Batt. Powered amp users...

[pigmode]

How can you tell when your amp needs new batteries?

 

[thomas]

what amp are you using?

with the headroom amps, they have DC-DC converters/regulators, so it will always feed the same voltage to the circuit, until the voltage drops below a certain level, where the sound will just cut out. With these amps, just run it until the battery dies, and put in new ones.

Most DIY amps and the Grado amp do not use DC-DC regulators, so the voltage of the batteries is fed right to the circuity. So the performance will gradually degrade as the batteries get weaker, and eventaully cut out when the voltage is too low. So if you want the best battery life, also run it until it dies, though the sound will be terrible towards the end. If you want the best sound, you should replace the batteries when you feel the sound is no longer sufficeint/for high impedence headphones its no longer able to drive them without clipping.

 

[jude]

Aside from other obvious reasons (economy), I use NiMH rechargeable batteries because of the way they discharge -- that is, the discharge curve is quite flat (battery holds high voltage) up until it's just about out of juice, at which point the curve takes a steep dive. Most NiMH cells will remain in full voltage through 80% of a use cycle (according to information I read at Thomas Distributing, which is where I order my rechargeables from).

From an audio application perspective, this flat discharge curve can be advantageous, as you don't have continually dropping performance from the very beginning of installation like alkaline batteries.

Because I have chargers at home and at the office, I very frequently charge my batteries, so I haven't yet had my portable amps start acting up on me due to battery charge issues.

 

[pigmode]

I have a JMT. You're right though, it started clipping when playing my more demanding discs (MFSL). I could hardly detect any distortion with my other high quality CDs. I guess I left it on overnight a few times too often, lol.

 

[pigmode]

Jude, how does the batt. life of rechargables compare to alkalines? What brand of batteries and recharger are you using?

 

[jude]

Quote:

Originally posted by pigmode Jude, how does the batt. life of rechargables compare to alkalines? What brand of batteries and recharger are you using?

pigmode,

I wish I could be of more help to you on the battery life question, but I pretty much never let them die down enough to know (I charge them very frequently).

As far as chargers go, I'm using a MAHA MH-C204F, which I'm very happy with (I have two at home, and we keep two at the office, and we've probably got six or more altogether in my family). Checking out Thomas Distributing's site, I see they have a new charger that I've not used yet, but that I'm considering buying because it also charges rechargeable 9-volt batteries, which the MAHA MH-C204F does not do.

As far as batteries go, I use NEXcell, MAHA, GP, and POWEREX by MAHA.

 

[Redwoood]

Hey, somebody has 999 posts here.

Hey, jude, how's the weather in Michigan, right now ? (cheap way to make the 1000....)

Ok, to get on-topic again... the penguins use 9V batteries, right?
So do you have NiMH for them as well?

Bye

Redwoood

EDIT: Damn, too late!

 

[Tim D]

pigmode:

Rechargable NIMH technology on AA's or AAA's is great.

On 9V's...well things seem to still need working out although there are some accounts of good ones, it definitely lacks the standard that AA's have.

A lot of rechargable 9V's are not rated at 9V for instance...and there are instances of them having even more. 9V rechargable technology is not as mature or very common, or even standardized.

Also if you have standard JMT 1 9V fare amp, IMO a wallwart supplying 12V or more can be even better for home use, both battery saving and sound quality wise. I can flip through voltage settings on the wallwart with the 9V adapter, and see the LED grow brighter and dimmer. Cmoy's apparently can handle a lot more voltage than 9V and take advantage of it (like the RA-1 uses 2 9V).

 

[jude]

Quote:

Originally posted by Redwoood Hey, somebody has 999 posts here. Hey, jude, how's the weather in Michigan, right now ? (cheap way to make the 1000....)

Redwood, the weather's quite fine actually! 76.8 degrees Fahrenheit and very sunny (though I'm actually more of an autumn, winter and rain kind of guy). Wow, well will ya look at that! 1001 posts -- well on my way to Headphoneus Supremus! Hehe....never did get around to changing the user title structure, did we? Maybe later.

 

[pigmode]

Tim, I opted for the 8-pack of AA batt.s for the increased voltage. Anyway, thanks all, I'm off to order some stuff.

 

[ppl]

All of My Diy amps use Ni-MH and I put a Zener Diode in series with the LED and it's Droping resistor. When the Proper Zener is selected the Blue LED goses out and this tells me it is time to recharge or the Sound will stop in about 5 min. as Jude states NI-MH cells stay at a normal voltage untill thay are depleated. as far as 9 volts go the Radio shack 9 volt NI-MH Cat #23-526 is a true 9 volt. Thomas dist that Jude uses is a great place to get batteries and thay have the Plainview Medical grade 9 Volt that is also like the radio Shack ones true 9 Volt. I only use 9 volts in my Pocket Amp and AAA's in the others since i have had to replace most 9 volt NI-MH after about a year. and the AAA's and AA's have lasted for Years. The Notable exception is the Plainview 9 volts that are over 2 years old and still going strong and holding as good of a charge as when New.

 

[Beagle]

Quote:

Most DIY amps and the Grado amp...the performance will gradually degrade as the batteries get weaker, and eventaully cut out when the voltage is too low

Oddly enough, with the RA-1 I have found that different batteries give a different result when they start to go low. Usually, the red light on the RA-1 will get gradually dimmer over the course of a week. When the light gets almost dead, if you crank up the volume, the sound gets distorted. With other brands of batteries, the sounds starts to go before the light fades.

 

[DarkAngel]

I have Grado RA-1 and use NiMH rechargables, Ray-o-Vac, along with matching wall charger. Four 9 volt batteries and charger cost $35.

Grado says 40 hrs for regular alkalines but this is optimistic IMO,
figure more like @25-30hrs of good clean sound, as batteries start to die sound gradually becomes distorted. For rechargeable 9 volt NiMH figure roughly half the time for regular alkalines or @15hrs. Since you have two sets of batteries
no need to push the limits.

The new NiMH have no memory, and are said to be usable for 500 or more cycles, if you change once a week like me that is a long time (10yrs per set, 20yrs for my two sets)

 

[eric343]

I'm sure Apheared has a D-Cell battery pack made of the 8000mAh batteries... Heck knows I want some

 

[davidcotton]

Quote:

Originally posted by pigmode How can you tell when your amp needs new batteries?

When nothing works anymore????!!!!!