JRC4558, worst op amp EVER.... - Page 2 - diyAudio
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Old 18th November 2005, 08:32 AM   #11
Raoul is offline Raoul  United States
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It's about the distortion in a pedal, like schnullimaus said. Supposed to sound tube-like.

I think Stevie Ray Vaughan used a pedal that utilized the JRC4558D. I guess you can play like Stevie as long as you have the right opamp...


This is kinda funny... http://cgi.ebay.com/IBANEZ-TUBE-SCRE...QQcmdZViewItem
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Old 18th November 2005, 04:01 PM   #12
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You know the odd thing about the pedals using this chip, especially the tube screamer is they tend to be pedals people almost always modify. I'm willing to bet that along with all the mods Stevie had done to his, an opampectomy as one person coined it was part of the operation.

In all the guitar gear and stages I've used this op amp, it's been horrid. It was pleasing for a little while in my Crates distortion emulation circuit but after a month or two of use then switching back to the NE5532, the 5532 is superior beyond words.

Maybe it teams up with tube gear really well?
Maybe since a lot of tube gear has that ultra thick not so ronchy metal tone, the all around harshness of the 4558 adds bite to tube tone?
I think this when I hear how ronchy and brittle the Metal Zone is and it's one of the most popular pedals used with tube amps today.

I've got death metal pedal thread going. JRC4558's used twice in it. Due to the two chips and no gain control, this pedal is a well of noise and uselessness to a serious player. If it were modded though, I think it would be the most widely used pedal. An opampectomy and gain control modded into this pedal and I am willing to bet it is the closest thing to tube subtle overdrive there is. It's a tough call to be certain changing the 4558's won't take away from it's tubeness though. Based on my ears this pedal was someones flagship design based around this chip and they cut down the functions of the circuit because it was too damn good...
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Old 23rd February 2015, 03:15 AM   #13
kazeem is offline kazeem  India
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Thumbs down RC 4558

I AM A DJ SOUND HIRER AND TECHNICIAN I HAVE PURCHASED MANY DJ MIXERS BASED ON RC4558 OP AMP IC, TO MY EXPERIENCE ALL THE O/P OF MIXERS IS DISTORTED AFTER SOME ORDERS
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Old 23rd February 2015, 04:24 AM   #14
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Actually the hallowed spot for crappiest opamp on the planet way well be securely occupied by the LM324/LM358, an abortion of an opamp that makes even the 4558 sound good in comparison. It's even cheaper than the 4558.

Having said that, I agree with a lot of the posters here - when I see a 4558 or one of its variants in a piece of gear, my thoughts immediately turn to ripping that thing out and replacing it with something (just about anything) else.
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Old 23rd February 2015, 03:23 PM   #15
johnr66 is offline johnr66  United States
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The LM324 is a just a budget quad in a chip made for general purpose instrumentation. I wouldn't even consider it for audio with the slow slew and high noise. For it's intended purpose, it is fine. I use some I got for free for comparators in a solar project. Work just fine. Not, "crappiest on planet".
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Old 24th February 2015, 03:03 AM   #16
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Sure it is - replace the 4558 with an LM358, and you'll put that 4558 back in a big hurry.
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Old 24th February 2015, 03:20 AM   #17
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I have a non-DIY headphone amp using LM324's. I can grudgingly tolerate the sound quality, but they sure are noisy buggers. Know of a quieter substitute in the same DIP-14 package?
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Old 24th February 2015, 03:36 AM   #18
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Whoever used that opamp in an audio app (especially headphones), shoulda been shot, pronto. The 324/358 was most likely never meant for an audio application (how-so with a slow slew rate and class B output stage). Having said that, people used it anyway...I think the OPA4134 has the same pinout and infinitely different (and superior) specs. You may (probably) need to change bypassing and biasing to make the newbie opamp package behave.

For a historical perspective, the LM324 and LM358 define the pinouts of most quad/dual opamps out these days. The Raytheon RC4136 was a dissenting vote for the quad package pinout, but was not widely emulated.

Your mission will be to look at the biasing of the opamps to see if an improved device can be substituted without gastric disturbances. The 324/358 works well in single-supply apps as long as it's not asked to do anything much. Other opamps may take more exalted treatment. Post some schematics...
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Old 24th February 2015, 03:52 AM   #19
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The LM324 also has 1.5V supply range. The hpa is a 30 years old device and I have no schematics. Nor is it high priority. I was just curious what might be suggested for subbing.
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Old 24th February 2015, 04:07 AM   #20
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Would you really want to listen to an LM324 with +/- 1.5V rails? It would be all crossover distortion. When Raytheon introduced the RC4558 in the mid-70's, they made a point of comparing the 10 kHz waveforms to the LM324 - it was a shoo-in as the 4558 actually tried (sorta) to bias the output stage into AB vs. B.

Having said all of this, I haven't let an opamp near any of my audio projects for quite some time (except for one chip-amp indiscretion with an OPA541 that told me to stay where the good results are)...
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