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Old 14th July 2012, 10:21 PM   #1
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Default lm49710/49720/49870/49860

Hello there,

I am new, to the forum, and would like to know the differences between the LME49710
LME49720
LME49870
LME49860

I am trying to design a series of high fidelity portable amps that will use either one of the chips above, but I don't know enough about audiophile resistors, components etc to make a decent system or even electronics. So I thought I could ask here and maybe get some assistance?

I also don't know what the dual means..there are two of the chips inside but what is the purpose? - a balanced left and right?
Is there a benefit to dual chips over one?

Is there a benefit of balanced over mono sound wise?
Can any of the chips above provide a balanced output?

Is a balanced input better, considering that most high end devices tend to use unbalanced?
Considering its already recorded then I guess you dont want distortions in the cables hence a balanced design is more desirable?
does balanced TRS have the same effect as two output lines?

The first amp was a simple 4881M
mid range with 49710
and top end unit with two balanced outputs.

thanks

Iain

thanks

Iain
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Old 15th July 2012, 12:08 AM   #2
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The 49720 is just the dual version of the 49710. Same thing with the 49860 and 49870.

The only difference between the 49710/20 and 49870/60 is the later two have a higher voltage rating (not needed in most cases).

Yes, "dual" means two op-amps in one IC package. Duals make PCB layout easier for obvious reasons, but singles can come in handy for applications where they might be dissipating a lot of heat.

There's nothing inherently "balanced" about a dual op-amp IC, but if you want to build a circuit with balanced outputs you have to use two op-amps.

I don't have an opinion on balanced vs unbalanced. Plenty of info on that subject if you search.
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Old 16th July 2012, 02:41 AM   #3
johnr66 is offline johnr66  United States
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I wonder what the difference is between the LME49720 & LM4562. Data sheet specs are identical.
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Old 16th July 2012, 11:21 AM   #4
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Quote:
Originally Posted by johnr66 View Post
I wonder what the difference is between the LME49720 & LM4562. Data sheet specs are identical.
AFIK just the name. It's been suggested that when the LME series was introduced they just rebadged it.
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Old 16th July 2012, 05:05 PM   #5
qusp is offline qusp  Australia
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so your first headphone amp design, perhaps even first electronics design, you are seeking knowledge on what opamps you can use for balanced and you are dubbing it 'high end'? with a couple of 5 dollar chips? you'll have to do better than that i'm afraid.

there might be a couple of manufacturers, whom I wont name (you know who you are) that make glorified Cmoys and call them high end amps, but that doesnt mean they all do, or that you should. we have enough of that thanks.

I dont discourage you to have a bash, but I implore you to not enact the phrase high end without proper design, proper measurement validation.

its a pretty darn crowded marketplace, are you sure you know what you are getting into? sure you can look at SOME of the offerings around, see the pretty cases and see how easily some of these chaps will open their wallets and think you can make a killing, but most of these people that can charge this sort of money (500+) have earned a name for themselves for being around for a while.

the market and consumer is becoming more savvy, I believe unless you have an audiophile gimmick, or the amps are very well designed, very compact and very attractive (this means a small run of custom CNC enclosures) you will fade into the background pretty quickly.

the chips you have mentioned are good, if somewhat whitebread, you would have to do something special with them to make a great amp

most high end devices use unbalanced input? sounds like all youve done is give the pages at HF a pretty cursory glance and are not even a headphone fan; do you have any high quality headphones? dont say beats....

excuse the skepticism, its just that it sounds like you are looking to release a range of high end headphone amps yet.
• you are not a headphone hobbiest
• you have never designed a headphone amp
• you have never really designed an electronic device
• you have not done your research
• you do not know your customer
• you have misjudged your customer

Last edited by qusp; 16th July 2012 at 05:13 PM.
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