1604	2008-04-26 23:05:05	Rick	Op-Amps in EMRFD
Message	Date	From	Subject
I can't speak for Wes and Bob, but all of my circuits in chapters 8, 9 and 12 and the few scattered throughout the other chapters use NE5532 op amps. I design many signal processing circuits, and my usual requirements are low noise, high output drive capability, and very low distortion. The NE5532 nicely fits those requirements for many of my applications. I used them in all of the circuits I described in EMRFD. I built a receiver nearly 20 years ago using some available LM324 op-amps and quickly discovered the output circuit issue, which is well documented in the literature. I added current sink resistors to fix the problem in that particular circuit, and then did a search to find a better generic op-amp to use in my projects. I have been keeping NE5532 dual op- amps on hand ever since for use in my prototype designs and experiments. Data sheets are available on the web for most common op-amps, and they are written to be read by all of us who use op-amps. A few hours studying different op-amp data sheets is very helpful in understanding the differences and similarities. The differences can be major, and the NE5532 would be a very poor choice for some common op-amp applications. After I have a working prototype that I can measure, I sometimes experiment with different parts from the excellent offerings from Analog Devices, Linear Technology, National Semiconductor and several other companies that have continued to push the performance envelope for op-amps. The NE5532 was a good choice for my low-noise analog signal processing circuit designs nearly 20 years ago. Perhaps I would choose a different generic op amp if I were to select one today, but it has become one of my familiar and trusted components, along with the 2N3904, 2N3906, 1N4148, and J310. Best Regards, Rick KK7B
1606	2008-04-27 10:03:15	Frank	Re: Op-Amps in EMRFD
Any chance there's a quad version of the '5532? I'm facing some tight space constraints. I've pored over op amp literature for days....this is my first time using op amps for audio. In the past, I've rolled my own diff amps and complementary driver stages as I've needed circuits, and have used op amps mainly as parts in DC power supplies and biasing. The previously-mentioned MC3403, interestingly enough, claims specifically to not have crossover distortion, but "no crossover distortion" seems not to be a parametric element referenced in any selection guides. I rather expect those who've used op amps at audio for years have understood the issue for so long that it's passe; indeed, an internet search of "op amp crossover distortion" yields surprisingly few hits on the topic, most of them suggesting how the silicon designer avoids the issue - not the end user. So, I'll get some of the 3403s
1607	2008-04-27 11:13:13	Wes Hayward	Re: Op-Amps in EMRFD
Hi all, The op-amp thing is interesting and one of those things that is especially dramatic when we discover it for ourselves. The LM-324 and similar parts, usually derivatives, really are rather poor for audio applications. The little glitch that occurs when the part runs out of drive capability is small enough that you have to look carefully for it when first examining a 'scope trace. But you can sure hear it. Once looking with a little bit of care, it shows up with ease on a 'scope. It is instructive to listen and watch at the same time. I recently discovered some similar distortion in the audio output amplifier in a receiver. I ended up replacing the current hog follower output that is in the upper right corner of Fig 6.78 with one of Rick's designs. See Fig 9.47. The new circuit is extremely clean. I took a look at Fig 3.58 (a poor number choice!) and noted that I had been specific about the op-amp type in the caption. I then went looking in my junk, but alas, could not find the board. It is around somewhere. We really did build it. I suspect that I used 1458s for that model, for that was a favorite at the time. The 1458 is just a dual 741. I never noticed the glitch with that amplifier. That example ran from a 12 volt supply and was always running with pretty low output. I'm with Rick -- I really like the 5532 as a general purpose op-amp. I keep some in stock (I even know where they reside in the the junk) in both DIP and SOIC-8 packages. The noise is pretty good, although not as good as things like the OPA-27. The OPA-350 series is low noise and a great general purpose part although I don't have much direct experience with it. Both of these feature lower noise than the 5532, but not by a lot. At one time we treated the 5534 as a quad that was otherwise identical to the 5532, a dual. I don't think that this is the case though. Also, I have seen comments about variations in the 5532 depending on the manufacturer. After I first saw this, I checked my stock and the DIP versions I have are all older Signetics parts. There is a comment at the very end of the RC Active low pass section on page 3.25 where the distorti
1609	2008-04-27 16:18:53	michael taylor	Re: Op-Amps in EMRFD
> At one time we treated the 5534 as a quad that was otherwise The (TI) NE5534 is a single op-amp version in an 8-pin package, of the NE5532 dual op-amp. Both are available for ~$1 in single quantities, so they should be both cheap enough to encourage experimentation with (rather than using the "classic" 741 and MC1458 / LM747), -Michael, VE3TIX
1614	2008-04-28 07:05:23	ehydra	Re: Op-Amps in EMRFD
They cost Euro 0,20 in Germany. I think that is approx. $0,30. - Henry michael taylor schrieb: >> At one time we treated the 5534 as a quad that was otherwise > > The (TI) NE5534 is a single op-amp version in an 8-pin package, of the > NE5532 dual op-amp. Both are available for ~$1 in single quantities, > so they should be both cheap enough to encourage experimentation with > (rather than using the "classic" 741 and MC1458 / LM747), > > -Michael, VE3TIX > > ------------------------------------ > > Yahoo! Groups Links > > > >
1624	2008-04-29 17:52:25	jr_dakota	Re: Op-Amps in EMRFD