National LME49600 Reference Design Project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Member
Joined 2009
Paid Member
Is the LME49720 the optimum choice for the servo? I would have thought that a FET op-amp with a low offset would be better here. And then perhaps increase the value of R14 and R17 to attenuate noise from the op-amp?

With the LME49720 there could be 11mV offset from the offset current + the 1M resistors. With e.g. LF411 this could be reduced to 0.5mV from the offset voltage. The error from the offset current would be only 25uV (typical at 25 deg C) and 100uV max.

Of Course National would like to sell a lot of LME49720's, but it may not be the best choice for the servo.
 
might I suggest you add an soic8 pattern inside and connected to the dip8 so people can choose to use soic8 directly instead of having to use an adapter? just about all modern high performance opamps are nolonger made in dip8, only SMD and high bandwidth/speed chips and their decoupling will perform better if connected to the PCB and opamp pins directly
 
I am still learning about electronics, so please pardon any stupid questions i ask.
Is is possible to use the LME49600 in a headphone amp by itself?
My source has no problem driving my headphones to high volume, and it should be ok to have no gain.

Yes, I believe so. Most sources have plenty of voltage to drive the headphones to maximum, but not enough current. The LME49600 can provide the current.
 
Did anyone try to build this eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices ? their design used lme49710 + lme49600, or any comment?

Yes, I built that amp and wrote about it here:
http://www.diyaudio.com/forums/headphone-systems/206431-my-head-phone-amp-project.html

Jim's Audio boards are good quality in my opinion, with complete gold plating and plated through holes. The schematic as provided has way too much gain, but that's an easy fix.

A servo is not required.
 
It would be fun to make discrete version of the this chip. It looks to me like a variation on the diamond buffer from Walt Jung.
 

Attachments

  • LME49600 schematic.gif
    LME49600 schematic.gif
    21.2 KB · Views: 688
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.