OPA4228 help needed

afxdave · 8th April 2004, 02:36 PM

At the guidance of members here I went ahead with some OPA4228 ICs for my phono pre-amp. I am very staisfied with them, but now digi-key won't get anymore in until July. Would the OPA4227, or OPA4277 be just as good?

I'm ordering both to try them out.

macboy · 8th April 2004, 04:09 PM

The OPA4227 is the version of the OPA4228 which is internally compensated to be unity-gain stable. Since you are using the opamps in a phono pre-amp (with a reasonably high gain), you do not need a unity-gain stable amp. The OPA4228 has much better specs than the OPA4227 (the 4227 tradesoff bandwidth and slew rate for stability at lower gains). As long as the 4228 is used in a high gain application and you ensure that it is stable, it will outperform the 4227.

The OPA4277 is entirely different. It is not a suitable replacement for the OPA4228. It is much noiser, has a much lower gain-bandwidth product (an important consideration since you are using a high gain) and a much lower slew rate. You will probably be dissapointed with this opamp in this application.

afxdave · 8th April 2004, 04:25 PM

Thank you so much. I'm on the phone to cancel the order for the 4427 and 4227 ICs. It's tough for me to sniff out the proper ICs since I'm still learning what features to look for.

I was very impressed with the sound of the OPA4228 compared to both the TL084 and TL074. My ears don't lie to me, so I think I'm going to stick the the OPA4228.

8th April 2004, 02:36 PM	#1
afxdave diyAudio Member Join Date: Jan 2004 Location: West Hartford, CT	OPA4228 help needed At the guidance of members here I went ahead with some OPA4228 ICs for my phono pre-amp. I am very staisfied with them, but now digi-key won't get anymore in until July. Would the OPA4227, or OPA4277 be just as good? I'm ordering both to try them out.

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8th April 2004, 04:09 PM	#2
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	The OPA4227 is the version of the OPA4228 which is internally compensated to be unity-gain stable. Since you are using the opamps in a phono pre-amp (with a reasonably high gain), you do not need a unity-gain stable amp. The OPA4228 has much better specs than the OPA4227 (the 4227 tradesoff bandwidth and slew rate for stability at lower gains). As long as the 4228 is used in a high gain application and you ensure that it is stable, it will outperform the 4227. The OPA4277 is entirely different. It is not a suitable replacement for the OPA4228. It is much noiser, has a much lower gain-bandwidth product (an important consideration since you are using a high gain) and a much lower slew rate. You will probably be dissapointed with this opamp in this application.

8th April 2004, 04:25 PM	#3
afxdave diyAudio Member Join Date: Jan 2004 Location: West Hartford, CT	Thank you so much. I'm on the phone to cancel the order for the 4427 and 4227 ICs. It's tough for me to sniff out the proper ICs since I'm still learning what features to look for. I was very impressed with the sound of the OPA4228 compared to both the TL084 and TL074. My ears don't lie to me, so I think I'm going to stick the the OPA4228.

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