OPAMP upgrade before and after...

[paul_5]

Here's some recordings I made with a Jazz bass into a Chord BCH-50 bass chorus pedal that I really liked, but thought a little bit too noisy for my tastes.

As it's an analogue unit it's ripe for upgrading components, particularly the opamps.

It uses 2 LM4558 opamps - but only 1 is upgradeable as it's using one of them for more than just a gain stage, so I replaced just 1 of them with an NE5532; identical pinouts mean that it's just a simple swap.

The audio files (DI'd into Protools) are here:

https://soundcloud.com/paul_5/sets/chord-chorus-modifications

[Davebassics]

I haven't got my posh headphones with me at the minute, will listen when I get the chance.

What are your thoughts?

[Beer of the Bass]

Despite the higher noise in the first clip, I think I prefer the sound with the 4558. The highs are a little more prominent and it comes across as a bit clearer sounding. It's a subtle difference and might be entirely in my head, but I'm fairly sure I can hear a difference in the highs as well as the noise level.

[rmorris]

Noise lower with 5532. I think the 4558 clip might have a little more level ? which could account for (Beer's) opinion about sounding clearer. Also high frequency noise may lead to perception of enhanced higher frequencies through psychoacoustic effects.
It might be good to try replacing the other 4558 too if pinouts are identical (all pins) ?
I've always been led to believe that the big noise factor in analogue chorus (and other time based effects) is the analogue 'Bucket Brigade Device' (BBD) device(s).