Very good reminder. Because the AD797 and L1115 are the top choice op-amp in high end moving coil phono stage, people erroneously assume they are also good for MM.
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Anybody try this phono preamp ?
- Thread starter gaetan8888
- Start date
Dust might cause the output to hit the rails and the gain to fall , then input impedance fall and hard clipping might arise.Maybe that is not about normal listening to a clean record and this is irrelevant...I heard some njm4558-4559 toys and they perform very pleasing when saturated ...that is maybe why some guitar distortion box like them a lot.
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When the output hits the rails you by definition always have hard clipping, or am I missing something? Recovery from clipping may be different depending on the type of op-amp, but I don't see why that would have a direct relation with the small-signal open-loop differential input impedance.
The NJM4558/4559 op-amp are very slow (1-2 V/us). Is it sacrificing the sound quality for softening the hard crippling? A better solution would be to design more headroom to avoid crippling all together.Dust might cause the output to hit the rails and the gain to fall , then input impedance fall and hard clipping might arise.Maybe that is not about normal listening to a clean record and this is irrelevant...I heard some njm4558-4559 toys and they perform very pleasing when saturated ...that is maybe why some guitar distortion box like them a lot.
It is true for the inexpensive commercial audio equipment for the mass market. It is not true for the high end audio market.More headroom means higher supply voltage and heat ...nobody likes it too much apparently.
For us DIY, we want to get high end sound quality without breaking the bank. Higher supply rail and larger heat sink is one of the low investment, high return approach. Some mid-fi audio brand such as Parasound, NAD or Rotel, among others in their higher end series also like this approach.
But it works only if you get the higher quality, faster op-amp. A high slew rate op-amp can have fast settling time spec too if you choose carefully. The NJM4558 or similar will kill the sound quality no matter what you do. In general, avoid op-amp designed for equipment use. Good op-amp designed for audio use may be a little more expensive, but is worth it. Just don't buy fake part because it is cheap.
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