INFO: using lmh6321 instead of BUF634
Oct 17, 2008 at 10:13 PM Thread Starter Post #1 of 6

linuxworks

Member of the Trade: Sercona Audio
Joined
Oct 10, 2008
Posts
3,456
Likes
63
just a public service reminder:

for those that choose to use the (cough cough) buyable part as a buffer instead of the burr-brown 'we don't stock that' chip) on things like the pimeta amp - 2 things you need to remember to do:

1) lift pin 5 before soldering. I'm not a fan of fully cutting it off (in case you pick the wrong pin and realize later your goof) and lifting it is enough to keep it out of harm's way while you solder the other pins.

2) leave out the 200ohm resistor (R11 on tangent's schematics).

I believe his instructions do mention #2 but not #1.

here's a link to some discussion:

http://www.head-fi.org/forums/f6/pos.../index354.html

here are some of my shots of what I'm talking about:

2950472504_b878c18434_o.jpg


2950472156_5efed393f9_o.jpg


just posting this in one thread for easy reference
wink.gif


.bl
 
Oct 17, 2008 at 11:40 PM Post #2 of 6

rds

Headphoneus Supremus
Joined
May 4, 2008
Posts
2,045
Likes
30
Quote:

...on things like the pimeta amp - 2 things you need to remember to do:


Just to clarify that these tips are specifically for the Pimeta and not necessarily for other amps using the buf634
 
Oct 18, 2008 at 3:31 AM Post #4 of 6

linuxworks

Member of the Trade: Sercona Audio
Joined
Oct 10, 2008
Posts
3,456
Likes
63
Quote:

Originally Posted by error401 /img/forum/go_quote.gif
I'd still clip the extra lead off after testing the amp.


you mean, once the chips are soldered in and verified working?

yes, I agree, then its safe
wink.gif
but can the pin be snipped off safely once the chip is soldered that close to the board? I guess so - but is it worth the effort?

I have 2 pimetas now and I really can't tell the audible diff between the 2 buffer types. I'm glad there's an alternative that's almost a direct drop-in for the very hard-to-find 'normal' part.

.bl
 
Oct 18, 2008 at 3:39 AM Post #5 of 6

error401

1000+ Head-Fier
Joined
Oct 11, 2006
Posts
1,244
Likes
11
Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif
yes, I agree, then its safe
wink.gif
but can the pin be snipped off safely once the chip is soldered that close to the board?



Not difficult at all with a quality pair of cutters, or even a sharp knife. Is it worth it? No, not really. It's not even really necessary to lift it on the PIMETA since the pads don't connect to anything. It's just one of those little neatness things I guess.
 
Oct 18, 2008 at 8:32 AM Post #6 of 6

tangent

Top Mall-Fi poster. The T in META42.
Formerly with Tangentsoft Parts Store
Joined
Sep 27, 2001
Posts
5,969
Likes
56
Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif
I believe his instructions do mention #2 but not #1.


Yes, sorry. I didn't realize when I wrote that that there were traces making shortcuts through the buffers' pin 5 in a few places. The BUF634 doesn't use that pin, so it's harmless with that chip, but not with the LMH6321.
 

Users who are viewing this thread

Top