In this test, I compare the output voltage swing under different loads to see how each opamp IC performs. Patreon www.patreon.com/user?u=12254451 Mail: PO box 362, Vandalia, OH 45377 Email: johnaudiotech@gmail.com Thank You!
Who else besides me would like to see a push pull MOSFET final in the JAT EZ? Hmm, So, John, how many up votes will it take to make a MOSFET final happen?
Hello John, I see you check out Cool Dude Clem, like your channel, one of my oldest subscriptions. Great information as always. I hope you and your family, Brother, are all doing well. The voltage divider to the Non-Inverting input, with filter cap from 4.7 to 10 mF works good to power op-amp from a single supply rail. Voltage divider resistors from 10 to 100K. Glad your still doing videos, I have learned a great deal. After 9 days of forest fire smoke starting Labor Day, Sept 7th, the air has been clear and have had some welcome rain. Closest fire to me was 10-15 miles, nothing in immediate area. All the best from Oregon, Cass.
When uA709 needed some diode addition to protect it against latch-up and when uA741 corrected that plus added internal frequency compensation, I found that both specified a minimum load resistance of 2 kilo-ohm. That was the "industry standard" for years after. Also, it was not only the output, the input common mode range was a limiting factor. Eventually we got rail-rail input or rail-rail output chips and finally chips that combined both features. However, most of them continued for quite some time to be limited to supply voltages good for 5 V use. But the chip prices have gone precipitously down since the uA741 introduction while various performance numbers have improved. In the old days, magazine articles used to publish their own evaluations including such as Price per Performance. As to voltage -- I still worry about my op amp characteristics and occasionally need to go back to my stash of (obsolete) LM343 that offers +/- 30 V power supply rating. In most other situations, and especially audio or other low noise requirements.my favorites have been and continue to be the OP27 or OP37 genre, available from multiple manufacturers due to wide cross licensing.
I really like pcb-rnd for doing pcb layout and was using geda for schematic capture but I moved to lepton-eda which is more stable but file format compatible.
Idk what 4.5 mhz means on an rca ca3240e. Would these chips work properly in a distortion pedal I have compared to other non 4.5 mhz op amps in the same class?
Hi John, thanks for the comparison of OPamps under load. I would say, that the most OPamps dont like a load under 600 ohm (resistive) due to the limited thermal conditions in the chip, especially when used with a higher supplyvoltage. The data sheet tells that the duration of output shortcut is unlimited, but there is no protection of overheat in regular chips.
It is like those who use a 5 volt regulator IC with a 25v input voltage and complain why the chip gets so hot even with small loads. Thermal design must be considered.
I am impressed of the NJM4556. I think it is another good candidate for a 30 Ohm stereo headphone amplifer delivering 0.5 V output voltage allready at a power supply voltage of +/- 3 V. It consumes a relatively high quiescent current of 9 to 12 mA and it has twice the input noise of the LM4562, so it is not well suited for phono preamps. The NJM is also capable to operate 30 Ohm headphones in class A mode up to a quiescent current of about 50 mA (with a suitable JFET between the output and the negativ power rail). The power supply voltage should be limited to +/- 6 V in this case, especially if it operates in stereo mode with both internal opamps.
Thanks for the video - very educative! :) But I am not sure about the current calculations at the end? Should you take the RMS voltage, e.g. for the NE5532 10.8Vpp => 3.82Vrms => 38.2mA with 100Ohm load? That will also make the NJM4556 79.9mA which fits a bit more the datasheet :)
Yes that would make sense but the signal was not a sine wave due to the clipped tops. Current limit circuits will limit on some max level and I wanted to see what that was. Outside of audio, opamps are used for DC and non sinusoidal waveforms so it is useful to see where current limit kicks in.
No, John is quite right. If your opamp is clipping solidly at 10.8Vpp, then it is almost certainly swinging 5.4V each side of ground. Into a 100R load, that is exactly 54mA, which is clearly the current limit built-in to the output stage.
Cool vid! I'm always swapping Op-Amps in and out of my audio gear, just for curiosity mainly. I'm sure you know this but, those Op-Amps are garbage by today's standards. Just from Ti alone you have: the OPA627, OPA827, OPA1612, OPA1620, OPA1655, to say the least. Then if you want "high current"... you can have the dual channel LME49726 with 350 mA or the single channel LME49600 with 250 mA!
what is your best for audio in a dac? i want perfect square wav rendering (band limited to 20-25khz).. no crosstalk, low noise, low distortion etc.. maybe stable with some small DC offset (can it clean DC or you need cap to clean it?)
Have you done a video on your pilot signal. I just learned to get my oscilloscope to measure fft but it's hard to interoperate without that pilot signal as a 1% reference
I was using the LME49710 but when they discontinued it I had to switch to the much more expensive LT1037 and now I am on the OPA1611. I know a lot of people like the ADA797 but some of it's other limitations made it less attractive to me.
The OPA1611 is fine if you have a low source impedance. The AD797 also, but it needs a compex compensation compensationnetwork. I also use the OPA627 or the OPA827 depending on the application.
@@ralfstocker7742 Yea I work in a hearing research lab so we have PXI chassis with multiple 24bit delta sigma converters. Our engineering department shares one and we have a number of HP DSA's. (I actually have a pair of HP 35665A's in my apartment) The rest of the opamps are not "unsuitable" it's just that source impedance, input offset, and etc can be wrong for a given part.
@@johnyang799 I thought about that but honestly time had marched on. You are right the wording "had to switch" was rather over stating it but we wanted to see if we could get a lower noise floor with something newer.
@@christophschuermann6512 I was aware of the OPA627 and it's cousin the OPA637 which I had used in some high speed current sources. The OPA827 I had never seen before. How have you liked it and what were you doing with it?
strange... For my ears TL072 on high pass filter sound better than more chips i tested( TL082, NE5532P, YG4558, JRC4558D, RC4558, BA4560, JRC4565D)...And for subwoofer/ low frequency JRC4558D and TL082
John, for FUTURE CHALLENGE I would like to suggest to you to try to build up and test a circlotron power amplifier. They are very simply designed and called super symmetric and highly linear with very low THD+N. The challenge of these amplifiers is their floating dual power supply (but this can be simulated by two Li-Ion batteries or well separated lab power supplies for the first tests). ibb.co/cFKb74q (I think the connecting points for the feedback resistors must be switched directly to the P1- and P2- points).
If you are still looking for a collaboration on the project you want to have boards made for you should talk to Paul over at Learnelectronics, he’s a great guy that has made boards for many projects.
