Xin IV amps: OPAMP ROLLING GUIDE AND RECOMMENDATIONS.
I thought of putting up a guide as the data are scattered everywhere. It will make easier for the newbie’s and shall we make it a habit to list down the tested and recommended opamp configurations here for the benefit of all?
OP-AMP Rolling
• Take off the lid in Supermini.
• For Supermacro, take off the 2 back screws, remove back plate and batteries. Take off the 2 front screws with a 5/64" socket wrench and the volume knob with a 1/16". Remove the front panel. Before you move the circuit boards out of the case, make a mark on the case bottom; so later you can put the boards back in the original direction. This is important for proper case grounding. From the back, push the circuit boards out of the front (don't push on the battery contacts!). Lift the upper board so you can access the opamps and sockets.
In above picture SMIV (Macro) has two OPA134s(single OPAMP) in L\R with 2X HI-C BUF634 in L\R buffer channels. It has OPA2134(Dual opamp) in 3rd and 4th channels with 2X Lo-C BUF634s in thier buffer sockets. If someone uses dual opamp like OPA2134 in L\R it has to put in the position illustrated in the second picture. it will look like,
Use a small flat screw driver to lift the old opamps. Remember its direction - the first pin is at the left bottom; you'll put in the new opamps the same way. It might make things easier if you take out the buffer for channels 3&4 first in the case of supermacro.
• Before you put the new opamps in, push the pins (legs) against a desktop surface to make sure they become vertical. Fresh opamps have legs slightly stretched out making them too wide to be inserted into the sockets holes.
• Align the legs to the sockets holes (first pin to the left bottom hole) and push the opamp down into the socket with a flat screw driver.
That's it. A tweezers or classic Swiss Army knife are handy tools for rolling opamps. Before you put the circuit boards back into the case, you may test the effect using the included AC adapter. This way, you can easily swap, test and compare more opamps.
Source: macro manual
OPAMP TABLE
Supermacro
L\R Channel-OPA2134, OPA134, OPA2107, NE5534, OPA627, AD8397, OP275, AD8066, AD8620,
3\4 channel -OP275, OPA 2134, AD8397*, JRC4580,
Buffers------ HI-C BUF634, Lo-C BUF634, HA5002**
Supermini
L\R Channel(OPA2134, AD822, AD8620, ST-WV: need buffer) AD8397#, AD8656# and AD8616#, solid tube, LM8272,
3\4 channel AD8397*, AD8656 and AD8616
Buffers-----LMH6643***
* need a special version for 3\4 channel
**must be mounted on special adapters
*** Supermini can not take BUF634 and HA5002 as beffers
# They have internal buffers
Important notes
Buffers
These are output drivers used in L\R and 3\4 channels when the opamps doesn't have the output capacity due current and voltage limitations. For Supermacro, Buf634 and Ha5002 can be used as mentioned above. In case of Buf634 220 ohm resistors are soldered between pin 1 and 4 of BUF634s to set them into Hi-C mode for better sound. Lo-C BUF634 (without 220ohm R) seems to have more smooth and warm sound. It has the benefit of having longer battery life.
Ha5002 is set to High C internally. HA5002 is thought to be better buffer for the 4th and 3rd channel in Supermacro. They must be mounted on special adapters.
As AD8397, AD8656 and AD8616 has internally built buffers they do not need buffers for functionality. When they are installed in L\R or 3\4 one has to bypass the buffer socket. This can be achieved with a dummy opamp provided by Dr. Xin or connecting the pin 1 and 3 of OPAMP socket with a wire or resistor lead. The pin 6 and 8 too should be connected likewise.
Supermini can not take BUF634 and HA5002 as buffers and only buffer available is LMH6643.
For more refined and high end sound one can stack the buffers. Stacking is done by soldering two or three buffers of same class on top of each other to their corresponding same pin siblings. (eg: pin 1 to pin 1, pin 2 to pin2 .....etc,) This will drain more power from the batteries and limit the battery life.
Stacked buffers
OPAMPs
Some of the really good opamps used in the Mini can be destroyed if used in the SM-3/4 amps due to the higher voltages used. So when an new opamp is used in Supermacro or Supermini it is always prudent to check the DATA sheets of the OPAMP, to see whether its optimal operational voltages are met in the amp. Failing to do so will give either suboptimal performance or fried OPAMPS!!! The operating voltage inSupermacro is 12V-15V depending on the power source. Supermini without Dc-Boost provides voltages below 5V (3V). If OPAMPS with more higher voltages are used with supermini one has to enable the DC to DC boost (5.5V) with the jumper inside.
SOURCES FOR OPAMAP DATA CAN BE FOUND HERE!
http://www.fixup.net/talk/topic.asp?TOPIC_ID=1970
There is no DIP8 version of the AD8397 and AD8620. they need an adaptor.
OP275 and AD8610 are more detailed than OPA627, let alone OPA2134. BB chips tend to be rich and dark.
AD8066 (needs an adapter), OP604 and AD743 (single channel) supposed have better imaging and soundstage.
OPA2134 or OP275 in 3rd and 4th, seem to work better for those, who need energetic and bright sound with smooth extended treble.
For IEMs AD743 seems to be a good choice in L\R.
Please let your opinions flow to make it better!
