AD826AN - bad batch? - diyAudio
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Old 4th August 2008, 02:05 AM   #1
pftrvlr is offline pftrvlr  United States
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Default AD826AN - bad batch?

I have 4 AD826AN I bought a while ago. I assume they are drop-in replacement for the NE5532 or other dual op amp.

I used it in a simple op amp I/V stage, it was producing no sound. I then tried it in a balance to SE converter after a CS4397 DAC, it does not work either, while other opamp (5532, opa2604, opa2322, lm4562, ad8620) are all working fine in the same position. None of the 4 AD826 works!

So it makes me wondering if I got a bad batch of the AD826, or it is just so temperamental that some mod of the circuit required?

Any one has any experience with AD826 at all?
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Old 4th August 2008, 03:30 AM   #2
sandyK is offline sandyK  Australia
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Default AD826AN - bad batch ?

pftrvir
The AD826AN is a VERY fast dervice, more suited to video applications etc. I expect that it would require careful bypassing of the supply pins to ensure stability. Most likely the devices are unstable in your application. Why not try one with supply pins bypassed as close as possible to pins 4 and 8 as shown in the data sheet ?

SandyK
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Old 25th October 2008, 04:18 AM   #3
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Default Hey there...............

These were plug and play in my Rotel RCD-990.

No issues and excellent sound.

I agree that you could be getting oscillation though.
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Old 25th October 2008, 08:37 AM   #4
Mooly is online now Mooly  United Kingdom
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Agree with all the comments so far, but I would have thought you would hear at least "something", even if it was wiping out radio and tv for miles around
You need to 'scope it and see, even measuring the voltage on the output pins may show up something. Have you used sockets ?
A bad batch, if they are genuine parts then no, it just doesn't happen like that. Now if it were a 741 marked as an AD826 Measure those voltages. Can you feel the IC warm ?
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Old 25th October 2008, 01:11 PM   #5
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Default Yep....................

Parasitic oscillation will have you think that the device is not working- when in reality, it is oscillating at several Mhz (depending on the the speed of the device.)

The best bet for you is to put your scope leads across the load, set the scope for "auto detect", move your cursors to find the frequency- and wallah!

If you see no oscillation, then either the chip is in backwards, the circuit is wired incorrectly, or you have a bad chip.

Check your +- power rails as well.
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Old 25th October 2008, 11:33 PM   #6
kevinkr is offline kevinkr  United States
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Where did you get these particular parts and are you absolutely certain they are not counterfeit? This would not be an unusual outcome if the parts were ersatz.

They do need a little more attention to layout and decoupling than your generic audio op-amp, but you should hear something..
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Old 26th October 2008, 12:15 AM   #7
spock is offline spock  Canada
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I used them as drop ins for 5532's a few years ago with no issues.
Could they have been subjected to SE somehow? A good jolt of static would likely kill them.
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Old 29th October 2008, 04:23 AM   #8
pftrvlr is offline pftrvlr  United States
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They are counterfeit!

The fake 826 I orderd from eBay are actually single amp, who knows what the chips really were. Thankfully I got refund from the seller.

Later I ordered 4 Ad826 from digikey, and find that they are pretty easy to work with.

Thanks for all the feedbacks.
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Old 30th October 2008, 02:01 AM   #9
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....and thank you for letting us know the outcome; not many people do this....

Regards,
Boky
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Old 30th October 2008, 02:36 AM   #10
spock is offline spock  Canada
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Lucky to get your money back. Thanks for the update. One more reason for "buyer beware!"
Digi key is great. They're delivery is second to none IME.
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