using opa627 for ne5534?

[Svart]

just wondering if it's a plugnplay type of thing. the datasheets show that the VCC,VSS, i/o pins are the same, but they confuse me a little on the offset, comp and balance pins.. do those terms mean EXACTLY the same thing? also according to the opa627 datasheet they hint to not *having* to set the ic up for any offset unless you *have* to.. Since i've never worked with the opa627 before I would like some pointers/opinions before I try to make it work.

oh and by the way, it's just for fun, not trying to replace the 5534s, just after a different color/attribute.


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[PRR]

> do those terms mean EXACTLY the same thing?

No. Or rather: the names mean the same but the crap you connect to them may be very different for different chips.

Ignore Offset. We don't hear DC, and few audio circuits have any need for trimmed offset voltage.

The Compensation will likely be VERY different. Read the datasheets and compensate as recommended for the specific topology and gain in your application.

It happens that OPA627 is internally compensated for gains as low as unity, and furthermore they clearly state that pin 8 usually used for Compensation on single 8-DIP amps is "No internal connection". So in many cases you CAN just stuff a 627 in a 5534 hole.

Be darn sure you have good supply bypasses close to the chip. The 627 has negligible rail rejection above 1MHz, and is liable to oscillate in a layout where a 5534 isn't quite unstable.

627 has higher voltage noise (much lower current noise) than 5534. Probably not enuff to be a problem. 627 has negligible input bias current while 5534 has large bias current: ideally you could use larger input bias resistors for less loading (though in many audio circuits, there is little advantage).

5534 has nearly no distortion, 627 has less (at least on specs). Unless the 5534 is being abused, I would not expect any difference in "color" except maybe in clipping.

 

[Svart]

thanks PRR, I haven't had a chance to read your reply until just now, but shortly after i posted this topic yesterday I went ahead and stuffed a few opa627s in one of my GSSLs in place of the 5534(opa2604 instead of the 5532s). I just bent the unused legs up away from the sockets so they didn't go through the 5534's comp circuit since i didn't know how that would affect it. The opa627 works fine without oscillation. I do notice a difference the sound, the detail of the audio is a little bit higher and the harshness is less than the 5534. Couple this with using the 2604 instead of the 5532 and even less harshness can be had from this combo. I just did this because I had some samples laying around, but anyone looking for a *huge* difference in going from a .50$ opamp to a 15$ opamp is going to be disappointed.

I'm making a few adaptors to put two single opamps(opa627, etc.) in place of a dual opamp (5532) in a summing areas of my console to see what happens, I don't expect a big difference but lets face it, experimenting is fun.


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