[Dan Kolton]

I changed both pairs of op-amps in my Insight pre-amp some time ago, but just now got around to changing those in my Ultra and Insight DACs.  This was the sequence:
1 Listen to both DACs with an orchestral and a choral CD.
2 Change op-amps in the Ultra.
3 Repeat 1.
4 Change op-amps in the Insight.
5 Repeat 1.

In step 3, my bionic eared wife couldn't really hear a difference.  She could in step 1.  of course, she didn't really know which she was listening to in any test (the order of presentation was varied from test to test).  During step 5, she thought the difference was again similar to 1, but overall both were "smoother and more detailed".  I agreed, except that I could pick out which was which in 1, 3, and 5 (I didn't always remember which was connected).  The new chip allows more inner detail to be heard.  The difference between DACs is as I described in another post.

[turkey]

I just Insight+'d my DAC.

It took longer to remove all the screws on the cover than it did to swap the chips.

I think it might sound a bit better now, but it's hard to tell. It doesn't sound any worse at any rate.

[Wayner]

New Dac has less screws 12 insted of 18.

Wayner 

[dB Cooper]

New Dac has less screws 12 insted of 18.

Wayner 

That way, it's probably less likely to screw up the sound
<crickets chirping>












Tough room... 

[turkey]

I'm sure Frank has already determined whether the chips he supplied are affected or not. I'm posting this for those who purchased chips on their own as an FYI.




Dear Customer,
Texas Instruments strives to provide the highest quality products for our customers
and to remain in compliance with our strict quality standards. This is a formal
notification that we have identified the following issue were we would like to
announce a Selected Inventory Exchange Process (SIEP).
Texas Instruments appreciates your business and apologizes for any inconvenience
this may cause. We stand ready to work with you to minimize any problems this
issue might cause. Feel free to contact us at the numbers listed below, or your field
sales representative, if you need more information.
MATERIAL AFFECTED:
OPA627AP
OPA627BP
DESCRIPTION AND TECHNICAL DETAILS:
Five batches of OPA627 were inadvertently assembled using OPA637 die. The
device shipping labels and package symbol indicate an OPA627. However in
actuality the device is identical to an OPA637.
Batch # LTC
3471584WEE 8AW7R1B
3482388WEE 8AW7R2B
3479200WEE 8AW7R2B
3481246WEE 8AW7R3B
3484007WEE 8AW7RCB
Affected Batch # and LTC
RISK ASSESSMENT:
The risk depends on the customer?s application. Per the OPA627/OPA637 datasheet
(SBOS165), ?The OPA627 is unity-gain stable. The OPA637 is stable in gains equal
to, or greater than five.? Gain-bandwidth of the OPA637 is five-times that of the
OPA627 (80MHz vs. 16MHz). Slew rate of the OPA637 is 135V/us vs. 55V/us for the
OPA627.
If your application can function properly with the OPA637 then there is no need to
exchange material. There are no long-term reliability issues.
DISPOSITION:
The separate spreadsheet lists information pertaining to the affected material,
which is affected by this issue and was shipped out of Texas Instruments to your
company and must be returned for replacement to TI.
TI-50128
Please review your stock for the affected material and respond to the email below
with information on LTC and quantities found.
Texas Instruments Customer Service will immediately provide an RMR # to return
the material from your site by TNT.
Thank you for your co-operation,
Fred Nakovic
Texas Instruments ? Tucson AZ
Customer Quality Engineering
Tel: 520-750-2046
Fax: 520-750-2695
mailto:f-nakovic@ti.com

[Wayner]

Frank tests all the chips before sending them out. If you sent the unit in to get the upgrade, I'm sure it was bench tested.

It would be interesting to know if he ran into any "funny" ones or not.

That is quite the mistake on TI's part.

Good heads up, Turkey.

Wayner

[avahifi]

We do test all the chips before shipping.  The only unity gain application where it would make any difference is in the Inverter circuits.  In all other circuit applications (preamps and DACs) a 637 die would work just fine.  We have observed no problems at all with our 627 supplies.

Frank Van Alstine

[rcag_ils]

I haven't noticed any negative effect from my Ultra DAC, and the ICs I have don't fall into the affected LTC, so I guess I am OK.

Good service from TI though.

[avahifi]

I finally had time to day to check the codes on my most recent supply of 627 op-amps.  They are NOT from the batches affected.

Regards,

Frank

[turkey]

We do test all the chips before shipping.  The only unity gain application where it would make any difference is in the Inverter circuits.  In all other circuit applications (preamps and DACs) a 637 die would work just fine.  We have observed no problems at all with our 627 supplies.

Frank Van Alstine

The 637 is specced with a faster slew rate and settling time. Since you don't need a unity-gain stable opamp for the preamps and DACs, why not use the 637?