The neverending story of the JRC4558D!

[Der Groovemeister]

I desoldered some JRC4558D chips from an old Sony cassette deck and put them in my Eternity- and Blues Pro clones... (instead of the reissue NJM/JRC4558D)
Wow! I like em much better. More open, loose and a little more raw.

So don't throw away old equipment: Take it apart!

[Renegadrian]

I told all my friends to keep the electronic equipment ready for the bin for me! And also those light bulbs, as you may have read in the light bulbs topic! A lot of components can be easily reused...

[edvard]

Just discovered one yesterday on an old tape deck board...

[deadastronaut]

yep!...my mates are always bunging me their old stereos..videos...etc....anything really...well handy..

i got hold of an old patchbay off one of them....loads of nice jacks...free..yay!...

[Paul Marossy]

If there IS any difference between the sound of the old manufacture JRC4558 chips and the new manufacture ones, I would have to say that it's due to manufacturing technology being better today than it was back then. According to my sources, the new ones are identical to the old ones in their design.

[Der Groovemeister]

According to my sources, the new ones are identical to the old ones in their design.

Yeah man, that's what i read everywhere also. But they really sound different!

[Paul Marossy]

According to my sources, the new ones are identical to the old ones in their design.

Yeah man, that's what i read everywhere also. But they really sound different!

Just wondering why that would be. 

[caress]

According to my sources, the new ones are identical to the old ones in their design.

Yeah man, that's what i read everywhere also. But they really sound different!

Just wondering why that would be. 

hmmmm they want it to sound different, so it does. 

[Paul Marossy]

According to my sources, the new ones are identical to the old ones in their design.

Yeah man, that's what i read everywhere also. But they really sound different!

Just wondering why that would be. 

hmmmm they want it to sound different, so it does. 

Yes, I did think of the physchoacoustic aspect of it, and that was actually my first thought. The only way to really reliably test if there is any difference between new ones and old ones is to do some sort of blind taste test with a group of people.

[trjones1]

Yes, I did think of the physchoacoustic aspect of it, and that was actually my first thought. The only way to really reliably test if there is any difference between new ones and old ones is to do some sort of blind taste test with a group of people.

I'd be willing to bet that in a true double blind test no one would be able to reliably tell the difference between different types of opamps, much less between old and new manufacture JRC 4558s.  

[Derringer]

it basically all comes down to the tolerances when manufactured i'd imagine

[Der Groovemeister]

I'm sorry guys! I am an audio restoration engineer by profession. So my ears are trained to hear even the tiniest differences in sound. Please believe me: i really hear a signifficant difference!

[R.G.]

I'm sorry guys! I am an audio restoration engineer by profession. So my ears are trained to hear even the tiniest differences in sound. Please believe me: i really hear a signifficant difference!

I do believe you. You really, really do hear a difference. It is very well documented by people who research human hearing that what you hear in your head is a very, very highly processed and messed-with version of what went in your ears, including inserting what you think you ought to hear. If you ever decide that you SHOULD hear a difference, then you absolutely will.

However, I would bet a modest amount of money that you would NOT be able to tell the "vintage" 4558 from a new one in a properly constructed test where you had to distinguish by sound alone. In fact, I've been party to a test where a group of professional guitarists - that is, people who make their living on guitar tone - could not definitively tell whether a real 4558, or other types of opamps were being substituted into the same pedal. Some claimed differences, but most said "no difference". The crucial difference in testing is making sure that you must distinguish between the test alternatives with only your hearing, no information whatsoever about exactly what is being tested at any one moment. It's the only way to keep personal biases, even unconscious ones, from affecting your perception.

[Electron Tornado]

I'm sorry guys! I am an audio restoration engineer by profession. So my ears are trained to hear even the tiniest differences in sound. Please believe me: i really hear a signifficant difference!

Unfortunately, it's only a single, anecdotal data point, subject to bias since the testing was not blind.

Being an engineer, you could do the DIY community a great service by testing a group of 4558 chips, to include the ones in question, and present some data that shows where they, or any of the others differ. Then show and explain how any difference(s) have an audible effect on the signal in a specific circuit.

Also, being an engineer, doesn't it just drive you nuts not knowing why two of the same chip seem to be different?

Who knows, the "better sounding" chip may have a flaw that gives it that "better" sound, but it slipped through the cracks in the quality assurrance department. Any difference in sound may be due more to happy accident than being vintage.

But until there's data......

[petemoore]

  ahh...nothin'.
  I thought the difference mattered for a while there, it did.

[Paul Marossy]

It is very well documented by people who research human hearing that what you hear in your head is a very, very highly processed and messed-with version of what went in your ears, including inserting what you think you ought to hear. If you ever decide that you SHOULD hear a difference, then you absolutely will.

And thus there are many people out there who are profiting from this phenomenon of human hearing and perception. And it also gives birth to all sorts of fallacies propogated on the web.  

[DiscoVlad]

http://www.youtube.com/watch?v=bpTv2jAree8

[Der Groovemeister]

Unfortunately, it's only a single, anecdotal data point, subject to bias since the testing was not blind.

Being an engineer, you could do the DIY community a great service by testing a group of 4558 chips, to include the ones in question, and present some data that shows where they, or any of the others differ. Then show and explain how any difference(s) have an audible effect on the signal in a specific circuit.

Also, being an engineer, doesn't it just drive you nuts not knowing why two of the same chip seem to be different?

Who knows, the "better sounding" chip may have a flaw that gives it that "better" sound, but it slipped through the cracks in the quality assurrance department. Any difference in sound may be due more to happy accident than being vintage.

But until there's data......

I'm sorry I am not an electrical engineer. As an audio restoration engineer I restore old recordings. So I am not able to do extensive testing on the chips. But it would probably not show any signifficant difference from a technical standpoint. There is written a lot about that already.

Some people say you can't hear it, and some people say they can.

[tg509]

Some people say you can't hear it, and some people say they can.

The main difference I've come across between vintage components and their more modern counterparts seems to be consistency!

[amptramp]

Around 1985, I acquired a Minshall Model E organ from 1951 with a tone generator that featured 36 12AU7 tubes.  I decided to build a better tone generator from 12 Fairchild µA2240 devices which consist of a 555 timer connected internally as an astable with 8 divider stages with open-collector outputs all in one package.  I bought 15 devices just to allow for failures and I am glad I did.  The 12 that were from Malaysia worked fine.  The three from Korea didn't work at all once the board was connected.  It may have been a matter of internal ground connections or a different foundry, but IC's from different places or times at the same place may have different characteristics.

The 4558 is a dual op amp based on the design of the µA741 which really does not have enough high-frequency gain to get consistent closed-loop response in the upper frequency range.  Thus, the typical op amp connection does not necessarily allow sufficient feedback factor to stabilize high-frequency gain when the stage gain is high.  You may get noticeable changes in treble response because feedback does not compensate enough to mask the differences.  Slew rate may also change and may be important if the signal output is large or the gain is high like in a tube screamer.  It also has a fairly high input bias current and this affects some designs as it may vary the bias point.