OP Amp Rolling Revisited

Recently a kind user who goes by ‘passive420’ on the diyAudio forums had a conversation with me about all things DIY and so he sent me a few OP Amps to test in my Whammy headphone amp to see what I thought of them. So firstly I would like to say a big thank you to Rich for loaning me these OP Amps for testing.

LT1361 installed in the Whammy.

So first up is the LT1361 by Linear Technology which is now owned by Analog Devices.

Operating Voltage: 15v MAX
Slew Rate: 800v/µs
DC Offset: L -14.1mV / R -14.4mV
Gain: Unity Gain Stable
FET: No

Very clear and detailed with punchy bass, sounds quite good but the DC offset might be a concern for some. As a result I found with some tracks that certain notes and sounds seemed a little rough.

LT1128 installed into the Whammy using a BrownDog adapter.

Next up is the LT1128 by Linear Technology which is now owned by Analog Devices.

Operating Voltage: 15v MAX
Slew Rate: 5v/µs
DC Offset: L -3.5mV / R 1.4mV
Gain: +1
FET: No

Although clear and nice sounding with punchy bass I find this one a little rough around the edges and it sounds like the soundstage and detailing is being held back almost as if it has been toned down slightly.

OPA627BM single OP Amps installed in the Whammy on a dual BrownDog adapter.

Lastly we have the OPA627BM single OP Amps by Texas Instruments.

Operating Voltage: 18v MAX
Slew Rate: 40v/µs
DC Offset: L -0.2mV / R -0.1mV
Gain: Unity Gain Stable
FET: Yes (Di-FET)

Very clear, neutral sounding with wide soundstage. Bass is there but its natural and less pronounced. Voices very clear and upfront. Can hear every tiny little detail. An outstanding OP Amp. Excellent DC offset measurement.

It will be pretty obvious which one is my favourite out of these three and with the OPA627BM being a very high end OP Amp manufactured on a Di-Fet process its pretty easy to understand why. I think I actually prefer these to my OPA2107.

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