Axiom Home Page Forums General Discussion Technical Questions 220 volt vs 120 volt for subwoofers

Hello,

This is my very first post so if I should be doing this elsewhere, please let me know. As well, maybe this has already been asked and answered. I am having the family room rewired and because I have an EP500 subwoofer, I see that it can powered for 220 or 120. I am just wondering if there is any benefit in powering it 220 V. The run would be dedicated to the subwoofers (hoping to add a second one, one day). I know that the minimun gauge of wire for 220 is 12 however I am thinking of running 10 gauge. This might be overkill however. any thoughts on this would be much appreciated.

thanking you in advance for all comments

vic650

It doesn't practically matter for the 500 but the higher voltage will give you more flexibility. Audio gear exists that provides higher output with a higher supply voltage.

Regarding gauge, it depends on length of run, ampacity, allowable voltage drop and conductor material. For a 40 foot run, 10A load and 1V drop, 10 gauge copper is fine.

In Canada the CEC requires:

120v with 12/2 loomex is fine. 20A breaker and 5-20R tamper proof receptacle.

If you run 20A 240v you will need a red jacket 12/2 loomex and a 6-20R tamper proof receptacle with 2 pole breaker. You will also have to buy a new cord for your sub. Using a normal resi receptacle with 240v is a big no no.

#10 for resi runs less than 30A is overkill, but fine if you have it around.

I wouldnt bother with 240v unless you know what you are doing. Follow the NEC in the US. Local codes supersede the NEC if the standard is higher.

Trevor, while were on this topic, do you know how much can be sourced transiently on a 15A residential circuit before a breaker trips? I've looked for amps vs. time to trip curves for breakers and can't find any.

I keep wondering how it can be that I'm powering all my basement gear through a 15A circuit and have not managed to trip it. Voltage is rock stiff too.

Typically the only circuits in our North American houses that have/need dedicated 240v. are Stoves and Dryers or Large shop tools. The 240v. is for users in other Continents.

If you were to put a dedicated 240 outlet for just your sub/subs is total overkill. Staying all 120V. is sufficient. The EP500 has it's own Toroidal power supply as well.

Sole dedicated line Much better use with for your AVR/Amps/ C.D. Blueray etc. Aficionado's with BIG Amps. recommend a 120V. 20A line Maximum for high power demands 30A Will potentially fry your equipment
As a total anti Ground loop scheme each Outlet should be direct to breaker for ultimate trouble prevention.

Depends on temp conditions and age of breaker. In commercial, we can sneak out a longer time curve for compressors or large motors with a breaker with a 22KA interrupting rating vs 10KA with same overcurrent setting.

Page 32 onwards explains inverse time curve. Higher the current, shorter the trip time.

https://www.downloads.siemens.com/d...load&fct=getasset&id1=BTLV_26555

Hello TrevorM,
Thank you for the detail answer. It all makes perfect sense. Just asking more out of curiosity then anything, on the cord requiring changing. Do you know if Axiom has two different cords type since their subwoofers can be quickly converted from 120 to 240 Volt.

Hello brendo,

Thank you for your answer. You mention dedicated for AV/amp/blueray. Just to clarify, do you .ean dedicated line for each or do you mean dedicated one for all ot them and only them.i.e. All three components

Vic650

Hello Mojo,

Thank you for providing a reply.

Vic650

There are a number of people on this channel whose ears perk up when they hear the word "overkill". I may have become one of them.

My last house had a 240V outlet box in the garage for the previous owner's Big Honkin' Welder (I always regretted moving before having anything to plug into it) and it seems to be becoming more common for people to run 240V to recharge electric cars.

I'm starting to think that it's time to start using 240V for other applications... we have to buy two or three amplifier boxes to power active LFR's, and with a 240V in-feed that could probably be combined into a single box (maybe even including DSP).

The subwoofer possibilities are... interesting.

So John. I think you're telling us 120 is for pussies.

I’d run a couple of dedicated 15 or 20amp 120v circuits into the room and call it a day.
Since I have no power in the media room at the moment ... I’m running everything off a single 15A circuit and haven’t blown any thing yet. It’s a lot more stuff then your talking about. The reason I can get away with it is that my power needs are mainly dynamic. I turn on the amps and subs one at a time and play it at reasonable levels. The dynamic power comes from the stored Power in each amp

In theory you can get twice the power into the room with 220 per circuit but you’re creating headaches for your self.

I dont know. I would send an email to them and ask.

advice@axiomaudio.com

4x the power is output if the load impedance is unchanged and voltage doubled assuming no heat loss. The example assumes a resistive load with no protection.

120v at 6ohm load

I=E/R 120v/6ohm= 20A P=ExI 120v x 20A= 2400w

240v at 6ohm load

I=E/R 240v/6ohm= 40A P=ExI 240v x 40A= 9600w

Thats why it’s a big no no to use a 120v recept (5-20R) with 240v. Plug something in that needs 120v normally and a fire can occur.

The subwoofer power cord for 240 is different than 120.

BTW, I power 2x500, 1x800, 1x1000-8, 1x1000-2, 1x1500-2, 2xDSP, active LFR1100, 2xQS10, Onkyo, PS3, wireless router, cable modem all from a single power bar. I've turned it up louder than my ears can stand in my 4200 cu.ft. space and even with the lowest lows, the voltage at the power bar is rock solid.

Hello Mojo,
Thanks for that, the power bar is supplied with 120 v at 15 A or 120V at 20A?.

Hello TrevorM,
Thank you for the illustration and the address. I will ask the people at Axiom about what their subwoofer cable can handle. Just would seem to me that they would have provided a power cable that would be able to handle the higher volt requirements. Having said that I realise one should never assume.

120V, 15A. That's good for 1800 continuous "RMS" Watts.

If you examine the document at the link Trevor posted, you'll see it takes 25 seconds for the molded circuit breaker to trip at 3 times the nominal current rating. For a 15A breaker, that's 45A for 25 seconds. 45A at 120V is 5400W of "RMS" power and 7600W of peak power. No musical transient lasts that long. This is what's called an overload condition. Overloads are different from short circuits. Breakers react differently to overloads (thermal loading) compared to short circuits (magnetic loading).

The link is for an industrial breaker of course. I'd like to find the curves for a typical household breaker. Not sure they're similar to what I described above. One thing I do know is a 15A breaker does not instantaneously trip at 15A.

fine 4x I know the math.
The point I was trying to make is that it’s easier to deal with what’s standard. And that it’s probaby not needed. That said, guess you can find 240 power strips and the like out there if you really want. Overkill will give you options. I put in a sub panel for my HT ... power will not be an issue in the room (as I can always add a circuit plus it keeps the ground runs short).

Lol. Always a smartie pants I am....

I knew you knew. Just making Vic aware of what can happen if he jury rigs stuff.

BTW thinking on this the 230v switch on the amp is likely for users overseas. It is not North American 240 with 2 hot legs. In the UK etc they have single leg hots at 230 instead of 120. Likely still set up for one pin as neutral with the torroid tap.

Just stick with 120....

Also, I can back Mojo and rrlev that a single 20A cct is fine. I run a 2200va centralised UPS in my mech room that serves the basement HT, living room plasma and oppo and a 2ch room setup. Runs all three no issues simultaneously.

Had a BBQ party once and the power went out. Ran the 2ch setupfor 45 mins on battery cranked and kept BBQing.... power came back. All good. Pretty sweet with 15 people here. Lol.

Interestingly enough, the 240V circuit would see 4 times the impedance compared to the 120V circuit due to the turns ratio of the 240V transformer used on the EP500. As a result, the EP500 would draw half the current at 240V as 120V.

The power the EP500 needs doesn't change ... double the voltage then you'll need to halve the current.

I think Trevor was trying to calculate available power at the plug ... the numbers will be different depending on how you want to approach it. What Trevor presented was power used into a resistive load when the voltage is doubled. Although the math is correct, I do not think he's getting the answer he's after ...

Home wiring is only allowed to carry so much current for a certain wire size (for safety). For the same wire size doubling the voltage (i.e. only changing one variable, in this case voltage) gives you double the power. Now, if you want to change both current (wire size) and voltage ... which is valid in that standard receptacles are available for a number of voltages and amperages ... going from a 15A 120V outlet to a 30A 240V outlet will give you 4x the power.

Is the current halved because the power doesn't change or is the current halved because the equivalent input impedance is quadrupled?


True dat.

U tell me ..,, What’s the simplest explanation?

The simplest explanation is the current is an artifact of the subwoofer's equivalent input impedance being immersed in the applied electric field.

The current is halved because the 2 primary transformer windings would be changed from a parallel to two in series configuration with the switch. Look up dual voltage autotransformer.

Example Diagram.



Example with dual voltage autotransformer with 2 6ohm primary windings.

120v 2x 6 ohm windings in parallel = 3ohms So- 120v/3ohm = 40A

240v 2x 6 ohm windings in series = 12 ohms So- 240v/12ohm= 20A

That implementation results, as you've described, in a quadrupling of the input impedance.

Yessir

That's the simple explanation?? Hope you guys don't go into teaching

Hello Everyone,
Decided to go with 120 V supplied by 12 gauge wire and 20A breaker.( with the appropriate receptacles). I like the fact of making it easy, not something I typically do
Thank you for the great conversation material and all the comments

Vic650

That's smart. A 20A circuit will give you 30 zetta electrons per second more than a 15A circuit.

Wow this is one mega topic.
Lucky so many knowledgeable people who have already made a dedicated room.

Vic for your ease it would be best to make sure each outlet in the room is separate to avoid grounding issues. 120V./20A. is sufficient for AVR/Amps high power items. Though 15A. is typically enough. I would Put the 20A. only on the lines you may use or intend to use for main sources.

One detail is the items will only draw so much power anyhow. Extra on tap is good though most items will not need it as they can't draw any more than they are designed to.

I wouldn't put it quite that way, but...

... yeah