Ye olde Op-Amp in Digital gear question again

ThorstenL · 19th June 2003, 11:59 AM

Koinichiwa,

So, here we again. For a SPECIFIC set of application I am trying to find out what peoples experiences have been with replacement Op-Amp's.

The fundamental limitation is that the device must be available as SO8 SMD Dual Op-Amp part, cost is not a concern (within reason).

Applications are twofold:

1) Input Buffer and signal conditioning for Crystal Semiconductor "Delta Sigma" AD Converters (CS5396).

2) Output Filter & Buffer for Crystal Semiconductor "Delat Sigma" DA Converters (CS4396)

Both sections are part of Pro-Audio gear.

Since I found ages ago the LM6172 to be a good choice for such applications times have moved on and there seems to be a new "best" dual OPA every week or two.

I'd appreciate any input, however, the differences in operation and design between for example DS and Multibit DAC's make what is best for one not neccesarily the best for the other.

I admit to having my Eye on the AD8620 (IIRC). Any others?

Sayonara

RobM · 19th June 2003, 01:56 PM

OPA627?

For my personal applications I use either 627 or 5332, with a class A follower in the feedback loop if it's an output buffer, followed up with a JT-OLI-3 to prevent RF induced oscillations while maintaining a low output impedance.

RobM · 19th June 2003, 01:58 PM

Oh, you want a dual opamp. So that shoots out the 627. Shame, that's such a nice opamp.

ThorstenL · 19th June 2003, 02:02 PM

Koinichiwa,

Quote:

Originally posted by RobM
Oh, you want a dual opamp. So that shoots out the 627. Shame, that's such a nice opamp.

I know. The 627 would be my first choice on the AD input (maybe also output). But as we are dealing with SMD making adapters would be so messy that I might as well redesign the whole PCB, except all i want is to mod the unit... ;-)

So, what Dual, SO8 SMD package Op-Amp sounds like the OPA627 or even better like the 637 except being unity gain stable?

Tough one, I know....

Sayonara

RobM · 19th June 2003, 02:19 PM

Does the OP270 come in SO8? I know it comes in a DIP8...

ojg · 19th June 2003, 04:24 PM

My favorite dual op-amp right now: AD8022
Open-loop bandwidth to over 20kHz and open-loop gain at a sensible 80dB. Very low noise (2nV/2pA) and fairly low distortion.
Very high bandwidth/speed but max Vcc of +-13V.

IMHO, the OPA627 is getting a little old and slow.
The AD8620 is a very good "traditional" op-amp.

-ojg

jean-paul · 19th June 2003, 09:23 PM

Quote:

IMHO, the OPA627 is getting a little old and slow.

Werner · 20th June 2003, 05:24 AM

Hi T,

bought a 2496?

W

carlosfm · 20th June 2003, 04:57 PM

Hi Kuei,

Have you tested the OPA2132?
Well bypassed it's fantastic, and you may not even need an output cap, as DC ooffset is so low (I have 0.2~0.3 mv on my headphone amp, with OPA2132 and BUF634, without any caps in the signal).
The 2134 seams the same, and is cheaper, but I haven't tried it.
I've used the OPA2132 on several CD players and preamps and it's very good.
Audibly much better than the OPA2604.
Well, the OPA627 is the top, but you whant double...

carlosfm · 20th June 2003, 04:59 PM

Quote:

Originally posted by ojg

IMHO, the OPA627 is getting a little old and slow.
The AD8620 is a very good "traditional" op-amp.
-ojg

19th June 2003, 11:59 AM	#1
ThorstenL Previously: Kuei Yang Wang Join Date: Nov 2002 Location: Somewhere nice on planet earth	Ye olde Op-Amp in Digital gear question again Koinichiwa, So, here we again. For a SPECIFIC set of application I am trying to find out what peoples experiences have been with replacement Op-Amp's. The fundamental limitation is that the device must be available as SO8 SMD Dual Op-Amp part, cost is not a concern (within reason). Applications are twofold: 1) Input Buffer and signal conditioning for Crystal Semiconductor "Delta Sigma" AD Converters (CS5396). 2) Output Filter & Buffer for Crystal Semiconductor "Delat Sigma" DA Converters (CS4396) Both sections are part of Pro-Audio gear. Since I found ages ago the LM6172 to be a good choice for such applications times have moved on and there seems to be a new "best" dual OPA every week or two. I'd appreciate any input, however, the differences in operation and design between for example DS and Multibit DAC's make what is best for one not neccesarily the best for the other. I admit to having my Eye on the AD8620 (IIRC). Any others? Sayonara

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19th June 2003, 01:56 PM	#2
RobM diyAudio Member Join Date: May 2003 Location: West Orange, NJ, USA	OPA627? For my personal applications I use either 627 or 5332, with a class A follower in the feedback loop if it's an output buffer, followed up with a JT-OLI-3 to prevent RF induced oscillations while maintaining a low output impedance.

19th June 2003, 01:58 PM	#3
RobM diyAudio Member Join Date: May 2003 Location: West Orange, NJ, USA	Oh, you want a dual opamp. So that shoots out the 627. Shame, that's such a nice opamp.

19th June 2003, 02:19 PM	#5
RobM diyAudio Member Join Date: May 2003 Location: West Orange, NJ, USA	Does the OP270 come in SO8? I know it comes in a DIP8...

19th June 2003, 04:24 PM	#6
ojg diyAudio Member Join Date: May 2003 Location: Norway	My favorite dual op-amp right now: AD8022 Open-loop bandwidth to over 20kHz and open-loop gain at a sensible 80dB. Very low noise (2nV/2pA) and fairly low distortion. Very high bandwidth/speed but max Vcc of +-13V. IMHO, the OPA627 is getting a little old and slow. The AD8620 is a very good "traditional" op-amp. -ojg

20th June 2003, 05:24 AM	#8
Werner diyAudio Member Join Date: Jan 2002 Location: Belgium	Hi T, bought a 2496? W

20th June 2003, 04:57 PM	#9
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	Hi Kuei, Have you tested the OPA2132? Well bypassed it's fantastic, and you may not even need an output cap, as DC ooffset is so low (I have 0.2~0.3 mv on my headphone amp, with OPA2132 and BUF634, without any caps in the signal). The 2134 seams the same, and is cheaper, but I haven't tried it. I've used the OPA2132 on several CD players and preamps and it's very good. Audibly much better than the OPA2604. Well, the OPA627 is the top, but you whant double...

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