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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2019 at 7:24pm
Definitely scale back your power expectations! Especially if your source is a 110Ah lesiure batt. It will quickly become a very flat, unhappy battery if you ask it for anything like 1500 watts continuous. 

All the big-power car amps are really designed to run with the engine on - so the bus voltage is about 14.4, often with extra high-power alternators to back it up. In addition to the high power consumption when running audio signal, they are not designed for low idle current, and will draw a few amps all the time, even when the audio output power is low. So your battery will still flatten quickly, even if you are only playing at a low level.

If you have lots of money, you *could* look into lithium batteries. With those, sustained high power is less of a problem. The drone-racing boys have sorted that out quite well. But, it gets expensive REAL quick. Also, given that car audio is based around the nominal 12v battery, it can be difficult to get a fully-charged voltage your amp is happy with, that also allows the pack to drain all the way to 0% (either it will be too high when fully charged, or your amp will cut off before it is flat). 

DC-DC converters are something a lot of us use. These are boards that take in 11-24v DC (or an even wider range like 3-30v) and output a stabilised, usually higher DC voltage like 48v. This allows the use of different types of battery with your system, and keeps the voltage to the amp stable as the battery drains. However, they are only available in power ratings up to about 500 watts, so you can't really make a super high power rig with them. 
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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valve head777 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2019 at 7:39pm
Originally posted by APW APW wrote:

Originally posted by carlosdelondres carlosdelondres wrote:

How many Ah is the battery? - even a 220 Ah only has ~3.5kWh at most at that sort of discharge rat mode.  So running ~1kW system, maybe 3-4 hours before battery completely discharged, assuming reasonable duty cycle. And only discharge to 50% if you plan on getting much life out of the battery.


^^^^ this ^^^^

Assuming 100% efficiency, at 1500 watts a 110Ah 12v leisure battery (110Ah is a typical size for a leisure battery) will last less than an hour as your amps will be puling 125amp from the battery, however, in the real world your amps are only going to be about 80 - 85% efficient at best so to deliver 1500watts continuous you would be drawing at least 147amps from your 12volt battery, you would get about 45 minutes running if delivering 1500watts continuous into your speakers.

As audio isn’t normally a sign wave and depending on the music content you will probably get about 3 to 4 times this running time…. On a good day with a new fully charged battery you may get about 2.5 to 3 hours until the battery is completely dead.

And also as above... If you want your battery to last any length of time only discharge to 50-60%



Sorry more to add about batteries. The above calculation isn't taking into account the fact that the faster the amps are pulled from a battery, the LESS capacity it has. The  nominal  capacity of 110ah is at a 20h rate. This means 5amp load. The rate you are suggesting of 125+ amps will get nowhere near 45 mins and has the potential to distort the plates due to heat.
The suggestion of 48v nominal is good because although 4x 12v batteries are used, the current demand is lower. It's high current that knackers electronics due to heat (and batteries).
One more thing. The voltage drop under load must be taken into account. Large loads like above will see 10.5- 11v.
There is good info to be had within the off grid, marine and camping communities on batteries ie correct sizing. It's all important because if you plane an 8 hour party, and run out after 3..........


Edited by valve head777 - 19 March 2019 at 7:44pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote valve head777 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2019 at 7:46pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2019 at 8:07pm
Is your sub bass reflex? Could look at how much it would cost to build a more efficient sub so you can get the output you want with less power and battery drain. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Majestic Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2019 at 9:14pm
Great advice guys, food for thought. Thank you all so much :)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote REIER Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2019 at 11:30am
I also believe it would be wise to aim a little smaller in regards to amp power. Think sensitivity, not amplifiers watts. 

You need to have a sensitive system to make a portabel 12v rig work. This is of course because of the limited power available, so you need woofers that makes a lot of noise for small amount of watts. That fane 18XBs seems to be really sensitive, 99db 1w 1m in 8 ohms. You have 4 ohms, so probably even a little more sensitive. In the right cabinet, you will be suprised by the output with 300w. It will be enough for lots of people. As mentioned before, if your battery capacity is 110 ah on lead acid, that means you have max 50 ah available if you want the battery to last till next summer as well. 

Average current drawn with for example pioneer gmd8604 is 4,4A in 4 ohms, so those 50AH will last about 11 hours. I firmly believe this is the best route.

I used to have a hornsub setup with Pioneer GMD9601 that delivered 500 watts into two 8ohm speakers i paralell, so 250w each, and I rarely turned the volume all the way up, it was litererally more sound than I needed for most occasions. But you know, we all have different needs. What is enough for me might be just the start for you ;)  But I really believe you would be surprised about how little it takes to fire up sensitive woofers =)


Edited by REIER - 20 March 2019 at 11:31am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2020 at 5:53pm
been looking at a load of 4/5/6 channel amps. these look decent and can be configured to run bass plus two channels for mid/high

Hertz HPD 4
Bassface DB4.5
Precision Power PC1000.5D
Taramps TS 2000X4
Fusion SG-DA41400

The Taramps looks like the best spec. Not sure about importing from Brazil - think you just pay the VAT which would bring it up to ~£300 same as the others.

just spotted an ex-demo Bassface for £165 on ebay which is half the price of any of the others new. there's two more left if anyone is looking.


Edited by snowflake - 30 December 2020 at 6:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2021 at 9:45pm
bassface amp arrived going into protect mode so it's been returned.

another Brazilian amp:
http://bandaaudioparts.com/amplifiers/elite-line/elite-4000-4/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spanners5 Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2021 at 10:58pm
Originally posted by valve head777 valve head777 wrote:

Originally posted by APW APW wrote:

Originally posted by carlosdelondres carlosdelondres wrote:

How many Ah is the battery? - even a 220 Ah only has ~3.5kWh at most at that sort of discharge rat mode.  So running ~1kW system, maybe 3-4 hours before battery completely discharged, assuming reasonable duty cycle. And only discharge to 50% if you plan on getting much life out of the battery.


^^^^ this ^^^^

Assuming 100% efficiency, at 1500 watts a 110Ah 12v leisure battery (110Ah is a typical size for a leisure battery) will last less than an hour as your amps will be puling 125amp from the battery, however, in the real world your amps are only going to be about 80 - 85% efficient at best so to deliver 1500watts continuous you would be drawing at least 147amps from your 12volt battery, you would get about 45 minutes running if delivering 1500watts continuous into your speakers.

As audio isn’t normally a sign wave and depending on the music content you will probably get about 3 to 4 times this running time…. On a good day with a new fully charged battery you may get about 2.5 to 3 hours until the battery is completely dead.

And also as above... If you want your battery to last any length of time only discharge to 50-60%



Sorry more to add about batteries. The above calculation isn't taking into account the fact that the faster the amps are pulled from a battery, the LESS capacity it has. The  nominal  capacity of 110ah is at a 20h rate. This means 5amp load. The rate you are suggesting of 125+ amps will get nowhere near 45 mins and has the potential to distort the plates due to heat.
The suggestion of 48v nominal is good because although 4x 12v batteries are used, the current demand is lower. It's high current that knackers electronics due to heat (and batteries).
One more thing. The voltage drop under load must be taken into account. Large loads like above will see 10.5- 11v.
There is good info to be had within the off grid, marine and camping communities on batteries ie correct sizing. It's all important because if you plane an 8 hour party, and run out after 3..........

Valve head is right...... we have 6x 110 running 24 volt on our boat.....(plus 1x starter battery and 1x 110 for 12v fridge) you'll be shocked how quickly they need topping up.   have used 130 battery's but isn't noticeably better.... just more expensive. also flattening the battery's ruins them big time. on our boat we try to keep voltage above 24.4 volts (12.2 volts if was running 12v ) ..... we def charge them if they get down to 24.2volts (12.1 for 12v)  doing this makes the batterys live for YEARS longer. (i realise this is running a home not the odd party)  try to stay away from low box batterys (less lead) also if poss try to get the ones you can top up the acid.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2021 at 10:58pm
Sorry to hear your bassface was junk.

I can personally recommend the Kenwood KAC-X1D monoblock.

600w rms into any load, very reliable.  Most powerful kenwood ever made, (recent models not so). Ten year old now, and rare as unicorns, but pop up on the bay occasionally.

Used one for mobile lithium rig, thumped away from 16.8v down to less than 11v.  Faultless.

The KAC-X4D was a.much rarer matching 4-way 150wrms (or 2x300w).
I ran both on a 100A breaker and could trip with to much welly (amps were fused 60a each).  I could get four or five loud hours from about 120 18650 lithium cells (about 25 laptops worth of cells).


Edited by I-shen Soundboy - 11 January 2021 at 11:12pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spanners5 Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2021 at 11:03pm
wow 16.8 volts! thats ace!        the 6 volt battery's are supposed to be far superior than the usual 12v leisures too    
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 12 January 2021 at 11:20am
Originally posted by I-shen Soundboy I-shen Soundboy wrote:

Sorry to hear your bassface was junk.

I can personally recommend the Kenwood KAC-X1D monoblock.

600w rms into any load, very reliable.  Most powerful kenwood ever made, (recent models not so). Ten year old now, and rare as unicorns, but pop up on the bay occasionally.

Used one for mobile lithium rig, thumped away from 16.8v down to less than 11v.  Faultless.

The KAC-X4D was a.much rarer matching 4-way 150wrms (or 2x300w).
I ran both on a 100A breaker and could trip with to much welly (amps were fused 60a each).  I could get four or five loud hours from about 120 18650 lithium cells (about 25 laptops worth of cells).


I'm looking at four channel amps because they usually include seperate filter for each pair of channels, so can be used as a two-way crossover for bass and mid/high. saves on external crossover and load diversification should get the best out of the amp power supply.

I have looked at some 24V amps made for trucks but the ones I have seem very expensive - less of a competitive market and lower volums. I have got a 48-60V amp module in the garage that I just ran straight of four batteries in series, but some of these car amps seem like better value.
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