[drphoto]

I just got Lepai T-amp (see post in C&C circle). It needs more current than the 3 amp wall wart. Regulated linear PS too expensive. Plenty of regulated switching types out there that are $20 or less.

But I got to thinking maybe a big LiPo or even a motorcycle battery might work and be cleaner.

My question is can I hook it up to the amp directly? Or would it need to go through some sort of regulator?

thanks

[Steve]

I just got Lepai T-amp (see post in C&C circle). It needs more current than the 3 amp wall wart. Regulated linear PS too expensive. Plenty of regulated switching types out there that are $20 or less.

But I got to thinking maybe a big LiPo or even a motorcycle battery might work and be cleaner.

My question is can I hook it up to the amp directly? Or would it need to go through some sort of regulator?

thanks

I will go step by step since I am unfamiliar with your expertise. No harm meant drphoto.

Is there a minimum and maximum supply voltage rating for the T-amp listed? If so, I would use a voltage within that range.

If 12 volts is within the low to high supply voltage range, yes you could use a lead acid motorcycle battery, or a car battery for longer life.
 
The output power will depend upon the supply voltage actually used in the recommendation range. For instance if one doubles the supply voltage, the
output power may rise by 3.5 times or so. Ok, what does this mean?

If the recommended voltage range is, say 10 to 30 volts, much more power output will be obtained with two motorcycle batteries are connected in series
for 24 volts than with 12 volts. However, a 12 volt supply may supply enough output power for your system.

Cheers and hope this helps dr.

Steve

[drphoto]

Steve, thanks for the reply. My experience is somewhat limited when it comes to the tech side of things. I have a basic understanding of electronic theory and I can solder pretty well. But that's about it. From what I understand, the nominal voltage is 12v, but the amp puts out max power at around 14.3V. And most users who are savvy say it needs at least 6 amps. I just wanted to make sure that if I use a battery I didn't need some sort of voltage regulation. i'm assuming that DC from a battery doesn't need any 'smoothing' from filter capacitors. Again, based on my rudimentary knowledge those are required in power supplies that use AC input to smooth the DC after rectification by the diode bridge.....correct? And I believe lead acid batteries actually output voltage more along the lines of 14V anyway, which would be a bonus.

Again thanks. I'm really enjoying this little amp. As per my post in C&C, the rated power output is a joke, but it does a lot of things very well.

[Steve]

Steve, thanks for the reply. My experience is somewhat limited when it comes to the tech side of things. I have a basic understanding of electronic theory and I can solder pretty well. But that's about it. From what I understand, the nominal voltage is 12v, but the amp puts out max power at around 14.3V. And most users who are savvy say it needs at least 6 amps. I just wanted to make sure that if I use a battery I didn't need some sort of voltage regulation. i'm assuming that DC from a battery doesn't need any 'smoothing' from filter capacitors. Again, based on my rudimentary knowledge those are required in power supplies that use AC input to smooth the DC after rectification by the diode bridge.....correct? And I believe lead acid batteries actually output voltage more along the lines of 14V anyway, which would be a bonus.

Again thanks. I'm really enjoying this little amp. As per my post in C&C, the rated power output is a joke, but it does a lot of things very well.

Ah, yes, it sounds like it was designed specifically for battery operation, which is good as it is designed differently. I don't mean that just the diodes and filter capacitors might be missing (unless it also can be operated from the wall). 6 amps, a car battery might be better as the battery's internal impedance will be lower, and with better regulation. However, the amp appears to be specifically designed for batteries.

One point, filter capacitors might be on board due to multiple stages, thus isolation between those stages.

Cheers
Steve

[drphoto]

Steve, thanks again for taking time to reply.

I looked at some motorcycle batteries and they were saying only like 1 amp. (but 10 amp/hr) not sure that will work, unless you know otherwise.

Stupid question. If I were to get a bench type PS, they generally show +V, -V and ground connections. The barrel connector to my amp is center pin pos & barrel neg. So I assume that means neg goes to the -V post on PS? Not to the ground. Right? I'm guessing that would just create a short. (told you I'm a little weak on the tech part)

cheers mate,

joe

[Steve]

Steve, thanks again for taking time to reply.

I looked at some motorcycle batteries and they were saying only like 1 amp. (but 10 amp/hr) not sure that will work, unless you know otherwise.

Stupid question. If I were to get a bench type PS, they generally show +V, -V and ground connections. The barrel connector to my amp is center pin pos & barrel neg. So I assume that means neg goes to the -V post on PS? Not to the ground. Right? I'm guessing that would just create a short. (told you I'm a little weak on the tech part)

cheers mate,

joe

Not a dumb question Joe. 1 amp/hr will discharge rather quickly. The internal impedance will increase rather rapidly, meaning the voltage will drop rather dramatically with loss of output power. A car battery is much much better, but also much heavier. Yes negative to the -V post.

Cheers and your welcome.
Steve

[mikeeastman]

Car batteries are not sealed and will gas off. Check out AGM on sites that sell solar equipment, also if you get a Cetek charger it will output 7 amp so it would be able to keep up with your amp and you could get by with a 20-30 amphr battery and the cetek is very quiet noise wise so you can leave charging will you listen and it will keep the battery at about 14v.

[Steve]

Car batteries are not sealed and will gas off. Check out AGM on sites that sell solar equipment, also if you get a Cetek charger it will output 7 amp so it would be able to keep up with your amp and you could get by with a 20-30 amphr battery and the cetek is very quiet noise wise so you can leave charging will you listen and it will keep the battery at about 14v.

Good point Mike. Gas is not your friend. But couldn't one enclose the battery with reasonable care, or too much headache with pressure, and proper materials?

Another quick question. In your experience, is there much hum produced at the output of the amp by adding a charger to the battery terminals while playing?
I ask because the battery's impedance is not zero, thus not perfect in reducing ripple produced by the charger, the rectifier. Maybe not enough hum to matter?

Cheers
Steve

[mikeeastman]

Steve, yes you could build a box but you would have to vent it to the outside. It won't have to be pressurized just sealed box with small hole near bottom of box for intake and on opposite end of the vent, which should be on top of box. I use a Cetek 7002 charger on my battery that powers all my sources, and it is dead quiet even when charging, so you should have no hum.

   Mike

[drphoto]

Sealed car batteries vent minimal gas from what I understand. And it would be hydrogen, which is not toxic. (flammable of course, but I don't smoke)

Right?

But I just checked auto zone website. Car batteries are pretty expensive. I may just get one of those $20 regulated switching PS from Amazon. Yeah, prefer linear, but I want to keep this a C&C system.

As described in my post there on the amp, I'm having fun with this setup because it greatly exceeded any expectations I had, which was simply "I hope it works". Once I start trying to make it 'better' then I fall into that old trap of becoming overly critical and ruining all the joy. I got enough stuff to worry about without obsessing over a hobby. 

But again, thanks for all the feed back.

Somewhere down the road, I may try to built an 'ultimate T-amp'. but for now? nope.

[Steve]

Sealed car batteries vent minimal gas from what I understand. And it would be hydrogen, which is not toxic. (flammable of course, but I don't smoke)

Right?

But I just checked auto zone website. Car batteries are pretty expensive. I may just get one of those $20 regulated switching PS from Amazon. Yeah, prefer linear, but I want to keep this a C&C system.

As described in my post there on the amp, I'm having fun with this setup because it greatly exceeded any expectations I had, which was simply "I hope it works". Once I start trying to make it 'better' then I fall into that old trap of becoming overly critical and ruining all the joy. I got enough stuff to worry about without obsessing over a hobby. 

But again, thanks for all the feed back.

Somewhere down the road, I may try to built an 'ultimate T-amp'. but for now? nope.

Your quite welcome Joe. It has been awhile, but I do know that with vented batteries, sulfuric acid is released. Every year I have to use baking soda to
neutralize the acid on the case and parts of the car body.

Cheers and all the best Joe.
Steve

[Speedskater]

There are several different constructions for car batteries and more new types for electric cars.
A better choice would be a deep cycle battery, that's similar to a car battery but not designed to start a big engine. Many sailboats have deep cycle batteries in there small cabins.

[srb]

I think the AGM (Absorbent Glass Mat) is preferable to the Gel Cell type and has lower internal resistance.

The problem with deep discharge batteries is the life may only be ~ 200 cycles when discharged to 80%.  Discharging to 50% roughly doubles the number of cycles and discharging to only 10% may increase the life up to ~ 2000 and more cycles.

That would mean to get a respectable battery life you would size the battery appropriately so you wouldn't need to discharge more than 10% to 20% in a days use or between charges.  That might mean a size similar to perhaps the smallest car battery, but maybe not one as small as a motorcycle battery.

You mention that the amp is recommend to have a 3A power supply, and other recommendations from users have suggested a 6A supply.  I imagine that is to accommodate peaks and transients for dynamic range, but it probably won't need near 3A average for listening.

A power meter like the Kill-A-Watt would be useful in determining how much power is consumed in actual steady state use over time to determine the battery size and runtime, as even the motorcycle size batteries should be able to provide any amount of peak current that might be required.

Steve

[Speedskater]

Much more info on batteries for boating.
http://www.westmarine.com/WestAdvisor/Selecting-a-Marine-Storage-Battery