Well, U2, U3 and U4 are in your audio path, the others are "housekeeping". It doesn't appear to use a servo either.
I don't believe you will see any improvement from replacing the audio ones, but if you really have to, LM4562 or LME49720. The housekeeping staff should be left alone.
I don't believe you will see any improvement from replacing the audio ones, but if you really have to, LM4562 or LME49720. The housekeeping staff should be left alone.
The Absolute Maximum supply voltage is +-10v so it wouldn't be happy at the usual +-15v to +-18v found in 5532 circuits.
https://www.nisshinbo-microdevices.co.jp/en/pdf/datasheet/NJM2122_E.pdf
Interesting. Relatively minimal circuitry and a single-ended Darlington output loaded by a current source? It's not a Zen or Son Of Zen, but someone's been listening to Papa. The output current isn't huge, neither is the slew rate, still I'd bet a buck the low noise & distortion on this thing would make for a dandy phono preamp, where high gain is required anyway.
U6 the TL-072 appears to be a clip detector or something. Comes up with a result that drives an LED through U7. Don't mess with it. Noise is not an issue.
U3 U4 the critical sound path IC's are 5532. No improvement likely, those are quiet and fast enough. The power supply has handled those all these years, no problem. Leave them alone.
U3 U4 the critical sound path IC's are 5532. No improvement likely, those are quiet and fast enough. The power supply has handled those all these years, no problem. Leave them alone.
Basically, a nice sounding design. Reliable. Most Hafler products go the distance and sound good.
The schematic you posted for pro-5000 has lateral fet transistors. 2Sk176 , 2SJ56 . These are the transistors that half the posters on this forum want to build an amp around. Out of production for decades. There are copies from Alfet sold in the UK. I don't know if the results are as legendary as the Hitachi originals. Below 0.1% HD I view the speaker as a bigger problem than the amp.
An upgrade from the 5532 is an njm2114.
Isn’t going to be like world peace or anything however, and definitely not worth going under the knife for…
For line level/low currents, the tl072 is fine.
Isn’t going to be like world peace or anything however, and definitely not worth going under the knife for…
For line level/low currents, the tl072 is fine.
Yes, this NJM would be intended as for line/phono stage with relatively high gain indeed. Or for instrumental noise measurement too (with not so great claims from it though).
I'd avoid the LM4562 in an input circuit, its very sensitive to EMI. If input noise is an issue the first thing to look at is the 2k2's directly on the inputs. Only then consider changing U2 for a lower voltage-noise chip (and be aware of stability issues, modern opamps can be more fussy than a 5532). Best to leave well alone really.
Well, that is with all BJT input devices. Not just the LM4562. But JFet input devices have issues with common mode signals. Therefore you filter inputs to signal stages (good engineering practice) and choose the device depending on the application.
In short, know your parts.
In short, know your parts.