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#375343 - 05/06/12 03:53 PM Re: Axiom Amplifiers: The Next Generation [Re: Da_Gimp_Pimp]
fredk Offline
axiomite

Registered: 12/06/07
Posts: 7059
Loc: Canada
Originally Posted By: Powertothepeople
We all try to justify superfluous purchases....

No SWMBO no TWMBJ. I just check my bank account.
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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!

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#375348 - 05/06/12 05:40 PM Re: Axiom Amplifiers: The Next Generation [Re: fredk]
Da_Gimp_Pimp Offline
connoisseur

Registered: 06/23/07
Posts: 4025
Loc: Sitting down somewhere
Originally Posted By: fredk
Originally Posted By: Powertothepeople
We all try to justify superfluous purchases....

No SWMBO no TWMBJ. I just check my bank account.


laugh
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#375412 - 05/07/12 01:40 PM Re: Axiom Amplifiers: The Next Generation [Re: Da_Gimp_Pimp]
Murph Offline
axiomite

Registered: 10/05/06
Posts: 6841
Loc: PEI, Canada
Originally Posted By: Powertothepeople

Speaking of tube amps, my friend who's totally def really likes mine. He claims he can hear a difference. I'm confused, but I'm not questioning him. Not because I don't want to, but because I can't do sign because I can't move my fingers.


"Why, I can hardly hear it! You'd have to be deaf to hear that."
--Murray, Flight of the Concords--
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#375418 - 05/07/12 03:38 PM Re: Axiom Amplifiers: The Next Generation [Re: SirQuack]
Nick B Offline
devotee

Registered: 08/05/06
Posts: 496
Originally Posted By: SirQuack

Does this design reroute unused power to the other channels needing the power, like Tom's design, that was a nice feature?


I know that Ian said that it does act in this way, but I am not understanding how. From the table Ian gave on the first post, on the 1500 series amp, it says that with one channel driven there is 325 Watts into 8 Ohms. That figure remains pretty consistent as more channels are driven into the same load. The previous Axiom amp was able to dump all of the power supply, the whole 1500 Watts when one channel is driven. This seems like a different design that Tom's in this regard. Though with real world material, 325 Watts should be more than enough, for even the most demanding material.

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#375425 - 05/07/12 05:58 PM Re: Axiom Amplifiers: The Next Generation [Re: Nick B]
Andrew Offline
Axiom Engineer
veteran

Registered: 12/18/01
Posts: 176
The table shows continuous power output figures. This is power that you have available for any length of time that it might be required. What we have not stated is peak or instantaneous power ratings and this is where you are able to momentarily sink far more power into the load than the continuous numbers suggest. This is the power supply "steering" that you are thinking of from the A1400 and the new amplifiers all have this same capability.

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#375427 - 05/07/12 06:09 PM Re: Axiom Amplifiers: The Next Generation [Re: cohesion]
Andrew Offline
Axiom Engineer
veteran

Registered: 12/18/01
Posts: 176
Hi Mike,

I know that Ian, Amie, and Steve are all hard at work with creating the web pages for these new amplifiers. They will feature more in-depth specifications. Is there something specific that you'd like to know? The power ratings that Ian gave in his original post are at 1% THD+N.

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#375506 - 05/08/12 11:06 AM Re: Axiom Amplifiers: The Next Generation [Re: Andrew]
Nick B Offline
devotee

Registered: 08/05/06
Posts: 496
Originally Posted By: Andrew
The table shows continuous power output figures. This is power that you have available for any length of time that it might be required. What we have not stated is peak or instantaneous power ratings and this is where you are able to momentarily sink far more power into the load than the continuous numbers suggest. This is the power supply "steering" that you are thinking of from the A1400 and the new amplifiers all have this same capability.


Yes, but if there are two, three, or four channels driven then there is also 325 Watts continuous power available to each channel. When 5 channels are driven the number drops to 300 Watts available continuously to each channel, since there is only 1500 Watts that can be had out of the wall. My question is: If 1500 Watts can be split up between the channels so that there is approximately 300 Watts continuously given to each channel, then why can't there be 1500 Watts continuously given if there is only one channel driven? Or 750 Watts if only two channels are driven? Was this limited to 325 Watts continuous since there are some speakers that cannot handle more than than on a over a period of time, or am I missing something? I still don't really understand.

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#375524 - 05/08/12 01:00 PM Re: Axiom Amplifiers: The Next Generation [Re: Ian]
tomtuttle Offline
axiomite

Registered: 06/20/03
Posts: 8292
Loc: Tacoma
Continuous <> Peak.
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#375568 - 05/08/12 10:20 PM Re: Axiom Amplifiers: The Next Generation [Re: Nick B]
Andrew Offline
Axiom Engineer
veteran

Registered: 12/18/01
Posts: 176
Originally Posted By: Nick B

Yes, but if there are two, three, or four channels driven then there is also 325 Watts continuous power available to each channel. When 5 channels are driven the number drops to 300 Watts available continuously to each channel, since there is only 1500 Watts that can be had out of the wall. My question is: If 1500 Watts can be split up between the channels so that there is approximately 300 Watts continuously given to each channel, then why can't there be 1500 Watts continuously given if there is only one channel driven? Or 750 Watts if only two channels are driven? Was this limited to 325 Watts continuous since there are some speakers that cannot handle more than than on a over a period of time, or am I missing something? I still don't really understand.


Ok, I can see where you are having trouble. It's a little difficult because there are two factors at play here. On the one hand we have this large power supply that can supply lots of "power" to how ever many channels need it. On the other we have to look at the amplifiers themselves. By definition, an amplifier cannot swing or deliver more than the available DC power supply voltage to a load (speaker). Once we take losses, including the amplifier's efficiency, into account, the available voltage swing is reduced even further. It's this voltage swing that determines the maximum, continuous output power that the amplifier can deliver into a given load, assuming that we have unlimited current available. So, even though we might be able to deliver 1500 watts from the power supply, the amplifier is limited by the rail voltage.

Time for some quick math:

Let's assume P is power, V is voltage, I is current, and R is resistance. I'm going to leave the complex reactive speaker impedance out of the discussion and assume the load is purely resistive! wink

P = V x I
From Ohm's Law we know that I = V/R
Substituting this equation into the first equation we get:
P = (V x V)/R

In the A1500 we are running +/-85Vdc rails, which means the peak to peak voltage is 170Vdc. However, we can only swing voltage in one direction or the other at a given time. This means we need to use our peak voltage, which is 85Vdc. Power is usually, somewhat erroneously, specified in watts RMS, so we need to convert peak voltage into RMS voltage. To do this we multiply the peak voltage by the square root of 2 (0.707).

Therefore, Vrms = Vpeak x 0.707.
In the A1500 this gives 85 x 0.707 = 60.095 Vrms.

Going back to our original power equation, our maximum output power into 8ohms is:

P = (60.095 x 60.095)/8 = 451.23 watts

But wait a second, this assumes that the entire amplifier is 100% efficient, which it's not. We need to apply the approximate efficiency to the RMS voltage, and this is 90% in the A1500. This gives an actual RMS voltage swing of

V = 60.095 x 0.9 = 54.0855

Redoing our power calculation now gives:

P = (54.0855 x 54.0855)/8 = 365.66 watts

So this is the maximum single channel output power, no matter how much current is available from the power supply. Why does Ian's table state 325 watts for one channel? Because we're still in the preproduction stages of these designs and we wanted to be conservative until the final numbers are in. smile
I hope that was not too hard to follow and helps to clarify the continuous power ratings.

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#375569 - 05/08/12 10:30 PM Re: Axiom Amplifiers: The Next Generation [Re: Ian]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17783
Loc: NoVA
So one does wonder, then, how this would relate to the A1400-8's maximum single channel output power.
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