[Big Red Machine]

http://cgi.ebay.com/Burr-Brown-OPA627-Precision-Hi-Speed-Difet-OPAmp-OPA627_W0QQitemZ160305186712QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2552ef0798

How would I know that these are not knock-offs?

[Jon L]

It's strange that the photo cannot be enlarged in that ebay ad.  Even from the small photo, the white OPA627AP label seems awfully too clear and bright.  I seem to recall all my previous OPA627's having a subtler, fainter labelling..  I can check for sure once I get home.

[srb]

Is this not the same chip at Digi-Key for $18.38?
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=OPA627AP-ND
 
Steve

[droht]

fwiw, here is a shot of my presumed-legit non-ebay purchased 627:

[Big Red Machine]

Ebay ad for $25 is for a pair.  I sent a note to a buyer of these to ask if they are okay.

I thought about upgrading my AVA Topp Dac with 4 of these.  I would take 5 minutes to swap them out.

[srb]

Ebay ad for $25 is for a pair.  I sent a note to a buyer of these to ask if they are okay.

BRM, I thought it was for one.
 
Outside of the use of a plural "Amplifiers" once at the end of the second phrase below (but he also mistakenly used the plural word "Someones"), I couldn't find any reference to it being a pair.
 
Burr-Brown OPA627 Precision Hi-Speed Difet OPAmp OPA627
 
"This auction is for a Brand New Burr-Brown OPA627AP DIP-8
Precision High-Speed Difet ? OPERATIONAL AMPLIFIERS"

This is an original OPA627 Op Amp, not a remarked, fake OPA ICs
 
True, the picture shows a pair, but I just took that to be top and bottom views.
If it is indeed a pair, I would be sure just to say so.
 
Steve
 
 

[WGH]

Here is a photo of the Op Amps I bought from AVA.



The chips on eBay look nothing like these.

[ecramer]

[WGH]

What I meant was that the eBay chip does not have the "R" after the BB logo. It could mean nothing.
You pays your money, you takes your chances.

[Browntrout]

Why not buy from a reputable retailer such as Digikey which was suggested earlier? That is what I do.
  Secondly the mono OPA637 is much better sounding in my experience, use two on Browndog adapters for the best sound in your DAC.

[Big Red Machine]

Why not buy from a reputable retailer such as Digikey which was suggested earlier? That is what I do.
  Secondly the mono OPA637 is much better sounding in my experience, use two on Browndog adapters for the best sound in your DAC.

This is what Terry is doing to his Music Hall DAC I believe.  The adapter boards still press into the original sockets, correct?

[Browntrout]

I would remove the socket and solder the adapter in. This means there is a proper solder joint instead of a push in joint.
  I have both types of adapter, for the surface mount opamp and the one with legs, and both have round cross section legs so I think they are not meant to be pushed into a opamp socket as these are designed for flat wide legs not thin round ones.
  Though, looking at the picture above and remebering you can specify the type of leg cant you? Either way I'd remove the socket.
  I did a thorough mod to a Cambridge Audio Azur 640P phonostage and posted it on Vinyl Engine a year or two ago and I and others noted the improvements to be had from good quality opamps and resistors for that matter.

[Big Red Machine]

So is it feasible to use a pair of the mono chips in this mount for every location of the stereo chip I have and it would sound better than just using a better stereo chip straight up?

[avahifi]

All the opamps used in any current AVA units are single (mono) devices.  No dual (stereo) devices are used.

Frank

[Big Red Machine]

In that old Topp DAC there are little heatsinks glued to the top of each chip so I am not sure what p/n they are and if I need 4 mono chips or 4 stereo chips.  Isn't the 627 chip a stereo chip?

[avahifi]

OPA627s are mono chips.  Please e-mail me a photo of the DAC board top side and I will advise exactly which chips to replace.

Regards,

Frank