Originally Posted by Max Green
I have seen some Jamo XLN 25i's for sale for $80.
Long term: 150W
Short term: 250W
Impedance: 4-8 ohms
Would that be a decent PA-type speaker paired with my Yamaha RX630RDS?
Time to throw a few things you must understand about speakers. First of all, how many watts it handles does not mean high output. The way to make a speaker higher in efficiency is to increase the size of the radiating surface and keep the cone and voice coil as light in weight as possible--more weight requires more force to move it.
The reason PA speakers, theater speakers and stadium speakers are so !#1!!! loud is they follow those principles--AND they can handle a ton of power. They also use compression drivers, horns, waveguides and every trick in the book to boost efficiency. There are trade offs with all speaker designs, you can give up efficiency in the deep bass response to boost efficiency is common, you'll see giant 18" bass bins that will break your drywall but only go down to 40Hz or so--by design. I can get an 8" subwoofer that goes deeper in bass than a 100 pound 18" PA bass bin easily, although the little 8 incher will go deeper in bass than the giant 18" monster--it can't provide any real high volume output.
Moving to the math part, run a few numbers at you. For a basic party in the basement, a good number to shoot for is 120dB at one meter. Back in the day of dorm parties, I had a pair of 15" 3-way speakers that were rated to do 122dB at one meter at 200 watts RMS. Generally speaking, my amplifier would be bumping along with the 10 to 80 watt lights on the meters for power. The speakers were rated 100dB one watt/one meter--do the math! 10 watts is +10dB of gain and 80 watts is +19dB of gain--add the gain to the efficiency of 100dB at one watt = 110dB to 119dB at one meter.
For this reason, my general concept is my systems should be able to hit around 120dB at one meter to be viable for rockstar/dance party/hell raising mode. It is a general number, you can go less if you don't need rockstar levels of output, are in a small room inside or go higher if attempting to have a block party in the backyard--just a rough number.
You are using an AVR--they are designed to provide peak power for movies which they do very well. A very good tool for that job but--you are pushing it beyond it's design. Dance music is very compressed so the AVR will be loaded down with a very high signal level with very little time to cool down the output transistors. PA amps use plenty of power transistors, larger heatsinks, limiters to prevent clipping and fans to monitor the temperatures inside the box. Throw a dance tune with a heavy bass line in, the PA amp will increase the fan speed to keep itself cool and operating in range. AVRs don't have a fan so will shut down the party with thermal overload protection (you hope!)
Now comes fun with math! OK, say you want 120dB at one meter for rockstar mode. Your Yamaha has 75 watts so convert it to dB gain or basically +19dB of gain. Subtract that +19dB of gain and you'll need speakers that output 101dB at one watt/one meter to get rockstar mode. Say you want to run the AVR at half power max--or 3dB of "headroom" to prevent overheating the thing--then you'll need speakers that produce 104dB at one watt/one meter.
How many consumer audio speakers produce 104dB at one watt/one meter? Well, a Klipschorn would do it--very pretty speaker with a few square meters of very nice wood veneer. Square METERS? Yeah, they are HUGE speakers as 3-way fully horn loaded speakers are. Cost?
There are other boutique companies out there that also build very high efficiency, fully horn loaded systems for folks that use 5 to 20 watt tube amps--and you don't want to know the size and cost.
To give you an idea, back in the day I had a pair of PA speakers rated to go down to 45Hz, were 103dB one watt/one meter and quickly introduced me to the members of local law enforcement from a basic 65 watt per channel Onkyo receiver. The downside was they weighed 157 pounds each, stood 4 feet tall and had more carpet than the entire cast of the musical Hair.
Back to what you have, basically you won't get rockstar mode with your size/cost/aethestics restraints--but what can you get? Well, I would go down to the local music store and look at PA speakers that sound good but require subs/bass bins. The Mackie C200 is a 10" two-way that has really good sound quality and run here in the colonies around $160 to $199 each. They pump out around 95dB one watt/one meter, have post mounts for wall mounting and weigh less than 30 pounds. Measure out those speakers and amble on down to your used speaker store and purchase the cheapest speakers you can find working or not that are larger than those Mackies (or whatever you choose) Drag them home, cut out the front bezel of the speakers and gut the box of drivers/crossovers etc. Use the rear input terminal and you can put a SpeakOn connector or whatever connection is on the back of the PA speaker. Get insulation, carpet padding or whatever and pack it behind/beside/top and bottom of the PA speaker and secure the speaker from the handles to the inside of the donor speaker. Take the stock grill and place over the PA speaker face and viola! You have a pretty speaker with a PA speaker inside that can't be seen.
The next issue is subwoofers--to get high output and deep response out of them requires a lot of air movement--speakers are air pumps. The same rules apply but are more extreme, you can get away with just keeping adding more subs until you get the SPL you require. Works in America!
The least expensive way to do that and to make sure you don't let the magic smoke out is by using basic 18" powered PA "subwoofers" (more of a bass bin) Get a pair of those, raise the crossover on the Yamaha as high as it will go (120 to 200Hz) to take the bass load off the AVR and let the PA sub amps handle that.
Another lower cost way is to build your own bass bins using reasonably priced 18" PA drivers. This requires you know how to build boxes properly, understand how ported speakers work and can properly setup the PA amp to power them properly AND protect them from frequencies they can't do. Not as easy as you think but plenty of information at the DIY section of thise forum. That is a very deep rabbit hole though--if you decide to go that way because you want to learn how all this works, like the idea of custom building boxes that fit into your room or want to stealth them to look like end tables...a good option but you have to go all in.
To give you an idea of "how loud is loud" go to a THX certified theater and watch an action movie. Might get an app for your phone to read dB to become familiar with those numbers in real time. Say you decide that you want your party system to do exactly that, then things get interesting.
Here is a rough approximation of what it would take to do that in your room, with your AVR and at distances that you choose. If you like the THX reference level, put 105dB down as desired loudness level and whatever distance you are from the speakers. Since you will be using two speakers, put down 2 for speaker number and so on. The program will give you a rough idea of what you need.
If it was me, I'd scan the for sale places for PA speakers, get their specs and go for powered PA subs in party mode. Costs more that way, they are larger but even 20 years from now it is always good to have a pair of PA speakers--they rock in garage sound systems.
Enjoy the spl calculator--it will quickly answer basic questions for most speakers as long as the efficiency ratings are accurate. Good luck.