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OPA1656: High-Performance CMOS Audio Op Amp

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sawyers

sawyers

Member
Joined 2006
TI's SoundPlus opamp family are astonishingly superb designs. I'm using the OPA1612 dual opamp in a commercial design. Harmonic distortion <0.15ppm, intermodulation way below that, 1.1nV/root Hz at 1kHz with a 10Hz 1/f corner and will cheerfully drive 600 ohms.

What's not to like with that, and all the other SoundPlus family?

Craig
 
Bonsai

Bonsai

www.hifisonix.com
Joined 2003
hifisonix.com
Paid Member
johnc124 said:
Well, considering I run TI's op amp business, you could say I'm very, very familiar with how many we sell over the lifespan of a part. Because of my role in the company and the nature of your question I can't give exact numbers, I can highlight some publicly available facts:

1. The lifespan of an op amp is long. Way longer than most other semiconductors. The OPA627 was released in the 90s and we're still selling them in high volume. I have other products of similar age that are still ramping up! I often describe making a new op amp like buying a stock. It might not make you rich tomorrow, but check in 20 years to see how it's doing.

2. You can see our earnings reports on TI.com, in the investor relations section. In 2020, TI reported almost USD$10.9B in revenue from analog, with an operating profit of $4.9B (from analog). That tells you 2 things: we sell A LOT of chips, and even at prices you may think are low, they have decent margins.

3. TI's R&D as a percentage of total revenue in 2020 is about 10.5%. We're pretty good at controlling the cost of the development process. So if we can develop a new op amp for less cost, and it will live in the market for decades, the risk of making a new part is fairly low.

Inventory levels on TI.com are extremely low at the moment, but that says less about the TI store than it does about the buying spree most of the market is on at the moment. For parts that are in high-demand, the inventory level on TI.com will mirror what it is at other distributors.

To the previous comment about TI setting up product distribution infrastructure being an interesting business decision: I don't think TI is alone or even first in this step. For example, I believe Microchip had an online store before us and many company's are also following suit. I don't think this is very different than many companies across multiple industries wanting to be able to sell directly to their consumers. With automation, the cost of these facilities is drastically reduced. I was laughing reading the comments about "humans putting chips in bags", all of that is definitely done by robots, at blinding speed, 24 hours a day, 365 days a year.
Click to expand...

I was a product line GM at Philips Semiconductors (then NXP) for 10 yrs in power discretes. I used to envy the IC guys. Once or twice a year I’d take a knife to the portfolio and EOL the older non-performers much to the chagrin of the sales and mkt guys. I think opamps and certain building block parts (eg classic v. Regs like the 7815 etc family) have a very unique life cycle that is as you say decades long. The innovation rate in power mosfets for auto (big business for us) and computing and telecom was very high. Basically newer, better cheaper parts every year. It’s tapped off a bit now, but 20 yrs ago a 20 mOhm 55V mosfet was a big deal. Now they’re sub 1 mOhm in power SMD packages and it’s the packaging that’s the performance bottleneck. These things switch 50A in <3 ns with a decent driver.

Exciting times :)
 
Tolu

Tolu

Member
Joined 2007
I am very sad about the discontinuation of the LME49710/LME49720HA with TO-99 (metal can) package. They were sonically far above the plastic packages. I think that due to the high price they were sold only in homeopathic quantities. Controllers don't love music.
 
sawyers

sawyers

Member
Joined 2006
I too lament the demise of the metal can versions. Punishingly high price, but mechanically stress free, and sonically preferable.

Of course the trend is to surface mount only (like the device that is the subject of this thread). I've just invested in a binocular microscope, vacuum pick up, 0.3mm solder and a flux pen with that trend in mind.
 
G

gdb

Member
Joined 2012
I purchased 10 OPA1656's. I did an A/B comparison to LME47920 (metal cans), burson V5i, V6 and also the Sparkos Pro discrete op-amps on one of my DAC's. I prefered the sound of my DAC with the OPA1656's hands down even over the discrete op-amps. I think it's a matter of circuit design and implementation. I looked at the Slew Rate as my main guideline. Slew rate has a huge influence on what our ears hear IMO over distortion levels that are far lower than the human ears threshold. Again, it's the circuit topology that is the most important to get the best sound out of any op-amp. Years ago the MUSES 01 was $35 in Japan and it was at the time way ahead of it's time. Today, I still have the same 2020 amplifier and the opa1656 sound much, much better at a fraction of the cost. So I don't think there is a singular correct answer.

Happy listening as always and experiment for yourselves. Your ears are the best measuring device for what you hear and enjoy. Not a data/spec sheet. They are guidelines at best. I have probably 30 op-amps that are sitting in a bag. Not all of them are rejects. I will always keep the LME47920 cans with heatsinks for a rainy day. They still rank among my favourite op-amps. I use all of my op-amps in preamps and in tone control devices. So I have a criteria that isn't the same as everyone else. One last thing, newer is not always better with op-amps. Some of the old Burr Brown before TI absorbed them are truly great sounding. They don't measure well, but they sound terrific.
 
D

dotneck335

Member
Joined 2012
gdb said:
...... it's the circuit topology that is the most important to get the best sound out of any op-amp. .......Some of the old Burr Brown before TI absorbed them are truly great sounding. They don't measure well, but they sound terrific.
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I hear this a lot, but I've yet to see specific examples of what 'topology' sounds GOOD and what 'topology' sounds BAD. Other than the obvious mistakes of poor grounding techniques or the like.

gdb said:
Some of the old Burr Brown before TI absorbed them are truly great sounding. They don't measure well, but they sound terrific.
Click to expand...

What devices are you referring to, exactly?
 
W

WatrixReloader

Member
Joined 2006
Great piece arrived today - Im using it after the DAC (NPC SM5872BS) output of my Marantz CD63.
Rolling opa1642, opa1612, muses8920, 2xopa627bp, lme49720na, opa2134.

My favorites at the moment opa1642 and this one opa1656.

...ah so much other untested opa's ...1678 still on my list ina1620. But I really like the FET's in that position. Any futher recommendations?

my favs 1642/1656, 1612, lme49720na 2xopa627bp,
 
S

soekris

Member
Joined 2009
soekris.dk
Paid Member
I would be very interested in hearing opinions on opa1678 versus opa1656, as I'm using both in different products.... opa1678 should sound much like the opa1656 as it seems to be the same architecture and process, just slower, higher Vos, higher noise....
John, are they in fact much alike ?
 
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G

gdb

Member
Joined 2012
dotneck335 said:
I hear this a lot, but I've yet to see specific examples of what 'topology' sounds GOOD and what 'topology' sounds BAD. Other than the obvious mistakes of poor grounding techniques or the like.



What devices are you referring to, exactly?
Click to expand...

I have an old rotel cd player that had some pre-ti burr brown opamps.
I'll have to dig them out as I definitely did not junk them.

they are used in in the RCA analogue output stage, the 1656's sounded much more refined than many others that I tried out.

The rotel cd player is somehow still working without any issues having travelled across the pacific as carry-on.

I'll have to dig up the service manual to know exactly which op-amps they were. my suspicion is the 2604 old logo BB, not the new logo BB on them.
 
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