Metal Can Raytheon RC4558T

Motter · Post by **Motter** » 20 Oct 2012, 01:06

Forgive me if this is in the wrong forum, these are not for sale.

I found about a dozen of these today in a surplus warehouse at work. I'm just curious if they're considered rare/good-sounding/expensive. I definitely plan to build a few tubescreamers with them

Greg · Post by **Greg** » 20 Oct 2012, 01:49

IMHO.. metal can opamps are generally equivalent to those in modern packaging.. and in a circuit that derives distortion from diode clipping, I doubt you'll hear a difference.

I think a lot of the difference people hear when swapping opamps in circuits like the TS are from impedance changes, more than any inherent characteristics of the opamp circuit.
Opamps are designed to amplify accurately... so, a metal can 4558 will have the same specs as a plastic version, and sound the same I suspect.

They definitely win points for Mojo looks and rarity.

tubehead123 · Post by **tubehead123** » 07 Feb 2013, 17:55

70s opamps (metal can or DIP) generally sound dirtier in stompboxes due to the IC process used to create them, which was lower precision than the ones used to produce the newer opamps...

roseblood11 · Post by **roseblood11** » 07 Feb 2013, 20:20

was that a joke?

danielzink · Post by **danielzink** » 07 Feb 2013, 22:03

roseblood11 wrote: was that a joke?

Probably not.

He can probably hear the difference between film and ceramic capacitors as well.

tubehead123 · Post by **tubehead123** » 08 Feb 2013, 16:55

ic sockets aren't commonly put into production pedals but you can put them in yourself without too too much hassle...then you can swap opamps in and out and hear the differences between them: era of production, bipolar inputs (5532, 4558, 741), jfet inputs (TL072, TL082), mosfet opamps (TI TLC family), different manufacturers etc. etc.

roseblood11 · Post by **roseblood11** » 08 Feb 2013, 21:40

Do a double-blind test, everything else is nonsense!
A friend did that with a couple of 741's, new ones, vintage ones, plastic and metal can types, even early clones from the soviet union...
Result: forget it

tubehead123 · Post by **tubehead123** » 09 Feb 2013, 00:02

sure, that's between different manufacturers of the same part trying the meet the same specs. the 741's bandwidth is so low that it's barely useable for audio work, you won't see that much of a difference with that part because the gain-bandwidth of the part is low and it's probably externally compensated (rolled off) with capacitors on the board, which attempts to resist variability in the opamp. try sub'bing a newer, higher bandwidth part into that same circuit and see the difference. with dual dips most of them are internally compensated (e.g. fixed in the part and not in the circuit) so there is usually more audible variability with those kinds of circuits.

ymmv as always tho...

Greg · Post by **Greg** » 09 Feb 2013, 05:11

tubehead123 wrote:sure, that's between different manufacturers of the same part trying the meet the same specs. the 741's bandwidth is so low that it's barely useable for audio work, you won't see that much of a difference with that part because the gain-bandwidth of the part is low and it's probably externally compensated (rolled off) with capacitors on the board, which attempts to resist variability in the opamp. try sub'bing a newer, higher bandwidth part into that same circuit and see the difference. with dual dips most of them are internally compensated (e.g. fixed in the part and not in the circuit) so there is usually more audible variability with those kinds of circuits.

ymmv as always tho...

That's the point isn't it.. opamps are made to specifications.
A completely different opamp with different specs is another story.

roseblood11 · Post by **roseblood11** » 09 Feb 2013, 22:45

tubehead123 wrote:sure, that's between different manufacturers of the same part trying the meet the same specs. the 741's bandwidth is so low that it's barely useable for audio work, you won't see that much of a difference with that part because the gain-bandwidth of the part is low and it's probably externally compensated (rolled off) with capacitors on the board, which attempts to resist variability in the opamp. try sub'bing a newer, higher bandwidth part into that same circuit and see the difference. with dual dips most of them are internally compensated (e.g. fixed in the part and not in the circuit) so there is usually more audible variability with those kinds of circuits.

ymmv as always tho...

The 741 is from the stone-age and the 4558 is one day younger.
You just use technical terms to explain your religous beliefs.
But I'm really not interested in starting that kind of discussion again and again...

danielzink · Post by **danielzink** » 10 Feb 2013, 03:10

cork sniffer: A derogatory term used to describe a person that tends to overanalyze physical properties that may not even be relevant.

These people seem to split hairs on details and are usually just percieved as windbags who just like to hear themselves speak.