Axiom Home Page Forums General Discussion Home Theater I think i'm going to go all out

Well Ive finally gotten a real job, and what better way to spend that money than on home theater stuff eh?
Anyway, I have a Harmon Kardon 330 receiver and was thinking of getting a sweet axiom setup. Mostly the epic 80 home theater : http://www.axiomaudio.com/epic80_350main.html
without the sub. (I have an SVS). I was wondering that since the center (vp 150) and the rears (qs8's) are both 6 ohms, and the fronts (M80 ti's) are 4 ohms, would this just kill my reciever? I mean it has a protection mode and a fan so I'm not that worried about it, but would it even sound decent? Or should I shop for an amp? (I dont know much about amps.) I mean the min power on all these Axiom speakers is very little, but since my receiver does 55w per channel(20-20k) in 8 ohms, does that mean it does 1/2 of that in 6 ohms or 1/4 of that in 4 ohms?

Related question: would the M80ti's be too much for a medium sized room? Or would they rock even more?

Extra related question: All amps do is increase the power right? The sound processing is still handled in the receiver? The cords just go : receiver - amp - speakers right?

Thanks in advance everybody.

Welcome to the forum GafofskikofskiYou do have a shorter name we can call you right.

Anyway, if you had your setup in an unusually large room and liked to crank it high you might experience a shutdown. But in a medium sized room like yours the Hk will deliver the goods with the 4ohm m80's along with the vp150 and qs8's. No problem there. Axiom themselves recommend denon and hk to drive the m80's.

If you would like to save a little coin and have a similar sound the m60's will rock hard too.

What are the dimensions of your room anyhow? That way we can recommend you down the right path.

Later, Mike.

Yes Gaf, welcome. I agree that unless your room is huge(you imply medium)and you listen at a deafening(literally)level, your 330 should be fine. Theoretically an amplifier would put out twice the power into 4 ohms compared to its 8 ohm rating, but almost none do that and maybe 50% more would be a fair average

If your last question refers to adding a separate amp, then yes, it just supplies power(which may not be an increase if the receiver amps were already enough)while the processing is all done in that section of the receiver, bypassing its internal amplifiers.

Welcome aboard. Can we call you G-ski ?

Another vote for "330 will be fine".

Regarding room size, the only thing to watch out for is making sure you leave enough space to place the speakers properly and not have everything crowded together. If you're running the M80s full-range (ie "large") they like to be a couple of feet from the wall in many rooms to get the smoothest bass response so you *might* end up with the fronts of the speakers 4 feet from the wall behind them. You probably don't want the seating position squeezed right up against the back wall either so think about exactly where everything is going to go.

I imagine if you run the M80s in "small" mode this wouldn't be as much of an issue but not 100% sure. Some people go with M60s because placement is a bit less of an issue -- they're a couple of inches shallower (15 vs. 17 inches) and don't put out quite as much low bass so they can usually go a bit closer to the wall.

If you think you're going to be tight for space you might want to think about 60s, otherwise the 80s will be fantastic.

Wiring with an external amp is just like you said -- the receiver pre(amp)-out signals are wired to the power amp inputs, so you bypass the power amp in the receiver but still use all of the other circuitry (inputs, processing, pre-amp, volume & tone controls etc..) from the receiver.

Ok, thanks alot everybody, I feel better now. I was looking at amps and could'nt believe the prices on some of those! My room is about 14x20 and I usually listen to movies at a reasonable volume (probably around 105 db at the loudest parts). What do you think about running the M80 speaker size at? Large would be more stressful on the receiver obiviosly, and that puts no cutoff on the sound too right? So should I probably put the on small and cross them over around 50-60hz? or lower?

BTW, my current setup is a bit of mix and match if anyone is curious
HK 330
Center: Klipsch synergy C-2
Fronts: Axiom M22ti
Rear: older optimus bookshelf(really looking foward to this upgrade)
Sub: SVS PCi 25-31

I run my M60s in "large" for music (with <40 Hz also going to sub) and "small" for movies (crossed over at 80 Hz).

I guess if I really wanted to crank the music I might run in "small" for that as well but large seems to be fine. I'm running an HK 630 with M60s, which I think will be pretty darned close to your HK 330 with M80s (less power, but more efficient speakers). Just make sure your receiver can get good airflow, ie it doesn't have a shelf or other equipment right above it.

Running in "small" but crossing over at 60 Hz is probably a real good compromise and doesn't require anywhere near as much fiddling with the bass management settings.

Ok now I'm confused, I thought 4 ohm speakers were less efficient?

M80s are more efficient in the sense that for the same 1 watt of power coming in the M80 is rated to generate a 95dB SPL in a typical room vs. 93 dB SPL for an M60.

Efficiency is really independent of impedence, but the fact that the M80 is a 4 ohm speaker gets you even more sound out of the same receiver -- up to a point.

Power amps are normally limited by the voltage level of their power supplies, ie they can only generate a certain voltage swing before they start to clip. When you turn up the gain, you turn up the voltage, until you hit the limit the amp was designed for. The current depends on the speaker impedence -- a 4 ohm speaker draws 2x the current than an 8 ohm speaker at the same voltage, so it's getting twice the power at the same volume control level.

Twice the power => 3 dB more output (someone check me on this please). Added to the 2 dB higher efficiency and at the same volume control setting the M80 is going to be ~5 dB louder than the M60.

You can't say "my amp puts out 100W at 8 ohms so it must put out 200W at 4 ohms" because a typical amp starts to run into current limits (or overheats, or whatever) before you reach 200W BUT until you hit those limits you are getting twice the power for any particular volume control setting.

Note that there is nothing "magic" about 8 ohm impedence, it's just the closest thing we have to a standard so most companies design their products around it. Different subsets of the audio industry run with different standards -- eg. headphones tend to be higher impedence because they do NOT want to consume the same power as your speakers at any given volume control setting or your ears would implode. Subwoofer drivers are often <4 ohms to let you crank even more power from a given amp. I think the EP500 driver is <2 ohms.

JB

Ok, all cleared up. Thanks alot guys! Now I have another question, After reading the forum for a while, I'm second guessing the M80s. Should I get the M60s? Why do people say the 80s are hard to place? Ive also read that the M80s sound very similar to the M60's, how could this be with such different stats and not to mention 2 tweeters and an extra 6.5" woofer?

Ahh, I always worry when I talk about placement. There isn't anything odd about the M80, it's just a bit bigger, makes a bit more deep bass, and so is a bit more sensitive to placement than M60s. Not a big deal.

The only "problem" with 80s IMO is that people buy them for a smaller room because the are the top of the line and end up having to stick them in the corner or against the wall in order to fit in their room. If you stick M60s into the same position they will sound boomy and crappy as well -- but they're a couple of inches less deep so you don't have to stick the backs so close to the wall.

I imagine you get the same difference between 80s and 60s as you do between 60s and 50s, 50s and 40s etc... it's just a question of getting the right size speakers for your room. The challenge is that in some rooms speakers can be happy close to the wall and in others they need to be way out in the room to sound good -- and it's hard to predict.

So.. the issues are :

- M80s give you a big, nice speaker for a decent price -- if you buy them "because they're the best" and they're too big for your room you might not be happy

- the speakers look small in the pictures but they are almost 18" deep, so with a bit of space behind them the fronts can be 4 feet out into the room

- deep bass extension is really good so if you place them badly you will notice more than with speakers that don't go deep into the bass (placement in the room is mostly a low and mid-bass thing)

- the Axioms are rear-ported which again is a good thing normally but is a problem if you stick 'em up against the back wall

I think the stats are actually pretty close between M60s and M80s. The only difference is the extra midrange, extra tweeter and larger cabinet -- they both have 2 6.5" woofers. If you ask Axiom they will tell you that the main difference is that the M80s can play louder and fill larger rooms -- the M60 was designed specifically to give M80 sound but in a smaller speaker at a better price.

Hope this helps.
John