the marketing dept of TI dominates. Some processors never have silicon errata, how come, they resolve the processor errors in the compiler, so you have to use the code composer studio, or sensor studio whatever they call it. if you don´t use that, you`re in for some nasty surprises.
Great. It's nice to know that us analogue dinosaurs aren't the only ones being mislead by 'Big Silicon'
Unless your cabling capacitance is quite large, the 10pf input capacitance seems insufficient.
I know current fashion is very input capacitance to suit primarily Audio Technica, but when it gets very low, it will sound like the life is sucked out of the music.
One can increase the loading resistance, but I find keeping total capacitance around 200-225pf, and resistance @ 47k, works pretty well with most cartridges. I run mostly Audio Technica MM cartridges @ about 240pf (100pf in phono stage) and 47k and it sounds great. 140pf sounds pretty sad.
I know current fashion is very input capacitance to suit primarily Audio Technica, but when it gets very low, it will sound like the life is sucked out of the music.
One can increase the loading resistance, but I find keeping total capacitance around 200-225pf, and resistance @ 47k, works pretty well with most cartridges. I run mostly Audio Technica MM cartridges @ about 240pf (100pf in phono stage) and 47k and it sounds great. 140pf sounds pretty sad.
You mean the wrong opamp in the wrong circuit and a lack of subsonic filtering isn't enough of a mistake?
Its a high gain circuit DC coupled from end to end so will output a large DC offset and likely bash the bass driver to the end-stops when cueing or with a warped disc.
The single stage topology with RIAA network as feedback is hard to beat, and a FET opamp or other low-current noise device is the usual choice given source impedances up in the deci-henry range that efficiently convert input current noise to voltage noise...
If the best noise figure is what you're trying to achieve, then Mark is right ;-)
Maybe the dual approach gives you more magic pixies. No one can argue with that -)
Maybe the dual approach gives you more magic pixies. No one can argue with that -)
An NE5534A is indeed much better for moving magnet. If you want an op-amp that's even worse, try the LT1028 or LT1115: 3.4 pA/sqrt(Hz) when measured with unequal impedances driving the positive and negative inputs.
Nah, there are other ways that give lower noise, if that is what you are after. But it's all either **** and giggles or just to be different at that point.
Techniques to further reduce the noise can actually make an audible difference during the silence in between records.
NE5534A: 0.4 pA/sqrt(Hz)
LM4562: 1.6 pA/sqrt(Hz)
AD797: 2 pA/sqrt(Hz)
LT1028/LT1115: 3.4 pA/sqrt(Hz) with unequal impedances
Nothing beats the LT1028 when you want high noise, except a bunch of them in parallel, like Elektor once used (noise current increases with the square root of the number of paralleled devices).
LM4562: 1.6 pA/sqrt(Hz)
AD797: 2 pA/sqrt(Hz)
LT1028/LT1115: 3.4 pA/sqrt(Hz) with unequal impedances
Nothing beats the LT1028 when you want high noise, except a bunch of them in parallel, like Elektor once used (noise current increases with the square root of the number of paralleled devices).
No, I didn't. It's an ultralow equivalent input voltage noise, ultrahigh equivalent input current noise op-amp.
Sorry, I missed all the later replies to this....
Click my signature line for a link to the LT thread 🙂
I do, I took the magazine monthly back then and followed intensely all the audio stuff. The tone control of that preamp imo is one of the best I've ever seen.
I can't take credit for the attached RIAA noise calculator (I may be wrong but I seem to remember finding it on Bonsai's web site).
This is useful for comparing expected noise performance from op-amps in a real RIAA circuit. The NE5534 fares pretty well and betters the LM4562 in such a circuit.
The LM4562 is an excellent circuit but really is for low input impedance applications. I believe the NE5534 was optimised for use in 47kohm MM RIAA circuits.
As Mark mentioned, FET op-amps work well for high input impedances. My current RIAA stage uses an OPA1656 and is working admirably (silent, crystal clear and full of life)
This is useful for comparing expected noise performance from op-amps in a real RIAA circuit. The NE5534 fares pretty well and betters the LM4562 in such a circuit.
The LM4562 is an excellent circuit but really is for low input impedance applications. I believe the NE5534 was optimised for use in 47kohm MM RIAA circuits.
As Mark mentioned, FET op-amps work well for high input impedances. My current RIAA stage uses an OPA1656 and is working admirably (silent, crystal clear and full of life)