Axiom Home Page Forums General Discussion Stereo So NOW I'm a real Axiom owner...

Hey Boom what are the dimensions of your room?

15x15?

You said earlier:
"The room is 15 feet wide. The couch puts me about two feet from the back wall, and the VP100 sits about two feet from the front. So I'm about 11 feet from the speaker."

The words might be crap; it's situation-dependent. It depends what you are listening to, how loud and on the specs of your system.

One use case is heavy metal music. This music has a low crest factor and if you listen to it loud, you might need an amp that is beefier than you thought. Say you buy an amp that is designed for 100W, 20dB crest factor continuous, into an 8 Ohm/45 deg phase angle load. If you listen to heavy metal music at 100W, with a speaker of that impedance, the amp might shut down or the output transistors may cook if their power dissipation exceeds their safe operating area.

Another use case is improper matching of components. If you plan on using that amp with M80s, you'll need a whopping 436W at maximum gain to maintain linearity. This calculation is based on Soundstage measurements of M80v2s which are around 3.5 Ohms/45 degree phase angle between 20 and 900 Hz. Above 900 Hz, they are almost purely resistive.

Depending on how the amp is designed, it might shut down or the output voltage will sag. The effect of sagging voltage is audible distortion.

The matching of speakers to an amplifier shouldn't be over-looked for those who like their audio loud. I'm quite satisfied with how well my M80s are matched with my Onk at "low" listening levels. When I turn them up however, the bass and mid-bass simply gives up. When I substitute my buddy's much cheaper KEFs, the bass is full, tight, punchy and controlled at that higher volume (the KEFs have other problems though so I'm not saying they're better).

Now is that an Axiom problem or an Onk problem? It's neither; it's a system problem. It's not even really a problem because I have no need, other than playing around, to turn them up that loud.

We're discussing multiple topics:

What power do the speakers need? It DOES depend on room size and on how loudly the listener wants to go. Big room OR more loudness = RAPIDLY increasing power demands.

What power do multi-channel amps need? In addition to the consideration above, it also depends on the type of demand placed on the actual speakers by the soundtrack. With all speakers set to "small," and a self-powered sub in the room, no - you don't need much power per channel. After all - Only the center and subs have any work to do - everything else is effects.

But for stereo-only listening (assuming a two channel amplifier) and with NO subs, then things become more demanding for the amplifier. If the speaker has a complicated & lossy crossover (think Thiel) then the amp must be more robust. If the speaker has low impedance (particularly over a broad section of the audible frequencies), then the amp must also be more robust.

Any stereo amp that can't double its wattage into half the impedance is limited by its power supply. For most speakers, and at lower volumes, this isn't an issue. In fact, Axiom speakers seem to have a benign impedance curve (rarely below 4 ohms and only for limited frequency ranges). But despite claims to the contrary, an amp that CAN double its output at half the measured impedance is an amp that is NOT limited by its power supply.

Note that this says NOTHING about how the amp sounds! Lots of "pro" amps can double their wattage into half the impedance, but they sound grainy, bright, and just plain ugly.

Best, to my mind and specifically for stereo listening, is to have a mono or stereo amp that has a muscular power supply.

Such an amp is gross overkill for multi-channel listening (which is why AVRs lack the capability - even on flagship models). Different purposes - different designs.

I don't put the Axiom amps down for not providing that much current for multi-channel designs - it isn't needed. I also note that the two-channel Axiom amp DOES double its wattage from 8 to 4 ohms.

Boom

You missed dynamics. Rock n roll has little, pop even less. You need about 3 db of headroom for most rock. Classical, on the other hand, requires about 10 db of headroom. That extra 7 db of headroom can add a LOT to the power requirements, particularly if you like to listen loud.

A proper power calculator, one that allows you to set the headroom, is an extremely useful tool in picking an amp/receiver for your space.

As mentioned before, I figured out that I would need no more than something like 68 watts to drive the M80s at reference (plenty loud for me) with 10db of headroom. I did the test and pushed them well beyond that using my avr without any change in the quality of the sound.

In the end, buy what you want and be happy, no matter what anyone else says.

If I remember correctly, the axiom multi channel amps have the ability to dynamically direct the power to the amps you are using, so you do not lose any of the power from the power section listening two channel.

I also missed speaker sensitivity, but y'all already know about that...

All multi-channel amps & receivers do the same. There's but one power supply, & the channel using the most power at any given time takes what it needs.

Well, I spoke with Debbie via phone yesterday regarding my December 15th order. I'd tried contacting Axiom via e-mail but without any response (!?).

They claim to be having quality control problems with their incoming raw materials, and hope to have my speakers shipped by the end of this week.

An audio amigo has offered to loan me a second pair of Emotiva XPA-1L mono block amps. So when (if) my speakers arrive, I'll be powering them with a total of four identical amps. We'll see if I can hear any difference...

Cheers - Boom

Sweeeeeet!

To cool,
hope it's not to much longer.