Battery Pack For Amp

After reading David Kan's February 2007 6moons review of the Trends Audio TA-10 amp at http://www.6moons.com/audioreviews/trends/ta10.html I decided I'd like to experiment with battery power to see for myself if it can actually improve the sound quality of my soon to arrive TA-10.1 as claimed. Not that it will necessarily need improving for the use I'll be putting it to, but I'm curious. Kan mentioned he was using a Xantrex Powerpack 300 EP for his tests. This battery pack was designed primarily for automobile use and incorporates a compressor pump and hose for inflating tires, booster cables to jump-start your engine as well as a built-in flashlight. That's all well and good, but I have no use for a compressor pump, booster cables or any more flashlights, and in the room where my TA-10.1 amp will be used space is at a premium (part of the reason I bought the mini amp in the first place.) Can someone recommend a more compact, bare bones battery pack that would work well with the likes of a TA-10.1 amp?

I realize hooking things up to any old rechargeable 12 volt battery would do the job, but there's one caveat Kan states in his review:

"The Tripath T-2024 chip has an absolute working parameter of 8.5 to 16 volts DC - either too much or not enough is bad for the chip."

The Xantrex Powerpack 300 EP has an auto-shut-off feature that sets off a low-battery alarm at 11 volts and shuts down when the voltage drops to 10.5 volts; a nice safeguard for the Tripath chip -- the sort of safeguard I'd like my bare bones battery unit to have, too.

Any recommendations anyone could make would be most appreciated.

Hi,

I have a Diyparadise Charlize TA2020 amplifier, that I power using a rechargeable 12VDC SLA battery. This battery has a 7Ah capacity, and I take care not to run the amp with it for more than 4-5 hours, before recharging it.

With the battery powering the amp, I measure very close to 12V at the battery terminals, so I do not think you will have an issue with frying the tripath chip due to overvoltage.

On the other side, below 10.5V, you are going to end up reducing the life of the battery. I am not sure low voltage will damage the amplifier itself, but I could be wrong.

To protect the battery, you could hook up a relay whose coil has a minimum operating voltage of around 10.5V. Any voltage below this will de-energize the relay, and open a contact that will disconnect the amplifier from the battery, and connect the battery to the charger. You will need to search a little bit to find a relay that drops out at exactly the voltage you want.

I do not know of a readily available battery pack with the kind of protection that you are looking for.

Hope this helps,

Ashok

Thanks, ashok, for the suggestion. While I'm no electronics wiz, I'll start by looking for that relay and see if I can work things out from there.

Battery hookup to amp

Hi tonsl,
The way I see it is that the battery is able to deliver a lot more current than the power supply of the amp or even the AC Power thingy, my previous experience in building amps was that I would always design a regulated power supply for exactly that same reason...(more/better bass definition and power handling and less hum too) also do not forget that the protection circuit of that thingy is also adaptable to a battery feeding the same amp, it's called an over voltage/under voltage protection circuit. You could ask someone with abilities in electronics in your area to make one for you.
Just my opinion, hope this helps a bit.
Maurice

Thanks for the input, Maurice. I'll see what I can put together and hope it doesn't destroy the Tripath chip in my amp. If you see a mushroom cloud on the horizon you'll know something went horribly wrong!

i have no plans to use my trends audio tripath amp with a battery pack, but i am very pleased with it on a pair of vintage, hi-eff. Frazier speakers. imaging and dynamics like i cannot believe

Overvoltage protection

Hi tonsl,
I was thinking again about your "hesitation" about your Tripath amp module being damaged and I remembered a quick and inexpensive way to tackle the overvoltage bit with a minimum of fuss... just go to your nearest or usual electronic store and get a zener diode rated at around 15 to 15.5 volts at 2w (1w would probably be ok too) and connect the zener in PARALLEL with the 2 wires feeding the amp, with the cathode (black band usually) connected to the positive and the other side to ground but also do not forget to insert a fuseholder in SERIES with the positive wire BEFORE the zener (you will have to find out what the maximum current drawn by the Tripath is?? let's say it's 5a then you put a 6amp fuse or 5 1/2 amp) what this will do is that let's assume the voltage goes higher than a 15v zener, well the higher it goes above the zener voltage and the more the zener will act as a short accross the battery and at a point above 15v it will blow the fuse quite quickly because after you go over the voltage of the zener it reacts fast... (don't worry too much about the "short" accross the battery because it will not last very long and the battery will only see it as a momentary surge of current...) and as for the low voltage bit, I would not worry about it because all it would do is lower the efficiency of the Tripath.
Hope this helps also
Maurice

Thanks, Maurice. This sounds like a quick and easy safeguard for overloads. I'm still not sure about underloads, though. As mentioned in my first post, the article I was quoting from stated: "The Tripath T-2024 chip has an absolute working parameter of 8.5 to 16 volts DC - either too much or not enough is bad for the chip." Possibly when the author indicated that underloads were "bad for the chip" he just meant that the chip would not work properly, or to full capacity, rather than meaning that the chip would be damaged. It does seem unlikely that the chip would be damaged by insufficient power. Or is this something peculiar to the Tripath chip?

shrinkboy stated:

"i have no plans to use my trends audio tripath amp with a battery pack, but i am very pleased with it on a pair of vintage, hi-eff. Frazier speakers. imaging and dynamics like i cannot believe."

Have you by chance tried the Trends amp with any other speakers? In keeping with the mini theme of the amp I was planning on using some Minimus 7 speakers (acoustic bass version) with mine. I've heard mixed results when using such speakers with Sonic Impact's Super T-Amp, but nothing about using them with the Trends amp.

Hi tonsl, Like you said the Tripath will not perform at full potential below this voltage, and furthermore with my 30 yrs+ of audio and electronic "tinkering" I would be EXTREMELY SURPRISED if something BAD would happen... undervoltage only prevents the circuit from operating at it's full potential... nothing else. You said "The Tripath T-2024 chip has an absolute working parameter of 8.5 to 16 volts DC " and that's exactly that: WORKING parameters.
P.S. I just went to the Tripath site and I read the complete 18 page pdf about the specs of this unit and I'm quite certain there is NO problem for low voltage, it will NOT be FULLY functional...that's it. It would be like operating a 12v car headlamp with a 6v battery... dim.. Anyway why would you make it work at that low voltage??? the sound would be BAD before that anyway...
Truly
Maurice

I have some experience designing Tripath-based amplifiers. Overvoltage beyond the published spec is definitely a bad thing and likely to destroy the chip. The more sophisticated Tripath controllers have a built-in undervoltage monitor and will shut down the amplifier if the voltage drops below a threshold set by a resistive voltage divider. Tripath chips in a well-designed and laid out setting are also pretty forgiving of shorted outputs. With a battery only supply not float charged you will probably wind up "pumping" the amplifier if you allow the voltage to drop too low. When the battery voltage sags enough to trip the undervoltage shutdown, it will probably be under load. The shutdown removes the load, the voltage rises, and the amplifier turns on again, which drops the voltage and it shuts off. Depending on the care the designer took, this may happen at an audible rate with a lot of turn-on pop and sound like a machine-gun.

When I designed the Mouse amp, I put in a one-second time constant for short circuit faults and undervoltage. This allows things to recover gracefully in the event of a problem with only a faint turn-on "tick". The Mouse runs on a 30-volt supply, not 12, though. I've been playing with battery options but the most logical configuration is five, 6-volt SLA batteries in series. The batteries would be about four times the size of the amp itself and ten times as heavy. The Mouse is quite a bit different from the single-chip designs in terms of power output and drive capability. There are actually three Tripath chips in it, the controller and a separate power amplifier for each channel. A Mouse with battery supply will push about 90 WPC clean at 4 ohms.

The 2024 chips are all-in-one controller and power stage and not as flexible as the TC2001 controller and separate TP2050 power amplifier, also much lower power. A battery isn't going to help much if you're using an 8-ohm nominal load as you're voltage-limited. Depending on the design of the amplifier and its stock power supply and wiring, it might help the bottom end and also give more output if your speakers have impedances that dip to 4 ohms or below.

An SLA battery on float charge is about 2.25 volts per cell, so a nominal 12-volt battery is 13.5 volts if you float-charge it and operate the amplifier while charging. This shouldn't hurt anything and you can leave the charger connected permanently if it is a constant-voltage float type. But, most power supplies sold as battery chargers are pretty dirty. You could design a clean regulated 13.5 volt regulated supply and float the battery across it which would give the best of both worlds, the high current battery capacity and not having to worry about running the battery down. The 7AH batteries mentioned are very common, seen often in burglar alarm service and the like.

Note that these batteries are capable of very high currents. You'll want a fuse close to the battery to keep from melting wires in the event of a short in the amplifier or charger.

Maurice:

I think you summed it up nicely when you stated "why would you make it work at that low voltage??? the sound would be BAD before that anyway..."

Very true. If there's really no danger to the chip from undervoltage -- and apparently there isn't (contrary to the article I quoted) -- then there's really no need for an alarm or auto-shut-off feature on the battery.

Jukin Jay:

The float charge method you mentioned sounds like the best, most hassle free way to go when using battery power. I'll definitely be looking into this further. Incidentally, the last time I saw the Mouse Amp mentioned here the website for it wasn't yet up. I just found out it now is and had a look at it ( http://winsome-labs.com ). The three-chipped mouse amp sounds like the wave of the future in miniature amps. I'd like to see it featured in the stereomojo roundup of new amps to be covered this month ( http://stereomojo.com/AMPSHOOTOUT_000.htm ).

Thank you both for your input.

tonsl-- i am very far from some o' these other guys in my knowledge and understanding of the electronics involved here, but, i have hooked the sonic impact tripath 2024 amp to a variety of speakers, up to and including the ADS L-810, a big, 4 driver, 3-way, acoustic suspension speaker, on which it sounded amazingly good. i have also run it on the Minimus 7. it will run on the Min 7, but i have come to think of the Tripath amps, like the Trends Audio one i just picked up, to be in the same league as low watt tube amps. and this then leads you to high efficiency, revealing speakers to really show off what these little guys can do. so i would recommend the same to you: just because it is small doesn't make it a 'mini'-- it will fill a room with great sound and all the dynamics like soundstage and depth of field that we like.

tonsl said:

Maurice:

Jukin Jay:

The float charge method you mentioned sounds like the best, most hassle free way to go when using battery power. I'll definitely be looking into this further. Incidentally, the last time I saw the Mouse Amp mentioned here the website for it wasn't yet up. I just found out it now is and had a look at it ( http://winsome-labs.com ). The three-chipped mouse amp sounds like the wave of the future in miniature amps. I'd like to see it featured in the stereomojo roundup of new amps to be covered this month ( http://stereomojo.com/AMPSHOOTOUT_000.htm ).

Thank you both for your input.

Click to expand...

Thanks for the link, I have written to stereomojo and am willing to loan them a unit if they wish.

EDIT: Stereomojo replied, they are no longer accepting amplifiers for the "shootout".

tonsl said:

After reading David Kan's February 2007 6moons review of the Trends Audio TA-10 amp at http://www.6moons.com/audioreviews/trends/ta10.html I decided I'd like to experiment with battery power to see for myself if it can actually improve the sound quality of my soon to arrive TA-10.1 as claimed. Not that it will necessarily need improving for the use I'll be putting it to, but I'm curious. Kan mentioned he was using a Xantrex Powerpack 300 EP for his tests. This battery pack was designed primarily for automobile use and incorporates a compressor pump and hose for inflating tires, booster cables to jump-start your engine as well as a built-in flashlight. That's all well and good, but I have no use for a compressor pump, booster cables or any more flashlights, and in the room where my TA-10.1 amp will be used space is at a premium (part of the reason I bought the mini amp in the first place.) Can someone recommend a more compact, bare bones battery pack that would work well with the likes of a TA-10.1 amp?

I realize hooking things up to any old rechargeable 12 volt battery would do the job, but there's one caveat Kan states in his review:

"The Tripath T-2024 chip has an absolute working parameter of 8.5 to 16 volts DC - either too much or not enough is bad for the chip."

The Xantrex Powerpack 300 EP has an auto-shut-off feature that sets off a low-battery alarm at 11 volts and shuts down when the voltage drops to 10.5 volts; a nice safeguard for the Tripath chip -- the sort of safeguard I'd like my bare bones battery unit to have, too.

Any recommendations anyone could make would be most appreciated.

Click to expand...

If you have not resolved this, I can refer you to some simple low voltage shutoff circuits that do not require significant voltage differential between input and output voltages. Just PM me and I can send you some links.

I brought this one up from the depths because it too is an oldie but a goodie.

One more thing- when using those bosster battery packs- the battery inside is usually just a gelled electrolyte type. The battery is replacable, as well as the option of transplanting the circuitry to it's own box.

You do not want to discharge those batteries below 80% capacity, and you also do not want to leave them on a float charge as it will cook out the battery in about a year if your lucky.