Does anyone have some experiences with AD8671?
It seems to be a good replacement for (used to be) popular NE5534/5532. Ad 8671 has very low noise, low THD, high PSRR, it is unity gain stable... Drawbacks are that it is available just in SMD package and that in comparison with other adored opamps such OPA627, AD825, AD8065, ... it is quite slow - 4V/us. I plan to use it in active xover.
More info:
AD8671: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8671,00.html
AD8672: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8672,00.html
AD8674: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8674,00.html
Thanks
Daniel
It seems to be a good replacement for (used to be) popular NE5534/5532. Ad 8671 has very low noise, low THD, high PSRR, it is unity gain stable... Drawbacks are that it is available just in SMD package and that in comparison with other adored opamps such OPA627, AD825, AD8065, ... it is quite slow - 4V/us. I plan to use it in active xover.
More info:
AD8671: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8671,00.html
AD8672: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8672,00.html
AD8674: http://www.analog.com/Analog_Root/productPage/productHome/0,2121,AD8674,00.html
Thanks
Daniel
PMA said:
OK, so what else suitable do we have for active xover? I would prefer low noise, "normal price" (no OPA627) and dual/quad packages. I remember some opamp data measurements provided by BigBobo and the result was NE5532. I would like to use something newer ;-) but I do not want "nice"/colored sound. What are other possibilities? AD8066?
PMA said:P.S. At zije cesko-slovenska komunikacia! /in czech and slovak/
and also in English
AD8610/8620
Thanks, I have printed out datasheets for AD8671, AD8065, AD8610 and have read them last evening. AD8610 looks quite promissing, it seems to be "creme de la creme" of AD opamps. I was afraid how much will it cost but have found that it should be about three times cheaper than OPA627 so I could breathe it out. (Though AD8065 is again about three times cheaper than AD8610). Same should probably apply also to dual packages.
I will definitely check the price at our local AD distributor.
Daniel
PMA said:
Thanks, I have printed out datasheets for AD8671, AD8065, AD8610 and have read them last evening. AD8610 looks quite promissing, it seems to be "creme de la creme" of AD opamps. I was afraid how much will it cost but have found that it should be about three times cheaper than OPA627 so I could breathe it out. (Though AD8065 is again about three times cheaper than AD8610). Same should probably apply also to dual packages.
I will definitely check the price at our local AD distributor.
Daniel
AD8671 low noise 10 MHz Fet input op amp http://www.analog.com (type ad8671 into the search box yourselves, it will be good practice for some of you)
The data sheet specs look really good – if anything Analog’s marketing people may have missed just how significant an advance this represents in low frequency low noise performance in monolithic Fet input op amps
The low frequency noise #s given are ~ 5x better than the AD743 and the max/typ spec #s for low frequency noise is incredibly tight at 1.3x
3x lower input C and 3-10x higher cmrr suggests that cm current induced distortion with higher (unbalanced) source impedance is also going to be superior
the quad device makes paralleling the 4 op amps for ½ the noise very attractive – the low 1/f corner makes this actually useful over nearly the entire audio range where other fet op amps fail to show useful improvement due to 1/f corner frequencies nearing 1KHz
the audio THD distortion graph looks good @ 0.0006% into 600 Ohms and the flatness of the graph may actually evidence of poor measurement technique – the distortion should continue to decrease with lower frequency until it meets the noise floor
the slew rate is less than impressive at 4 V/us but adequate for most audio applications
it is likely the best use of the AD8671 will be in composite op amp arrangements where the low noise of the AD8671 is combined with a high output current high bandwidth output op amp in a common feedback loop – relieving the AD8671 of large slew requirement
a single AD8671 should make an excellent mm phono preamp front end, the paralleled quad could be good with mc cartridges or ribbon mics
(no you can’t just solder all the like pins together but you can sum the outputs of multiple individual op amp feedback amplifiers which are amplifying a common input signal)
no i'm not being paid by AD but if they just happen to add a few extras to my sample request i won't complain
The data sheet specs look really good – if anything Analog’s marketing people may have missed just how significant an advance this represents in low frequency low noise performance in monolithic Fet input op amps
The low frequency noise #s given are ~ 5x better than the AD743 and the max/typ spec #s for low frequency noise is incredibly tight at 1.3x
3x lower input C and 3-10x higher cmrr suggests that cm current induced distortion with higher (unbalanced) source impedance is also going to be superior
the quad device makes paralleling the 4 op amps for ½ the noise very attractive – the low 1/f corner makes this actually useful over nearly the entire audio range where other fet op amps fail to show useful improvement due to 1/f corner frequencies nearing 1KHz
the audio THD distortion graph looks good @ 0.0006% into 600 Ohms and the flatness of the graph may actually evidence of poor measurement technique – the distortion should continue to decrease with lower frequency until it meets the noise floor
the slew rate is less than impressive at 4 V/us but adequate for most audio applications
it is likely the best use of the AD8671 will be in composite op amp arrangements where the low noise of the AD8671 is combined with a high output current high bandwidth output op amp in a common feedback loop – relieving the AD8671 of large slew requirement
a single AD8671 should make an excellent mm phono preamp front end, the paralleled quad could be good with mc cartridges or ribbon mics
(no you can’t just solder all the like pins together but you can sum the outputs of multiple individual op amp feedback amplifiers which are amplifying a common input signal)
no i'm not being paid by AD but if they just happen to add a few extras to my sample request i won't complain
C
I have just looked at the AD8672 specs for my DacMagic dac stage modification.
This is to replace a LME49720 that poses as a Differential multipolar bessel filter at the DAC's output - Wolfson DAC is operating in dual differential mode.
the goal is for the AD8672 to drive the XLR output + RCA stage. The RCA stage is currently running with a LME49720. Would this benefit from 8672 too or better use something like OPA1612 ?
I have just looked at the AD8672 specs for my DacMagic dac stage modification.
This is to replace a LME49720 that poses as a Differential multipolar bessel filter at the DAC's output - Wolfson DAC is operating in dual differential mode.
the goal is for the AD8672 to drive the XLR output + RCA stage. The RCA stage is currently running with a LME49720. Would this benefit from 8672 too or better use something like OPA1612 ?
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