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Old 21st October 2011, 01:09 AM   #31
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AD827 $10-$40 on eBay.

http://www.ebay.com/sch/i.html?_trkp...4&_sop=3&_sc=1
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Old 21st October 2011, 01:22 AM   #32
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Very interesting book! Has someone read it?


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Originally Posted by SoNic_real_one View Post
Hint: emitter degeneration
Book.
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Old 21st October 2011, 01:25 AM   #33
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I am thinking of purchasing the op-amps on eBay. Is there any risk of buying fakes ones? I mean, does it exist fake op-amps (LM4562, OPA627, AD797)?




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AD827 $10-$40 on eBay.

ad827 | eBay
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Old 21st October 2011, 01:50 AM   #34
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Originally Posted by Audio Maniac View Post
I am thinking of purchasing the op-amps on eBay. Is there any risk of buying fakes ones? I mean, does it exist fake op-amps (LM4562, OPA627, AD797)?
Basically, IC OPAMP NE5532/NE5534 is nothing wrong. Both Musical Fidelity in UK and MBL in Germany currently use it in audio amplifier design and sell it at many $$$bug. They do not solely plug and play, but use a set of “jig and fixture” to perform testing, sorting and component matching of IC OPAMP before use. Thus, it sounds good. However, the methodology of component matching may be secret to the company.
Alternatively, IC OPAMP LM4562, OPA627, AD797 are good choice, but higher price in comparing to NE5532/NE5534. I do not comment eBay, but recommend more reliable suppliers such as Digitkey, Farnell or Mouser, etc… in which the component must not be fake.
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Old 21st October 2011, 01:54 AM   #35
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Try Digikey, Mouser, Avnet...
LM4562 is some 3$ for DIP, 1.5$ for SMD. The metalic can is expensive - some 20$ - and I don't think it is worth it.
Try also AD8599 - really a good OpAmp, on par with LM4562.
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Very interesting book! Has someone read it?
More from it:
http://www.eetimes.com/design/audio-...s?pageNumber=3

Last edited by SoNic_real_one; 21st October 2011 at 02:17 AM.
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Old 21st October 2011, 02:39 AM   #36
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When you've installed the sockets, get somebody to swap the opamps without letting you know which ones they've put in. See if you can reliably identify any of them over a number of swaps.

Many people insist they can hear differences, but many others think that there's no audible difference; TI, who manufacture highly regarded DACs, recommend NE5532s and NE5534s for use in the very applications where you are intending to replace them. Most of the people making recommendations NEVER undertake the unsighted comparisons, they rely on swapping the chips themselves... ...and stuff that people write in threads like this one.
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Old 21st October 2011, 03:10 AM   #37
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AD827 - $12.47:

Digi-Key - AD827JNZ-ND (Manufacturer - AD827JNZ)

By the way, using a socket in this type of circuit may have a detrimental effect on sound because of stray reactance conflicting with high frequencies and fast rise times, it's best to solder the opamp directly into PCB. Afterwards, proper circuit performance needs to be verified using an oscilloscope.

Mike

Last edited by Michael Bean; 21st October 2011 at 03:12 AM.
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Old 21st October 2011, 07:44 AM   #38
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Alant4321, Sonic_Real_One, Counter Culture and Michael Bean,

Thank you very much indeed for your contributions! I'd like to say I relly enjoy this forum. Some time ago I got unexpected results with an ordinary Radio Shake integrated amp due to precious info given here. That encourages me to go further and modify my new DAC.

MiniMax DAC comes with IC socket but after choosing the best op-amp, I'll solder it on the PCB. I haven't got a scope and I don't plan to buy one, but I may pay a guy who modifies audio gears to test the reability of the chosen op-amp before soldering it.

I'm quite ceptical as regards some audio tweeks, such as "magic" power and digital cables and I'm certainly performing blind audition tests to avoid "placebo effect".

Last edited by Audio Maniac; 21st October 2011 at 08:03 AM.
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Old 21st October 2011, 10:55 AM   #39
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Personally I did a test replaced on My Denon only ONE OpAmp. That was taking care of the front and rear R channels (they kept the L and R separated - good job).
At that point I really wasn't sure which speaker is that channel and I was able to pick up a "winner" after a few songs that I knew very well (to make sure). The channel that sounded best was the one with the new OpAmp.
Denon uses better OpAmps in the end-of-line players, receivers. Is a way for them to make a marketing difference and ask for twice the price.
A lot of companies used the 5532 simply because it was (and still is) the best CHEAP OpAmp that you could get - good for the beancounters.
TI recomands that for some DACs because they knew that japanese electronics design people (culture) would be inclined to pick up a DAC for their designs if it did have 5532/5534 shown. But is not the only one shown in their data sheets...

Last edited by SoNic_real_one; 21st October 2011 at 11:01 AM.
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Old 3rd January 2012, 10:36 PM   #40
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[QUOTE=Mooly;2752167]The AD797 is one that needs care... it might have stability issues as a drop in replacement.

Keep it simple... the OPA2604 and LM4562 should be fine. For a single opamp for the output I would have an OPA604 to hand.

Hi Mooly,

You seem to like the OPA2604. Have you tried the LME49990? Any opinons?

regards
Bob
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