Directed 1100D - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 9th March 2011, 02:27 AM   #1
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
Default Directed 1100D

Got a few little issues with this amp I am trying to track down. Biggest issue I think is that I have a little bit of hum in the output. I am thinking that the shield ground in the amp is damaged although I have not found any blown ground traces. Should the rca input shields in this amp be tied to secondary ground? I am not getting continuity between either rca shield and secondary ground. One of the rca output shields is tied to secondary ground. The second issue is that the transformer seems a bit noisy. If I push down on it the noise gets considerably quieter. Is this the sign of a larger issue or do I just need to secure the transformers windings with some silicone or e6000? Maybe a few foam pads on top of the transformer that hit the bottom plate once its installed?
  Reply With Quote
Old 9th March 2011, 02:44 AM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Is there a hum with no RCAs plugged in?

Is the signal source ground connected to the amplifier's power supply ground?

Move the windings around a bit if the noise is an issue. Unless the noise will be a significant problem, don't apply anything to the windings.
  Reply With Quote
Old 9th March 2011, 03:28 AM   #3
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
No rcas plugged in equals no hum. Low level hum is present with the rcas plugged in and if I touch the speaker terminal it gets a bit louder. The signal source is grounded to the same place as the amplifiers ground. Shouldn't I have about 1 k between the rca shields and the amps ground terminal? Twisting the transformer just slightly took care of almost all the noise there.
  Reply With Quote
Old 9th March 2011, 04:13 AM   #4
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
This amp uses an active input circuit. In amps that use isolated secondaries to break ground loops, there is often 1000 ohms between primary and secondary grounds. In amps with active input circuits, the resistance between the shields and the primary ground is generally very high (mega-ohms to OL on a multimeter).
  Reply With Quote
Old 9th March 2011, 11:54 AM   #5
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
Should there be continuity between the two rca input shields? Because there isn't. Should there be continuity between the rca input shields and rca output shields?No continuity there either. Should any of the shields be connected to secondary ground? Only one of the output shields is. Do you have a schematic for this amp ?
  Reply With Quote
Old 9th March 2011, 11:59 AM   #6
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The two output shields should be connected to the secondary ground (if I'm not mistaken).

The JBL BP1200.1 (look in the JBL folder) is similar to this amp.
  Reply With Quote
Old 9th March 2011, 12:31 PM   #7
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
Cool I will look into that when I get home. Thanks.
  Reply With Quote
Old 12th March 2011, 01:46 PM   #8
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
I looked at the schematic for the jbl and couldn't really find where the shields go. As best I could find they basically just connected to each other through 100k ohm resistors. I have the amp in the car now and it works fine. There is a little noise through the sub but it isn't noticeable unless you have your ear to the sub. If I hadnt already heard the noise on the test bench I probably would never have noticed it. Are some class d's just a little noisy? Seems like I had an earthquake that had the same low level hiss/hum.Maybe my power supply is inducing the noise. Although the amp works fine in the car I still feel there is a problem due to the fact that when it was on the bench and i broke the ground connection between the amp and signal source it made a terrible noise through the sub. I have a viper d1200.1 here which is virtually the same amp and when i break the ground connection between the signal source and the amp there was no change and no terrible noise.
  Reply With Quote
Old 13th March 2011, 12:17 AM   #9
spooney is offline spooney  United States
diyAudio Member
 
Join Date: Dec 2006
After looking further at the schematic all the shields eventually end up connecting to one of the opamps in the preamp section after making their way through a series of resistors. I think I am chasing a problem that doesn't exist. I guess it would make sense that I was getting feedback through the sub when I broke the ground connection between the signal source and the amp. Two totally different ground references probably isn't a good thing.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Directed 250D mbates14 Car Audio 2 9th February 2011 09:32 PM
Directed 750 D mike49504 Car Audio 35 23rd July 2010 04:51 AM
Directed D800 mike49504 Car Audio 8 21st June 2010 02:50 AM
Kenwood KA-1100D (faulty) all parts available matski Swap Meet 3 30th October 2006 07:40 AM
DEI 1100d, what could be wrong? Gsteg Solid State 2 1st March 2004 06:03 AM


New To Site? Need Help?

All times are GMT. The time now is 01:52 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