Best replacement opamp but not for sound reasons.

[Walrus]

Figure 14 in the That design note "Upgrading Modular VCAs" http://www.thatcorp.com/datashts/dn127.pdf
shows a 5532, but I only need a single opamp. As I understand it, the 5534 is not unity gain stable unless external
compensation is used. But I don't want to add extra bits.
I just want a simple and cheap equivalent of the 5532. Recommendations appreciated.

 

[Kingston]

http://www.ti.com/product/lme49710

solid choice, very stable in the many environments I've used it. Doesn't hurt it's a bit of a performer, too.

 

[tv]

+1 LME49710

or, alternatively, try OPA27

 

[Walrus]

Thanks Kingston and tv, I'll give the LME49710 a try.

 

[druu]

Doesn't hurt it's a bit of a performer, too.

Rrrrright, so replacing a 553x for a LME497x0 is all good again is it mate? 

 

[fpliuzzi]

Hello,
Just a thought... if at some point you did want to try out using the 5534 without doing any mods to your PCB, just bend pins 5 and 8 of the chip outward 90 degrees so they're parallel to the circuit board (or straight up if need be). Then you can just solder the 5534's 22pF unity gain compensation capacitor directly across those two "flying" leads.

This way the PCB remains unchanged and you can plug other op-amps into that socket if you want to compare the performance of a few op-amps in that position. I used this technique on a console that I built many years ago. It gave me a lot of flexibility when I wanted to try out various op-amps.

Regards,
Frank

PS, On my console I did not need to implement the 5534's offset-voltage nulling circuit (shown on 5534 datasheet). This made it easy for me to solder the cap directly to the op-amp pins.

 

[Brian Roth]

Figure 14 in the That design note "Upgrading Modular VCAs" http://www.thatcorp.com/datashts/dn127.pdf
shows a 5532, but I only need a single opamp. As I understand it, the 5534 is not unity gain stable unless external
compensation is used. But I don't want to add extra bits.
I just want a simple and cheap equivalent of the 5532. Recommendations appreciated.

The only "extra bits" to make a 5534 unity gain stable is a single 22 pF cap connected between pins 5 and 8, which could be easily added to the foil side of a PCB.  That's not to say that other opamp choices MIGHT provide improved performance in the particular circuit....

Bri

 

[Kingston]

Rrrrright, so replacing a 553x for a LME497x0 is all good again is it mate? 

For the specs he has given us, yes. If you are trying to make a point about blind opamp swapping, this isn't the place. See the original post.

[edit]

And further, LME49710 and LME49860 are just about the best generic utility task audio opamps to date. You can quite safely "throw" them anywhere, as they don't oscillate easily. They don't improve on 5534/5532 a whole lot (performance-wise) but are much less prone to problems in wildly varying PCB implementations and PSU's. Just my personal experience.

 

[Walrus]

OK, so I could easily find space to add one 22pF cap to my board, but checking prices on Farnell, in small quantities it's just as cheap to buy the LME49710 as it is to buy the 5534 and a 22pF! 

 

[Rossi]

Why not use a 5532 and just ignore the second opamp?

 

[Walrus]

Why not use a 5532 and just ignore the second opamp?

That's what I have been doing.  ;D
It's just that it seems a terrible waste!

 

[Kingston]

Why not use a 5532 and just ignore the second opamp?

That's what I have been doing.  ;D
It's just that it seems a terrible waste!

Use it as a servo "for free" elsewhere in the design. Beats a simple electrolytic. Well, most of the time at least.

 

[joaquins]

But an OP27 or a 5534 are more expensive than a 5532, how is this a waste? +1 with servo! 2 caps and 3 resistors, 5532 won't have as low offset as OP27 but I've been using 741 for this task in some places where dead offset is not so critical.

I thought it wont fit in the board... If you don't use the second op amp at all it should be shorted -IN to OUT and +IN to GND to avoid oscilations that could reach the one you are using (cause shared supply)

JS

 

[Rossi]

Why not use a 5532 and just ignore the second opamp?

That's what I have been doing.  ;D
It's just that it seems a terrible waste!

Well, instead of changing the opamp, just change your perspective: How often can you feel like a rich man for just 50 cents?  ;D

 

[Walrus]

Our supply of API 2551B vca blocks is beginning to run low, and as our replay desk in Studio 2 has about 225 of the little blighters in it, and
Studio 1's desk has 50 ish, I decided to make a quick and (not to) dirty drop in replacement.

EDIT: It's using the THAT 2180

 

[Walrus]

350 VCA card schematic....

 

[Walrus]

The board....

 

[tv]

Pricewise, imho the quantity rules out the OPA27.
I hope the LME47910 will work just fine!