LM4562 vs OPA2134 vs [ ? ]

Discussion in 'Sound Science' started by Acke, Dec 15, 2017.
  1. Acke
    Im interested in op amp rolling for my amp since its not expensive to try out and I was surprised to find a lot of variation between them, the amp has a very simple circuit so my results could be more siginificant than with other amps. Using hd600s and 400is to test them

    Ive compared the NE5532, NJM4556 and LM4562 so far.

    LM is the best overall, it sounds the most balanced, very natural/smooth/clean, doesnt exaggerate anything but can sound lacking in impact. strangely its probably the most boring sounding one when paired with 400i but the best sounding with hd600
    NJM has a more analytical, detailed sound but it sounds a bit thin and isnt as smooth... This is also used in o2 amp and it sounds like this op amp defines the analytical sound of that amp, I will have to try the LM in the o2.
    NE was the most coloured sounding, seemed to hide a lot of details but had a fairly musical, mid-focused sound, could sound uncontrolled in very intense tracks... however there was loud pops and click when powering on and off the amp with the particular IC I had, seemed to work ok otherwise but I ordered a replacement to be sure I heard its real sound.

    I am curious to see if there is more room to improve with other op amps?

    So far I read the OPA2134 as an upgrade to the LM but its quite expensive, has anyone experience with this op amp or do you know any op amps that you consider an upgrade from the LM4562?
     
    Last edited: Dec 15, 2017
  2. Strangelove424
    This probably isn’t the answer you want, but I’m going to present it to you anyway. An op amp is part of a larger circuit and is chosen because its specs match those required for the circuit. The sound quality comes from the entire circuit, not the op amp. Switching op amps is likely to cause as much harm as good. For instance, in this post I am responding to one of many people who burned out a Burson v5: https://www.head-fi.org/threads/mat...p-and-excellent.475618/page-341#post-13652862

    The Burson v5 is an especially egregious situation because Burson went out of their way to create a low-volume audiophile op amp that bolstered features like gold plated connection, channel separation, and EMI shielding. Features that would appeal to the audiophile crowd willing to spend an insane $60 on an op amp. Then they went out a suggested that their op amp could be used as a direct replacement for almost any other op amp on the market, despite having different voltage specs! The level of irresponsibility here is repugnant, and the reasons for failure seen in my post have displayed themselves rampantly in the wild. You would be far better off with a good ‘ole tried and true Texas Instruments 49860 beater. BTW, 49990 is a just a cherry picked lme49860 for wider voltage range, so don’t believe the kool-aid when everyone says they sound better… it’s the same op amp.

    Obviously, not every op amp is a piece of junk like Burson’s but the trend for audiophile op amps (Muse is another popular one) imho is a form of snake oil. The job of the amplifier should be to provide clean gain. If you would like to alter the tone of the amp, do so with DSP such as EQ. Those changes will be controllable, and immediate. No opening up your amp, waiting 10 minutes for the caps to discharge, going in with pliers, and then losing all audio memory of what it sounded like before. With EQ, you can hear it immediately and tune to get exactly what you want. When you alter the sound signature with an op amp, more than likely you are just making the amplifier perform non-linearly. I’ve had op amps before I though “increased detail” and upon further inspection just increased harmonic distortion in the treble. That DAC I rolled op amps in came with its own flat factory measurements made with a $15k SYS-2722. I look back and wonder what I was thinking to mess with precisely measured perfection. I could only make it deviate from that perfection. All I did when I tried rolling op amps was mess up good engineering.

    This is a good read about op amp myths: http://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html
     
    Speedskater likes this.
  3. Acke
    I think what you are saying is true in most circumstances nowadays, i actually tried rolling the o2 amp's 4456 for something else but it always sounded off, the 4456 has a very high output current and the o2 was designed around that fact.

    In the other case of this amp that I built rolling the op amp completely changes the sound, going from the original ne5532 to the lm4562 refined/changed the sound to a point where I stopped thinking of the amp as fun project and started using over the o2 (though only with the 400i). the sound difference was what I imagine rolling a tube sounds like (I also designed this with the dip socket exposed on the underside so its as simple as tube rolling)... I think this could be down to the sheer simplicity of the amp but also highlights how significant the op amp can influence the sound.

    I believe CMOY amps employ similar simple designs where the op amp has a massive effect on the sound, thought I might get some replies from people who have tested some of the more expensive op amps in these kind of circuits
     
    Last edited: Dec 16, 2017
  4. Strangelove424
    I’m mainly talking about commercial pre-built amps like the O2 that have been engineered and sold according to a standard of measured performance. It’s tough to improve the performance without redesigning the whole amp. In fact, the opamp myth link I pasted was from the O2’s original designer.

    For DIY amps, there are forums for electrical engineering hobbyists that can help suggest an op amp that will fit for your particular circuit design. Sure, a DIY amp is going to require some op amp rolling for testing, after all you are the one engineering it. In that case, it would also be a good idea to measure each op amp’s performance as well, depending on the equipment you have access to.
     

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