The best sounding audio integrated opamps

tvrgeek,


But, isn't there room for those of us who can't be bothered to understand it all? There must be others, like me, who simply want to try different opamps in their particular device(s) to see which one they like the sound of best. Perhaps it isn't the opamp, but the circuit's response to the opamp; the point is, the sound changes (for better or worse) and we can decide which one we like best. Opamp rolling, for us, is "just tinkering"; a way to maybe find unexpected synergy, maybe not, in the true spirit of the "hacker".

Of course there's room for you and in fact a lot of useful information comes this way - not to mention the fact that the hi fi industry is full of tinkerers. DIY too! Hasn't this thread yet got a definitive list of what is worth trying and what isn't? Surely that's it's aim? And I assure you that life is too short for most hi fi companies to take into account which amps reference which rail or the size of the bypass caps and few do anything different from you.
 
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Of course there's room for you and in fact a lot of useful information comes this way - not to mention the fact that the hi fi industry is full of tinkerers. DIY too! Hasn't this thread yet got a definitive list of what is worth trying and what isn't? Surely that's it's aim? And I assure you that life is too short for most hi fi companies to take into account which amps reference which rail or the size of the bypass caps and few do anything different from you.

:cheers:

Perhaps there should be two main (sticky?) opamp threads; one for subjective, anecdotal reports and the other for technical discussions.
 
LME Opamps

Hi Everyone,

I have not posted for quite awhile but now that TI/National has eliminated the entire audio group in Santa Clara I am unemployed again and I now have loads of free time to look at my favorite online forum again.

Please keep buying the LME metal can parts if you like them because you never know when they may stop producing them.

Hope the LME parts do well in your testing event. Please use the metal can HA parts for all critical analog circuits... Excepting the great the LME49811 poweramp preamp driver which only comes in a plastic package because we were never able to get the approvals to put it into a metal package. However I do have a couple of LM4702's (the first actual LME part made on the new process for audio!) in a multi pin T03 package though. I even have a demo board for it...I really need to get it running again at home except the fact that I don't have a good analyzer at home to measure it! Anyone have an AP2 Cascade 192 for sale cheap!:D;)

Best "Unemployed Audio Engineer...Again" Regards,

Audioman54 / Mark
 
LME Answers

Carl,
Unfortunately there are unions for engineers allowed in Silicon Valley...and no engineers over 55!

Mooly,
Talking about and working on audio “Stuff” always cheers me up.

CFT,
Bob Pease was able to hear the difference between the LME49710' and 713's in the sound room at National and was shocked that he could do that at 67 years old. We used identical D/A preamps for the listening tests. (I designed, and hand built, 10 of these as demo units to show off the LME parts and my Avatar is a pic of that preamp. Please check out the attached pic of an AP2 Cascade 192 THD+N plot of that preamp before and after a power supply change Bob Pease suggested. We actually presented that change to my LME base power supply regulator circuits at AES in SF several years ago.)

One unit had all metal can LME Opamps and the other one had all plastic dip LME Opamps. We matched the output levels of both D/A preamps to within 1dB and then sealed up the units and labeled them A and B. I then switched out the externally identical units and Bob listened to them in our sound room at National. (That sound room, which is closed up now, had Wilson Watt Puppies driven by the LME49811 power amps that I designed – See TI/National AP Note AN-1490 which is the LM4702 version of the same demo power amp. The LM4702 was the first part made on the new Vertical High Voltage process that made all the rest of the LME series of parts) Switching out the two identical units in this way resulted in a true double blind test... without having to use those poorly designed double blind switch boxes that always screw up double blind tests because they degrade the sound in the switch box.

When we were done with the listening tests we opened the units up to see if unit A or unit B had the cans or plastic parts the results were…(Insert suspenseful pause here) ..Bob chose the metal cans over the dips every time we did the test! (We did it twice as I recall.) Bob thought the metal can unit "Just Sounded Better" and was shocked that he could hear the difference. That led to some investigations about why...but Bob then had his terrible auto accident going to the wake for another IC industry legend Jim Williams and passed away before we got a chance to finish the tests.

(Analog engineering legend Bob Pease killed in car crash | EDN

Bob thought the reasons for the better sound with the metal cans might have been:

A. The plastic package is constraining to the layers of the chips which could cause problems with mechanical heat stress inside the die layers during thermal events...
B. The shielding of the can... (Only electrostatic though not magnetic which is usually a bigger problem)
C. The slightly larger round legs on the can
D. The thermal dissipation of the can
E. The exposed die mounted on a ceramic substrate inside the metal could handle the thermal transients "better"
F. Insert your guess here

But sadly we never got the chance to check out any of these possibilities together.

I hope some of you are enjoying listening to our LME Opamps! A ton of work (5+years), millions of $’s and some luck (and prayers) went into getting the LME series of parts produced.

Best LME Audio Regards,

Audioman54 / Mark
 

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Oddly enough, I've been getting recruited left and right, despite also being vintage 1954. Helps to be a scientist instead of an engineer, perhaps. Companies seem to need a grown-up in charge, just to keep the whiz kids focused.

Best of luck, I wish I could do something to help.:(

I'm just a few years younger than SY and getting offers of potential employment in audio/consumer electronics regularly - which I've abandoned for the time being for medical electronics. Make sure your linkedin profile is up to date, and good luck.

I have a few of the metal op-amps, still figuring out what to do with them, IIRC there are pair in the I/V converters of my SACD player, otherwise I'm a tube guy at home. :D
 
Hi Kevinkr,
I am surprised those are in your SACD player. Which player is it? Which LME opamp did they use? LME49710's or 713's? Are they the metal can HA parts? Also, please ping me if you hear of any audio jobs in the SF/SJ Bay area.

SY,
Are the jobs you are seeing located in the SF Bay Area?

Carl,
That is the published circuit for the power supply in the headphone AP Note for the LME 49720's but my (& Bob's) changes are different...a bit better as reflected the graph of the output of my D/A preamp with all LME parts. To bad AES lost the video of our power supply presentation. I could have posted it for everyone. Bob would have liked that.

Audioman54 / Mark
 
"... That is the published circuit for the power supply in the headphone AP Note for the LME 49720's but my (& Bob's) changes are different...a bit better as reflected the graph of the output of my D/A preamp with all LME parts. To bad AES lost the video of our power supply presentation. I could have posted it for everyone. Bob would have liked that. "

Can you share the schematic and details?
 
Hi Carl,

Not quite ready to publish those changes yet...but if anyone can find the video of the AES presentation in SF with Bob and I that we gave together on Sat Oct 4th 2008, that presentation has 95% of the changes in that video. Let the hunt for the video begin!

Was anyone from DIY at that presentation? I thought you were there Carl?

Audioman54 / Mark