diyAudio - Entries for January 14, 2013
Go Back   Home > Forums > Blogs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

Modification of the S.M.S.L. sAp VI headphone amplifier

Posted 14th January 2013 at 11:29 AM by rjm (RJM Audio Blog)
Updated 27th December 2016 at 01:38 AM by rjm

I couldn't even build it myself for the price they are selling it at, $50 on ebay. It caught my eye for the linear, split power supply. I love the chrome 3-pin power connector, too.

As is usual when you buy cheap ultra-Chinese audio gear via eBay some adjustments are needed, however.

The basic problem seems to be a little mix up with the input coupling capacitors. It came with polar electrolytic capacitors, following the markings on the circuit board. If you lstudy the schematic I sketched up below you will notice the input signal and DC offset can swing in both positive and negative directions relative to the op amp inputs - polar capacitors in this position are a bad idea.

I recommend anyone buying this to replace the input caps with Nichicon Muse ES or similar 4.7 uF or 10 uF bipolar electrolytic caps. (I have some extra I can mail out. pm me if interested.)

Other than that it's a pretty solid circuit as far as I can see....
Attached Thumbnails
Click image for larger version

Name:	sApVI schematic.jpg
Views:	8227
Size:	244.7 KB
ID:	838   Click image for larger version

Name:	DSC_2499 1600.jpg
Views:	6110
Size:	107.3 KB
ID:	839   Click image for larger version

Name:	DSC_0835 1600.jpg
Views:	4811
Size:	195.8 KB
ID:	840   Click image for larger version

Name:	DSC_0837 1600.jpg
Views:	2313
Size:	204.6 KB
ID:	841   Click image for larger version

Name:	DSC_2449 1600.jpg
Views:	2163
Size:	410.3 KB
ID:	842  

rjm's Avatar
diyAudio Member
Views 10020 Comments 8 rjm is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 12:12 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2