diyAudio - View Profile: panson_hk
Go Back   Home > Forums > Members List

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

panson_hk panson_hk is offline

diyAudio Member

Gallery

    Statistics
    Number of Photos: 16
    Number of Comments: 0
    Number of times photos viewed: 268,237
    Disk space used: 9.3MB
    Last Photo Uploaded: IMGP3049.JPG
    compact-49811-with-thermaltrak

    Last Comment Posted: Never

About Me

  • About panson_hk
    Biography
    BEng, MPhil, PhD; IEEE, AES
    Interests
    DIY for audio and embedded systems; biking, hiking
    Occupation
    Independent consultant
    Country
    Hong Kong

Statistics

Total Posts
Blog
Wiki
General Information
  • Last Activity: Today 09:38 AM
  • Join Date: 19th August 2005

Friends

Showing Friends 1 to 10 of 13

Blog

View panson_hk's BlogRecent Entries
Latest Blog Entry

Posted 23rd September 2011 at 08:19 AM by panson_hk Comments 1
Posted in Uncategorized
The THD performance of this board can be improved by separate the input/NFB ground from the decoupling grounds. This is a common mistake in many kits.

Simply cut the trace as shown in the figure and connect the input/NFB ground to supply ground via a separate wire. THD improves as shown in the figure.

Posted 5th September 2011 at 11:17 PM by panson_hk Comments 0
Posted in Uncategorized
The board is ready for test. The bias level is adjusted via monitoring the THD level as well as the distortion residual.

THD vs power for 20 Hz, 1 k and 20 k for 8 Ohm are shown in the figure. It is so high compared to all my 498xx amps. For 1 k, we should have THD lower than 0.0008 %.

Let test the THD vs power without load. Without load connected, output stage contributes very little distortion. This can be used to check whether the 49810 functions as spec or not.

Posted 5th September 2011 at 01:10 PM by panson_hk Comments 0
Posted in Uncategorized
The amp is assembled and ready for testing. It is designed to have two rails: one for LME49810 (suggested +/- 60 V) and one for driver/output (suggested for +/- 45V). The speaker protector uPC1237 also has an input for detecting the presence of AC (half-wave rectified).

In my initial test, one rails supply to 49810 and the output stage. The positive is also connected to the AC input of upC1237.

Posted 5th September 2011 at 09:26 AM by panson_hk Comments 0
Posted in Uncategorized
This kit is available in many sellers in eBay and TaoBao. My one is purchased from TaoBao. The output stage does not have protection. All the resistors are pre-inserted. What a nice service to save some time.

The 49810 heatsink screw holes are not aligned well. I also worry about its size.

The Miller compensation cap is a pre-soldered chip cap on the bottom side as shown in the picture. Fuses are pre-installed in the fuse holders.

Output are five pairs of 5200/1943.

Posted 16th August 2011 at 06:29 AM by panson_hk Comments 3
Posted in Uncategorized
I briefly measured the LM3886 x 3 parallel board this morning. THD vs freq for one, two in parallel and three in parallel are measured.

Load of 4 Ohm was also tested. When using one 3886, the on-chip protection activates periodically when doing low frequency (~ < 500 Hz) test. No such protection operation happens for the same output level for higher frequencies (>1kHz). The problem goes away when using 3886s in parallel.

More systematic tests will follow.
Recent Comments
Can you comment on the...
Posted 3rd January 2014 at 07:10 PM by HoneyBadger HoneyBadger is offline
I saw your post with...
Posted 20th August 2011 at 01:45 AM by abraxalito abraxalito is online now
Yes, I used 22k filter....
Posted 19th August 2011 at 03:21 AM by panson_hk panson_hk is offline
Plots look very interesting...
Posted 16th August 2011 at 09:20 AM by abraxalito abraxalito is online now
Hi Panson - I'm always...
Posted 15th August 2011 at 03:34 PM by abraxalito abraxalito is online now
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 01:49 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2