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Op amp swapping
Op amp swapping
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Old 19th August 2010, 08:28 AM   #11
Mooly is offline Mooly  United Kingdom
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Op amp swapping
Will just add that personally although sockets have their uses, I don't like them and prefer to solder device direct in the PCB.

That said you will be fine with sockets, and no you won't hear any difference between them.
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Old 19th August 2010, 08:31 AM   #12
theAnonymous1 is offline theAnonymous1  United States
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Originally Posted by liquias View Post
Which socket is best? Will I hear the difference ?
I wouldn't worry about hearing a difference; I would worry more about which one will hold up better to multiple op-amp swaps. I prefer the bottom "machine pin" type.

How about trying LME49720HA (TO99) and LT1364? PM me if you're interested.
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Old 25th August 2010, 11:26 PM   #13
liquias is offline liquias  Israel
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Default Thanks guys,

For everything.

I am now waiting for the new op amps to arrive. These things usually take time around here. I was wondering though, I read that a new op amp takes time to "Break-in".

I wanted to ask:
a) Is it true ?
and if it is:
b) How and when can I be sure if it happened already ?
c) How long does it usually take ?
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Old 25th August 2010, 11:55 PM   #14
SY is offline SY  United States
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Op amp swapping
a) If you believe it is. There's no actual evidence that this happens, no plausible reason that it even could happen, and the people who know more about these things than anyone (the designers and manufacturers) don't believe it happens, but if you believe, that's what you'll hear.

b) It will take as long as you believe it should take, deep in your heart of hearts.

c) It usually takes as long as the belief of the listener demands.

Qualifier: Some electrical parameters are temperature dependent and there *could* be some warm-up time changes, but that's distinct from "break-in," since it will happen every time you turn the device on.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
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Old 26th August 2010, 05:35 AM   #15
BrianL is offline BrianL  United States
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Op amp swapping
It is curious that in the manufacturing process, the complete testing of an op-amp takes a second or less. To do so in this amount of time means that the op-amp must be meeting all specs at room temperature (or whatever test temperature, if not room temp) with virtually zero warm-up/break-in time. So, if this can be done practically in production, it's curious that somehow a device in an AUDIO product should take many orders of magnitude more time to 'break in'.
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Old 26th August 2010, 05:42 AM   #16
brainf is offline brainf  Philippines
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Originally Posted by SoNic_real_one View Post
That's ridiculous. I did swap directly 5532 with many and it is not such a great OpAmp. LM4562 was the best for me, OPA2604 was ok too (but not so good). There are some AD8599 OpAmps that I will try soon, just didn't have the time till now.
I preferred the LM4562 over OPA2604 too - cleaner top end and much more dynamic in a Cayin CDT-15A.
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Old 26th August 2010, 11:26 PM   #17
dave w p is offline dave w p  England
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As a bit of insurance it's always worth spraying any sockets with switch cleaner, or even WD40. It will coat the surfaces with a preserver and give better contacts especially in the long term.
The HIFI site
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Old 21st October 2010, 09:52 AM   #18
liquias is offline liquias  Israel
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Default Feedback

Resurrecting, since I promised to post feedback from my tests. (And since I have some new questions...)

OK, so I bought LM4562 op amps and as Mooly recommended I also bought the OPA2604 op amps.

I finally had the time to conduct one of the tests.

I have only tested the Sherwood CD1000C player so far. It's easier since it has only one (dual) op amp at it's output.

So I switched between the jrc4560 op amp and the opa2604 amp. sound took a couple of steps for the better. everything is more emphasized and colorful. all the instruments got presence, and musicality. Voice became a couple of meters closer. I'm very happy !

Then I tried the LM4562. This is a strange one. At first what I could hear was a little less emphasis of everything (like the sound is a little less colorful) but a very large difference in detail. everything got "crisp" and clear. I liked this sound for the few first seconds.

But then I noticed I pickup a distinct distortion. It sounds like the twitter in my speaker has gone bad. (this gave me quite a scare BTW...) I tried decoupling the op amp with 0.1uF cap (between pins 4 and 8) and this doesn't change anything. sound is still distorted, I have no idea why, or how to solve this. Changing back to the opa2604 solves this problem of course.

Any ideas why the 4562 gives me this kind of trouble ? Am I doing something wrong ?
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Old 21st October 2010, 10:51 AM   #19
Mooly is offline Mooly  United Kingdom
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Op amp swapping
Thanks for reporting your findings back... I love the sound of the 2604.

As to the LM4562, well it's hard to say for sure but it certainly shouldn't distort in any way at all. A scope check would reveal what is happening but at a guess it may be verging on instability perhaps due to capacitive loading on the output pin. If you can try adding say 47 ohms in series directly from the outputs (pin 1 and 7) before they connect to the PCB to isolate the opamp. Worth a try.
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Old 21st October 2010, 11:11 AM   #20
Xoc1 is offline Xoc1  United Kingdom
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CD player output stages usually can be improved by replacing the capacitors on the voltage rails. Using decent capacitors here can help with stability with faster op amps. It is usually possible to remove the DC blocking capacitor from the output stage and also remove the muting transistors for another improvement.
Thurther mods would really then involve upgrading the rest of the CD player. Again capacitor upgrades for the rest of the player are good.
You could look at some of the mods that others have tried to get a idea of what is possible.
One Website I found recently that was helpful
Ray's Audio Page
I modded a pair of old Marantz cd52 players last week using Elna caps for the analogue circuits, sanyo oscons for the digital, and some analogue devices op amps. The sound is more resolved than my stock Arcam CD72.(double the price!)
Time to upgrade that next
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