Good day all, I am simulating a proposed design for an active crossover.
It specifies LM4562 opamps in S&K Linkwitz-Riley 4th order high and low pass filters.
Simulation predicts worst case current at 95mA rms : is this a reasonable/ acceptable load for the opamp ?
Many thanks for your advice.
It specifies LM4562 opamps in S&K Linkwitz-Riley 4th order high and low pass filters.
Simulation predicts worst case current at 95mA rms : is this a reasonable/ acceptable load for the opamp ?
Many thanks for your advice.
The lm4562 would not come to close to that level of current delivery. Its certainly 'safe' in that no harm would be done, but it just wouldn't do it. The data sheet suggests -/+26ma as a maximum load current with short circuit levels around 45 to 50ma.
If you are seeing those kind of levels in a simulation (and the signal levels are realistic levels) then you need to scale the filter design components to bring the peak currents down.
The NJM4556 opamp has much higher current delivery but would still fall short (around -/+70ma_
If you are seeing those kind of levels in a simulation (and the signal levels are realistic levels) then you need to scale the filter design components to bring the peak currents down.
The NJM4556 opamp has much higher current delivery but would still fall short (around -/+70ma_
Would you mind sharing it? 95 mA is very unusual in this application, scaling the components as Mooly suggests is easy enough, so it's all the more surprising that whoever designed it didn't do it themselves...
Hi again, thanks for your responses - it seems that I have forgotten to insert a comma - the value is 9,5mA rms : sorry.
The data sheet does claim 20+ milliamps but does not state whether that can be maintained. What I am really asking is whether delivering 9,5mA is sustainable ?
The data sheet does claim 20+ milliamps but does not state whether that can be maintained. What I am really asking is whether delivering 9,5mA is sustainable ?
9.5ma rms is no problem at all and is only the same as delivering -/+8 volts peak/peak into 600 ohms. Even a TL072 would just about cope with that.
...but the TL 072 would suffer in its voltage output and higher distortion. A TL072 is NOT a driver chip for 600Ω! But I suspect you already know that!
Yes, and the limited drive ability is what is always mentioned with the TL0 series 🙂 but even so it should still manage the 9.5ma rms current needed here (and which would be 8 volts peak across 600 ohm, just just over 5.5 volts rms across 600 ohm)
It was just to show that the LM4562 would easily handle this.
Don't underestimate TLO 072. If i'm not wrong, it's still the most popular opamp after NE5532. It works great within it's limitation. Most diy people doesn't need 600R drive capability anyway.
Edit- In low-fi subwoofer systems, 4558 still rules!
Edit- In low-fi subwoofer systems, 4558 still rules!
No such beast, its the TL072.
Well I'd try to avoid an opamp with phase-reversal if there are alternatives with similar / better performance without phase reversal.
The most popular opamp is likely the LM358 actually, opamps are not just for audio, and the LM358 is very cheap and works single-supply.
Well I'd try to avoid an opamp with phase-reversal if there are alternatives with similar / better performance without phase reversal.
The most popular opamp is likely the LM358 actually, opamps are not just for audio, and the LM358 is very cheap and works single-supply.
I was not comparing apple with orange, yeah 5532 is far better but tlo072 is very popular audio opamp among PA operator & technicians.
Edit- I never had the luck to witnness phase reversal of tl072. So it is ok for me. He he.
Edit- I never had the luck to witnness phase reversal of tl072. So it is ok for me. He he.
Being a FET opamp it means simpler circuitry for level controls and equalizers/tone controls of course, not need for capacitor on every pot's wiper...
Lm358 works great for subwoofer filters.
Lf353 is a much better op amp then TL072
However at loads > 2k less noticeable.
Lf353 is a much better op amp then TL072
However at loads > 2k less noticeable.
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That's an advantage we can take with less current consumption... also with not so good speakers 5532 is full waste where distortion, frequency response is already not spectacular! If you do a survey you will see half of the world's population used to be (& happy) with such products & performance. This makes tl072 a champion. I compared both by listening & found nothing bad against tl072. Ok, the noise is very high for tl072 but that's not an issue most of the time. But if you sit & want high degree of listening experience, today you have better alternative than 5532.
I grabbed some LF353 too, The National version of TL072 but yet to compare both. Now I have other works to do.
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"Don't underestimate TLO 072. If i'm not wrong, it's still the most popular opamp after NE5532."
Maybe true. Doesn't mean it makes for good listening. 4558s are also VERY popular, and they absolutely SUCK. TL072s can be used in certain applications. They're noisy and gutless, but if you're using them in a line-level circuit that doesn't have to drive anything ≤10KΩ, they're OK.
Maybe true. Doesn't mean it makes for good listening. 4558s are also VERY popular, and they absolutely SUCK. TL072s can be used in certain applications. They're noisy and gutless, but if you're using them in a line-level circuit that doesn't have to drive anything ≤10KΩ, they're OK.
The sooner you accept the tl072, in line level circuits, the better life will be!
Any other application, likely not so good.
Any other application, likely not so good.
One rarely sees the bad sounding TL072* in branded audio gear, it are the NJM4580 and NE5532 that are the workhorses in relatively good quality stuff when it is about good numbers and cost reduction.
*However there seems to be a new/updated (or is it retro? 🙂) version of TL072 called TL072H (since 2020) with significantly better specifications. Buzzwords are solar, UPS, EMI rejection ratio but also professional mixers.
https://www.ti.com/lit/ds/symlink/tl072.pdf
Seeing what tantalum caps still have to endure I don't see hope for TL072H in DIY audio 😀 As much as we like certain opamps in audio, the market decides what is being produced in high numbers for many years.
*However there seems to be a new/updated (or is it retro? 🙂) version of TL072 called TL072H (since 2020) with significantly better specifications. Buzzwords are solar, UPS, EMI rejection ratio but also professional mixers.
https://www.ti.com/lit/ds/symlink/tl072.pdf
Seeing what tantalum caps still have to endure I don't see hope for TL072H in DIY audio 😀 As much as we like certain opamps in audio, the market decides what is being produced in high numbers for many years.
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While we're on the subject, I think the current "natural" replacement for the TL072 in a DIP package would be the TLE2072, a nice all round FET input opamp with decent drive capability, better noise, better THD and not too touchy stability-wise (IME). Worth mentioning too the TLE2062, good for heavier loads (spec'd @ 100R) and much lower idle current.