ultra low noise alternative

Depends if the circuit needs the minute input current of bi-fet op-amps.

There's no shortage of really quiet bipolar ones at sensible prices.

Graham

I would think it depends on the circuit whether a bipolar would work. OPA4134 is a good bifet, but you just can't expect it to work if you don't know the circuit. Power supply requirments are essential. Then there's the LME49740.

greg

I don't know why, but I was assuming audio applications. There are all kinds of applications that need to be fit into the mix. Is this for instrumentation and what is the circuit ?

greg

One big problem with the internet, unlike books, data disapears if its not current.

greg

is a good bifet,

Indeed. The question needs to be more specific.

Lovely isn't it ? And it's dual friend the LME49720, not to mention a single too, the 49710. Singles are rare these days but can come in handy.

Graham

That's what the TL07x series was designed for after all.

Graham

Keep those good books ! ;~)

Graham

I have seen the TLO7x series in many applications.

For a long time I was bent on getting a TLO75 replacement. I guess I got over it.

greg

Oh yes, they're very versatile and not especially expensive, so well adaptable to mnay circuits, however that WAS their intended primary market.

BTW, it's TL zero seven (five), not Oh (the letter) seven (five). Just being pedantic ! ;~)

Graham

it for an trace elliot bass amp. see circuit here:

except ic1, all ops are TL074. i already replaced ic1 with an OPA 2134 (excellent result) but still have some great humming even when nothing is connected to the input and mute is pressed. it's definitivle the main board, not the AHA. so i wanted to replace all those cheap noisy TL074 with the OPA 4134 - unfortunately, the PA series (DIP14) is dead;-)

OPA4134

Changing op-amps won't affect humming one tiny bit. You have some other problem. Could be all sorts of things. Take it to a tech.

Graham

OPA4134

kinds

instrumentation

problem. Could be all sorts

i am the tech! ;-) the humming is my 2nd problem, i first have to solve the noise, and as the TL074 are pretty good noise generators, i want to change them first to have a "clean hum" to start look for and as the OPA 4134 is dead, i was looking for some other alternative.

dont

pin-

op-amps.

OPA4134

Power

kinds

instrumentation

problem. > Could be all sorts

Must be a pretty cruddy circuit if TL074s are noisy in a guitar amp !

I guess you're going to be looking at a TI/BB or AD device but I'm not up to date on low noise fet input devices, I tend to use bipolar myself.

I'll tell you one thing though. Modern TL0's may be a fraction quieter than old ones. I know the TL081/2/4 spec changed.

You might want to post in sci.electronics.design. Lots of people are well up on their devices there.

Graham

You were given two models.

Put some sockets in there and compare.

greg

I have been saying TL O for 30 years. Now I stand corrected.

greg

I SAY it that way too but write it the other way. In the UK (and I'm sure the USA too) 'oh' is often used colloquially to mean zero but not written like that.

Graham