Burr Brown OPA 2143 vs NJM2068

LM4562 is the newest audio amp from National Semiconductor (they got awards for it) intended for hi-end audio. It has excellent AC (THD=0.00003% IMD=0.00005%) and DC (0.2uV/degC) specifications. Unity Gain Bandwidth is 55MHz and slew rate is 20V/us. It work from 5V to 36V. Power supply rejection is excellent. It has pretty strong drive (600 Ohm specified). As for the known product - Benchmark DAC1 USB uses it in the output stages replacing previously (DAC1) used NE5532. Replacing all chips in Benchmark is probably too expensive for Benchmark ($5 for LM4562, $0.55 for NE5532) since there is a lot of them (about dozen packages) and NE5532 is very decent in the AC (pretty bad at DC).

It is difficult to talk about sonic character since I have never heard it (new product) and Benchmarks design objectives are very specific (promoting natural sound and avoiding warm sound). My audio experience is also very limited.

How it compares to OPA627 - I don't know. According to Benchmark's technical director John Siau they tested OPA627 and got worse results than NE5532. Mr Siau even stated in details which harmonics got worse. On the other hand Steve from Empirical Audio who moded a lot of Benchmarks says that OPA627 is better since it performs better/cleaner at low levels (microdynamics). Steve is probably the person to answer question about sonic characteristic of LM4562.

OPA627 is, as far as I know, a single package amp while LM4562 is dual amp available in DIP, Metal Can and SOIC (SMT) packages from Digi-Key for about $5. LM4562 is very good at AC and DC and having wide banwidth and wide supply range can replace any audio op-amp in the dual package. I think that National created also single packages but with different part number - I can find out.

Word about NE5532 - it was initialy designed by Signetics. Signetics became member of Philips Company and early Benchmarks used thin sounding Philips NE5532. Around year 2001 Philips factory burned down and they stopped making NE5532 selling license to Texas Instruments. TI redesigned them with larger die and the newer Benchmarks that use them have much fuller sound. Benchmark has output cap since NE5532 has pretty bad DC offset and drift.

In general audio OP-Amps are a very narrow class of all OP-amps. If you're not sure if amp belongs to this class download data sheet in pdf and check for THD vs Frequency and THD vs Output Voltage charts. Don't even bother if you don't see it.

Thanks for the info, Kijanki! My technician advised me to change the opamps of a Hafler P3000 poweramp. I think he said it had TL... and advised to change them by the OPA 2134. As I started investigating a little bit, they seemed to be not the last word in audio opamps. I don´t know anything about electric nor physical configuration of them. Any other advise? Thanks.

TL... is probably TL082 or 72 or 62 or something from this family (pretty bad for audio). If you can go with OPA2134 (dual) then go with LM4562 - it is exceptional amp. It is probably 8 pin DIP thru hole plastic package (2 rows 0.3" apart of 4 pins each 0.1" apart. Pinout of packages is standard - always the same. Both OPA2134 and LM4562 are dual and pinout is the same. Be sure that package is plastic DIP as I described a not a metal can. Metal can package (not very common) can be soldered into DIP (same order of pins) but not the other way around. LM4562 is available in all versions. When you change amps go for the best and most expensive. Few dolars more won't make any difference to you. It makes often difference to manufacturer but sometimes reason is different. They just simply cannot constantly change amps when new and better once are released (every year). It would require prototype testing over and over again and create nightmare in service. I suspect that they never change to better amps without a big reason. Design is treated as closed. Be sure to test your amp with cheap speakers. In spite of op-amps being stable there is always a chance as with any repair of bad solder joint or short - very small chance but still..

Kijanki, I recall he said they were 4 TL081. I´m sure he said they were 4 and not absolutely sure the model. I think the TL081 are the single versions og the TL082. Another technician advised me to use AD818. Do you know them? I have them in a DAC. Thanks for all the other advise. I´ll use it when I take it to the technician I choose.

Joaco - TL081 is a single amp. It is very old and very cheap amp designed as a improvement over 741 type (one of the first op-amps). It is not an audio amp. LM4562 comes in single version with completely different number starting with LME.... - I have to check again.