Why to drive headphones, the Herald people used an AZ386 instead of a 4558. they used the 4558 mixer IC to drive the 50 kohm input impedance of the AZ386. I bought this RA88a disco mixer for $15, the cheapest of the cheap.
You have received some good information for others, so what is your point? I wonder why some folks are like that?
If you are poking at a CMRR rating, you are looking far closer than the application demands. Engineering 101, keep your concerns in line with the application. Which by the way includes choosing the appropriate part. Of course, you need experience to do that.
One suggestion for the expert headphone amp designer here. Ever heard of an NJM4556? Better than a 4558 and actually designed for driving headphones. They sold millions of them over the years, they can be found in more places than you can imagine. They are inexpensive due to volume, not because they are cheap. TI has a bunch of current types available and a visit to their site might be helpful. Then you can be on the bleeding edge if you wish.
Now, if you are emotionally invested in using the 4558 for some unknown reason, and you are designing this from scratch, why not build in a buffer stage? Wrap it in the feedback loop and there you go. A pair of J-Fets (like Curl) or a biased BJT stage (2N3904 & 2N2906 would work well) both suit your purpose.
Like I said, you have decided to use a 4558 in face of the fact that there are far better parts for the job. Okay, fine. Don't expect me to debate with you.
If you are poking at a CMRR rating, you are looking far closer than the application demands. Engineering 101, keep your concerns in line with the application. Which by the way includes choosing the appropriate part. Of course, you need experience to do that.
One suggestion for the expert headphone amp designer here. Ever heard of an NJM4556? Better than a 4558 and actually designed for driving headphones. They sold millions of them over the years, they can be found in more places than you can imagine. They are inexpensive due to volume, not because they are cheap. TI has a bunch of current types available and a visit to their site might be helpful. Then you can be on the bleeding edge if you wish.
Now, if you are emotionally invested in using the 4558 for some unknown reason, and you are designing this from scratch, why not build in a buffer stage? Wrap it in the feedback loop and there you go. A pair of J-Fets (like Curl) or a biased BJT stage (2N3904 & 2N2906 would work well) both suit your purpose.
Like I said, you have decided to use a 4558 in face of the fact that there are far better parts for the job. Okay, fine. Don't expect me to debate with you.
If you want a new op-amp, go to the selector guides provided by vendors:
https://www.ti.com/amplifier-circuit/op-amps/audio/overview.html
It's a huge stretch to call 4558 similar to a 741. They are nothing alike for audio purposes. The TL07x series have better audio specs but my experience is that they don't sound much different than 4558. The common mode range matters not for most audio circuits where the inputs are biased at zero volts.
If you want something "audiophile", then you make your own discrete circuit, otherwise you use a "good enough" op-amp like the TL07x series. Note there is now a TL07xH improved version.
https://www.ti.com/amplifier-circuit/op-amps/audio/overview.html
It's a huge stretch to call 4558 similar to a 741. They are nothing alike for audio purposes. The TL07x series have better audio specs but my experience is that they don't sound much different than 4558. The common mode range matters not for most audio circuits where the inputs are biased at zero volts.
If you want something "audiophile", then you make your own discrete circuit, otherwise you use a "good enough" op-amp like the TL07x series. Note there is now a TL07xH improved version.
Ironic of you to mention experience, when you say that CMRR doesn't matter for bipolar op amps.
good information isn't "just choose a different part" when I specifically asked about this specific op amp.
I even nodded at ideas that might improve the performance of the 4558 which you and others have ignored.
Just because the part isn't up to your standards doesn't mean improvements for it in a circuit cannot be discussed.
And if you're emotionally invested to scorn the 4558, keep in mind that the same improvements may also apply to your op amps of choice
good information isn't "just choose a different part" when I specifically asked about this specific op amp.
I even nodded at ideas that might improve the performance of the 4558 which you and others have ignored.
Just because the part isn't up to your standards doesn't mean improvements for it in a circuit cannot be discussed.
And if you're emotionally invested to scorn the 4558, keep in mind that the same improvements may also apply to your op amps of choice
I'm not. It works fine in many applications. I am also very aware of what works and what doesn't improve op amp performance.
However, you are the one who wants improved performance. Everyone has tried to offer valid suggestions to you, now you wish to debate whatever.
Go for it. I'm out, your questions has been fully answered in my view.
However, you are the one who wants improved performance. Everyone has tried to offer valid suggestions to you, now you wish to debate whatever.
Go for it. I'm out, your questions has been fully answered in my view.
4558 has a slower slew rate than 5532 and TL07x...TI part is faster, so quicker to respond to changes in input signal.
And they cost almost the same, about 20 US cents here.
I cannot understand your fixation with the 4558, so I will also be out.
One of the guiding principles in my life is to never argue with a drunk / fool / person who will not listen to you.
Your decision, you live with the consequences.
End of rant.
And they cost almost the same, about 20 US cents here.
I cannot understand your fixation with the 4558, so I will also be out.
One of the guiding principles in my life is to never argue with a drunk / fool / person who will not listen to you.
Your decision, you live with the consequences.
End of rant.
Don´t worry, it is a flat out lie.
But way back then the former Industry Standard had been 741, so datasheet HAD to include that line to improve sales.
Real dual 741 equivalent was 747.
So much so it used a 14 pin DIP package so it could keep 741 offset nulling, which requires 2 extra pins oer Op Amp.
A slightly more advanced dual 741 version was 1458, which is still preferred today in certain niche roles (basically driving reverb tanks).
I am old enough to having started with 709 😱 , go figure, and being surprised by the fancy new 741 which did not require external compensation.
I bought my first ones each one being packged in its individual box (same as tubes), inside a TO5 type round metal case, with 8 gold plated legs.
Boy they were ëxpensive.
Much later, I was again surprised by 4558, the first widely available Designed for Audio dual Op Amp.
Only audio specific one had been RC4739, very good, but somehow it didn´t get the big sales needed to stay.
But it´s the proper answer, even if you don´t understand what you asked.
How do you expect to "improve" it?
By opening the black epoxy case and doing some microsurgery?
Obviously impossible, proper way is to replace is with an already improved one.
H
HAYK
You might improve by using both opamps in composite. The audio quality of opamp to my standard is the OLG @20khz. High quality ones reach 70db, this one is less than 50db.
if inverting offers improvement
slew, noise rejection.
about all you can do.
other than keeping gain low.
Far as Revox sound.
Most the magic was likely the tape/analog sound itself.
And likely natural compression people liked
running recordings hot with any tape machine.
And overall harmonic profile tape can have.
slew, noise rejection.
about all you can do.
other than keeping gain low.
Far as Revox sound.
Most the magic was likely the tape/analog sound itself.
And likely natural compression people liked
running recordings hot with any tape machine.
And overall harmonic profile tape can have.
H
HAYK
Can you explain what you mean? Looking at the datasheets there isn't much difference.
Hi HAYK,
That's a simulation. Pure fantasy.
Now try it in real life with a sine wave - then load it. Oops!
I used the 709 before anything else was available. The 741 was great as it was internally compensated (making life easy for designers with non-critical applications). The LM301 was nice back then too. Yes, cans. I also used 747's and almost everything that came out. The 308 was sloooooow, but had it's uses. The TL07x family was great when it came out. They don't sound very good by today's standards.
Anything that was packaged in a can was horribly pricey. Even transistor pairs.
The thing is, arguing to improve the 4558 no matter how you do it is pretty silly. You'll never get performance like you will for not much more. I think someone is just trying to stir things up.
That's a simulation. Pure fantasy.
Now try it in real life with a sine wave - then load it. Oops!
I used the 709 before anything else was available. The 741 was great as it was internally compensated (making life easy for designers with non-critical applications). The LM301 was nice back then too. Yes, cans. I also used 747's and almost everything that came out. The 308 was sloooooow, but had it's uses. The TL07x family was great when it came out. They don't sound very good by today's standards.
Anything that was packaged in a can was horribly pricey. Even transistor pairs.
The thing is, arguing to improve the 4558 no matter how you do it is pretty silly. You'll never get performance like you will for not much more. I think someone is just trying to stir things up.
µA741: slew 0.5V/µs, voltage noise unclear - I've seen 60nV/√Hz, 23nV/√Hz, 20nV/√Hz in different places..., 20mV rise-time 0.3µs
RC4558: slew 1.7V/µs, voltage noise 8nV/√Hz, 20mV risetime 0.13µs
So 3 times faster and perhaps 3 times quieter.
There is no denying you shouldn't use a 741 for anything important in audio. The performance of various brands was all over the map. But I have to say, the 4558 while better when it was introduced, falls severely short of quality performance.
Trying to improve performance of a 4558 is a bit of a joke. It pretty much is what it is, simple as that.
Trying to improve performance of a 4558 is a bit of a joke. It pretty much is what it is, simple as that.
And the 741 has massive rail sticking problems. Look at the large signal waveform. I think it has overdrive phase inversion as well.
Note that the slew rate for 15VP at 20 KHz is 1.884 V/uS, so a 4558 is close at 1.7, but a 741 is good for about 5KHz max. This turns sounds like cymbals and voice sibilants into mush. The 4558 is the dual version of the famous 4136 quad which was used in many audio devices. Unfortunately, the 4136 had a strange pin-out so it is not compatible with other quads.
Use those op amps in an RIAA phono pre (with all that crazy high frequency preeemphasis) and it will sound like the stylus mistracking. Gross.
The 4136 was class B, and really a terrible op amp. Yes, the pin out was designed to lock designs into that chip. I made my own custom interposers for years to rid equipment of their 4136 millstones.
Hi wg_ski,
lol! Over all the white noise? How could you hear any mids or highs???
Besides, no one would listen to anything designed with 4558 in a mag phono stage, those types used crystal cartridges!
Hi wg_ski,
lol! Over all the white noise? How could you hear any mids or highs???
Besides, no one would listen to anything designed with 4558 in a mag phono stage, those types used crystal cartridges!