Being there has been a lot of identifiable op amps mentioned here, could you please let us know the other op amps under test, you know the ones that beat up on the opa1611. It would at least make your post more meaningful. And it would help us all out so we would know which ones to use then, OR at least try.
Thank you in advance.
You haven't looked very hard
http://www.analog.com/static/imported-files/data_sheets_obsolete/OBSOLETE WATERMARK/AD504.pdf
AD504 | This product is Obsolete | Obsolete | Analog Devices
With a slew rate of 120mv/sec this device has no place in audio.
Changing opamps JAVS DAC-2
I have recenlty acquired a Korean Javs Dac-2 March. It uses TI Burr Brown PCM1792A and 3 double opamps: 1x LME49710HA (doubled) and 2x LME49860. I'm not quite sure why there is 3 pieces (suppose one is buffer?). I haven't got an electrical scheme and I'm a newbie actually.
I was thinking of switching the LME49860 with some better ones: a pair of doubled OPA627AU and pair of AD827 eventually. I don't know if to change the LME49710HA, because I read here that it's actually a good one. Any opinions?
I have recenlty acquired a Korean Javs Dac-2 March. It uses TI Burr Brown PCM1792A and 3 double opamps: 1x LME49710HA (doubled) and 2x LME49860. I'm not quite sure why there is 3 pieces (suppose one is buffer?). I haven't got an electrical scheme and I'm a newbie actually.
I was thinking of switching the LME49860 with some better ones: a pair of doubled OPA627AU and pair of AD827 eventually. I don't know if to change the LME49710HA, because I read here that it's actually a good one. Any opinions?
LME49710 is a single device... one of the new high performance opamps aimed at audio.
The LME49860... is similar, but is dual and has the ability to run on up to 44 volt rails (-/+22)
You won't "better" these really from a technical aspect, so you have to be very clear what if anything you are trying to achieve. Also measure the rails and make sure that anything you use is OK... your DAC probably doesn't use the full 44 volts but you must check.
I still like the OP604 and OPA2604 because they seem (to me) to be very musical in the best sense of the word... but only you will know by listening.
You shouldn't run into stability problems seeing as the standard fit is high performance already.
The LME49860... is similar, but is dual and has the ability to run on up to 44 volt rails (-/+22)
You won't "better" these really from a technical aspect, so you have to be very clear what if anything you are trying to achieve. Also measure the rails and make sure that anything you use is OK... your DAC probably doesn't use the full 44 volts but you must check.
I still like the OP604 and OPA2604 because they seem (to me) to be very musical in the best sense of the word... but only you will know by listening.
You shouldn't run into stability problems seeing as the standard fit is high performance already.
Apparently the LME49710HA seems to doubled? There are to metal caps on a board placed in a 8 PIN DIP socket with two LME49860 placed in 2 other sockets aside.
This setup does sound nice. It's very precise and clear in ups, nicley articulated (hats, high pianos, bees and other), but in mids (egz. vocals, guitar, rhodes synth) sounds a bit dull - I would need a sharper, more contoured sound. Lows seem to be a bit messed some times and unprecise (maybe due to bassy DT770Pros?).
Overall sound is a bit too cold for me, would like to hear something more warm (tube-like?), maybe more spacious. After reading previous entries I discovered AD827 might be a good choice (being warm and precise). I was also considering doubled OPA627AU from Hong-Kong Ebay (if it's a good idea?), as they are those legendary, clear, precise, spacious and so on.
As to the voltage I only know my current manufacturers choice DC input is 12V 2A (but the DAC is capable of 9-24V, 1-3A inputs.
I have no idea what might be the rail voltage.
From Korean manual I can also read there is something about +/- 10V in the opamp section. Here is the link to the manual http://mikone.republika.pl/JAVS_DAC_2_K_manual.pdf
I will also look into your suggestion for OP604 and OPA2604. Thx for reply.
This setup does sound nice. It's very precise and clear in ups, nicley articulated (hats, high pianos, bees and other), but in mids (egz. vocals, guitar, rhodes synth) sounds a bit dull - I would need a sharper, more contoured sound. Lows seem to be a bit messed some times and unprecise (maybe due to bassy DT770Pros?).
Overall sound is a bit too cold for me, would like to hear something more warm (tube-like?), maybe more spacious. After reading previous entries I discovered AD827 might be a good choice (being warm and precise). I was also considering doubled OPA627AU from Hong-Kong Ebay (if it's a good idea?), as they are those legendary, clear, precise, spacious and so on.
As to the voltage I only know my current manufacturers choice DC input is 12V 2A (but the DAC is capable of 9-24V, 1-3A inputs.
I have no idea what might be the rail voltage.
From Korean manual I can also read there is something about +/- 10V in the opamp section. Here is the link to the manual http://mikone.republika.pl/JAVS_DAC_2_K_manual.pdf
I will also look into your suggestion for OP604 and OPA2604. Thx for reply.
Here is a photo of the DAC-2 board. http://mikone.republika.pl/dac2.jpg 2 x LME49710HA marked in red (in a single socket - purple) 2 x LME49860NA in orange, Burr Brown PCM1792A in green. That's the manufacturer's setup. Still wondering why is there three OpAmps? If some are for buffer, which then?
Because sound is so subjective, you are the only one who will know if any change suits you.
However, you mention wanting a warmer, more "tube like" sound and that's exactly what the OPA604/2604 provide. I like that sound. Have also used the AD845 single opamp as well with good results.
Supply rails to the opamps... just measure them from ground to the supply pins on the opamp. That's pin 4 for the negative rail for all, and either pin 7 for the single or pin 8 for the dual.
Would have to see a circuit to say for sure what and how each device is used, or have the unit in front of me to test.
Edit,
Read the section on sound quality here... but remember... it's you that has to be convinced
http://www.datasheetcatalog.org/datasheet2/2/04hz8dw0dwzt7ethry7uh4td04fy.pdf
However, you mention wanting a warmer, more "tube like" sound and that's exactly what the OPA604/2604 provide. I like that sound. Have also used the AD845 single opamp as well with good results.
Supply rails to the opamps... just measure them from ground to the supply pins on the opamp. That's pin 4 for the negative rail for all, and either pin 7 for the single or pin 8 for the dual.
Would have to see a circuit to say for sure what and how each device is used, or have the unit in front of me to test.
Edit,
Read the section on sound quality here... but remember... it's you that has to be convinced
http://www.datasheetcatalog.org/datasheet2/2/04hz8dw0dwzt7ethry7uh4td04fy.pdf
Last edited:
In Samuel Groners report about the measured performance of Opamps the OPA604 came out really bad and showed high amounts of all 4 distortion mechanisms invertigated. I whould strongly sugest the new OPA1641/42 when you really whould like to hear whats on the recording. I modified a CD player that had the OPA2134 and OP2604 and could not beleave what i heard. So much more information without sounding spitty in any way.
I was trying to understand why you decided to put a buffer in front of the pot.
Buffering the output of the pot makes sense.
When you have configured the Opamp as a voltage folower you get less distortion in the treble when you use a resistor with the same value as the source impedance instead of the short between Pin2 and Pin6. I am also astouned that you use a pot BEHIND the buffer. That destroyes the nice low output impedance and a buffer does not make much noise so you win little in SN with the pot at the output.
YES!!!!
Some opamps behave so badly when output is fed back to -IN that the datasheet shows this extra resistor.
I have concluded that using this extra resistor cannot be any harm when any opamp is used in unity gain follower mode.
I already made a correction in #1873. The pot is before of the opamp in the signal path. You don't see that? Or there is delay due to the server?
Is the the common-mode distortion in series-feedback configuration?