Need op amp for computer sound card help

[ralph-bway]

Hi I have a Gigabyte GA-990FX-Gaming motherboard. The on board sound comes with a OPA2134 op amp that's easily removable to swap out.

Gigabyte offered an Upgrade kit that included the following 3 chips:

OPA2111KP
LT135CN8
AD827JNZ

Doing a search on the internet I found many well regarded op amps (mostly for headphone amps) and enough info that I know very little and need to ask what specs should be matching the above op amps so I don't fry my motherboard or the op amp.

Most important, what are the specs that are important to match so I don't damage anything?

This is for listening to music (Fusion Jazz). Good imaging, detail, sound stage, and transient response are most important to me. Any suggestions on op amps is very appreciated.

 

[FauxFrench]

Hi I have a Gigabyte GA-990FX-Gaming motherboard. The on board sound comes with a OPA2134 op amp that's easily removable to swap out.

Gigabyte offered an Upgrade kit that included the following 3 chips:

OPA2111KP
LT135CN8
AD827JNZ

Doing a search on the internet I found many well regarded op amps (mostly for headphone amps) and enough info that I know very little and need to ask what specs should be matching the above op amps so I don't fry my motherboard or the op amp.

Most important, what are the specs that are important to match so I don't damage anything?

This is for listening to music (Fusion Jazz). Good imaging, detail, sound stage, and transient response are most important to me. Any suggestions on op amps is very appreciated.

OPA2134 is known to have a very fine sound (see datasheet for THD) so make sure you really have a much better alternative to use instead. Also LM4562 is a very good OP-AMP but it is arguable how much better it is than OPA2134.

When you replace an OP-AMP with another type, the most important factors to take into account are pin-layout, supply voltage range and the actual supply voltage. Then, most other parameters are secondary such that they may influence the sound but it will still work.

Personally, I doubt that you can do much better than OPA2134. At least, most of those I know are on level with OPA2134 or worse.

 

[nenad88]

Opa1688 maybe?

 

[FauxFrench]

Opa1688 maybe?

I fully agree that it is on par with OPA2134 and has an attractive low supply range. I'm not sure if it is really better in sound.

 

[ralph-bway]

Thanks for the help & info. I appreciate it.

 

[Mark Tillotson]

Most important, what are the specs that are important to match so I don't damage anything?

The pinout and the max supply voltage and HF stability.

However there's way more to it than that. The existing circuit is designed around one specific chip, and has the right decoupling for it, and feedback network that is stable with that chip, and may assume particular things about the voltage noise and current noise and output drive level and bias current and offset voltage and unity-gain stability.

Just swapping opamps without understanding this can lead to sub-standard performance from a perfectly capable opamp, or even HF oscillation that can damage stuff down-stream.

Its not unknown for a circuit to oscillate at HF without damaging the circuit, but with mild to severe effects on the audio-band performance of the circuit, distortion, noise etc. If only mild effects the naive would assume that opamp is poor, whereas its the circuit not matching the opamp's characteristics.

Moral is use a decent oscilloscope to check for such problems, and understand voltage and current noise if noise levels are an issue (lots of people don't understand current noise, yet its often the dominant source of noise in circuits!).

 

[ralph-bway]

"However there's way more to it than that. The existing circuit is designed around one specific chip...."

That's what I got the further I dug.

Thanks everyone for the advice, and helping me avoid a costly mistake.

 

[Douglas Blake]

In line with what Mark has written, I just want to add that swapping parts seldom has only the effects one desires and usually doesn't even have those effects either.

If your current card has decent frequency response, clear sound, and adequate output, I would strongly suggest the "If it ain't broke don't fix it" approach and look elsewhere for improved sound.

 

[ainami]

Like others have said, swapping op amps could lead to a poorer performance just as much as better performance. Also, we don't know what function this op amp is actually doing (whether it's a DAC I/V stage or a buffer output stage). There appears to be a small SOIC-8 SMD chip mounted right next to this socket which could be an I/V opamp.

In that Gigabyt kit, the OPA2211 and AD797 are both bipolar op amps. AD797 has it's own problems if you don't apply the special high frequency compensation cap across pins 6/8. I can't find a match for LT135, so I think you mistyped this. There are several LT op amps that begin with that (LT1355, LT1351, etc.).

The stock op amp OPA2134 is a FET op amp, which generally works much better than bipolar for an I/V stage. It's also very stable and more forgiving with circuits that are not designed as well. You could try op amp swapping with unpredictable results. If you want a better op amp that matches this OPA2134, try getting an OPA2132P, which is a much better version of the 2134. Price is $11.51 from Digikey.

 

[Rolox]

Like others have said, swapping op amps could lead to a poorer performance just as much as better performance. Also, we don't know what function this op amp is actually doing (whether it's a DAC I/V stage or a buffer output stage). There appears to be a small SOIC-8 SMD chip mounted right next to this socket which could be an I/V opamp.

In that Gigabyt kit, the OPA2211 and AD797 are both bipolar op amps. AD797 has it's own problems if you don't apply the special high frequency compensation cap across pins 6/8. I can't find a match for LT135, so I think you mistyped this. There are several LT op amps that begin with that (LT1355, LT1351, etc.).

The stock op amp OPA2134 is a FET op amp, which generally works much better than bipolar for an I/V stage. It's also very stable and more forgiving with circuits that are not designed as well. You could try op amp swapping with unpredictable results. If you want a better op amp that matches this OPA2134, try getting an OPA2132P, which is a much better version of the 2134. Price is $11.51 from Digikey.

Yes, OPA2132P sounds better than OPA2134 (difference might be subtle in some systems) and will most likely behave the same in the circuit. I don't like OPA2134 but I really like OPA2132P.

 

[jan.didden]

Also note that the 2134 is a FET input opamp. So if you replace it with a BJT input opamp, you may upset things like offset and stability.
Something to be aware of; check the data sheet in case of doubt.

Jan

 

[nenad88]

From TI forum.