Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Group Buys Members group buys

BPA300 Round 2
BPA300 Round 2
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
Reply
 
Thread Tools Search this Thread
Old 1st October 2009, 09:36 PM   #1031
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
Are the LM3886 on the heatsink? Without heatsink they will pretty hot.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 2nd October 2009, 02:12 PM   #1032
shmulik is offline shmulik  Israel
diyAudio Member
 
Join Date: Aug 2004
Location: country side
BPA300 Round 2
I gathered my wits, replaced the faulty LM and after meticulously checking placed the PA150 back on power. it now function well in the sense no smoke is coming out and heating is similar to the other board (hot, though). trying to kill the DC offset, I found myself running out of resistance and still have 6-20mv on the various LMs.
P-A, you write it is important to match the LMs' gain in each triplet, but the only control I have is over the dc offset. the gain is fixed by the fixed resistors.
  Reply With Quote
Old 2nd October 2009, 02:20 PM   #1033
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
The gain is one thing. The other thing to trim away the offset with the pot but I'll guess you may experience perhaps more offset in rare occasions since the offset voltage can be 0-10 mV times the gain. 20 mV offset at the output is good but the current flowing between the chips is the offset divided by you series resistance and this is a compromise. High resistor value, lower heat, higher output impedance, hotter resistors at high output power.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 3rd October 2009, 09:19 PM   #1034
shmulik is offline shmulik  Israel
diyAudio Member
 
Join Date: Aug 2004
Location: country side
BPA300 Round 2
Default DRV134 hiss

getting one step further, I assembled a DRV134 circuit (chip, 2 capacitors, connectors) on a strip board. as others before me, I encountered an excessive hiss on the drv outputs. I suspect it is circuit layout dependent, but I don't know how to verify or contradict it. I need to test the drv board in a more insulated environment.
I also suffer from another dreaded power amp problem - subtle hum. however, this hum seems to be picked up by the input cable, as it is there even when the cable is not connected on the other end.
  Reply With Quote
Old 4th October 2009, 06:18 AM   #1035
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
Do you have shielded wires? If not, you will create a perfect antenna.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 4th October 2009, 11:22 AM   #1036
shmulik is offline shmulik  Israel
diyAudio Member
 
Join Date: Aug 2004
Location: country side
BPA300 Round 2
P-A,
do you mean cabling between the RCA plug/PA150 and the circuit? they are all shielded and shield acts as ground. the noise is present only when the drv134 is powered. when fully connected (power, in and out) but not powered, or when I remove the circuit and let the wires to the PA150 hang free on air on one side there is no noise. when pulling the input to ground using 1K resistor the noise is almost totally muted. however, checking with an oscilloscope, I suspect the noise on the individual phases is about the same as without the resistor, but less correlated, and hence does not cancels out when bridging.

have you completed checking your implementation of a DRV board? do you have any noise issues?
  Reply With Quote
Old 4th October 2009, 03:40 PM   #1037
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
I haven't tested my board yet.

Have you connected the DRV134 according the datasheet (or like I have done). What kind of power supply do you have for your board?
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 4th October 2009, 03:49 PM   #1038
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
Quote:
Originally Posted by rhysh View Post
You should have another package tracking code by wednesday. I will keep posting updates.
Just wanted to remind you, it's soon the 10th of October.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote
Old 4th October 2009, 08:06 PM   #1039
shmulik is offline shmulik  Israel
diyAudio Member
 
Join Date: Aug 2004
Location: country side
BPA300 Round 2
Quote:
Originally Posted by peranders View Post
Have you connected the DRV134 according the datasheet (or like I have done). What kind of power supply do you have for your board?
for PS I'm using TeddyReg from PinkFishMedia :
http://www.pinkfishmedia.net/forum/s...ad.php?t=39990 with added LED on each rail.

the drv implementation has only connectors, and 2 electrolytic capacitors in parallel to 2 film capacitors between the +-V and ground for smoothing whatever is caught on the PS relatively long lines. I've tried adding a pulldown 100k resistor on the input with no change in behavior. also tried 1k resistors between outputs and ground - nothing changed.
The main abnormality I can spot is a difference in the level of noise (and DC offset) between normal and inverted phase pins. I cannot find an external cause for that difference.

any wild ideas are welcomed.

Shmulik

Last edited by shmulik; 4th October 2009 at 08:11 PM.
  Reply With Quote
Old 4th October 2009, 08:16 PM   #1040
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
BPA300 Round 2
If you compare my design with yours, what differs?
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 55 pcb's in order. 49 paid.
  Reply With Quote

Reply


BPA300 Round 2Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 03:23 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki