op amp

[goodguys]

Hi and thanks for taking the time to read this post.

I have purchased a nice dac which uses an Burr Brown opa2604 opamp.

Can anyone suggest a good upgrade. I was thinking of the ever popular BB opa627ap but have been told this is quite old and should really consider a modern one.

Can anyone please advise, something which works well in the opa2604's current environment (voltage, current, etc)

Many thanks in advance. John.

 

[AndrewT]

Some Members on this Forum say that the opa2604 is a good opamp for audio.

Do you realise you will have to develop the PCB and components to suit a different opamp?

 

[Mooly]

Some Members on this Forum say that the opa2604 is a good opamp for audio.

Me for one

You could always try the LM4562, as long as it is OK with regard to it not having FET inputs... and for 98% of applications it should be OK.

Have you a circuit for the DAC ?

 

[jcx]

you really need to know some things about the circuit - the 2604 is unusual in running from higher supply V than most standard op amps, and for rolling with modern chips many new processes have even lower than the older "standard" +/-18 V supply limits

there are newer fet input op amps seemingly aimed at the opa626/7 niche: ad8610/20, ada4627, opa826

some faster op amps will not be happy in layouts that work for slower chips

 

[goodsguys]

Hi. Many thanks for the replies.

OOps!! i did not know the entire circuit board had to be redesigned. I read this review Op-Amp review page
and it appears this guy was just dropping chips into the socket, he did not say anything about redesigning.

So just popping the opa2604 out of my dac and fitting in a higher spec chip is not possible?

I contacted the manufacturer be he declined giving me a circuit diagram.

 

[Mooly]

So just popping the opa2604 out of my dac and fitting in a higher spec chip is not possible?
QUOTE]

Virtually any dual opamp will work. To get the absolute best results requires optimisation... something 99% of folk just swapping devices never consider.

Just try the devices you are interested in, and have a look at my posts here,

http://www.diyaudio.com/forums/chip...g-audio-integrated-opamps-51.html#post2012422

 

[goodsguys]

Hi And many thanks for the reply.

Is there a drop in replacement for the tlo72cp and the opa2604 as an upgrade. A few forum members are reporting excellent results by using the lme49720 and opa 2134 as replacements for the tl072cp, the opa2227 as a replacement for the opa2604.

Best wishes. John.

 

[nelsonvandal]

The circuit board probably doesn't have to be reworked. What could be important is decoupling caps in close proximity to the opamp's power pins if you replace OPA2604 with a faster opamp. If needed, such caps could be hardwired.

What's the risk of too high voltage for eg LM4562 in a DAC? What's the risk of not enough current?

Some bipolar opamps have high input bias currents and maybe tweaking has to be done to get it right.

Op-Amp review page This is an OLD review and I wouldn't trust it. To my ears AD823 is awful and he gives it 9/10.

There are lots and lots of reviews here and at Head-fi.org http://www.diyaudio.com/forums/chip-amps/82610-best-sounding-dual-opamps.html

Happy opamp rolling! Don't go for expensive and exotic opamps. The standard opamps to try is LME49720 (the same as LM4562), OPA2134 and NE5532 (this one has high input current so you have to check for DC offset before connecting it to headphones or the amp/speakers if your DAC is without output capacitors). They all sound quite different and are cheap.

 

[Mooly]

You may not "improve" on the performance of what you have... you are just going to have to try and see. The 2604 is great as an I/V converter in DAC's if that's what it's being used as.

The LM4562 might be worth trying... it's not a FET device but has low input bias currents so should minimise any potential DC offset issues. Same goes for the LM49720.

Only you can decide if others are subjectively "better" or provide the kind of sound you are after.

 

[pinkmouse]

Thread moved to more appropriate area.

 

[SoNic_real_one]

My recomandations for dual OpAmps (direct replacement), based on my tests in my DAC's (CD/DVD players):
LM4562 (LME49720 is identical), AD8599 or OPA2134.
I did try OPA2227 and they are ok too - but I dind't feel that are better that OPA2604.

 

[4audioinc]

Just found out how good the OPA2604 chip is by accident... I have about twenty different chips or mods in clients gear... Recently did a LME49720NA combi for a dac unit and after getting a batch of defective (counterfeit) ic's from China, had to go a different route in the current mods for a customer... having a handful of 2604 ic, decided to give them a try... wow... ended up calling and upgrading other units to them... had no idea how musical they are.... and best part.. I do hove a good supply of them... I stock a lot of different ics for custom mods for clients. Still do need to look at the rail voltages doing these mods... did recently have good luck putting AD 8500 series in a Trident board using +/- 18.... after six months doing great... Check your pin outs for most of the duals and usually they are the same... lots to choose from currently.... (pun)... Lot of people rave about the 627... haven't heard them due to the price.. I feel there are other options... Bottom line.. out of about ten favorite chips, I like the 2604 best and personally use it now... Cheers!