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Old 24th February 2015, 04:22 AM   #21
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Quote:
Originally Posted by wrenchone View Post
Would you really want to listen to an LM324 with +/- 1.5V rails? It would be all crossover distortion.
It's powered by 2 AAA cells, so I suppose my answer is yes. You've gotten me more interested in creating a schematic of the thing. It is, BTW, a Transcend brand 5-band EQ HPA from the '80's.
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Old 24th February 2015, 12:43 PM   #22
johnr66 is offline johnr66  United States
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Originally Posted by wrenchone View Post
Sure it is - replace the 4558 with an LM358, and you'll put that 4558 back in a big hurry.
Why? I said I wouldn't use an amp intended for general purpose instrumentation for audio. I don't even care for the TL072 for audio.
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Old 24th February 2015, 01:00 PM   #23
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I've never heard a 4558 IC by itself.
Its always companied by other components in a circuit.
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Old 24th February 2015, 01:02 PM   #24
wg_ski is offline wg_ski  United States
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The LM358/324 app notes tell you specifically to use a pull down resistor from the output to Vcc- to get rid of the crossover distortion. Without it, it is intolerable. With it, it's not a low power op amp anymore.

The ONE GOOD THING a 358 has going for it is the buffered PNP input stage. Inputs will common mode to the negative rail (or GND with a single supply). That feature is needed way too often in peripheral support circuits, and real audio grade op amps just won't do it.
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Old 25th February 2015, 03:23 AM   #25
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Given the title of the thread, which did not specify any application niches, I think that the LM324/358 is still a contender for worst opamp on the planet. Given the price, it's probably also the most commonly used.

The fact that it includes V-/gnd in its common mode input range is most likely a reason why the LM324/358 so widely used/copied. I use it all the time to roll circuits for SMPS CVCC controllers in my day job. I would not let it near any of my usual home projects. Other responders to this thread have echoed that sentiment more or less vehemently (though not necessarily in agreement with my basic premise). Other builders of audio circuits have used it (I give them the benefit of the doubt) without considering its weak points (many!!!!).

I actually found it somewhat amusing that one could slather some lipstick on this notoriously bristly pig by throwing a bias resistor between output and gnd/V- to introduce the output stage to the unprecedented condition of Class AB bias. I'll have to search out the particular app note where that dodge is mentioned. I've only seen that option applied to far, far, better opamps.
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Old 25th February 2015, 05:48 PM   #26
wg_ski is offline wg_ski  United States
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The improvement is much greater on the 358 than it is with audiophile op amps. With these better op amps, any differences show up in the 4th decimal place if at all. With the 358 it shows up in the 1st decimal place. It's like somebody fixed it.

4558's don't let me sense power line zero crossings without a negative supply. The 358 does. That makes the 4558 "worse". The 358 with a bias resistor is on par with a 4558 without when it comes to sound. And why would I even use up my stash of LF412's in the EQ section of a DJ light controller, when 358's do the job just as well :-) Triacs aren't going to be upset by a little cossover distortion, or going into slew limit on the highs.
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Old 25th February 2015, 07:12 PM   #27
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Quote:
Originally Posted by MrGuitardeath View Post
OK OK I know a lot of people swear by them but in every application I have used them in, they sound and perform like garbage.

The point of this thread is, I don't get why people swear by them...

Scratchy, harsh, NOISEY, overly midrangey and they just severely lack detail. When comparing them to the NE5532, OPA2228 and OPA2604, the 4558 IMO is absolutely put to shame. Those chips have closer specs to a 12AX7 tube and also sound/perform sooooo much better. When I play arpeggios through a circuit containing a 4558, there is such a lack of detail and raspiness that it would be embarrassing in a live performance.

Can anyone possibly tell me why they like these chips so much?
My only thought is it teams up with tube amps better than the superior chips I mentioned...
I'd guess, you using it wrong. Did you ever compared your believings with proper measurements?
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Old 25th February 2015, 07:56 PM   #28
raul_77 is offline raul_77  Europe
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I think the same... until I listen a YBA CD Special. The opamps are the 4558, and the circuit are cheap!, the only components that YBA have improved are the output capacitors.

All other components seems of low quality, but the sound is glorious!. Listen and see this CD have that I think that is equal, or more important, the elimination of the electro-mechanical noise than the circuit and the quality of the components; in the inside the work are made for reduce vibrations with felts and a mastic, and the use of good cabling.

If the sound is so good, good, good and the opamps are the 4558, the problem can't be the opamps; other problems originate the bad sound. Listen a CD Special and think for yourself.

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Old 9th March 2015, 07:15 AM   #29
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Much of the problem with op-amps is advertising/datasheet claims that it works for Most applications, including many it isn't good at.

Another problem is any pre-conceived notion of exactly how you'll set the gain is guaranteed to cause sub-optimal performance; because, for a given application, one particular model of op-amp will only deliver optimal performance at its gain sweet spot, which depends on its stability needs and that figure will never match the figure that you actually wanted.
To say that simply:
Forcing it to do what you want, instead of what it needs, guarantees bad performance.
In that case, swapping the op-amp is a good idea, because there is probably a different model op-amp that has a performance sweet spot much closer to the needs of your particular application.


The 4558 can perform well, the 4580 can perform fantastically, but neither do a good job outside of a very narrow range of parameters. That is true of all amplifiers. Fortunately, they are all different, so it is possible to select a different one that comes closer to doing the job you wanted done.

Now, let's see a few problems:
Screeching tone? The gain is too low--replace with something compensated for lower gain.
Wonky response that goes to crap at high output? Linearity is insufficient, so either use it as a parallel amp or replace with something that has higher current capacity.
Dull as can be so that imaging/soundstage is bad although tone is good? The gain is too high, so replace with a faster or more nervous op-amp that actually requires that much gain.

The above problem-resolution comment assumes a well working power circuit with clean and sufficient voltage (which may not be the case).

P.S. Instead of replacing the op-amp, it is also possible to modify the support circuit to be suitable to the op-amp you already have. For some of the more difficult op-amps, the prospect is doable but overly time consuming, in which case, choosing a more suitable op-amp could be a more expedient solution.

P.P.S. In cases like these, where a given model of op-amp is often used wrongly, I think that we should suspect a very bad inaccurate datasheet.
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Old 9th March 2015, 08:03 AM   #30
djk is offline djk
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Possible LM324 replacement?

http://www.ti.com/lit/ds/symlink/tl974.pdf
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