Its always nice to look at some THD pictures 🙂. There is more difference in the measurements than expected between LME49720 and LM4562, even tho it has been stated multiple times in the op amp threads that they are infact exactly the same part. That is with the "Version 3 smd", ~10dB difference at high frequencies. With earlier version looks quite the same.
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Awful strange. Maybe there's inconsistency between unit to unit. After all they are hammered out of a automated machine like a machine gun. They each don't go through the meticulous QC process like the SIL-994's.
Or maybe due to the cheap tin pins on IC opamps, the conductivity is inconsistent each time they are inserted. Something that's a non issue with millmax precision machined gold plated pins and sockets. They press fit with 100% of the contact area touching. IC opamps just have the tin edges touching.
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Other Class D
Hello Sebastian,
I tried severall Class d amplifiers with the Confidence 5, but the Anaview AMS1000/2600 are still resting in my closet. I had a massiv Impedanz missmatch and so i didn't try them. I use a passive Line stage TX102 and a Matrix X Sabre DAC, don't know which output impedance the Matrix shows. Actual I tried a small shure amp, very nice and cheap. but this amp didn't show the Resolution of the hypex amps, more a amp for long time listening for less than 10% of the price of the Hypex NC amps. This weekend I introduced the buffer rev c into the Nord NC500, including the 994s. The sound is different from board B and the other OP's I tried. But to judge I will give them some more hours. also I have to try them with my TX102, now I use "The Truth".
Some words to SGD concerning the "cheap" build Nord amplifiers. Ok, here are the same housing I buy by myself in Italy. I like these. my DAC has a housing made from a massive block of alloy, I preferre the money spend for the electronic despite the rather good sound of the Matrix X sabre. I changed the buffer board of the Nord NC500 in less than an hour. Not that bad drilled. The moderate effort of the enclosure made it possible to sell these amps for an really interesting price. I preferre soldering joints against plug connection, the sound is better with better Long time contact. So I changed in a second building step most of the connections in my Hypec NC400 to soldering connections. In my Noth Amps the Live Connection didn't fall apart by itself. So I have to endorse Colin a little bit.
Hello Sebastian,
I tried severall Class d amplifiers with the Confidence 5, but the Anaview AMS1000/2600 are still resting in my closet. I had a massiv Impedanz missmatch and so i didn't try them. I use a passive Line stage TX102 and a Matrix X Sabre DAC, don't know which output impedance the Matrix shows. Actual I tried a small shure amp, very nice and cheap. but this amp didn't show the Resolution of the hypex amps, more a amp for long time listening for less than 10% of the price of the Hypex NC amps. This weekend I introduced the buffer rev c into the Nord NC500, including the 994s. The sound is different from board B and the other OP's I tried. But to judge I will give them some more hours. also I have to try them with my TX102, now I use "The Truth".
Some words to SGD concerning the "cheap" build Nord amplifiers. Ok, here are the same housing I buy by myself in Italy. I like these. my DAC has a housing made from a massive block of alloy, I preferre the money spend for the electronic despite the rather good sound of the Matrix X sabre. I changed the buffer board of the Nord NC500 in less than an hour. Not that bad drilled. The moderate effort of the enclosure made it possible to sell these amps for an really interesting price. I preferre soldering joints against plug connection, the sound is better with better Long time contact. So I changed in a second building step most of the connections in my Hypec NC400 to soldering connections. In my Noth Amps the Live Connection didn't fall apart by itself. So I have to endorse Colin a little bit.
Yes when you consider you get a completely built amp made from premium parts for pretty much the same price as the parts alone for the NC-400's, if you don't like how the AC wires are crimped on, it's not too hard to do something about it. Toss the case in the trash and build a new one if you want.
No difference at all, all within measurement error. Pretty much look like it is the distortion of measurement device, not the opamps, as well as with Sparkos and SIL.
There is no difference at high frequencies. I see a bump of noise for lower frequencies. This is most likely a measurement artefact (some mode/level auto-switched), hardly an op-amp difference.
PS. When measuring top op-amps notching of fundamental is needed, or else results will be masked by measurement tool own performance. As happened in this case.
After tweaking my speakers a bit (toe-in and especially bass setting), i think now i finally understand what people are raving about the 994s. Very dynamic and clear/fresh re-presentation with good soundstaging. The sound was a bit muddy or bass heavy earlier, but i think now the problems are gone.
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If those measurements are of the APx-525 itself, what's being done different with this aPX-525 measurement?
The 1khz peak is offsetting at 0dB instead of at around +15dB like in the previous measurements?
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I suppose that is showing that it's being driven to the 14.6dB gain. So if it was only being driven to 0dBfs, would the THD be 14.6dB down. We must subtract 14.6dB to get the true -dB number.
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dB scales are proportional to the peak level. Usually the peak is chosen as 0dB level. The 0dB can be 2VRMS, 4VRMS or whatever. Usually it is told what the 0dB is, since obviously it is harder to get good SNR with low signal level.
Or is there some sort of standard that the 0dB level is certain signal strength when measuring source related things? I only know REW, not these pro-equipment.
Or is there some sort of standard that the 0dB level is certain signal strength when measuring source related things? I only know REW, not these pro-equipment.
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I would like to see some measurements with low frequencies being driven. I hear this is where the discrete designs slaughter the IC's. And not just millisecond bursts, they need time to heat up. Like when real music is being played through them.
Any idea as to why that would be?
So would the differences only show up when the temperature of the opamp is high enough?
The exact opposite would be expected of any major fab. Parts are going to be pretty much dead nuts. WRT tin pins, that's nonsense.
The self-inconsistency wrt 4562 vs 49720 leaves a big "?!" in the testing. Exception could be made if they're in different packages (soic vs dip), but that either suggests that the test itself is inconsistent or assembly of the buffer boards.
That's what I heard about the shortcomings of IC opamps. When they are subjected to frequencies under 100hz due to heat, they don't preform as well. But of course the proper tests to demonstrate this are never on the datasheets.
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That's not what I heard about the AKM DAC chips. The reason Sonny at Phison Audio didn't go with dual mono chips in his PD2 DAC was inconsistencies from chip to chip.