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Axe FX 2 and devialet phantoms

Ytolyccuz

Inspired
Hi,

I'm tust curious to learn if anyone has tried hooking up the axe to a pair of these. Interested to hear your feedback.

Thanks!
 

DLC86

Fractal Fanatic
Hi,

I'm tust curious to learn if anyone has tried hooking up the axe to a pair of these. Interested to hear your feedback.

Thanks!
Never heard of these but seeing they're wireless speaker I assume there would be one big problem: latency
 

Rex

Legend!
The Axe doesn't have wireless connectivity, so how would you connect it, anyway? That's not a big deal, though. These things smell fishy. ("Thrust force?" That's not even a loudspeaker term.)

For the price of one of these, you could buy yourself a pair of very good, pro-level monitors, and get stereo and accuracy—two things which Devialet doesn't claim to offer.
 

Ytolyccuz

Inspired
Thanks for the feedback. Less than 13 kgs for a powered speaker with enough loudness and accuracy sounds too good to be true.

Still would like to hear any feedback if anyone has had experience with these.

TIA
 

selta

Power User
4500 watts, and it can only produce 108 dBSPL? Something doesn't add up here...
Because there's a very steep curve (nearly logrithmic) when trying to do a "watts to dB" conversion (even though, technically, you can't extrapolate watts to volume directly). To double volume, you need roughly 10 times the wattage. Sooo
100 watts will be twice as loud as 10w.
1000w will then be 2x 100w, or 4x 10w.

Extrapolating this a bit... if you go from say, 500W to 4500W, that's only a 9x increase in wattage, so not quite enough to increase by double in volume (which would be +10dB).

Add on top of this... 1000W into a single 12" speaker with a tiny x-max, versus say 100W into 8x12" speakers with slightly larger x-max, and the 8x12 setup will be orders of magnitude louder.

With those things said... 108dB is pretty damn loud. And with a THD of 0.0005%, too. But I don't think live use is the intended target of these ;)
 

Rex

Legend!
Because there's a very steep curve (nearly logrithmic) when trying to do a "watts to dB" conversion (even though, technically, you can't extrapolate watts to volume directly). To double volume, you need roughly 10 times the wattage. Sooo
100 watts will be twice as loud as 10w.
1000w will then be 2x 100w, or 4x 10w.

Extrapolating this a bit... if you go from say, 500W to 4500W, that's only a 9x increase in wattage, so not quite enough to increase by double in volume (which would be +10dB).

Add on top of this... 1000W into a single 12" speaker with a tiny x-max, versus say 100W into 8x12" speakers with slightly larger x-max, and the 8x12 setup will be orders of magnitude louder.

With those things said... 108dB is pretty damn loud. And with a THD of 0.0005%, too. But I don't think live use is the intended target of these ;)
The point is that, if you dump 4500 watts into a speaker and only produce 108 dB SPL, that speaker is horribly inefficient. By comparison, the power amps in my Event ASP8's have a combined output of 280 watts, and I've measured 111 dB from 1 meter away.

Another point: that power outlet in your wall—the one that the Phantom needs to plug into to make sound—can only deliver 1800 watts. If the Phantom puts out 4500 watts, where does the extra 2700 watts come from? ;)
 

selta

Power User
The point is that, if you dump 4500 watts into a speaker and only produce 108 dB SPL, that speaker is horribly inefficient. By comparison, the power amps in my Event ASP8's have a combined output of 280 watts, and I've measured 111 dB from 1 meter away.

Another point: that power outlet in your wall—the one that the Phantom needs to plug into to make sound—can only deliver 1800 watts. If the Phantom puts out 4500 watts, where does the extra 2700 watts come from? ;)
AC mains supply has basically nothing to do with power output.
An amplifier is defined as a device that amplifies both voltage and current in a way that the power out to the speaker divided by the audio power into the amp is greater than 1. Since the audio power of the signal into an amp is in the range of a couple of mW, and the output power is in watts, this condition is pretty easily met.
Second, the amplifier has a power supply that operates at a different voltage(s) than the AC supply, therefore currents do not translate 1:1. Also, the amplifier's power supply performs an averaging operation on the AC supply, and most are chosen so that the averaging function and the duty cycle of the audio work hand in hand (to a reasonable degree).
Third, without knowing the duty cycle of the signal being amplified, you can't calculate average audio power... which is necessary for the AC supply calculation.

The math is simple for an engineer who does this all the time, but it's probably not terribly intuitive the first time through, maybe the second or third as well. We have to perform these calculations when designing amps and power supplies, when developing the UL/CB Scheme test protocols, and for some of us who work with pre-packaged SMPD/Class D modules it's even more important to understand these dynamics and how control of these parameters are passed back and forth between the SMPS and amplifier as there is additional processing happening in some of these cases.

The easiest way to do this is to base everything on the power equations rather than jumping between voltage and current all the time. Below are the standard calculations (for a class D SMPS amp) used for this purpose:

AC power source = 120V x 16A = 1920 Watts

AVERAGE audio power out = Audio Power x duty cycle = P x .125 (using the 1/8-rated power per UL/CB Scheme)

AAP x amplifier efficiency = power draw on DC power supply = AAP x .85 (using a typical 85% efficient amp)

AVERAGE AC power = power draw on DC power supply x SMPS efficiency = AACP x .9 (using a typical 90% efficient SMPS)

So solving the entire string of equations:

(1920W x .9 x .85)/0.125 = 11750Watts

Back to the 4500W

Let's use an average power supply efficiency of 90% and an average amplifier efficiency of 90% (pretty typical of this amp, though efficiency is not a single number and through some unique control integration between the power supply and the amplifier, in many areas as the amp efficiency rises the power supply efficiency falls and vis-versa yielding an almost flat 81% efficiency (which happens to be the same as 100 x .9 x .9 = 81%). Let's now increase the duty cycle from 1/8 to 1/3 which is very demanding. The equation solves as: (1920W x .9 x .9) / 0.333 = 4700W of audio power.

I could go on, but I don't know how much EE knowledge you have. No offense meant at all, but judging from your initial inquiry, I'll assume it's not very high (or at least, not in audio amplification). To put very simply - the power supply voltage is not anywhere near the same as the mains voltage, hence, your standard Ohm's law cannot be applied without a tad more investigation.

I also don't doubt that they're inefficient. They're targeted for home audio reproduction, not live music production. Two very different design goals.
 

Rex

Legend!
AC mains supply has basically nothing to do with power output.
It has everything to do with power output. An amplifier can't put out more power than it draws from the supply. Depending on the design, it might be able to do so for a brief transient, but the supply needs time to recover from that.


So solving the entire string of equations:

(1920W x .9 x .85)/0.125 = 11750Watts
Help me understand the part where you divide by the duty cycle. That's the exact opposite of my understanding. Your equation indicates that, as the duty cycle goes down, power goes up. It also suggests that, if you make the duty cycle low enough, you can get a megawatt out of your wall outlet. I'd love to see a demonstration of that. :)


Back to the 4500W...

...Let's now increase the duty cycle from 1/8 to 1/3 which is very demanding. The equation solves as: (1920W x .9 x .9) / 0.333 = 4700W of audio power.
That also puzzles me, for the same reason. You go up to a more-demanding 1/3 duty cycle, but you get less power out (4700 W vs. 11,750 W).


I could go on, but I don't know how much EE knowledge you have. No offense meant at all...
No offense taken. I have a bachelor's degree in EE. :)
 

selta

Power User
Super good then. Bachelors in EE is a good base to work from. How much Audio Power is in EE now a days?
If you remember your basic audio power equations, run through them and realize that the voltage is not going to be 120V. When coupled with a transformer, you can have a wide range of voltage. Transformerless design can are limited by a voltage doubler, though. I don't know the OPs speakers, but I'd guess they have transformer in there and not just a doubler.

So P = (V(peak)^2) / (2R) becomes

As you decrease the duty cycle (approach 1), your average power does increase. That's kind of how duty cycle works - it's the amount of time when the signal is active. If it is active 12.5% (0.125) of the time versus 100% (1.00), your denominator becomes bigger and average power goes up.

With a big enough transformer, sure. How high do you step up the voltage? I've worked with transformers that are 115V on the primary side and 3000V on the secondary. Truly massive and expensive.
 

Rex

Legend!
You must be talking about instantaneous power: brief bursts that are a fraction of a cycle long. If I'm pulsing a square wave into an LED, for instance, I get a certain brightness. If I reduce the duty cycle, I get reduced brightness, because I'm reducing the power, not increasing it.

The energy you get out of a system can never be greater than the energy you put into it, unless you believe that "free energy" pseudoscience. Over time, that limits the power out to be less than or equal to the power in.
 

selta

Power User
I specifically state Pavg for a reason. If you like to continue, let's take this to PM as we're getting far off course from the original discussion in this thread. Or start a new thread. Either way, I have stuff to get to for Chinese New Years :)
 

Rex

Legend!
I specifically state Pavg for a reason. If you like to continue, let's take this to PM as we're getting far off course from the original discussion in this thread. Or start a new thread. Either way, I have stuff to get to for Chinese New Years :)
Feel free to PM me.
 
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