Whats the deal with the last few letters at the end of ICs

[Hangingmonkey]

Ive got a TL072 CP and a TL072 CN

Likewise with the JRC 4558 D and DD

Are they the same thing and if not what to you guys do to choose which one when making your builds?

[mgwhit]

Apologies up front because I can't vouch for any of this, but the DD was once explained to me as a lower noise version of the D.  I've seen it elsewhere explained as "double shielded".  I've compared 4580D and 4580DD IC's in my Aristocrat and couldn't tell a difference.  DDs are usually a tad more expensive.

According to the TL072 datasheet, the N and P suffixes just denote a (barely) different "package thermal impedance" rating.  Nothing I'd worry about in a pedal.

[vvangelovski]

As said above, for the two examples you've given, there's no difference for pedal builds. Though for some opamps there might be variations that can affect the sound, so it's best to check the datasheet if you're not certain.

[Hangingmonkey]

Thanks guys

[al heeley]

some of the chips have higher or wider temperature tolerances, you may see LM741 with an A after it which extends temperature tolerance for normal operating parameters from 0 - 50C to -35 to 80C for example.