Interesting, you say that NE5534 is one of the best in a typical audio application. At the same time you deny that it is fantastic audio op amp. You are contradicting yourself here.
But since you are clearly a better engineer than I am, you can kindly explain, in what cases one would need your JFET buffers.
Not really a contradiction. A unicycle is a fantastic transporter. With only one wheel it can transport you over long distances. It is when you use it to go everywhere I start to see it as a stupid vehicle.
When we use dale resistors or use Scan-Speak drivers, we don't care with $10 difference, now why we care with $1 and use cheap opamp thinking that it will not ruin the sound? Opamps have had good reputation for bad sound. Which opamp is do you think responsible?
The strength of a JFET is it's inherent high impedance, low noise (including protect the circuit from interference) and DC operation (you can avoid capacitor in the input).
When you read spec-sheet, the single spec number is based on certain operating point. For example distortion is a function of gain and impedances (input and output). If you lower the impedances, the distortion will be less.
Check JRC2068 spec-sheet. Operate it in its best zone and it will outperform NE5532 soundwise. JRC2068's THD of 0.001% is near the hearing threshold. There is no proof that 0.000005% sounds better or audible. And it's 6 V/us slew rate at around +/-15V output swing is also above the 3.9 threshold. It's input noise is of course above hearing threshold, but it depends on the acceptable noise level of your audio system. That's why we need the JFET. BF862 is very low noise (and high current drive too).
Opamp speed is mostly a liability in design. It affects our hearing in a simple way no one will agree 🙂
NOTE: The image is to show that specification changes with operating point. It is not from opamps mentioned in discussion.
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depends on the design. I upgraded from NJM4558 to NE5532 and it was a dramatic improvement in clarity and lower noise. I pushed my luck and tried LM4562 and it was oscillation city. The amp was screaming at me.
Well, I will not waste my time to convince you into anything (nobody on any internet forum has ever convinced anyone -- that is the iron law of internet).
But there is a guy who knows a thing or two about op amps and according to him you are about 33% right with your strong preference for JFETs.
NwAvGuy: Op Amp Measurements
Below he also answers the OP who wanted to replace NE5534/32 with some ghastly high speed video op amp.
NwAvGuy: Op Amps: Myths & Facts
I love the statement from the NwAv guy:
"The 5532 is the corner stone of nearly all high-end professional audio gear which means most of your music has already been well steeped in 5532 goodness. If you dislike the “sound” of 5532 that means you must also dislike most of the music available."
"The 5532 is the corner stone of nearly all high-end professional audio gear which means most of your music has already been well steeped in 5532 goodness. If you dislike the “sound” of 5532 that means you must also dislike most of the music available."
popped in 5 OPA2134's. zero noise and the best sound ever. nirvana has been reached
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Let me get this straight. You replaced NE5532s with OPA2134s and got LESS noise? That seems odd, unless the circuit had a very high source impedance. The 2134s are faster and have less distortion than the 5532s.
If he cannot measure noise with the 5532 and cannot measure noise with the 2134 fitted, then we don't know which is noisier.
I think the noise contributed by the opamp in a DAC output circuit is minimal, in any case. Probably 100 db or more below the output signal level---not audible if using an NE5532 or better opamp. Other parameters are more likely to be relevant to the quality of sound.
It has been a couple more years, so digging up this thread.
For a drop in replacement, ( in this case a crossover) unity gain, no excessive drive problems, is the OPA2134 still the go-to? They sure ain't cheap but no SMT to DIP headers etc.
Well aware 99% of all my CDs went through dozens of 5532's, or worse. Most probably not even biased into class A.
For a drop in replacement, ( in this case a crossover) unity gain, no excessive drive problems, is the OPA2134 still the go-to? They sure ain't cheap but no SMT to DIP headers etc.
Well aware 99% of all my CDs went through dozens of 5532's, or worse. Most probably not even biased into class A.