OPA627 real vs fake

[loudnoises]

So i need a couple opamps, and i'd rather not end up with fakes. BBs hit my ears just right, so getting the real deal is of importance...

Am i better off salvaging or are there reputable sources out there? The prices are anywhere from $2 to $25 and i can't identify real vs fake (unless you tell me how ).

Or is there an equivalent, in-production opamp to the OPA627, that sounds as good?

 

[ferninando]

if you can buy from OEM you're assured of the real thing IMO.
try digikey or mouser. stay away from ebay for the fakes.
TI makes it. so you are good to go.

 

[loudnoises]

if you can buy from OEM you're assured of the real thing IMO.
try digikey or mouser. stay away from ebay for the fakes.
TI makes it. so you are good to go.

They're still in production? Well shoot i feel silly...

 

[mkane]

think I bought mine from parts connection. http://www.partsconnexion.com/semi_opamp_burrbrown.html

 

[absolon]

So i need a couple opamps, and i'd rather not end up with fakes. BBs hit my ears just right, so getting the real deal is of importance...

Am i better off salvaging or are there reputable sources out there? The prices are anywhere from $2 to $25 and i can't identify real vs fake (unless you tell me how ).

Or is there an equivalent, in-production opamp to the OPA627, that sounds as good?

opa627 chips should measure roughly 48kohms to 56kohms both ways across pins 1 and 5 and should draw about 7 to 7.5 mA quiescent current. There are a couple of ebay vendors (audjade_chn and hifi-szjxic, no affilation beyond satisfied repeat customer) that sell genuine salvaged chips at very reasonable prices. I've purchased a dozen 627 chips in single and dual configurations from these vendors for about the price of 2 from the above link and all were genuine. Your mileage may vary.

 

[Alan0354]

Take a look at this one OPA604 or OPA2604 dual. https://www.digikey.com/products/en?keywords=opa604

I am using this one, cheap, available, low THD, 20MHz, unity gain stable. Take a look at the datasheet and compare.

Slew rate is faster on the OPA627, but OPA604 at over 20V/uS is plenty plenty fast for audio. I did a big comparison test with all the top notch audio opamps including a $70 discrete opamp, I picked OPA2604 and OPA604.

 

[loudnoises]

Take a look at this one OPA604 or OPA2604 dual. https://www.digikey.com/products/en?keywords=opa604

I am using this one, cheap, available, low THD, 20MHz, unity gain stable. Take a look at the datasheet and compare.

Slew rate is faster on the OPA627, but OPA604 at over 20V/uS is plenty plenty fast for audio. I did a big comparison test with all the top notch audio opamps including a $70 discrete opamp, I picked OPA2604 and OPA604.

ooo thanks Alan!

As you may have noticed, I'm all for cost savings. At 10% of the price, that's totally worth checking out and fits my meager budget very well.

 

[Alan0354]

Ha ha, I am born cheap also. Compare the datasheet in more detail. I only spent a few minutes to look at the important spec( for me). OPA604 is a very nice sounding opamp. Something about the FET input opamp, all the ones I choose are FET input. Both OPA627 and OPA604 are FET input, so you are covered.

 

[ferninando]

We need more info like this on swapping OPAMPS.
They can do so much IMO.
I vote for Alan0354 to institute a sticky
for all things OPAMPS for audio.
Alan, would you be interested in doing something like that?
No worries if not.

 

[Alan0354]

We need more info like this on swapping OPAMPS.
They can do so much IMO.
I vote for Alan0354 to institute a sticky
for all things OPAMPS for audio.
Alan, would you be interested in doing something like that?
No worries if not.

I don't mind, question is how do you convince the forum to put it as sticky?

Alan

 

[ferninando]

I think there is a forum moderator who (unknown to me)
who can arrange it.
But thinking more about it maybe just forget it. OK?
I shouldnt have mentioned it.

 

[loudnoises]

The mods are pretty damn cool, and it'd likely be bumped up all on it's own.

 

[Bratwurst7s]

The OPA2107 is a good bit expensive (ca €18) but sounds oh so very very good. I like them much better than the OPA2134 fwiw.

http://www.mouser.de/ProductDetail/...GAEpiMZZMvtNjJQt4UgLd0UjFS%2bBnCWIevHBc0SQLk=

Cheers,
James

 

[Alan0354]

The OPA2107 is a good bit expensive (ca €18) but sounds oh so very very good. I like them much better than the OPA2134 fwiw.

http://www.mouser.de/ProductDetail/Texas-Instruments/OPA2107AP/?qs=sGAEpiMZZMvtNjJQt4UgLd0UjFS%2bBnCWIevHBc0SQLk=

Cheers,
James

Distortion is higher than the opamps that designed for audio. In the THD graph in page 6, THD is 0.001% to 1KHz and start rising to 0.003% at 10KHz.

I like the OPA2604/OPA604 better than OPA2134

 

[loudnoises]

Seems the gamma 40 tuner also has a couple of the same opamps in it, which i've foolishly forgotten to actually state.

AN6552 is the part i'm looking to replace. From everything i've read, socketing a dead rat would be an improvement on these opamps... if i can count correctly i need 6 in total.
Ouch. https://www.reddit.com/r/WTF/new/?count=50&after=t3_6dorcq
Ok so budget replacement it is, and the 627 is out for now. Sockets for sure, we'll see what the future brings I've heard the 604 is more neutral, and that's fine with me.
$3 a pop, can't go wrong eh?
eh?

 

[Alan0354]

I look at the data sheet of AN6552, it's just 4558. I think you can use a cheaper opamp than OPA2604 or OPA604.

OK, this is what I have on AN6552:http://www.datasheetspdf.com/PDF/AN6552/182164/1

This is the internal circuit:



This is RC4558:https://www.digikey.com/product-detail/en/texas-instruments/RC4558P/296-1414-5-ND/277060

This is the internal circuit of RC4558:



KA4558:https://www.digikey.com/product-detail/en/fairchild-on-semiconductor/KA4558/KA4558-ND/1050637

This is the internal circuit of KA4558:



You can see that the two circuit is identical!!!



So it's up to you, you need to do your homework a little, but if you are really using AN6552, either one of the RC4558 or KA4558 is a direct replacement........$0.39 ea.

Now you can be Mr. Cheap!!!! Follows me that born CHEAP!!!!....and proud of it.

 

[loudnoises]

At $.39 each i'd almost pay more for the sockets

They all work, so the motivation is purely fanciful. And if i don't end up keeping it, it's a selling point

I am hoping to make the tuner sound a bit better, it's rather flat right now and i'm hoping some BB magic will help. Yes, there's still homework to be done, and years of cobwebs to clear off of my old EE books and flashbacks of Fermental spitting everywhere...

 

[Alan0354]

The AN6552 is a dual opamp, how come you asked about OPA627 which is a single opamp? It is not a direct replacement.

For direct replacement you can use OPA2134 :https://www.digikey.com/product-detail/en/texas-instruments/OPA2134PA/OPA2134PA-ND/254686

The dual version of OPA604 is OPA2604, it's not easy to find a DIP8 version, I had to use a SO8 and put onto a SO8 to DIP8 converter pcb to do it. Now, don't buy from Amazon or other places other than the reputable place like Digikey, Mouser, Newark etc. I did buy a OPA2604 in DIP8 from Amazon and the waveform looked different from the SO8 I got from Digikey. I suspect it's fake. There are a lot of fakes out there.

 

[loudnoises]

Quite right. Dual, not single.

Occasionally there's a disconnect between what my head knows and what my hands type... luckily this tends to sort itself out once i write down everything.

 

[Hyperion]

Be careful with replacing older OP amps for modern substitutes, as there are some circuits in Sansui amplifiers (for example) that use older OP amps with fairly high supply voltage - say 20-22v - this can reduce your choices considerably. For me at least, and in Sansui amplifiers, the modifications required to reduce the supply voltage are beyond what my purist self will tolerate.

As it turns out the OPA2604 is the very one I have used to replace M5219L in more than one Sansui amplifier with that fairly high OP amp supply voltage.