what your amp sees), and Ra and Rb are the impedance of the two different speakers.

Substitute your speakers in, and you'll get

1 / R = 1 / 4 + 1 / 8

Making R = 8/3 or 2.667Ω

(Bet you wish you'd paid attention in math or physics class now).

Also need to make sure the amp is 2 ohm stable. I'm not recommending that you do it, it will probably sound terrible, as the 4 ohm speaker will get more of the voltage, but there's the theory to show what effect it will have on the amp.

Your last paragraph is what's important here (besides the fact that his amp is not specified for a 2 ohm load). The 4 ohm speakers have a lower power handling than the 8 ohm set. So you really need to know how much voltage they're going to see if you run that amp into them. This is where things get really complex since nominal impedance becomes almost irrelevant, it's usually just not worth the effort.

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DJ Tony
Let It Rip Karaoke

The speakers are not going to be good for singing - you can try. However if you MUST connect them both, i'd put 2 of the same speaker on 1 channel & the other 2 on the other channel - not recommended, but most amps today can handle a mismatched load like that. However again, you are very concerned with whether the speakers will be good for singing, no these will most likely be worse than even the JBL or Yamaha speakers you had tested - and those are designed for singing and PA use, not home theater.

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

The speakers are not going to be good for singing - you can try. However if you MUST connect them both, i'd put 2 of the same speaker on 1 channel & the other 2 on the other channel - not recommended, but most amps today can handle a mismatched load like that. However again, you are very concerned with whether the speakers will be good for singing, no these will most likely be worse than even the JBL or Yamaha speakers you had tested - and those are designed for singing and PA use, not home theater.

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

OK, that makes me hit google (it was a lot of years ago)...... Yep, reactance - now that brings back memories. In a speaker, the impedance increases with the frequency. Crossovers, with their coils and capacitors screw it up even more.

Forget it and buy some PA speakers

Only problem with this Lon is that you'd end up with both of those 4 ohm cabs on a single channel in parallel on one channel. Not only is the amp not specified for 2 ohm operation, the increase in power delivery to those speakers would be catastrophic (unless i suppose you could turn the input sensitivity on that channel way down to reduce the output level, but that's really taking a chance).

** EDIT ** Whoops, thinking of the wrong amplifier, the RMX 2450 will handle a 2 ohm load, however it's also going to deliver 1200W into that channel. That's 3x the power handling spec for those speakers (2x200 = 400W). I'm thinking, really not a good plan, I see major speaker failure in his future.

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DJ Tony
Let It Rip Karaoke

I was just going on the premise that he's already got so many great speaker recommendations just to let him sink or swim and learn by trial & error.....sorry was in a mood this morning, was driving over the Grapevine.

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

It's not that i am not taking people's advice on speakers recommendations, but it's because i have these speakers for a while now and hasn't tested them out on the current rig. I was just wondering if it's possible to hook them up together. I don't think i'll be hooking these guys up for karaoke anymore since they're really nice home theater speakers and i don't want to ruin them.

Hooking up the 7200's in series with each other would present a 400 watt @ 8ohm load on a 500 watt @ 8ohm channel.

Whereas connecting the KLF-20's in parallel to each other would create an 800 watt @ 4ohm load on the other channel, rated for 950 watts @ 4 ohms.

Careful use/adjustments of the individual channels' gains should allow for non-selfdestructive sound

One concern I'd have with placing the 2 differently rated speakers on the same channel instead, is would they be reacting differently to the same gain being sent to them? Would increasing the volume enough for the 8ohm speaker over drive the 4ohm sharing the same channel; or conversely, would adjusting the volume for the 4ohm speaker leave the 8ohm too quiet?

This is SOOOOOO wrong I'm not even going to bother going through the specifics other than to say to the OP DON'T follow this advice.

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DJ Tony
Let It Rip Karaoke