Anybody Use Large Power Inverters at Work or for Stereo-Lots of Questions

[cyclonecj]

I am already doing this...Mostly during the summer for Camping.

I
have a 1000 watt power inverter in the back of my truck hooked up to 2
big deep-cycle batteries. We use this to power lights, TV, DVD, stereo, satellite dish, etc. A few times for outdoor partys
etc, I have hooked up a CD player & amp with a pair of old
Heresys & it works perfectly. Also, during a power outtage, I just run an extension cord out to the truck, & power whatever I need.

Things to keep in mind..... I am using a cheap inverter that seems
to be clean enough, but you will want to find one that has a pure
sinewave output. They are a bit more money, but for your purpose it
will be worth it. Do a google search for "power inverter pure sinewave" & you will find a few options.

[thebes]

Wow, great stuff guys!

Dr. Who, Josh and Hifi Jim are just poking the bear, knowing full well that I equate the invention of audiophile cables with Ponzi's decision to start selling stock.

Don, pretty interesting stuff. However, I'm thinking that messing around with my main wiring panel is not probably not survivable by me, and hiring an electrician to do it probably goes way past my toy budget.

Cyclone, you da man. True sine wave, sounds like just what I'm getting at. I mean how hard can this stuff be. Every audio device I own takes AC and turns it into DC and no body starts talking about square waves etc. I mean, it's just reversing the process as far as I can see.

I found a website that sells these things and they say this:

"The problem with wave form only comes into
play when specialized pieces of equipment need to be
powered. Here are a few devices which could have problems
when they are connected to an inverter producing a modified-sine
wave signal: oxygen concentrators, fax machines, laser
printers, high voltage cordless tool chargers, equipment
with variable speed motors, electric shavers, and garage
door openers.

There are a few other applications -- high-end
audio video units, plasma displays, gaming systems,
and certain scientific testing equipment -- for which
true-sine wave is not usually required. Even so, these
applications can usually benefit from the improved clarity
of the electrical signal produced by a true-sine wave
power inverter. Users of these particular items have
usually spent a lot of money to achieve optimal results
from their equipment, and it would be a shame to have
a cheaper modified-sine wave signal cause inaccurate
readings on a piece of scientific equipment."

I'm thinking this might be a worthwhile, affordable experiment, and if it doesn't work out I have emergency backup power.

What say ye? Still skeptical?

[joshnich]

I would be way interested in your results if you decide to give this a try. There are many battery powered phono stages that people swear by. A friend of mine bought some records from a very strange guy who's whole system was battery operated. I think that this guy had aluminum foil over his windows and had other significant anti-social issues as well. But my friend said his stereo was on of the best he had ever heard! Since hearing that I have been somewhat intregued.

And yes you are right the cable thing was just a little needle!

Josh

[tigerwoodKhorns]

Thebes,

We have about 124v power here in the winter and about 116 to 117v in the summer and I used to get that late evening "bloom" even thopugh in the summer the AC runs all night.

Anyway, I now use a PS Audio Power Plan Premiere to run everything except my monoblocks. If you run low wattage amps you can probably run them off of the Premiere. I no longer get the late night "bloom" and everything is very consistent. I think that the Premiere is the same thing that Dr. Who is describing. Power regerators are basically amplifiers and the Power Plan Premiere is so inexpensive (compared to other companies out there) because it uses a switching power supply (like a Class D amp).

It will probably do what you want. Buy off of Audiogon and if you don't like it you can get your money back. I got a great deal a few years ago and paid somethigng like $1500 new, so $1100 is a bargain. They also have a 5 year warranty and PS Audio's customer service is just plain outstanding.

[leok]

I have to agree with the folks suggesting that an inverter may be noisier, in more ways that will degrade your audio, than what you get from the power company (modified by every device that's using that power plus a lightning strike or two). I 've used isolation transformers in industrial applications and have considered it for my oudio system (especially since I'm beginning to suspect that power surges have killed two power transfsormers) Sola makes some real nice power conditioning stuff for industrial applications, but they might make the audiophile stuff look cheap. Check it out.

Leo

[DrWho]

Cyclone, you da man. True sine wave, sounds like just what I'm getting at. I mean how hard can this stuff be. Every audio device I own takes AC and turns it into DC and no body starts talking about square waves etc. I mean, it's just reversing the process as far as I can see.

Turning DC into AC is exactly what an audio amplifier does....

You wanna power your tube amp with an amplifier?

[artto]

I think what you really need/want is a constant voltage transformer.

[mike stehr]

I had one of them little T-amps once, and brought in a typical common 12 volt car battery to power it. A common car 12 volt car battery seems like a dirty power source. A good amp/hour marine or GelCel type battery may be a cleaner source of 12 volts.

I used to get into car stereo, and I seem to recall the marine battery I used was a cleaner sound than the common 12 volt battery. Not to mention the extended charge the amp/hour battery had.

I think what you really need/want is a constant voltage transformer.

If Marty's power sags all over the place, and sounds dirty to him, it seems like a idea to me........I dunno......

[thebes]

Cyclone, you da man. True sine wave, sounds like just what I'm getting at. I mean how hard can this stuff be. Every audio device I own takes AC and turns it into DC and no body starts talking about square waves etc. I mean, it's just reversing the process as far as I can see.

Turning DC into AC is exactly what an audio amplifier does....

You wanna power your tube amp with an amplifier?

Who, Now you are just taking advantage of my technical ignorance. An easy thing to do!

Leo, oh Leo. Et tu Leo?

I checked out those Sola's and they are indeed spendy. I fur sure don't have a grand for some industrial, or audiophile, gizmo. What I fail to understand in the outpouring of negative vibes on this issue is any specific reasoning behind nixing inverters other than the generic "noisy". I'm sure you are all being kind by not smothering me in technical talk, but without some more specifics I guess I have some more questions.

Like:

If they are noisy is it inherent in their design? Supposedly tube amps are bastions of distortion yet they work for me and many others. Has anybody actually investigated these circuits for audio purposes?

Or is it, the components that go into the typical inverter? I mean, if it's just components, I can swap them out for better stuff.

I'm a bit leery of the supposed benefits of voltage isolation and regulation. It seems to me they are every bit as susceptible to circuit design, components etc. While they are great for voltage spikes , does simply regulating the power get rid of the dirt?

Arto , a cursory search on these transformers reveals they have problems of their own.

Mike, Tripp-Lite for one, strongly endorses deep cycle or jell for use with their inverters even though they aren't pure sine wave models.

By God, it's time to end this negativity and get with the positive. Is this a "Can Do!" forum, or a "Can't Do, sigh" forum?

Well I for one am not about to let our technical brain trust wither on the vine, smug in their genius, tucked into their comfy chairs, filled with the stuffing of certitude! Time to roll up the virtual shirtsleeves and get to work!

Just call me Francis Bacon Thebes.

[mike stehr]

I did a search on power inverters,(not saying much) and they seem to range from cheap to spendy.

http://www.invertersrus.com/pwrups6000w.html

A 2200 dollar 24 volt power inverter.....

""modified sine wave inverter with PWM control which continually monitors and corrects the inverter's output.""

Who knows how clean a 60Hz AC sine wave this unit would put out. I guess a guy could see on a oscilloscope. Maybe look for a inverter that pays attention to the distortion of the output.

I would think this particular inverter is used by truckers, larger motor homes, tour bus applications, etc....

Figure up what you are going to use for audio components to power off the inverter. Figure up the total current drawn, wattage, etc.

Amp/hour marine GelCel batteries are rated in hours and current drawn, where standard car batteries give a quick blast of current in a short cycle......sumthin' like that. I think maybe one reason marine batteries or GelCel "sound" cleaner, is they have better quality materials in the plates inside the battery. Where a dirt cheap car battery has cheap recycled lead plates or some such.

I'm not saying to buy a 2000 dollar 24 volt power inverter, I kinda doubt you would need 30 amps or better to run a tube amp and a turntable. But you may allow for a bit of headroom in current, for like power up of the tube amp. Where it will pull more current at start-up cold, then draw less as the amp warms up. That particular inverter even claims to recharge the batteries.......

You may get away with a inverter at 20 amps, or maybe less. Nonetheless, it seems if you want a good one, you have to spend more money.

[thebes]

Hey Mike, the ones you are looking at are modified sine wave which is basically a square wave. Cyclone suggested perfect sine wave inverters and from what I've learned they appear to be the "cleanest" .

Here's a really good article on the various types and they even recommend certain brands for critical applications like "portable recording vans"

http://www.solar-electric.com/solar_inverters/inverters_for_solar_electric.htm

Maybe I'm just looking at them wrong but it appears they sell these things by wattage, not amps, and I can't seem to figure out what the amp loads would be. Could that be taken care of by the size, and or, number of batteries?

[LarryC]

Second, I'll be running a 35 watt tube amp, a tube line and phono preamp, a TT and a tubed cd player. Would say a 700 watt inverter do?

Marty, what's the total wattage you want to run off this? Like, is the 35 w. amp a stereo item, and wouldn't it run about 150 or 200 watts? How many watts needed for the rest of it? My tube line stage units have been about 50 watts, and my TT maybe half that. What's the watts requirement for the tubed CD player?

The total should give you an idea. My P-300, for example, runs a TT, CD transport, an RTR and a cassette deck. It didn't do much for my former CAT tube pre in a trial run, and my amps chew up too much power for even one P-300 each. So, I just run motorized components with it.

Anyway, commercial units I've read bout have been spec'd in wattage consumed, not amps. Couldn't you estimate amps by dividing watts by 110, 117, or 120?

As I mentioned in e-mail, I'd be glad to loan you my easily-moved P-300 to see what that would do on sound sources including the CDP and TT (because the P-300 works so well on motors), and preamp if the P-300 has leftover wattage for it. I also have spare power cords which have done very well on tube preamps and motor components. All/any of this is easily loaned and switched in and out. It would be interesting to see what if anything comes out of trying any of these.

-- Larry

[cyclonecj]

For a reference, Here is the one I have been using for about 4-5 years now. Its an older Xantrex 1000 watt, & yes, very dirty (remember, I said I use it camping). I paid $79 for it.

I am happy to do some testing to get current specs if you want. Maybe I can even get Josh to do some testing with me.

[DrWho]

Cyclone, you da man. True sine wave, sounds like just
what I'm getting at. I mean how hard can this stuff be. Every audio
device I own takes AC and turns it into DC and no body starts talking
about square waves etc. I mean, it's just reversing the process as far
as I can see.

Turning DC into AC is exactly what an audio amplifier does....

You wanna power your tube amp with an amplifier?

Who, Now you are just taking advantage of my technical ignorance. An easy thing to do!

...

Well I for one am not about to let our technical brain
trust wither on the vine, smug in their genius, tucked into their comfy
chairs, filled with the stuffing of certitude! Time to roll up the
virtual shirtsleeves and get to work!

Just call me Francis Bacon Thebes.

Well Mr. Francis Bacon Thebes, I'm
of the belief that one should first understand a problem before
implementing a solution...otherwise, how do you know your solution
worked?

I was actually being quite serious about amplifiers being really
good at converting DC to AC. In fact, a good pure sine wave power
inverter is essentially going to be a switchmode power supply feeding a
class D amplifer that is playing a 60Hz tone from an onboard signal
generator. I
suppose you could always do a class A amplifier running right off your
12V car battery and boost the voltage
with a big transformer, but that wouldn't be very efficient at all,
especially considering it should be capable of delivering a good 100W.

I did a quick searh online for FFT's of power inverters and dirty AC
voltage, and here's what I found. First, an FFT of a simulated power
inverter (and simulated world is usually much better than the real
world):

And then here's an FFT of someone's dirty AC wall voltage:

I think it's quite obvious that neither is clearly better than the
other...and this is what we mean when we say power inverters are noisy.
Sure, you can get rid of all the crap from your wall's AC, but you're
going to
introduce new crap in the process. Flinging crap back and forth is a
lot like a food fight without the nice taste, pleasant smell, and all the pretty women...

Sure, you could design an audiophile grade power inverter that
creates less harmonics, but think for a moment what that looks like
from the mile high perspective (or is that an elevated consciousness
"high" perspective?) []

Using the car battery, your best bet would be to use a switchmode
power supply to boost the DC voltage so that you can use a class D
amplifier fed with a 60Hz tone generator to create 120Vac on the
output. You then connect this to the 120Vac input on your tube amp
which then rectifies it back to a DC rail and powers the amplifier.

The engineer in me looks at all these black boxes and quickly
realizes that you can accomplish the same goal without all the extra
circuitry. Don't you think it would make more sense to strip out the
AC/DC converter in your tube amp and replace it with a switch mode
power supply?
This would also get rid of the batteries, the chargers, and the power
inverter and all its complexity. I was being extremely serious and
practical when I made this suggestion earlier.

One of the "downsides" to the SMPS is that its rail is going to be way
stiffer and cleaner than the rail currently in your tube amplifier.
This has the side effect that all of the 120Hz ripple previously on
your power supply will no longer be present. One of the things I've
learned is that power supply ripple has a huge influence on the sound
of an amplifier, especially one that doesn't have enough power supply rejection
(which is demonstrated by your observation that dirty AC power has an
audible impact). Getting rid of the 120Hz ripple will
basically get rid of the warm fuzz that is being layed over all your
music.

That said, one could always inject a 120Hz error signal into the
feedback network of your SMPS such that you get the same voltage ripple
on your DC rails. This would actually be quite easy to do and would
preserve the tonality of your amplifier. It's not very audiophile in my
mind, but that's another issue []

[DrWho]

Btw, I just wanted to add that a dirty power inverter isn't a big issue if the devices its powering have good noise rejection in both the power supply and amplifier stages...but if that's the case, then you don't need clean power to begin with...

[mike stehr]

Interesting thoughts, Mike. But I think the tube amp Marty is mentioning, is a Marantz 8B or something.

From a practical standpoint, (to me, non-engineer layman) would be to flog the Marantz amp and use the proceeds to build a tube amp with a switch mode power supply.

[DrWho]

Hmmm, for some reason I always thought Thebes had a custom built amp? Must be that wild avatar... []

Btw, do we know that the Marantz is in good working condition? Some passive filtering on the power supply might be enough to fix the problem too (depending on what the problematic frequencies are). It'd be a whole heck of a lot cheaper too.

[mike stehr]

Hmmm, for some reason I always thought Thebes had a custom built amp? Must be that wild avatar...

Btw, do we know that the Marantz is in good working condition? Some passive filtering on the power supply might be enough to fix the problem too (depending on what the problematic frequencies are). It'd be a whole heck of a lot cheaper too.

I'm not sure if that's even the amplifier he is refering to. IIRC, Marty had Craig go through the amplifier.......I'm not sure on that either.

I'm kinda with you.......I mean, what's broke that we are trying to fix here?

[thebes]

Thanks Larry. Maybe an experiment with it would be in order.

Thank you my good doctor for taking the time flesh out your reasoning, which I do find mostly compelling. I'm also a big fan of less is more in audio, unless it isn't.[]

It would certainly appear from your research that inverter power is as dirty as ac power.

My thinking on this whole dirty power issue, and the attraction of batteries, is that is unclear to me that the major impact is on the amp. I'm thinking the dirty power affects all the components, so simply cleaning up an amp may, or may not, get you where you want to be.

Now, I do use a Marantz 8b, recapped by Craig, and with some of the finest power bricks ever made. Sure I only paid $50 for it, but people have told me that that's a reasonable price for one of these. However, I've also noticed this "bloom" for lack of a better word, with other amps. Others, whom I'm sure you would find credible, have also experienced this phenomenon. So I'm sure it's quite real and not simply a side-effect of the perfume The Twins wear. Check the comments out on this little tale I wrote:

http://community.klipsch.com/forums/p/93698/949035.aspx#949035

For all I know some guy in Idaho turns off his light at the same time each evening and it brings me a sigh of contentment here in a Virginia. Now if you can figure out a reasonably priced means of achieving what I hope to do with inverters, then I'm your man. Indeed, we can build them, add a ridiculous markup, and make a killing. We could call our company The Dr. Who and Dr. Thebes Traveling Electrical Show".

Now don't think for a moment I'm abandoning this idea. After all sometimes experimentation is the only way to test a hypothesis.

[Riot260]

We've been using 1000 wwatt inverters for years camping............running 2 Crowns bridged into 6 Cornwalls out on an island cover by sprawling oaks. We use a mini generator for cranking them up but when it is time to wind down and the volume gets turned down we switch to battery powered inverters they run for about 6 hrs not pushing them..........pushing them hard they last about 2 hrs then the batteries are dead.

Since last springs campout we have purchased some Class T DC amps. They work great especially on 100db+ speakeers. We're able to use a lawnmower battery instaed of (2) 18wheeler batteries. The Class T amps last all weekend but the Crowns do have more uumph for a shorter time.