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Old 7th August 2003, 05:26 AM   #1
cowanrg is offline cowanrg  United States
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Default current draw on a gainclone?

what is the typical current draw on a gainclone? im asking because ive been towing with making battery powered monoblocks. it would be cost effective for around 30 AH worth of batteries or so.
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Old 7th August 2003, 05:38 AM   #2
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What chip, what voltage rails, what impedence speakers, what.. umm... something else.. lol hmmm ah.. who knows.. lol
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Old 7th August 2003, 05:52 AM   #3
halojoy is offline halojoy  Sweden
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Default Re: current draw on a gainclone?

Quote:
Originally posted by cowanrg
what is the typical current draw on a gainclone? im asking because ive been towing with making battery powered monoblocks. it would be cost effective for around 30 AH worth of batteries or so.
Gainclones runs in Class B or at best AB.
So the current drawn is not very much.

Consumption increases the higher volume you play.
And of course the more music you play.
At idle it could be max 0.1-0.2A or like that
for a stereo.
For high volume, my guess is around 1-2 Ampere, for stereo.
Depends a little on how sensitive your Loudspeaker are.
You know SPL/1 watt input. Measured in dB.
SPL Sound Pressure Level at 1 watt input (8 ohm)

halojoy - would think that covers the basics
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Old 7th August 2003, 02:36 PM   #4
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Default Re: Re: current draw on a gainclone?

Quote:
Originally posted by halojoy

For high volume, my guess is around 1-2 Ampere, for stereo.

Am I spending too much money on 400VA toroids?
Halojoy, what do you call high volumes?
Remember, this is a power op-amp.
No miracles (anyway, I don't believe them ).

Anyway, cowanrg, make a search on this forum and you'll find the information you need.
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Old 7th August 2003, 03:08 PM   #5
halojoy is offline halojoy  Sweden
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dear carlosfm

1A per amp is an AVERAGE output of 4 Watt in 8 ohms = +6dB
this means an AVERAGE Sound pressure level of 88+6 = 94 dB
if Speakers have sensitivity 88dB (my have mostly 92-95)

94 dB is an awful lot of volume in a normal living room.

you might not believe this,
but there are Tube guys who lives happily with amps
of no more than 5-8W MAXIMUM output.

And what about JLH 10 W class A amp?
One the most famous DIY amps in this world.

Okay,
IF you have very large room and
IF you have very low sensitivity in LSP and
IF you have very low average impedance LSP, say 3-4 Ohm
IF you listen at full volume all day long

I can agree on the average Ampere Consumption would be
twice my first given number; 2 Amp/stereo

Of course you have not waisted your money
on your high spec power supply - an amp gets
no better than what the supply allows it to

In this case the guy wants to know how long his batteries
would expectedly last before being halfempty

30 AH rated should not be discharged no more than 50%
give us: 16AH/average Ampere=Hours of playing/per day
(I assume we charge during nighttime/work)

In my first case 16/2 gives 8 hours of total playing time
worst case 16/4 Ampere gives 4 hours

I myself have Carbatteries rated 60AH,
would give me at least 30/4 ampere = 7.5 hours playing time
That is totally sufficient.
no one listens to music on max volume like 7 hours a day.

For class A amplifiers, it is easier to calculate drawn current,
it is constant.
But class B is more effective, and dependent of musical power drawn.

Remember that music power (the power consumed in class B)
is a lot lower than RMS power.
That is why we see those high numbers sometimes
in advertising.

halojoy - knows nothing about which is best gainclone
but has a hunch on matematics, hopefully
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Old 7th August 2003, 03:55 PM   #6
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Halojoy,

Don't get me wrong.
Not everyone has 92-95db speakers.
And some of the best speakers need current to play at they best.
My Epos speakers are 86~87db, you need a good amp to drive them and my GC drives them very well.
But I woudn't use a 2A transformer.
What I have is a 2x24V / 8A toroid.

You didn't understand me, I wasn't talking about power.
I think that current delivery is much more important than power.
And 100 watts RMS is just the double of 10 watts RMS in terms of power, not 10x more.
I could live very well with a 20w amp with a good current delivery.
After all, you normally listen below 1 watt.
But 1 watt on a good amp is not like 1 watt on a bad one.
Even at very low volumes I can hear my Epos sing like they never had, and all the dynamics is there.
It's good to listen to music at night.
Impossible to do with the Nad amp I had, which had around the same power as my GC.

And BTW, I think that the PSU is the most important part of almost avery device, and amps more still.
Make compromises here and you're ruining everything.
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Old 7th August 2003, 05:53 PM   #7
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hi carlos,

there is nothing like voltage if you have speakers with low efficiency.....many watts are needed, and if they are a difficult load too then you need both voltage and amps.......
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Old 7th August 2003, 06:08 PM   #8
cowanrg is offline cowanrg  United States
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sounds good. all i wanted was a general estimate. i dont build things mated to any speaker, or to any particular volume level either. ~2 amps for stereo will work well. just toying with ideas of course.

it would be about the same price to do 30AH of power for monos than doing a couple nice toroidals...
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Old 9th August 2003, 05:20 AM   #9
Konrad is offline Konrad  Norway
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The LM3886 has an idle 50-80mA and therfore is making som heat, not mutch but inoff to be konsidered. +/-35v gives 60mA*35 *2 = 4.2w as a typical value.
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Old 9th August 2003, 06:58 AM   #10
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i think its more useable to know how much it draws when playing loud - with difficult load.
as i recall, its internal current limit is 5 amps.....
i would dimension the amplifier from that......
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