I. A. Op-Amp Type: JRC4558 vs. LM1458

The prevailing wisdom is that the JRC4558 op-amp sounds the best in Tube Screamer pedals. I made one set of recordings of the TS7 using the JRC4558 op-amp that came with it. Then I made another set using a very generic LM1458 op-amp, probably the most basic general-purpose op-amp around. The recordings were made using Test Rig 1. The TS7 had neither the output resistor mod nor the carbon composition resistor mod performed.

In each section below, one of the recordings was done with the JRC4558 op-amp and the other was done with the LM1458. They have been mixed randomly. Select the recording you think has the JRC4558.

Section 1: Blues Riff Recording A (1.397MB wav) Recording B (1.307MB wav)
Section 2: Long Power Chord Recording A (933K wav) Recording B (867K wav)
Section 3: Short Power Chord Recording A (112K wav) Recording B (113K wav)
Section 4: Lead with Dynamics Recording A (1.451 MB wav) Recording B (1.442 MB wav)
Section 5: Long Single Note Recording A (528K wav) Recording B (462K wav)
Section 6: Short Single Note Recording A (86K wav) Recording B (84K wav)
Section 7: Long Fourth Recording A (555K wav) Recording B (513K wav)
Section 8: Short Fourth Recording A (70K wav) Recording B (79K wav)


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The average score so far is 5/8 correct. I certainly can't hear any difference in the recordings, so I'm inclined to think that these op-amp changes are having no effect. But someone could prove me wrong!