I haven't heard OPA627, so I can't give a definitive answer, but I'm using OPA827 biased into class A in a (BUF634 buffered) headphone amp right at this very moment, and I can say with certainty that it sounds better than OPA2132, OPA2227 or OPA2107.
The qualities of this chip are exactly as I've heard described for OPA627 - very well controlled bass, with no treble harshness, resulting in a clean, dark sound.
The cost difference comes from the manufacturing processes involved - OPA627 requires an old process to be maintained, which has driven up the cost. At least, that's my understanding.
The qualities of this chip are exactly as I've heard described for OPA627 - very well controlled bass, with no treble harshness, resulting in a clean, dark sound.
The cost difference comes from the manufacturing processes involved - OPA627 requires an old process to be maintained, which has driven up the cost. At least, that's my understanding.
The business I work for ordered some samples to compare with OPA227 for our stage mixers, as we're considering introducing a "premium" model.
There's nothing except your own conscience to stop you from ordering a few samples from TI yourself, of course, but that could be considered abuse, since they cop the loss on the shipping on the expectation that you'll order a few thousand later.
There's nothing except your own conscience to stop you from ordering a few samples from TI yourself, of course, but that could be considered abuse, since they cop the loss on the shipping on the expectation that you'll order a few thousand later.
The mentioned OPA2107 (dual bifet) was new to me.
Looks like a nice op-amp for High-Performance Audio Circuitry
Comes in DIP-8 and SO-8.
Unity gain stable, +-5 to +-18V and like 4.5 mA supply current (<2.5mA per amp).
The precision, offset, is very good. Very low bias current.
Slewrate is good 18V/uS and gain bandwidth is moderate 4.5 MHz.
Such a bandwidth is, in my opinion, suitable for many general audio applications.
What is the cost for OPA2107, in compare to other op-amps?
If is a fairly low price,
this is a good one to become a universal op for the DIY Audio toolbox.
OPA2107 - Texas Datasheet
Regards
Lineup
Looks like a nice op-amp for High-Performance Audio Circuitry
Comes in DIP-8 and SO-8.
Unity gain stable, +-5 to +-18V and like 4.5 mA supply current (<2.5mA per amp).
The precision, offset, is very good. Very low bias current.
Slewrate is good 18V/uS and gain bandwidth is moderate 4.5 MHz.
Such a bandwidth is, in my opinion, suitable for many general audio applications.
What is the cost for OPA2107, in compare to other op-amps?
If is a fairly low price,
this is a good one to become a universal op for the DIY Audio toolbox.
OPA2107 - Texas Datasheet
Regards
Lineup
OPA2107 is one of those funny chips that is sometimes unobtanium. It is, however, a very good dual opamp for the price (digikey list them at $12.50). Generally, whenever I build something that needs a dual opamp, it's prototyped with OPA2132 to see if it works, and then, provided it can be given at least +/- 7V rails, swap OPA2107 in for the improved sound.
To put some opamps on a scale:
TL072: 50%. Functional, but not particularly pleasant to listen to.
OPA2132: 85%. Great value for money, but bass is indistinct.
OPA2227: 90%. Better than 2132, but poor value, as it's about the same cost as 2107.
OPA2107: 95%. A worthwhile improvement on 2132.
2 x OPA827: 100%. The best opamp I've yet tried - I suspect that for nearly every application, these will be limited only by other parts of the signal chain.
To put some opamps on a scale:
TL072: 50%. Functional, but not particularly pleasant to listen to.
OPA2132: 85%. Great value for money, but bass is indistinct.
OPA2227: 90%. Better than 2132, but poor value, as it's about the same cost as 2107.
OPA2107: 95%. A worthwhile improvement on 2132.
2 x OPA827: 100%. The best opamp I've yet tried - I suspect that for nearly every application, these will be limited only by other parts of the signal chain.
Have you tried the LT1028? I find it to be better than the OPA827 in every way, and especially timbre.
No, I haven't.....yet!
Thanks for the tip!
Jon
BTW, Farnell stock them, but they're about a tenner each. I'll have to wait until after Xmas!
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the lt1028/1128/1115 is a heavily biased large area bjt input op amp for low noise with low source and feedback impedance
it will likely have offset and definitely have large noise from the base current if just dropped in to a circuit designed for fet input op amps - not a direct replacement for jfet input OPA627 or 827
the compensation circuit is also unusual in enclosing the output stage and should probably be used in low/uinity gain apps of 1028/1115 - additional Cload isolation may also be necessary
it will likely have offset and definitely have large noise from the base current if just dropped in to a circuit designed for fet input op amps - not a direct replacement for jfet input OPA627 or 827
the compensation circuit is also unusual in enclosing the output stage and should probably be used in low/uinity gain apps of 1028/1115 - additional Cload isolation may also be necessary
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Yes, not a universal replacement. But, as a DAC differential to single-ended converter (& buffer), it is (well, certainly sounds like it is) perfectly stable. Also in a amplifier with a moderate gain of +4 it was stable.
BTW the LT1028 sounds better than the LT1115 (reflecting the cost of the chips).
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Short answer, no. There are legit sellers on the platform, but chances are you are most likely dealing with a fraud.