Discussion in 'General Electronics Chat' started by LED Man, Feb 21, 2008.

1. ### LED Man Thread Starter Active Member

Jan 15, 2008
62
0
Hey guys,

We got our electric bill last month and its way higher than last month. My roommate wants to blame it on us playing guitar/bass too much.

Anyway, can someone give me a good explanation as to why hes wrong?

2. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
Try a Google search on "post hoc ergo prompter hoc."

Keep in mind that he may also be right.

If you have baseboard electric heating, know that it is a common culprit of high January electric bills.

3. ### John Luciani Active Member

Apr 3, 2007
477
0
You could try watching the meter while someone is playing the guitar and bass at
full volume. Otherwise buy a power monitor.

(* jcl *)

4. ### LED Man Thread Starter Active Member

Jan 15, 2008
62
0
Isn't there a mathematical way to calculate this? Say its a 60 watt amp? That the same as a 60 watt light bulb?

5. ### nomurphy AAC Fanatic!

Aug 8, 2005
567
12
Let's say that you have a 100W amp. Although you may not be cranking it up to 11 (or are you?), let's say you're averaging 50W (which is pretty loud in a confined space).

sqrt(50W/8 ohms) = 2.5A

Now, I don't know your amp or circuitry or power transformer, but let's just say that because of amp inefficiencies you're drawing 2A from the line of 120VAC.

120VAC * 2A = 240W

So, even if the numbers I give above are somewhat off, this is only for one amp. If you're using more than one amp plus some other equipment, then it seems to me I'm in the ballpark (possibly even on the low side).

The upshot is, given the above numbers, your playing is equivalent to leaving on a 240W light bulb. If you're doing this for many hours a day, day-after-day, then you could definitely notice it in the electric bill.

6. ### John Luciani Active Member

Apr 3, 2007
477
0
To accurately calculate you need to know the efficiency of the amplifier. An
amplifier that outputs 60W may require a lot more the 60W input.

You could get a worst case number by multiplying the input voltage by the fuse rating
which would give you a maximum VA value.

(* jcl *)

7. ### Dynaman Active Member

Jan 17, 2008
46
0
No, I used to build MI and pro-sound amps for a living. If it is a 60w amp, you are probably drawing no more that half when actually playing (and it would be very loud), otherwise it is just idle current. It's not your issue. Energy costs are skyrocketing and see if you past your "usage baseline"

Aram

Dynastar Electronics

8. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
You might consider building a small 2-input practice amp using (horrors!) IC audio amps, and wear headphones.

No, it won't sound like the tube amps.

But your electric bill will be much more agreeable.