This is a detailed measurements of effect of swapping the stock NE5532P op-amp in Fosi P4 preamplifier with Sparkos SS3602 "discrete" opamp. The SS3602 costs US $79.80 and the NE5532P, US $0.47.
Swapping opamps in P4 is more challenging due to back connectors/switches that need to be disconnected. I am not sure how successful I will be putting it back together as some of the tiny screws are almost stripped now. I looked and there was no obvious mention of swapping opamps in P4 from Fosi so I suggest not trying it regardless of what you are about to see.
So far, we have tested these discreet opamps in both high-end and budget power amplifiers and a DAC. Suggestion was made to test in this pre-amp as that removes the variable of output stage swamping differences in opamps. So here we are.
Sparkos SS3602 Opamp Compared to 5532 in Fosi P4
Let's start with our dashboard of 1 kHz tone with unity gain:
Since this result was slightly different than when I reviewed Fosi P4, I re-ran every comparison you are about to see. Let's look at what happens with we swap that 5532P with SS3602:
Results are identical within the margin of moment to moment variations in measurements. We can confirm that the gain is the same as well (as it should be). Distortion and noise floor remain identical as well. For clarity on the latter, here is the SNR measurement:
Frequency response is the same:
So tonality and noise floor are the same. Let's expand our testing to full audible frequency sweep:
We see the distortion slightly rising with frequency with SS3602 as we go above 10 kHz. I re-ran the test and it was repeatable. From audibility it means nothing but does show that the discrete op-amp is not as good as our bargain standard part. Focusing on that, I ran the 19 and 20 kHz intermodulation test:
We see that again, Sparkos has higher distortion spikes but since they are ultrasonic and at any rate, very low amplitude, they are of no audible consequence.
For another dual tone test, let's run our standard SMPTE IMD signal which has both a low frequency 60 Hz and high frequency, 7 kHz tone (in 4:1 ratio):
This is as identical as the results get.
Conclusions
Once again we show that without circuit modifications, these expensive opamps either show no measurable effect, or what they show is negligible but not better. Subjective, uncontrolled listening tests of benefit are proof that we perceive differences that are not there. If the differences are as obvious as these proponents claim, they should be able to detect them easily in a simple level matched, blind test. I hope instead of protesting these results, they take half hour and perform such a controlled test. Heaven knows I have spent far more than that producing proof points of inaudibility.
I don't recommend you modify any audio device. If they perform excellently already, please leave well enough alone. If your system is causing fatigue, has high noise floor, shrunk soundstage, etc. then you should question how you arrived at it in the first place!
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Swapping opamps in P4 is more challenging due to back connectors/switches that need to be disconnected. I am not sure how successful I will be putting it back together as some of the tiny screws are almost stripped now. I looked and there was no obvious mention of swapping opamps in P4 from Fosi so I suggest not trying it regardless of what you are about to see.
So far, we have tested these discreet opamps in both high-end and budget power amplifiers and a DAC. Suggestion was made to test in this pre-amp as that removes the variable of output stage swamping differences in opamps. So here we are.
Sparkos SS3602 Opamp Compared to 5532 in Fosi P4
Let's start with our dashboard of 1 kHz tone with unity gain:
Since this result was slightly different than when I reviewed Fosi P4, I re-ran every comparison you are about to see. Let's look at what happens with we swap that 5532P with SS3602:
Results are identical within the margin of moment to moment variations in measurements. We can confirm that the gain is the same as well (as it should be). Distortion and noise floor remain identical as well. For clarity on the latter, here is the SNR measurement:
Frequency response is the same:
So tonality and noise floor are the same. Let's expand our testing to full audible frequency sweep:
We see the distortion slightly rising with frequency with SS3602 as we go above 10 kHz. I re-ran the test and it was repeatable. From audibility it means nothing but does show that the discrete op-amp is not as good as our bargain standard part. Focusing on that, I ran the 19 and 20 kHz intermodulation test:
We see that again, Sparkos has higher distortion spikes but since they are ultrasonic and at any rate, very low amplitude, they are of no audible consequence.
For another dual tone test, let's run our standard SMPTE IMD signal which has both a low frequency 60 Hz and high frequency, 7 kHz tone (in 4:1 ratio):
This is as identical as the results get.
Conclusions
Once again we show that without circuit modifications, these expensive opamps either show no measurable effect, or what they show is negligible but not better. Subjective, uncontrolled listening tests of benefit are proof that we perceive differences that are not there. If the differences are as obvious as these proponents claim, they should be able to detect them easily in a simple level matched, blind test. I hope instead of protesting these results, they take half hour and perform such a controlled test. Heaven knows I have spent far more than that producing proof points of inaudibility.
I don't recommend you modify any audio device. If they perform excellently already, please leave well enough alone. If your system is causing fatigue, has high noise floor, shrunk soundstage, etc. then you should question how you arrived at it in the first place!
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
