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Op Amp Rolling

Fleuch

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In the review of the Fosi V3 (Fosi Audio V3 Amplifier Review), Amir wrote “There are replaceable op-amps for those of you who have nothing better to do than mess with the design.” For those who want to do just that, it is difficult selecting which op amps to “roll with”.

Both the Fosi V3 and the Aiyima 07Max (and now Fosi ZA3) use NE5532 chips. Perhaps the first move is to drop in a chip from the same series but with a higher specification, and, as suggested in other threads elsewhere, purchased from Mouser or Digi-Key.

Moving on, there are many DIP-8 op amps to choose from, although many from Texas Instruments in this particular packaging are now marked as “End of Life”. As ASR thrives on numbers, what are the most suitable op amps to drop in as replacements for the NE5532, based purely on the specification sheets?

Texas Instruments identifies op amps considered suitable for audio applications: see https://www.ti.com/amplifier-circuit/op-amps/audio/products.html#. This list shows 71 products, with 14 chips in the DIP-8 package. Other forums provide additional suggestions, and the Mouser database provides yet more possibilities.

File 1 (attached) provides a list of possible drop in replacements for the NE5532, where the pin-out and supply voltages are compatible. Measurements such as THD + Noise and CMRR are high on the list and other measurements such as overshoot and settling time may be important for audio applications.

It is also important not to use an op amp that has high gain and/or classified as high speed, as this may lead to ringing and possibly the overall amplifier itself becoming unstable.

File 2 (attached) provides a rough “order of merit” under each of the parameter headings from File 1. The figures suggest the chips to start with would be the LM4562NA/NOPB and LME49720NA/NOPB.

One surprise from this list is the lack of entries for the MUSES01 and MUSES02 chips; MUSES03 is not included as it is a single channel chip and not a drop in replacement for the NE5532.

Finding “the right op amp” is not easy. Any advice on what to look for in the specification sheets will be much appreciated.
 

Attachments

  • File 2 ¦ Order of Merit for DIP8 OpAmps.pdf
    223.6 KB · Views: 175
  • File 1 ¦ Drop-in Compatible DIP8 OpAmps.pdf
    246 KB · Views: 167

Doodski

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Finding “the right op amp” is not easy. Any advice on what to look for in the specification sheets will be much appreciated.
Rolling a OP amp from a circuit that was designed and calculated for the OP amp that is in use from the factory is like shooting with a shotgun and hoping you hit something far away. I don't recommend OP amp rolling but if you want to go for it there are a ton of skills that can be gleaned from the operations. It's nice to see somebody going at it from a objective approach although we don't know what calculations the designer(s) performed while making this circuitry and any OP amp that would be swapped would be a guess at best.
 

Ken Tajalli

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I have some MUSES opamps for sale.
Only used for a few hours, otherwise NEW.
 

DVDdoug

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I agree. Best case you might reduce the noise but you shouldn't have a noise problem to begin with, and if you do the op-amp may not be the source of the noise.

The "magic" of op-amps is that they have super-high open-loop gain and the negative feedback ("corrective feedback") controls the circuit gain (so the op-amp itself doesn't affect it) and the negative feedback lowers distortion, flattens frequency response, and lowers noise. The result is an almost perfect amplifier with almost any op-amp!
 

DonR

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I think there is a benefit in rolling (within operating parameters) for phono preamps to sub in super low noise opamps, especially when the originals are not terribly low noise. For amps, not so much. At line level, the 5532 is already beyond audible.
 

MaxwellsEq

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I think there is a benefit in rolling (within operating parameters) for phono preamps to sub in super low noise opamps, especially when the originals are not terribly low noise. For amps, not so much. At line level, the 5532 is already beyond audible.
I agree: for line level there's no benefit, for phono pre, there may be a benefit. But I believe that the art of low noise working with low signal levels is achieved during the design phase, since that's the best time to maximize the parameters.

Therefore, again swapping out a 5532 for one of the lower noise equivalents does not give a certainty that the benefit from the quieter op-amp will be achieved! Even though the op-amp is quieter in theory, it needs the design to be based on that op-amp to guarantee better noise performance. And, of course with relatively high gain and less NFB, it may oscillate or behave strangely.

The only way I'd consider rolling op-amps would be if I knew and could model the circuit and if I had sufficient test gear to prove a measurable benefit and no negative instabilities or oscillations.

In my opinion, rolling op-amps without a full test rig is a bad idea.
 

solderdude

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The specs/performance of the Fosi V3 is solely determined by the amplifier chip, not the op-amp.

So whatever 'suitable' you put in there will not lead to higher performance.
This makes it a futile effort only costing money.
The reason Fosi has this 'feature' is because:
  • It is easy to do
  • people think it actually does something positive
  • It is unlikely performance gets worse (nor better) unless some really not suited op-amps are used
  • sales argument
  • people demand it or try to do this in another way
  • rolling op-amps is very similar to rolling tubes, as in plug and play, no real knowledge required, but with a different outcome
Funny thing is that obviously 'rolling transistors' seems to be skipped. Only rolling tubes and op-amps seems to be 'popular'
 

sergeauckland

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I agree: for line level there's no benefit, for phono pre, there may be a benefit. But I believe that the art of low noise working with low signal levels is achieved during the design phase, since that's the best time to maximize the parameters.

Therefore, again swapping out a 5532 for one of the lower noise equivalents does not give a certainty that the benefit from the quieter op-amp will be achieved! Even though the op-amp is quieter in theory, it needs the design to be based on that op-amp to guarantee better noise performance. And, of course with relatively high gain and less NFB, it may oscillate or behave strangely.

The only way I'd consider rolling op-amps would be if I knew and could model the circuit and if I had sufficient test gear to prove a measurable benefit and no negative instabilities or oscillations.

In my opinion, rolling op-amps without a full test rig is a bad idea.
Although even for a phono amp, the noise level from the 5532 is already so far below the noise inherent in vinyl, that whilst the electronic noise may be lower, playing an LP swamps any such benefit. 40 year old opamps such as the 5532 and those used by EMT and AEG Telefunken (5533 and TDA2310 respectively) result in 70dB + S/N ratios relative to 5cm/sec, so 80dB or so relative to normal peak levels on LPs that no audible improvement would result by changing these.

S.
 

Joe Smith

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Burson Audio in Australia recently offered to send me some of their "Vivid" series of Op-Amps to try in my original Aiyima A07 amp. I thought I'd take them up on that, agreeing to write about any differences I could perceive. I hope what they send will fit the amp, the series 6 ones look tall. I intend to make a test setup with my test speakers (some older KLH 902Bs) and a simple source in case there is any oscillation.

I do like the sound of 4562s in my Aiyima amps, I swapped them in for the stock 5532s. Don't really sound different, though, just did it to be sure they were genuine TI chips.
 

Joe Smith

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Replace the two op-amps with


You do not need a riser. There are YouTube Videos on it
The 30% off sale may still be going
Middle Earth, did you ever try any of the Burson op-amps? Just curious. Their V6 models are so much taller than the Sparkos, not sure if they will fit, but were offered free for testing...
 

Middle Earth

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Middle Earth, did you ever try any of the Burson op-amps? Just curious. Their V6 models are so much taller than the Sparkos, not sure if they will fit, but were offered free for testing...
No not the Brunson but Sparkos 3602
Right now from what I can tell there is no science behind the Sparkos swap. Subjective reports are positive.
I don’t regret doing it with Sparkos, but I am not qualified either objectively or subjectively to offer any opinion after going deeper into this. It is noted that repeatedly referencing the testing done by ASR on a different Sparkos op-amp makes no sense in this context as neither Sparkos or Fosi recommend that op-amp. Cheap Audio is pretty good with subjective impressions and he endorses the swap.
 

Matias

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fpitas

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GXAlan

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Muses and Burson are not the lowest distortion, Sparkos are.

It’s very interesting since the MUSES01 does not have low distortion by specifications nor those measurements, but on my phono equalizer, the MUSES op amps measured really well. There may be some window where the MUSES actually works well and some range where it saturates.

 
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