Maybe you can help me to figure out the peak power consumption of my amp.
I have bought Micromega M-150 from USA, but I live in Europe now. The amp's voltage is 120v, but I have 230v in socket here. So, I'm going to buy a step-down coverter 230v to 120v. Each step-down converter is designed for some maximum load, 150W, 450W, 600W, 1500W etc. So I need to know how much power my amplifier consumes from a socket to choose a coverter.
The problem is that I found three different points of view:
1) The Micromega's manual says:
Power consumption: Standby : 1W
2 channels -1/8 Pmax under 8 Ohms : 185W
The seller says this is the maximum and I should take converter with double reserve, let it be 450W
2) Hi-Fi News Lab Report says:
Power consumption (idle/rated o/p): 40W / 480W (3W, standby)
I was told in another audiophile forum that 480W is maximum. So we can take with reserve 600W converter.
3) On same forum another guy counted this way:
You should take the dynamic power for two channels and multiply it by two. It means like 300W*2*2=1200W. And as the dynamic power of this amp on 1Ohm is 690W you showd take at least a 1500W conerter.
So I'm confused... The converter I want (Krieger) is 1150W maximum available and costs too much with shipping.
Amp specs:
Power by channel: 150W for 8Ohms, 300W for 4Ohms (I have 4Ohms speakers)
Efficiency 95%
Two power supplies - one for each channel
I wrote to Micromega, but they were bought by another company three years ago and stopped support.
I hope someone here could help me with this problem.
Power consumption (idle/rated o/p): 40W / 480W (3W, standby)
This says to me the maximum draw is 480W at the rated output power. I agree with the advice you’re getting that the stepdown transformer should be rated for more than that, probably 2X minimum.
I'm not the expert you were looking for, but went bigger with an isolating trasformer myself (just to step down 20V myself). I read somewhere that loading up a transformer will cause voltage to lower and too much current draw could reduce sound quality. My unscientific choice was therefore to go much higher than the fuse rating on the box.
Power output: 150 watts per channel at 8 ohms (300W at 4 ohms), both channels driven
Thus, what speakers are you planning to use? Check impedance and not just rated resistance - if 8 ohms speaker actually drops to 4 ohms, count it as 4. So you need 300x2x2 - 1.2 KW transformer. Yes, transformer, NOT switching supply.
The power output of the amplifier is irrelevant to this discussion. What matters is its power consumption, tested by Hi-Fi News at 480 watts. There’s no need to make this complicated.
In the US, when you plug an appliance into an outlet, that appliance cannot draw more than 1800 watts because the receptacle is rated at 15-amps. The closest equivalent power source is the 1500 watt transformer.
Keep in mind the transformer wattage is the maximum it can handle and therefore you can go for a bigger VA or watt rating than the amplifier. Going smaller will affect the amp's performance as it will sag voltage at low impedance loads.
(That wall outlet that is rated for 1800 watts is fed by a pole transformer that can deliver hundreds of thousands of watts to your house yet your appliances don't care).
The transformer is a passive device, it literally passes voltage and current that is fed into it. A higher wattage transformer has thicker wires and is able to carry more current and therefore more power. If the transformer is undersized for the load it will overheat and damage. The size of the transformer you pick is based on economics. As an extreme example, you can hook up a 10,000 VA (watt) transformer to a load that only consumes 1 watt. Since you have much more capability than necessary, you paid for all that copper, size and weight for no reason and the job would have been done no different with a 1 watt transformer.
Your amp is made to work in an 1800 watt outlet. Therefore you should ideally select an 1800 watt transformer. In your example, the 1500 watt unit is the closest. No need to go smaller as it may have an effect on performance.
But I'll try to double rating, because my wallet is already bleeding
Remains to be seen what amount to double. 185, 480 or just get a monster transformer for 1500-5000W.
Taking into account all points of view, for now I think the best way to take a 1000W transformer because it will cover fully option 1, will be enough for option 2, and maybe suit for option 3 (cause I don't think I can listen to this amp so loud that it will need 1500W).
Most components will tell you on the back what the power draw is. This has nothing to do with Watt output for speakers. If it says it's 400w, then you should get a at least a 600w converter.
What is being missed is, this is MAX power draw, not continuous. That is most likely the power draw at clipping. If you listen to it at moderate volume, it is using far less power. My Marantz is 200w, and under normal listening it is only pulling .5a
@jea48, Yeah, thats what we are talking about. If we have consumption power 480W and take a transformer that can handle 1000W, isn't it enough to have a double reserve for peak power consumption? And again, if it depends on listening volume, I'm not gonna terrorize my neighbors. No matter that I love death metal, I like to listen to it on comfortable level, like a middle between relaxing and having fun you know.
What about LLC SMPS, it's advantages are possibility of low power consumption at light-load/standby and efficiency up to 98%, M150 has 95%, which must mean that the real power consumption is not far from it's power output. Again, quote from hifinews:
M150 is reinforced by a PFC (Power Factor Correction) version of its RPS power supply. Rated at 150W/8ohm, the M-150 delivers 2x167W/8ohm and 2x315W/4ohm with 175W, 335W, 565W and 690W available under dynamic conditions into 8, 4, 2 and 1ohm loads.
My speakers have minimum 3ohm, not less if I understand right Erin's graph:
But I don't understand what is EDPR, it's something terrifying.
You all are getting so far into the weeds with this. Just looked up the Amp, it's a 150w class A/B made in France, after reading the manual, it states max power consumption is 185w, so it is a very efficient amp, almost class D like.
If you get a 400w transformer, you will be fine with all the dynamic headroom you need. This is nothing like my vintage class A that at idle is consuming 400w and heating my house.
If you are still concerned about it, contact the manufacture and ask them.
Some switching power supplies have a jumper on the printed circuit board between the rectifier and the filter capacitor. With the jumpers in place, the circuit will act as a voltage doubler, converting 110V to 220V.
I'm not sure if the Micromega M-150 power supply has jumpers for voltage conversion, maybe it's worth asking a technician to take a look.
@imhififan that would be great, I have sent email to company-owner of Micromega, la boite concept, and to three repair shops which may have experience with this model. Hope someone will answer.
Quick question. Have you checked to see if the power can be changed internally? Almost all my equipment has a small switch or jumpers inside the box to change from 110-120 to 220-240.
@curiousjim I'm trying to find out now if it is inside. It is not possible to find a service manual on Internet. I asked a question to La Boite Concept customer service and on one french hi-fi forum. I don't want to open it myself, I'm afraid to break something. And I don't believe local services much, because they are working with vintage equipment mostly, not modern. But If I'll be sure it is possible, I'll go to service and ask to open it.
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