Hello,
I'm rebuilding/upgrading a pair of blown up KRK 5 G3 monitors that I got tossed for free.
I've seen people use OPA1642/1644 a replacements for the NJM4580s and TL074s on these amps....however I cannot source an OPA164x at the moment, seems to be some kind of shortage.
Can anybody please suggest some drop in replacements chips? I do little/no audio electronics so don't know what's good in this regard other than matching up the specs.
Also intending to replace the anonymous electrolytics with Panasonic FR (or maybe Nichicon) and the non-polars with Panasonic ECW-F or something from WIMA. Again I don't know what's "good" for audio applications only that these brands seem like safe enough choices.
I'm rebuilding/upgrading a pair of blown up KRK 5 G3 monitors that I got tossed for free.
I've seen people use OPA1642/1644 a replacements for the NJM4580s and TL074s on these amps....however I cannot source an OPA164x at the moment, seems to be some kind of shortage.
Can anybody please suggest some drop in replacements chips? I do little/no audio electronics so don't know what's good in this regard other than matching up the specs.
Also intending to replace the anonymous electrolytics with Panasonic FR (or maybe Nichicon) and the non-polars with Panasonic ECW-F or something from WIMA. Again I don't know what's "good" for audio applications only that these brands seem like safe enough choices.
Plenty here; https://uk.rs-online.com/web/p/op-amps/1219355
also Mouser have plenty of OPA1644 and OPA1642
Personally, I would use the TL range. You will notice no difference. Always fit the original part.
also Mouser have plenty of OPA1644 and OPA1642
Personally, I would use the TL range. You will notice no difference. Always fit the original part.
I'd not use a JFET input opamp (OPA1642 is an example) to replace a BJT input opamp (NJM4580 is an example). OPA1664 is in stock at Mouser as a BJT input opamp replacement.
@JonSnell Electronic - perhaps you used Octopart to see Mouser's stock. Its a bug in their system which I reported months ago. If you go to Mouser you'll see they're out of stock.
@JonSnell Electronic - perhaps you used Octopart to see Mouser's stock. Its a bug in their system which I reported months ago. If you go to Mouser you'll see they're out of stock.
Mouser has 20k+ "On order" with the earliest due at the end of the year 🙁 on the OPA 1662. The situation doesn't look better on the OPA1662 either , but they do have 1664s. Stock issues.....
Interesting...I'd have thought I'd have been fine putting a JEFT opamp in place of a BJT one...but not the other way around....
Ah , I wonder if RS will ship to Australia 🙁
I'm experimenting / upgrading here so fitting the original part would defeat the point (they are also not failed on the board as far as I can tell).
It'll work for sure but it'll be unlikely to be an upgrade because JFETs are normally noisier. There aren't any dual FET opamps below 4nV/rtHz but a reasonable choice of BJT ones.
I had been of the understanding that the NJM4580s and TL074 used on these amps was somewhat of a budget option.... so really the original question stands. What would be direct upgrades for NJM4580s and TL074 ....
Its not immediately clear what would upgrade NJM4580 which is already quite low noise. OPA1612 on paper has lower voltage noise but whether its lower noise in practice depends on the circuit impedances. TL074 is easily surpassed by OPA1644, that's a no-brainer.
Thanks that is very useful. I'll leave the NJM5480s in place. I actually need OPA1642 for the TL074 on these amps and unfortunately that's the one I'm having problem finding. Is there another suggested upgrade from the TL074 please?
Ahh it's not my day. Is there a general shortage or is it often the way with these things?
I think I have some OPA4134UA I could send your way, but I would need to check. If your're outside the US then the shipping would probably be just as much as buying them locally though.
Thanks for the offer but in this case it's the dual not quad types. I'm outside of the US also. I'm going to have to pause and rethink the opamp replacements since it's just the TL074s to replace.
Because they (normally) sell in the many-millions, which drives down price. They sell well (normally) because they are totally fine for many many applications. However the TL07 chips sound better if you paint them silver (don't get any on the legs).
Nearly ALL chips have been in short supply since the pandemic began. Many factories shut-down. Panic-buying is continuing shortages. Switch your hobby to knitting or whittling until the market settles down.
Thank you! Quite right, It's the NJM4580s that are the dual amps on this board. Since the consensus is to not bother replacing the NJM4580s, I think I 'll be fine replacing the TL074s with OPA1644s which I can get hold of.
