Part Sourcing Assistance/Advice Thread

[luvdunhill]

Not sure if anyone has used this stuff to touch up the inevitable scratch during DIY or perhaps to infill, but it seems to work pretty well! No before pictures from all the loading port area, but a tough area on the top where there is a matte finish..

 

 

[Craig Sawyers]

Heads up - the best (ie best noise performance) single opamp for moving magnet cartridges - the NE5534 in all variants has been obsoleted by both TI and ONsemi. So if you need some for stock before this excellent device is obsolete sand, now is the time to buy.

I've just ordered 50, which is enough to see me out.

[revolink24]

7 hours ago, Craig Sawyers said:

Heads up - the best (ie best noise performance) single opamp for moving magnet cartridges - the NE5534 in all variants has been obsoleted by both TI and ONsemi. So if you need some for stock before this excellent device is obsolete sand, now is the time to buy.

I've just ordered 50, which is enough to see me out.

 

Wonder what we will lose in terms of commercial products with this. Or worse, what will happen to the commercial products that suddenly have to swap out opamps on a short timeline and end up silently screwing new customers with a worse-performing product. A tale as old as time.

[Craig Sawyers]

Indeed. The combination of noise voltage and current was ideally matched to the resistance/inductance characteristics of a moving magnet cartridge. And lots of commercial designs used the NE5534.

I have a spreadsheet that calculates S/N ratio with RIAA. AT 5mV the NE5534A returns 77.9dB with a typical MM cartridge of 610 ohms and 0.47H. The nearest equivalent IC is the much more recent OPA1611/12. Lower voltage noise but critically higher current noise. That gives 75.3dB, so 2.6dB worse s/n.

My spreadsheet does not take account of 1/f noise. The OPA1611 has much better performance here than the NE5534A, so some of the 2.6dB will be eroded by that effect and it will make the comparison a closer run thing.

Discrete opamps can give lower noise for RIAA EQ, and indeed Sam Groner developed a discrete version of the NE5534A that was better performance all round https://groupdiy.com/threads/just-for-fun-discrete-ne5534.57544/ . No surprise that the low noise dual he specified in 2004 is obsolete though.

[luvdunhill]

3 hours ago, Craig Sawyers said:

Indeed. The combination of noise voltage and current was ideally matched to the resistance/inductance characteristics of a moving magnet cartridge. And lots of commercial designs used the NE5534.

I have a spreadsheet that calculates S/N ratio with RIAA. AT 5mV the NE5534A returns 77.9dB with a typical MM cartridge of 610 ohms and 0.47H. The nearest equivalent IC is the much more recent OPA1611/12. Lower voltage noise but critically higher current noise. That gives 75.3dB, so 2.6dB worse s/n.

My spreadsheet does not take account of 1/f noise. The OPA1611 has much better performance here than the NE5534A, so some of the 2.6dB will be eroded by that effect and it will make the comparison a closer run thing.

Discrete opamps can give lower noise for RIAA EQ, and indeed Sam Groner developed a discrete version of the NE5534A that was better performance all round https://groupdiy.com/threads/just-for-fun-discrete-ne5534.57544/ . No surprise that the low noise dual he specified in 2004 is obsolete though.

Cool - how would it compare to the LME49870, as that’s what I used many moons ago when I built mine… it plays the music for sure.

[Craig Sawyers]

2 hours ago, luvdunhill said:

Cool - how would it compare to the LME49870, as that’s what I used many moons ago when I built mine… it plays the music for sure.

Suffers from the same problem as the OPA1611 - similar high current noise (4 times higher than the NE5534A). Predicted SNR is 75.3dB - so identical to the OPA1611.

[Craig Sawyers]

A bit of good news - the OPA210 (single) and OPA2210 (dual) have a lower voltage noise, crucially the same current noise, as the NE5534A. They also has lower 1/f corners and stupidly low distortion. Introduced in 2018 it looks like it will be around for a good long time.

The critical number is - how does an RIAA stage with an opamp with vn and in compare with a noiseless amp?

With an NE5534A - 2.32dB noisier than no amp at all

With an OPA210 - 1.61dB noisier than no amp at all

Both numbers with a realistic MM cartridge load of 610 ohms and 0.47H

Both amps are very close to the maximum possible SNR with a noiseless amp - but the OPA210 is even closer than the NE5534A.

SOIC (or smaller) only and about 2.5 times the price of the now defunct NE5534A - but it looks like it does the job very nicely.

[luvdunhill]

On 12/7/2023 at 5:26 PM, Craig Sawyers said:

Suffers from the same problem as the OPA1611 - similar high current noise (4 times higher than the NE5534A). Predicted SNR is 75.3dB - so identical to the OPA1611.

Is that SNR after/including the RIAA EQ?

I suppose you can parallel the NE5534A as well…

[Craig Sawyers]

Yes.

It it based on a spreadsheet implementation of a model in a National Semi databook. But with more frequency data points, and with amplifier noise taken into account. 

And yes, you can always parallel opamps, summing their outputs via 10 ohm resistors. But even a single NE5534A is less than 2.5dB worse than the SNR with a noiseless amp (which is -80.4dB - depending on cartridge R and L) - so it is diminishing return. Parallel two NE5534A and you get to 1.6dB - so all you have found is 0.7dB in SNR. Parallel 4 and you find another 0.4dB and hence get to around 1dB of a noiseless amp.