Hello All,

i've been reading this forum since i discovered Axiom (quite a few years ago! ) and now, since i'm about actively looking on replacing my unadequate front speakers ( and soon to be full HT), i have a few questions that i hope you guys can answer.

my amp is a pioneer VSX-1018 that, according to the documentation, supports speakers with 6ohm impedance. my amp is also able to "bi-amp" a speaker with the front and surround back output. i already read that if you "unbridge" the M80(by removing the little gold connectors) that it doesn't change the impedance that much.

do you think that my amp can handle the load at moderate to low-high volumes??

also, maybe i can go with higher impedance M60's, i'm really not sure but the HT wizards on the axiom website tells me that for a room like mine (~3,500cubic feet) i should go with the m80's.

thank you!

I wouldn't try to bi-amp the M80s, but I think it's probably worth a shot. I think I've heard that the 1018s work with M80s. Still, with a room that large, you may end up needing an external amp anyway.

Mathieu, welcome. Good that you decided to join the group. You correctly put "bi-amp" in quotes, since this is simply an advertising ploy of some manufacturers that isn't actually bi-amping and has no real benefit. The same amount of power from the one main power supply section of the receiver is simply funnelled into the speaker through two sets of output transistors(one previously unused for back surrounds)rather than one. No increase in available maximum power can result from this.

Your listening distance is a more significant factor as to power requirements than is room size. The room doesn't have to be "filled" throughout with the sound level you need at your listening position. The 1018 should certainly have no problem driving the M80s at the moderate level you mention unless your listening distance is unusually long.

...and if the 1018 does have trouble (I doubt it too), Pioneer was still nice enough to include pre-outs on that model (they're gone from the 1019). So you can easily make use of external amps.

To be clear, I think using the receiver is worth a shot.

Just reread my post and realized it didn't make much sense.

You mean, of course, that the receiver is worth a shot, the bi-amping is not.

Yes, now that I've been unclear in 2 posts. Chris has it right.

thanks for all your input,

my "real" question really was "can my 1018 handle the 4ohm load at moderate levels"

i will eventually change the pioneer for something more appropriate ( as i will not need 7.1 in my living room). it's not that my living room is 3,500cubic feet, but my living area (living room/dining room/kitchen) is all open area with high ceilings, i wish i could send you guys some pictures but the house is still under construction

also, my listening position will mainly be about 10feet from the speakers.

sometimes i will want to only get ambiant music while cooking/having guest for dinner, or "loud" music with an expensive bottle of wine and some friends.

last, do you guys have some recommendations regarding amps/receivers that pair well with the m80's? under the 2k$ (CAD) mark would be nice. (i know that is a very personnal topic and we all have different earing, i just want some suggestions :), i mainly listen to Jazz/Rock/Classical/Pop, in that very specific order )

again, sorry for the long post, and thanks for your very valuable input.

Denon's full range of avr's work very well with M80s, I have run my M80s with an older 1804 and my newish 3808 with no problems at all. Most seperate amps work with 4 ohms, ie. Rotel, Denon, Outlaw audio, Anthem etc., but there are always few exceptions, Emotiva is hit and miss.

I see this statement often and think it's true in some cases but not in others, so will put down my thoughts here for comment. Let's take a 5-channel amp rated at 100 watts per channel with all channels loaded. The PS would be capable of 500 watts, and each of the 5 amps capable of 100 watts. If the mains were bi-amped so two amps were connected to each front speaker, then each front would get 200 watts and the fifth channel would still get 100 watts. The total output, and PS load, would still be 500 watts, but now each of the two front channels would get 200 watts vs 100 watts each before bi-amping. I realize that the picture is different if the amp isn't rated with all channels loaded, but it seems to me that you do get more or less doubled power per channel in many cases.

Except you're forgetting what happens in the speaker with the passive crossover network. When one amp is driving the full "system" inside the speaker all frequency ranges are going to some driver with an impedance with allows for easy current flow. But when you remove the straps; you separate the system into a high-frequency range with a high-pass filter, and a low-frequency range with a low-pass filter. The other half of those ranges basically end up seeing a very high impedance, and turning the amp's energy to heat.

So when driving the speaker system 100 Watts, across the range, drives some part of the speaker's full system. When bi-amping, 100 Watts drives the highs, and 100 Watts, drives the lows. You're still only getting 100 Watts to any part of the speaker.

If you were to use the pre-outs on a receiver, input them into an active crossover network, remove the crossovers components from the inside of the speaker (make sure your active network matches the passive parts in point and slope), then get separate amps, with fine grained gain control, along with a precise audio spectrum analyzer to balance the gain of each amp against the driver it is feeding for a flat response. You might get some benefit from bi-amping.

The bi-amping built into receivers, feeding a passive crossover network, is an entirely marketing based feature; one manufacturer offered it, so they all have to offer it.

EDIT: Oh, I forgot to add. In the presented scenario, with one PS providing power to multiple channels, when bi-amping, you're more likely to exhaust all that's available because you have two channels with exactly the same content being driven to the same levels, but half of it being used to make heat instead of sound. The way multi-channels amps get away with higher single channel ratings, is that in the real world it isn't common for more than a stereo pair of channels to be driven hard at one time in anything other than test signals. But with bi-amping you quickly run into cases with 4 channels being driven hard.

If I could figure out how to do it any more, this one would be going on my favorite posts list. I always know the simple answer, but I never remember the actual technical answer.

Don, that is not true bi-amping and your still getting 100watts as Chris explained. Here is a good article....

http://www.gcaudio.com/resources/howtos/biamping.html

Don, a further comment would be that you used "amps" and "channels" as if the two were synonymous. A receiver has only one amplifier with several channels to distribute its output. The output transistors in each channel simply act as valves to measure out the required voltage from the power supply section. They have no power of their own to create a doubling or any other increase.

You should read the Mother of all Posts... I made an attempt, but after the 2nd sentence I went over to the "Who I am and Why I'm Here" post and never made it back

wow, that is ONE BIG POST.

but i kinda like those, especially the "i'm building my theater" type one.

i just bought a new house and will be building mine shortly. i need ideas :P

John- I may be living in the past (I have plenty of it!). In my experience the output stage does have gain, that is, it amplifies the signal coming into it. A (relatively) small voltage at the input of the final (output) stage causes a larger voltage at the output of that stage. Also, the impedance that the final stage is driving is usually much lower than what the prior stage drives (the input impedance of the final stage), so the power gain is considerable. Your description would mean that the final stage has unity power gain, is that the way modern amps are built? I'm familiar with 1-output per channel stereo amps, but not 5 or 7 output per channel amps, maybe this splitting of the signal is where the unity gain comes in.

Chris- I (mostly) agree about only having 100 watts available to any part of the speaker system. What I was thinking, but didn't say clearly, was that if you bi-amp (passively) the speaker you unload each amp from having to drive all speakers. For example, if a signal has 90 watts of 100 Hz content and 10 watts of 10,000 Hz content for a total of 100 watts a single channel/amp has to drive that total power. But if you separate the highs from the lows than the tweeter amp is only driving 10 watts. The 90 watts of low frequency power on that amp sees the very high impedance of the HPF so is delivering only very low power at that frequency. Related to that, I don't really understand your statements about the crossovers dissipating lots of heat. If you define the crossover as just the reactive components (inductors and capacitors), then the only heat generated is due to the resistive and parasitic losses in those components, which is very low for high quality parts. The high impedance of the HPF at low frequencies and the LPF at high frequencies presents a high impedance load to the amp, so very little power goes to that section. (It's true that the resistive elements, which aren't really crossover but are for gain balancing, etc. do dissipate power, but that is equally true whether or not the speaker is bi-amped.) Of course, as you said, using an electronic crossover ahead of the amps allows all equalization and gain matching to be done without any passive components, so no losses.

Don, of course gain does take place in the output stage(typically 25-30dB), but the point is that the voltage to boost the incoming voltage by that amount comes from the one main power supply section. The output transistors simply act as valves to let through enough voltage to increase the incoming voltage say, for example, 28.28 times so that a tenth of a volt input would result in a 2.828 volt output and into an 8 ohm load would produce 1 watt(the usual speaker sensitivity measurement standard, of course)following Ohm's Law(power=voltage squared/resistance). So an amplifier is a power supply section plus one or more channels of output transistors. The output transistors themselves aren't complete amplifiers, and it isn't correct to describe a 7.1 receiver as having seven amplifiers.

I'm sorry, but this conversation has me bored to tears. ::walks away and hopes nobody notices::