JRC4558D Again.... So Where's The Magic Hiding?

[MartyMart]

Oh .... round metal can of course

I'll PM you Ton ....

[analogmike]

Lets take the TS

Guitar TS(a) TS(b) TS(c) amp

I leave the room and let someone try the TSs I tell them to change the TS order at least 3 times 

They will sound different due to the buffers if you run two TS's in a row.
You really need an AB loop box to do that, like this:



Mine has an LED that you can turn off for true blind AB testing.

[MikeH]

I have a TS-5, TS-7 and an 808 that I built.  My friend has a TS-9; We've tried them all separately and compared them.  Basically, my gilrfriend couldn't tell them apart, I could hear slight a difference, but couldn't say which I like more, but I'm sure my dog could explain all of the subtle differences in each one.

[johngreene]

The Raytheon RC4558 was an early opamp intended to get better results on these "edge" conditions. It spawned a host of similar devices from other makers, including the JRC4558 from NJR. These opamps were much more orderly in how they responded to bad input conditions and overloads.

I find this rather confusing since by the time Raytheon came out with the RC4558, Raytheon and JRC (NJRC) were the same company.

http://www.njr.co.jp/e_frame/ef_01_04.html

I wouldn't be all that sure that they were made in different foundries, rather just re-labled version of the same device. Yet people swear they can hear the differnce between a JRC4558 and a RC4558.

As for a little history:

The JRC4558 never 'disappeared' only to come back later re-invented. Back in the day that Ibanez was using the JRC4558 it was a low-cost, relatively low-noise opamp that was being used in thousands of different kinds of audio equipment. Peavey being one of the largest. Peavey started having reliability issues with the JRC4558. So they, along with a lot of others, dumped the JRC4558 in favor of other devices that were more 'reliable'. NJR continued making the JRC4558. What threw everyone off is NJR's part numbering scheme. JRC4558 is printed on the top of the part but if you want to order one, you have to know to ask for the NJM4558. The 3 letters that prefex the part number indicate the type of device, CMOS, Bipolar, etc. Some bright young pedal builder discovered that the NJM4558 Mouser electronics carried came marked JRC4558 and sounded the same as the originals in an original TS-808.
There was a period of time where people where buying this 'New' NJR4558's and re-selling them on the internet as NOS. However, if you just check the date code you can tell that they were not NOS but recently manufactured.

--john

[RedHouse]

...I wouldn't be all that sure that they were made in different foundries, rather just re-labled version of the same device....

FYI; chips (Integrated Circuits) are not made in foundry's, a chip Mfr has a way different set of tools and materials.

...I find this rather confusing since by the time Raytheon came out with the RC4558, Raytheon and JRC (NJRC) were the same company...

Back then, there was a huge difference between home-grown and off-shore silicon.

[Gilles C]

I have that round metal can 741 that I keep ready to be used in a circuit that would also use a tube...



Could call the box a "Double Mojo"? 

Gilles

[R.G.]

Back then, there was a huge difference between home-grown  and off-shore silicon.

Back then there was home-grown silicon...

[johngreene]

...I wouldn't be all that sure that they were made in different foundries, rather just re-labled version of the same device....

FYI; chips (Integrated Circuits) are not made in foundry's, a chip Mfr has a way different set of tools and materials.

...I find this rather confusing since by the time Raytheon came out with the RC4558, Raytheon and JRC (NJRC) were the same company...

Back then, there was a huge difference between home-grown and off-shore silicon.

I have talked to the people at NJRC. Have you?

-john

[aron]

First, I seem to recall something from Jack Orman a half dozen years back that suggested the differences between the JRC chip and other dual ops could easily be mimicked by means of a 1k fixed resistor in series with the diode pair.

Actually I found it to do the opposite. You could _minimize_ the differences between op amps by using this fixed resistor. I tried it and it basically made almost all of the op amps sound the same. Neat little trick.

[phaeton]

So then why is the lm747 (dual 741) $4.00 when the 741 itself in an 8-pin DIP is $0.25?

[Mark Hammer]

First, I seem to recall something from Jack Orman a half dozen years back that suggested the differences between the JRC chip and other dual ops could easily be mimicked by means of a 1k fixed resistor in series with the diode pair.

Actually I found it to do the opposite. You could _minimize_ the differences between op amps by using this fixed resistor. I tried it and it basically made almost all of the op amps sound the same. Neat little trick.

I think that's what I meant to say.   Jack, where are you?  Shed a little light here, even if it's only a 300mcd LED.