Surround Sound Theater

Maine Sail · Feb 13, 2009

Interesting..

Your system is interesting but quite inefficient. I would suggest that you invest in a true battery monitor like the Xantrex Link Lite or the Victron BVM-600 (LINK).

The TV:

You mention that you purchased a Toshiba 19" line voltage TV. The max rated amp draw for this device is .8 amps at 120 volts. When you use this device on a 12V system, through a 100% efficient power inverter, of which there is no such thing, the best possible current draw in amps you would see at 12V is 9.6A just from the TV! Unfortunately you would need to add inverter inefficiencies to this number which would raise your 9.6 amp draw at 10% to 10.56A. At 20% it's 11.52A. That is a LOT of juice and we have not yet added the stereo!!

By choosing a dedicated 12V LCD TV you could have saved a significant amount of current draw on your house bank. We also run a 19" high def TV only with built in DVD that only draws 3.9 amps with the DVD player running. If I run this same exact TV through a 400 watt inverter it draws 5.2 amps, same TV, just running on 12V vs. 120 volts. 3.9 amps at 12V to 5.2 amps via a 400w inverter is a full 25% more current use.

When I run the same TV through my 1200 watt inverter even more inefficiencies are added. Running off the 1200 watt inverter leads to a current draw of 5.8 amps. 3.9 amps at 12V to 5.8 amps via a 1200w inverter is a full 32.8% more current use than running the same exact TV on direct 12V. In short it pays to buy a TV that will run on 12V as opposed to only 120V.

The Stereo:

Your Samsung stereo is rated at a max power output of 1000 watts. 1000 watts at 120v is only 8.33 amps but when you run this same stereo on a 12V system the potential current draw at full rated power output, which will likely never happen for very long, is and could be 83.33A. Of course your stereo is lying to you about its input and the output is not what the input is so you are likely in the 6A to 18A range when run inverted.

You also said: "A previous owner had converted over to a two battery system"(a cranking battery and a house battery)"

Let's assume that you have a two battery system consisting of two group 27 batteries, one house & one start. It is common knowledge that batteries should not be discharged below 50% if you want to maintain a good cycle life and attain longevity.

The average group 27 battery is about 100 amp-hours in capacity. This leaves you with only 50 usable amp hours when you leave the dock at a 100% state of charge. Of course if you anchor out overnight and charge off the alternator you really only ever re-charge to about 80-85% of the banks rated capacity. This unfortunately leaves you with only 30 usable amp hours.

At 50 usable amp hours on your single battery house bank consuming nearly 10-20A for entertainment, which does not include any other devices like depth, speed, wind or VHF, you have 2.5 hours of TV/Stereo use before you have depleted your bank to the 50% level.

As I mentioned above it is a wise idea, especially with your system, to add a battery monitor so you know exactly what's going on. The gauge on the 1200w inverter should not be trusted and they are there mostly for looks not accuracy. While it is possible that you are only burning 8.3A, which would mean the manufacturers specs are fairly bogus, this is still a LOT of current to burn up on just a TV and stereo with a single battery bank..

This entire system could have been done very well, and actually had higher sound quality (HTIB's are the bottom of the pack when it comes to accurate sound reproduction), with a 12v DVD car stereo that has a virtual surround feature, similar to a Bose 3.2.1 system, and a 12V TV. A dedicated 12v system consumes considerably less current. At a decent listening level our TV/DVD/Stereo consumes a grand total of only 5.1A.. When listening to music only our car stereo with four 4 ohm speakers consumes 1.6 - 2A at 103db which is VERY loud.. We rarely play the stereo at 103db levels as the entire bay would hear it..

One can only go by the specs provided by both Toshiba and Samsung to be correct in their specifications but a battery monitor would tell you precisely what is going on. At the very least you drastically need to upsize your battery bank based on the system you are using..

Hope this helps.

Benny · Feb 13, 2009

I'm not po-pooing your idea but would like to offer a less expensive option for the less discerning sailor. We use a BOSE 3 speaker multimedia system ($200) hooked up to a 15" Samsung HDTV and a Sonny DVD player. The BOSE system is intended for use in computers but it works extremely well in the confined space of the boat's salon. The speaker system is hooked up to the auxiliary jacks of the tv and we use the simulated surround sound effect of the TV. The sound is crisp and clear, more than enough for the salon and it offers a huge improvement over the stock speakers of the TV. Power consumption is quite low. The speakers also pull double duty as the they are easily hooked up to our lap top or X-M tuner. They are also small and there is no permanent installation.

Bill Roosa · Feb 14, 2009

Stereo wattage

Hey guys
when a stereo says it has a 1000 watts output that is audio watts not electrical watts. Audio watts are a weird breed of power measurement that expresses something really useful to speaker and amplifier designers but is totally useless in computing actual power consumption. They chose watts because they where talking power and, well power is watts. Think of it as a poor choice of terms on their part. There is no direct conversion of audio watts to electrical watts as far as I know.
At full volume my 35 watt audio output just tweaks the ammeter. I can't even tell it moved unless I look at it when I turn the unit on.
If your assertion was true I'd expect to see 35/12=3ish amps which I've never seen.

You system is nice, not my cup of tea since the kids left, but I can see the utility. You may want a copy of my electrical system spreadsheet to size your new bigger battery bank.

Maine Sail · Feb 14, 2009

Bill Roosa said:
Hey guys
when a stereo says it has a 1000 watts output that is audio watts not electrical watts. Audio watts are a weird breed of power measurement that expresses something really useful to speaker and amplifier designers but is totally useless in computing actual power consumption. They chose watts because they where talking power and, well power is watts. Think of it as a poor choice of terms on their part. There is no direct conversion of audio watts to electrical watts as far as I know.
At full volume my 35 watt audio output just tweaks the ammeter. I can't even tell it moved unless I look at it when I turn the unit on.
If your assertion was true I'd expect to see 35/12=3ish amps which I've never seen.

You system is nice, not my cup of tea since the kids left, but I can see the utility. You may want a copy of my electrical system spreadsheet to size your new bigger battery bank.

I dug a little deeper and downloaded the user manual and finally found the rated power consumption is 80 watts or 6.6 amps + any inverter inefficiencies .

Unfortunately this means there is no way that this unit puts out any where near the "rated" 1000 watts. I own an audiophile grade 2 ch power amplifier rated at 150 watts per channel that weighs 65 pounds and requires a dedicated 20 amp circuit.. On a 120v circuit your amp draws only .66 amps..

Gotta love consumer marketing. Still a 6.6 amp draw with perhaps a 20% inefficiency is a nearly 8 amp draw on a 12v system.

Stereo power consumption is very dependent on how many speakers it is driving, impedance and the design efficiency of the speaker.

Here are three photos the ONLY differences are the speakers. One set is a highly efficient 4 ohm set and the others (KEF) are a set of 8 ohm inefficient speakers. The SPL meter and the amp meter don't lie. This clearly shows why it is best to use 4 ohm impedance speakers with car stereos and how a simple thing such as what speaker you choose to use can play a HUGE role in power consumption..

In this first photo the Kenwood stereo is powering the set or 4 ohm rated speakers and the volume is set to 27 the power consumed at volume 27 is 1.62 amps and the SPL meter reads 103db. The SPL was hoovering between 103 & 102 (mostly 102) so to be fair I'll call it 102db not 103db..

In this second photo the Kenwood stereo is powering the set of KEF 8 ohm rated speakers and the volume is also set to 27. The power consumed at volume 27 is 2.12 amps. The SPL meter reads 94 db but to be fair it was hoovering between 95 and 94 (mostly 95) and I happened to catch it at 94. I think it is fair to call it 95db. It should be noted that this is NOT an ideal location for an SPL meter but it was in the same location for both sets of speakers. Unfortunately to catch it all with the camera it needed to be where it was..

At the same volume setting the 8 ohm speakers produced less volume output and consumed roughly 131% more current than the 4 ohm speakers did. While all speakers will be slightly different it is safe to say that 8 ohm speakers will draw more current at a given volume than a comparable set of 4 ohm speakers.

The meters used are 100% impartial. That's why I used an SPL meter because my ears, while fairly good, can't determine a 1db difference in output volume. All things were tested exactly equal at a steady voltage input and the same stereo volume setting and test tone CD....

Car stereos on boats will consume less power using 4 ohm rated speakers and will also generally play a little louder at teh same input volume.

Lets assume that your personal volume comfort volume level is 102db. With the Symphony 4 ohm speakers I used you would consume 1.62 amps to achieve 102db, as in the photo above. If you wanted to achieve the same listening level of 102db with the 8 ohm KEF speakers it would require 4.58 amps (I caught it at 101 but it was bouncing between 101 & 102 the meter is very sensitive) !!!!!!!!!!!!!!!!!!!!

Is it safe to use 8 ohm speakers with a car stereo? Yes & it won't hurt it any but it certainly won't save any amp hours..

Maine Sail · Feb 14, 2009

javaprog said:
I wish I could have done a 100% 12V system. Could you provide a parts list for the system you describe and an estimate of the cost?

First let me just say that I would not have done a 5.1 system on a boat but rather a 2.1 so my approach is totally different. Let me explain why.. Sonically you just can't effectively get the true "surround" experience, the audio engineers mixed and intended for, on a boat. For this reason alone I would have never considered a 5.1. With today's car audio you can achieve a very high level of sonic quality and one that will certainly exceed that of a HTIB 5.1 experience when installed in a boat. Perhaps if your boat was a 60 footer and you had a center-line mounted chair, TV and center channel speaker you could come close to what the audio engineers intended the sound track to be.

In our old home theater it took six full hours with expensive microphones, spectrum analyzers & pink noise generators to get the system "tuned" for the room and to best match and re-create what the mixing engineers intended the movie to sound like. You just can't effectively re-create this experience on a boat.

The best option and the one I would personally choose is to use a the 2.1 setting on the DVD menu and play the movie in the mix intended for a 2.1 system. With today's car stereos and SRS or "simulated surround" you can achieve a very, very high level of sonic quality and not a bunch of misplace delays hitting you at the wrong time due to "room constraints".

Of course I am a self admitted "audiophile" and not a "tin ear" so to me a 5.1 system on a boat would actually annoy me to the point of not being able to sit through a movie. Most people are "tin ears" and this is just fine for them. I wish I had a much less critical ear but unfortunately I do not.

Still I would have opted for a 2.1 done in 12v using a car stereo with iPod input, DVD and one of the small powered subs such as the Infinity Basslink or any on this page Crutchfiled Powered Subs (LINK).

I use a set of Bose 151 Environmental speakers (LINK). Please do not confuse the 151 Environmental with the newer, cheaper and worse sounding 151 SE!! While sonically, at least to my ears, the 151 Environmentals pretty much suck, they are one of the only true 4 ohm "box" speakers still being made. If I wanted to drill holes and mount car speakers or marine grade speakers the sonic envelope really widens. JL Audio builds some amazing sounding marine speakers.

One thing to remember with most HTIB's is that you will have a HUGE hole of missing frequencies (not actually missing just not reproducible in a sub sat system). These frequencies are the mid bass response range. This is one reason while you'll never see companies like Bose publish a frequency response curve for their sub/sat systems..

By choosing at least a 6.5" diameter car, or good quality marine speaker, and a 12V sub woofer you can have a LOT more of the frequency range than you get from a bunch of teeny tiny 2.5" drivers, with very limited frequency range, and one sub..

The bottom line is if this sounds good to you then that is all that matters!

I would still invest in a battery monitor and a bigger house bank because you could very easily become dead in the water if you're not careful..

kloudie1 · Feb 16, 2009

A pretty neat demonstration, Main .. but there are some other factors that may be (I am not saying definitely that this is so) skewing the data that the instruments are telling us.. Speaker sensitivity is a measure of how much sound the speaker makes per watt of input power.. what may be happening here is that the 4 ohm speakers are very efficient (high sensitivity) and the 8 ohm ones are low sensitivity.. ?? For instance, the so called acoustic suspension speakers are very inefficient but have some sound characteristics that folks like .. they are available in 4 or 8 ohm models.. I figure you know this but was wondering if there were sensitivity numbers on the different sets of speakers? Generally speaking, a 3 decibel difference in sensitivity will make a 50% difference in the power required to drive at the same volume level .. I do agree that it is best to use the speaker whose nominal resistance is what the amplifier was designed for.
We are going to need some circuit design folks to comment on what happens when ya drive an 8 ohm speaker with an amp designed for 4 ohms.. My gear headed analogy might be like running a diesel (amplifier) into a restricted exhaust system (Ohms?) where it takes more diesel to make the same prop torque..?? I dunno..
I use the same Bose 151 environmentals that you are talking about, mounted to the forward bulkhead in the main cabin; they are driven by an old AIWA (Sony) tuner and casette amp, that has an "AUX" input where the Ipod can plug in.. Sounds fine!