powering an amp with a car?

jmercer91 · #1 02-01-2012, 07:25 PM

would it be possible to power an amp with a diesel car? looking to take a road trip in a week or two and wanted to know what would have to be done as far as grounding/power conditioning. any and all help is greatly appreciated.

**B-string** · #2 02-01-2012, 07:37 PM

Good sized/quality power inverter, connected direct to your battery. Leave the car running as it can drain the battery pretty fast if you push some volume.

jmercer91 · #3 02-01-2012, 07:40 PM

no need to run a metal rod into the ground or anything? kinda worried about grounding issues. can i get shocked/killed

jmercer91 · #4 02-01-2012, 07:41 PM

or worse... damage my amp!

**B-string** · #5 02-01-2012, 07:50 PM

Quote:

Originally Posted by jmercer91

no need to run a metal rod into the ground or anything? kinda worried about grounding issues. can i get shocked/killed

You could if you wanted but not necessary. Best to isolate the ground lug from the amp cord so you are not grounding your vehicle if you do.

Quote:

Originally Posted by jmercer91

or worse... damage my amp!

Just don't lick it or play in the rain?

If you buy one that is too small it will shut down and signal overload (on the power inverter) which is not good for your amp.

jmercer91 · #6 02-01-2012, 07:55 PM

sweet! thanks!

bobcruz · #7 02-01-2012, 11:20 PM

I never looked into this in detail but I remember there are two kinds of inverters, cheaper ones that produce square AC waves (if that's even proper terminology) and expensive ones that produce pure sine waves like you get from a wall socket. Could the cheaper ones cause issues with an amplifier? I'm thinking they might be intended for noncritical electrical needs like lighting or something. And I think there is a big difference in price, but this is from dim memory....

will33 · #8 02-01-2012, 11:26 PM

Quote:

Originally Posted by bobcruz

I never looked into this in detail but I remember there are two kinds of inverters, cheaper ones that produce square AC waves (if that's even proper terminology) and expensive ones that produce pure sine waves like you get from a wall socket. Could the cheaper ones cause issues with an amplifier? I'm thinking they might be intended for noncritical electrical needs like lighting or something. And I think there is a big difference in price, but this is from dim memory....

From my dim memory, there was a thread on here maybe a couple years ago from an over-the-road big rig driver that was inquiring about a combo amp to use with the power inverter in his 18-wheeler to play on long trips. I don't remember talk of the different inverters but there may have been. I think we concluded something like a Peavey 112 combo would sound like a proper bass, not take up too much space or tax the inverter too much while running things like a coffeemaker, TV, etc. I think big rigs run on a 24 volt system though and I don't recall enough about it to come up with good enough search terms to dig it up.

will33 · #9 02-01-2012, 11:36 PM

Well, I found it. Short thread short on info though. TB'er skychief mentions getting a bad, incurable buzz from the "modified wave" inverter as well. No idea on prices of these things.

need advice for the proper amp.

skychief · #10 02-02-2012, 12:32 AM

Roger that, will33.

A ground rod is a good safety measure.

And dont even try those "modified wave" inverters....theyre ok for running a vaccuum cleaner, or power drill, etc., but NOT for audio gear. They put out a square wave.... Amps cant deal with dirty AC. Ive tried SS and tube amps ... same results (very loud 60Hz buzz).

Spend the few extra $$$ and get a true sine wave inverter!

When sizing the inverter, use the TOTAL power consumtion of the amp and double it.

Say your amp draws 650 watts from the AC outlet. 650 x 2 = 1300. You would need an inverter rated for 1300 watts continuous.

Downunderwonder · #11 02-02-2012, 03:57 AM

If you've got a sansamp pedal you can use it to drive one of those tiny Lepai 12V amps, about 20 dolllars on ebay. They are very efficient. If you can unhook your speaker from your combo and use the 12V amp it won't run your battery down so quickly. Not so loud of course but if you're practicing it should be fine.

4-stringB · #12 02-02-2012, 02:20 PM

Why not just use any one of the plethora of car amps? They have EQ and many features. You can use a pedal or two to get your sound, and best yet, you can't get electrocuted. Hook them to your regular speaker and have at it.

dmusic148 · #13 02-02-2012, 02:26 PM

Quote:

Originally Posted by skychief

Roger that, will33.

A ground rod is a good safety measure.

And dont even try those "modified wave" inverters....theyre ok for running a vaccuum cleaner, or power drill, etc., but NOT for audio gear. They put out a square wave.... Amps cant deal with dirty AC. Ive tried SS and tube amps ... same results (very loud 60Hz buzz).

Mmmmm, really shouldn't matter. The amp turns it all into DC before using it anyway. My guess is the cheap inverter is throwing out lots of EMI into the air which is being picked up by the bass or the amp's preamp.

**B-string** · #14 02-02-2012, 06:25 PM

Quote:

Originally Posted by 4-stringB

Why not just use any one of the plethora of car amps? They have EQ and many features. You can use a pedal or two to get your sound, and best yet, you can't get electrocuted. Hook them to your regular speaker and have at it.

One, those car amps are not designed for the heavy voltage swings from a live instrument. Two, you would have to boost the signal from your bass to line level and pedals won't do that. That means you would need a preamp and that would more than likely be powered by 120Volts.

Downunderwonder · #15 02-03-2012, 12:20 AM

My sansamp pedal drives an amp just fine.

will33 · #16 02-03-2012, 12:53 AM

Quote:

Originally Posted by dmusic148

Mmmmm, really shouldn't matter. The amp turns it all into DC before using it anyway. My guess is the cheap inverter is throwing out lots of EMI into the air which is being picked up by the bass or the amp's preamp.

I'm no tech but I don't think it's that simple. An amps power supply has 2 or 3 stages in it other than the transformer to run power through, reduce ripple current etc. to get good DC. Throw a square wave into that instead of a sine and I don't think it would work right. You can't just put anything in one side of a transformer and get pure DC out the other side.

James Judson · #17 02-03-2012, 02:05 AM

Go find an inverter at a power boat company. They have a plethora of sizes and shapes and colors. Watch specs so you don't make smoke.

BassNeo · #18 02-03-2012, 02:27 AM

Start by finding out how many watts the amp will draw. Add a minimum 10% to that value and that will be the smallest watt inverter you can buy.

The biggest issue will be if the car's alternator can handle the draw. If you end up buying a 1500 watt inverter and you play heavily, the battery in your car can't keep up and all the power will be drawn from the alternator. It's similar to the whole ohm draw issue with your amp. Too much draw = fried amp.

Cars typically have between a 40 - 60 amp alternator. Larger cars, trucks and SUV's can go as high as 120 because they have stuff like DVD players, extra heaters in the back seats, etc. Big Rigs can come with 200 amp alternators, and the buzzing sound is likely from the charging system itself. The magnetic field created by those big alternators can interfere with anything that's not insulated properly.

As far as grounding, most good quality inverters have overload protection so if something goes awry it just shuts down. And you don't want to play Russian roulette with your gear buy buying a cheapo inverter, do you?

popgadget · #19 02-03-2012, 06:05 AM

You need a "pure sine wave" inverterif you go that route. You might also consider one of the inverter type portable generators such as the Honda eu2000i. It would run a small band and is very quiet and portable. That way you're not tied to your vehicle, and could actually use it to charge your vehicle battery if need be.

bassmeknik · #20 02-03-2012, 06:37 AM

I own a CHEAP modified sine wave inverter purchased at the local retailer known for Asian made goods and it works just fine powering my home made amp.

IMO the quality of the amps power supply is important and many amps have inexpensive power supplies and can only marginally deal with AC power line noise and alternator hiss (very common due to the powerful magnetic field). A well constructed power supply can swallow most line interference.

Cheaper "modified wave" type inverters will work if your amp is well built but a better quality inverter will make less noise leaving the amps power supply with less work cleaning up the noise.

Another suggestion I might make is to use your line conditioner (if you have one) from your stage rig connected between the inverter and amp and give the amp slightly cleaner power.

I agree with the poster that recommended a inverter twice the continuous power needed to ensure trouble free operation. Those things are notorious for being underrated, particularly the inexpensive models, and trying to run audio equipment with weak power IS asking for trouble.

If practice is your need then start trying different rigs to see if you can live with a car amp and some basic pre-amp to boost the signal to a useful amount for driving the amp. I have played with 12 volt rigs for years (a boater for life I am) and have dreamed of a high powered stereo for the boat for years, IMO the average car amp stinks (high distortion levels) so I am dreaming of my own amp design that would give me clean(er) sound than the average trunk mounted car amp.