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Old 5th November 2007, 07:49 PM   #1
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Default Audio CFB Opamp

Hot off the presses:

it's a wow

http://www.national.com/ds/LM/LME49713.pdf
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Old 5th November 2007, 07:59 PM   #2
x-pro is offline x-pro  United Kingdom
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Default Re: Audio CFB Opamp

Quote:
Originally posted by jackinnj
it's a wow
In what respect "wow"? I can not see anything particularly interesting from the datasheet. Perhaps it may sound good in some appliciations but that only a listening test can tell.

Alex
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Old 6th November 2007, 01:38 AM   #3
Ipanema is offline Ipanema  Malaysia
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This opamp spec sheet looks fantastic. BTW, can it drive a 32ohms headphone or is it good for an opamp based power amp since the current output is +/-100mA.

Thanks.
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Old 6th November 2007, 04:29 AM   #4
Tim__x is offline Tim__x  Canada
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Looks pretty nice.
Though the high value feedback resistors will ruin noise performance.
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Old 6th November 2007, 07:36 AM   #5
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The performance is similar other CFB opamps like the TPA6120 but since I like CFB it looks wow.
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Old 6th November 2007, 07:39 AM   #6
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Quote:
Originally posted by Tim__x
Looks pretty nice.
Though the high value feedback resistors will ruin noise performance.
It's a good point but also quite irrelevant because it's a CFB topology which is useless for high impedance network, it's against it's nature. In this case Tim, you must do you homework about CFB amps.
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Old 6th November 2007, 04:46 PM   #7
Tim__x is offline Tim__x  Canada
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I understand how CFB works. Look at page 6, good stability appears to require at least a couple Kohms of feedback resistance.

This CFB opamp is optimized for slightly higher values in the feedback network than many other opamps. It's not a huge concern, but it is a valid and considered complaint.
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Old 28th November 2007, 07:34 AM   #8
Tolu is offline Tolu  Germany
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I don't see the point. 1.2kOhm isn't the issue I think.
The slew rate is extraordinary.

I would test how it sounds in a preamp but National wants 30$ for 4 sample chips!

Anyone just tried it?
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Old 28th November 2007, 07:44 AM   #9
banana is online now banana  Hong Kong
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1.2Kohm would be an issue, if u multiple it with 16pA/rtHz current noise density. But that's the case only when gain is low.
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