Do all OPA2134PA's sound the same? - diyAudio
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Old 30th September 2010, 08:19 AM   #1
fap is offline fap  Australia
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Default Do all OPA2134PA's sound the same?

G'day all, this is something that I can't explain. Today I obtained some replacement OPA2134PA's for two that I accidentally blew up yesterday (yes, reversed power supply leads).

Anyway these replacement OPA2134's are from a different manufacturer, and I never thought the originals sounded that great. Anyway these OPA2134's sound fantastic. I'm wondering why? Are counterfeit dual op amps a possibility? Regards, Felix.

Last edited by fap; 30th September 2010 at 08:20 AM. Reason: Grammar.
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Old 30th September 2010, 09:13 AM   #2
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What do you mean that the new OPA2134 are from a different manufacturer?
The OPA2134 was initially manufactured by Burr Brown, now they are owned by Texas Instruments. It is the same IC. IMO they cannot sound different.
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Old 30th September 2010, 09:23 AM   #3
fap is offline fap  Australia
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G'day mate, yes it's a strange one, as the original OPA2134's in use sounded rather 'dry sounding' to me, if that makes any sense!

In fact when the originals were first installed I remember thinking that they didn't sound as good at the LM833's in there previously! But these OPA2134's sound nothing like the original ones. These replacements sound clean, crisp and dare I say it....musical. So I don't know.

Likewise I would have thought that an OPA2134 is an OPA2134! That's why I wondered about possible counterfeits. Yes these are Texas Instruments dual op amps. Regards, Felix.

Last edited by fap; 30th September 2010 at 09:25 AM. Reason: Additions.
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Old 1st October 2010, 08:56 AM   #4
fap is offline fap  Australia
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Default Op amp failures!

G'day all, I think I'm having a bad run with op amps of late because strange faults with op amps and particularly with the OPA2134 keep happening!

The other day one of my DIY stereo headphone amps suddenly failed on the right channel. A lot of difficult and painful fault finding followed and the failure was found due to several causes, namely a chance diode failure (a red LED to be specific used as part of a constant current source), and also the complete failure of the right channel of the OPA2134 input stage.

How common is that? It had been working happily for a couple of years then suddenly failed on the right channel without warning. Why, I wonder? Regards, Felix.

Last edited by fap; 1st October 2010 at 08:56 AM. Reason: Spelling.
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Old 1st October 2010, 09:52 AM   #5
sandyK is offline sandyK  Australia
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Quote:
Originally Posted by fap View Post
G'day all, I think I'm having a bad run with op amps of late because strange faults with op amps and particularly with the OPA2134 keep happening!

The other day one of my DIY stereo headphone amps suddenly failed on the right channel. A lot of difficult and painful fault finding followed and the failure was found due to several causes, namely a chance diode failure (a red LED to be specific used as part of a constant current source), and also the complete failure of the right channel of the OPA2134 input stage.

How common is that? It had been working happily for a couple of years then suddenly failed on the right channel without warning. Why, I wonder? Regards, Felix.
Felix
If you are talking about the Silicon Chip headphone amplifier from the Studio Series Preamplifier, then the most common causes appear to be due to poorly soldered joints in the area of the red LED.

SandyK
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Old 1st October 2010, 09:58 AM   #6
fap is offline fap  Australia
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G'day mate, yes that's the kit. Not a bad design at all. I use this one as a part of my general microphone preamp monitor amp set up for my weekly voiceover recording work for our National Ham Radio news service.

It was perfectly reliable until it failed this week, right in the middle of the weekly recording session! 'Murphy' I guess! Regards, Felix (vk4fuq).

Last edited by fap; 1st October 2010 at 10:01 AM. Reason: Grammar.
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Old 1st October 2010, 10:08 AM   #7
sandyK is offline sandyK  Australia
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Felix
You must be awfully unlucky then, because there have been >120 constructed by members of another forum, and very few failures reported after initial problems have been sorted out. Several were due to poorly soldered joints in the area of the Red LED.
SandyK
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Old 1st October 2010, 10:13 AM   #8
fap is offline fap  Australia
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G'day mate. 'Awfully unlucky'? Yep, that's been the story of my life! Try being born an Aspie and only realising it at age 47 (last year). Life isn't easy being an Aspie! Regards, Felix.
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Old 10th November 2010, 07:00 PM   #9
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Quote:
Originally Posted by fap View Post
... a chance diode failure (a red LED to be specific used as part of a constant current source)...
FWIW, I read this a couple of days ago:

"Beware of the very low melting point of the LED encapsulant and don't stress the leads before soldering. Otherwise the plastic when it softens transmits the stress to the bond wire and if you are very lucky it will break then and there. If you are very unlucky it will break at some indeterminate time later"

From Mic Preamp Schematic Collection
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Old 10th November 2010, 07:56 PM   #10
fap is offline fap  Australia
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G'day mate, very interesting. Thanks for the information. Regards, Felix.
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