Hiraga "le monstre"

[danieljw]

it was definately in class A

if you set the bias for 0.6A at 13.5V then it would be more like 0.5A at 12V

actually i am thinking of getting 2 50Ah lead acid batteries (car batteries)
for the le monstre... I just want to test it with a power supply first to see what its like and iron out and little glitches

-Dan

[neazoi]

Originally Posted by danieljw

it was definately in class A

if you set the bias for 0.6A at 13.5V then it would be more like 0.5A at 12V

actually i am thinking of getting 2 50Ah lead acid batteries (car batteries)
for the le monstre... I just want to test it with a power supply first to see what its like and iron out and little glitches

-Dan

I will have this bias setting in mind. If the difference is so small then the compensation circuit is not needed. (nice)

A warning about the NON Deep cycle lead acid car batteries, they can be damaged much more easily than deep cycle ones if they are deep discharged.
Car batteries are MUCH cheaper though. In Greece you can find one for 50Euros or so, where as deep cycle ones are about double the price.

[danieljw]

yes... I would love to buy some deep cycle lead acid batteries.

but car batteries here are about $100 or less if you get a good deal.

deep cycle in a 40+ Ah size are very expensive more than three times.

although i would prefer Sealed lead acid deep cycle... i have no problem making a charger/power supply which will keep them in good condition.

my plan is to make a voltage regulator based supply with a very basic transistor based switch on a relay.

so it runs on batteries until it hits 12V and then the supply charges back up and then turns off - what do you think ?

-Dan

[neazoi]

Originally Posted by danieljw

yes... I would love to buy some deep cycle lead acid batteries.

but car batteries here are about $100 or less if you get a good deal.

deep cycle in a 40+ Ah size are very expensive more than three times.

although i would prefer Sealed lead acid deep cycle... i have no problem making a charger/power supply which will keep them in good condition.

my plan is to make a voltage regulator based supply with a very basic transistor based switch on a relay.

so it runs on batteries until it hits 12V and then the supply charges back up and then turns off - what do you think ?

-Dan

It sounds ok to me. Even for the deep cycle batteries the manufacturer suggests not to discharge them less than 12v to last more.

Be aware of this "live" switching of the charger though. You may want to think to have a mute circuit to mute the music just before switching on the charger and then un-mute it a little bit after the charger is connected. But you have to test if this is necessary. Also you have to think of how you would charge the batteries, as they are in series. you cannot charge them one at a time.

In my implementation I use a double switch and when I want to charge the batteries, the amplifier is always stay off. also I am not charging the batteries because this was not recommended by the manufacturer, so another switch selects which battery should be charged each time (twice the time to charge both but a smaller charger needed)
My batteries are 80Ah so they take more to charge.

Another thing you ave to think of is that the charger may be quite noisy (some of them ar switching mode chargers) and this will have an effect in sound, so I do not know if this is a good idea to connect the charget at the time you listen to the music. If you want this, then maybe you should not go for a charger but for the hybrid hiragas approach.

In my setup I do not care about charger noise because when I charge the batteries, the amplifier is switched off.

[danieljw]

totally agree i plan to use a normal linear regulated supply the same supply which can run the amp to charge the batteries. the other option i thought was put a voltage display on the amp and just use the manual method.

I do have the original charging circuit somewhere...

-Dan

[neazoi]

Originally Posted by danieljw

totally agree i plan to use a normal linear regulated supply the same supply which can run the amp to charge the batteries. the other option i thought was put a voltage display on the amp and just use the manual method.

I do have the original charging circuit somewhere...

-Dan

The collected info, including the circuit you are looking for can be found in my audio page at Audio Constructions

check the le monstre under projects

[bobodioulasso]

I would see an automatic and silent charger automatically switched on when the amplifier is not in use. The charging power selected according to the time you want usually listen to your amp.

[danieljw]

thanks Neazoi, the manual switched option is probably the easiest.

[neazoi]

As bobodioulasso stated, a good technique would be to have the batteries charged when the amplifier is switched off. Using an automatic charger can compensate for over charging and battery maintenance, to keep the battery always fresh.

Then a simple circuit to switch off the amplifier when the voltage goes below 12v could be desirable! this can be made even more clever, by warn the user a few minutes before the voltage gets to 12v. (we do not like if the music cutts off rapidly)

[danieljw]

the switching off to charge idea even better !

another thing i did some rough calculations...

say the battery is 80Ah@12V that is 960Wh per battery total 1920Wh
the amp draws a continous (maximum) 12 watts or so for a stereo pair 24W

the run time is more than i expected originally..
maybe more like 40h ?!??!??!?!?!

not sure if this is accurate depending on the discharge curve of the battery

-Dan