Are There Lower Noise IC Chips Than A TL072?

[Paul Marossy]

I've seen the NE5532/34 ICs in several different things over the years. I know they are also good performers.

[StephenGiles]

Over at Prodigy Pro this very subject was discussed at length a few years ago. One of the points made by a very knowledgeable egg there was that a good test of IC noise could be seen from a 24 or more channel mixer running at a decent voltage level like dual 15 or even dual 18v. Perhaps the noise from 100 or so opamps when added together would provide a good comparison - assuming that one could be bothered to change them!! I suggest a trawl through the posts of global moderator there PRR.

I don't think that you will notice much difference in terms of noise between different opamps in stompboxes - you will of course notice the sheer "emperor's new clothesism" of using an opamp with an OP suffix, and upon announcing at a gig that your phaser uses OP.........the girls will be delighted

[R.G.]

In a way, the TL072 and NE553x are good examples of how different design points match different source impedances better.

The NE5532 is a good low noise device on its own, but it has a low input impedance. Where the abstract idea of an opamp is that its input impedance is negligibly high, the bipolar-input NE5532 has an input impedance of typically 200K, but a guaranteed minimum of only 30K. This works fine for lower impedances, but you don't get the high impedance you'd otherwise expect in the non-inverting circuit arrangement. It has great output drive and for a long time was the only integrated opamp which could drive 600 ohm lines well. It offers low THD, low IMD, and low slew induced distortion. This combination has made it the darling of the pro audio studio where high input impedance isn't the only thing to consider.

The TL072 is a JFET input device with very high input impedance. It does nothing to quiet input resistors, but it can easily work from high impedance sources and keep noise levels down. It can't drive 600 ohm loads as well as the 5532/4, but it can and does produce lower noise with high impedance sources; the TL072's input resistance is a million megohms (ten to the twelfth ohms), and its input noise voltage is 0.01pA/root-Hz. The 5532 has an input current noise of 0.7pA/root-Hz.

If you can live with the low input impedance, the NE5532 is probably a better choice, especially if you have to drive 600 ohms lines. However, if you know enough to know that you need that, you should maybe look at something like the LM4562 dual. If you are worried about the input impedance and noise at the same time and can give up driving 600 ohm lines to +10dbm, the TL072 is going to work fine.

There are newer opamps as well. I like the performance of the LM833 a lot.

And Steve's right - there's the mojo factor.

When I mojo opamps, I use ...discrete... opamps with hand-selected monolithic pairs. 

[Paul Marossy]

There are newer opamps as well. I like the performance of the LM833 a lot

I've seen those in a few new pedals. I will need to look at the data sheet for it...

[d95err]

Um, I've always been pleased with the results of the 5534 singles and the 5532 dual opamps where noise might be an issue. Nice and cheap too.

+1   

I use 5532's for just about everything. It made a huge difference in noise in my Orance Squeezer clone, replacing the original 4558. I don't know how a TL072 would have worked there though.

[cab42]

I use 5532's for just about everything. It made a huge difference in noise in my Orance Squeezer clone, replacing the original 4558. I don't know how a TL072 would have worked there though.

I have a TL072 in my OS and I have no notable noise issues.

Regards

Carsten