unity gain stable single channel DIP opamp

lordearl · 12th July 2010, 04:49 AM

looking for something to replace two single OPA627 (currently on adapters) I have in the output stage of my DAC

any suggestions would be great!

Mooly · 12th July 2010, 06:27 AM

There are literally dozens of threads on this subject, however for great sonics I still think the OPA2604 has a bit of magic about it.

You are just going to have to try a few and see what you think.

lordearl · 12th July 2010, 07:24 AM

Thanks mate - I've read dozens and dozens of threads about this type of thing over the past year or two, but it's the "unity gain stable" thing that gets me - what is the statistic on the data sheet that lets me know whether it is unity gain stable or not?

Mooly · 12th July 2010, 07:34 AM

Usually mentioned specifically as one of the main features... if not you have to read through the data sheet. There's no "parameter" as such in the specs that indicates it is or isn't... although words such as "internally compensated" usually mean it is, and devices that have "external compensation" usually aren't.

http://www.datasheetcatalog.org/data...wn/mXtutss.pdf

jcx · 13th July 2010, 05:42 AM

how can anyone offer meaningful advice without the basics of V or Iout, what signal levels, power supply V?

Mooly · 06:15 AM

Quote:

Originally Posted by jcx

how can anyone offer meaningful advice without the basics of V or Iout, what signal levels, power supply V?

The OPA2604 covers most bases having a supply range of -/+4.5 to 24 volts, 600 ohm drive capability and good (it's docile to work with) stability.
As a replacement for the OPA627 (on dual adapters as the OP uses them) I feel it it should operate perfectly in a DAC whether used as I/V conversion/filter buffer etc.
If you want to retain the single devices and adapter use the OPA604
Whether the OP can hear any difference subjectively will be interesting to know.

lordearl · 13th July 2010, 06:48 AM

Sorry, yes, a schematic will help:

I just received my Wolfson 4.0 BIY DAC :)

Mooly · 13th July 2010, 07:18 AM

OPA604 should be perfect. When you mentioned using adapters thought you meant making a dual out of two single SMD devices.

Read the last part of this data sheet "sound quality",
http://www.datasheetcatalog.org/data...n/mXyzsxss.pdf

that's Burr Browns take on it... in use I have found it offers excellent sonics, can't really say more than that... only you will know if you hear/detect/like the device.

lordearl · 13th July 2010, 07:22 AM

OK thanks, I'll give them a go. I tried out the LME49710NA (as you can read in that thread), but did not notice a huge difference, so it should be interesting to try the OPA604 and compare it with both the OPA627 and LME49710NA.

I don't think there are many other candidates there that would be suitable opamps. I'm leaving the four OPA627 in the filter stage as it's too expensive to replace all 6 chips!

qusp · 15th July 2010, 07:38 AM

remember they also need to be bipolar input for your dac.

mooly, I recommended the BUF634 to lordearl, as I figured they were single channel opamps acting as unity gain buffers (the stock opamp is OPA134), but of course we didnt get good results as they are also taking a bipolar input

12th July 2010, 04:49 AM	#1
lordearl diyAudio Member Join Date: Jun 2007	unity gain stable single channel DIP opamp looking for something to replace two single OPA627 (currently on adapters) I have in the output stage of my DAC any suggestions would be great!

12th July 2010, 06:27 AM	#2
Mooly diyAudio Member Join Date: Sep 2007	There are literally dozens of threads on this subject, however for great sonics I still think the OPA2604 has a bit of magic about it. You are just going to have to try a few and see what you think. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

12th July 2010, 07:34 AM	#4
Mooly diyAudio Member Join Date: Sep 2007	Usually mentioned specifically as one of the main features... if not you have to read through the data sheet. There's no "parameter" as such in the specs that indicates it is or isn't... although words such as "internally compensated" usually mean it is, and devices that have "external compensation" usually aren't. http://www.datasheetcatalog.org/data...wn/mXtutss.pdf __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

13th July 2010, 07:18 AM	#8
Mooly diyAudio Member Join Date: Sep 2007	OPA604 should be perfect. When you mentioned using adapters thought you meant making a dual out of two single SMD devices. Read the last part of this data sheet "sound quality", http://www.datasheetcatalog.org/data...n/mXyzsxss.pdf that's Burr Browns take on it... in use I have found it offers excellent sonics, can't really say more than that... only you will know if you hear/detect/like the device. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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12th July 2010, 07:24 AM	#3
lordearl diyAudio Member Join Date: Jun 2007	Thanks mate - I've read dozens and dozens of threads about this type of thing over the past year or two, but it's the "unity gain stable" thing that gets me - what is the statistic on the data sheet that lets me know whether it is unity gain stable or not?

13th July 2010, 05:42 AM	#5
jcx diyAudio Member Join Date: Feb 2003 Location: ..	how can anyone offer meaningful advice without the basics of V or Iout, what signal levels, power supply V?

13th July 2010, 06:48 AM	#7
lordearl diyAudio Member Join Date: Jun 2007	Sorry, yes, a schematic will help: I just received my Wolfson 4.0 BIY DAC :)

13th July 2010, 07:22 AM	#9
lordearl diyAudio Member Join Date: Jun 2007	OK thanks, I'll give them a go. I tried out the LME49710NA (as you can read in that thread), but did not notice a huge difference, so it should be interesting to try the OPA604 and compare it with both the OPA627 and LME49710NA. I don't think there are many other candidates there that would be suitable opamps. I'm leaving the four OPA627 in the filter stage as it's too expensive to replace all 6 chips!

15th July 2010, 07:38 AM	#10
qusp Sometimes a square peg fits a round hole just fine diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	remember they also need to be bipolar input for your dac. mooly, I recommended the BUF634 to lordearl, as I figured they were single channel opamps acting as unity gain buffers (the stock opamp is OPA134), but of course we didnt get good results as they are also taking a bipolar input

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