what happens if DC blocking capacitors is removed - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 November 2012, 03:35 AM   #21
diyAudio Member
 
Join Date: Jul 2003
Location: Dona paula, Goa
No challanges for the metallized polypropylene.

Gajanan Phadte
  Reply With Quote
Old 9th November 2012, 04:58 AM   #22
diyAudio Member
 
Join Date: Aug 2012
I tried a new config 1uf styroflex 50v || 1uf polysterfilm || 8600pf polystyrene 63v cap and now the bass is tighter and still mids and highs are well balanced much better than before (1uf styroflex cap...)...

thinking of other configurations...
  Reply With Quote
Old 9th November 2012, 05:20 AM   #23
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
Quote:
Originally Posted by AndrewT View Post
If you don't know this then you should not be considering this modification.
You are behaving like a foolish child, who has no appreciation of danger and takes risks because they have no previous experience to fall back on. The not so foolish child listens to their parents.
Jeez Andrew, the OP asked a very fair question. You are overreacting.

In regards to the popular LM3875 and LM3886 chips, there will be 40-120mV DC at the output regardless of filtering capacitors at the input or having the feedback filtering capacitor. This is a bit high compared to most amps and may affect the sound of the speaker, but it will not damage the speaker.

Last edited by cotdt; 9th November 2012 at 05:23 AM.
  Reply With Quote
Old 9th November 2012, 06:16 AM   #24
diyAudio Member
 
Join Date: Jun 2011
In what frequency do you have the low frequency cut off?
Both at the input and at the feedback loop?
Andrew asked you this...
And im also curious about it...
  Reply With Quote
Old 9th November 2012, 06:32 AM   #25
diyAudio Member
 
Join Date: Aug 2012
anything less than 150 there is definitely more than 3db cuttoff... i cant hear the upper bass or lower mids... no warmth in male voice...
  Reply With Quote
Old 9th November 2012, 07:26 AM   #26
diyAudio Member
 
Join Date: Jun 2011
And the resistor in parallel with your input source? = Your input impedance therefore is?
  Reply With Quote
Old 9th November 2012, 11:42 AM   #27
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by cotdt View Post
...............In regards to the popular LM3875 and LM3886 chips, there will be 40-120mV DC at the output regardless of filtering capacitors at the input or having the feedback filtering capacitor.
This is the typical rubbish posted by ill-informed Members.
Take your version of physics to another Forum.
__________________
regards Andrew T.
  Reply With Quote
Old 9th November 2012, 11:45 AM   #28
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
R is guessing by swapping in and out components.
If R would just do some numbers, he could home in on solving the missing bass without having to guess.

Eg, if we/he knows that the input filter is not rolling off the bass early AND if we/he knows that the NFB capacitor has virtually no AC voltage across it (by being sufficiently higher RC) then we/he knows it is not the filter frequency that is at fault. We/he knows to look elsewhere.
At the moment neither he nor us have a clue where to look because R won't state what the RCs are in the amplifier.
__________________
regards Andrew T.
  Reply With Quote
Old 9th November 2012, 01:11 PM   #29
Igla is offline Igla  Slovenia
diyAudio Member
 
Join Date: Jun 2003
Location: Slovenia
My LM3875: no caps at the input and no feedback caps....I have about 30mV DC at the output.....6 years and still running and no damage to the loudspeakers. My DAC has output caps (TDA1543/CS8412) so no need for another caps at the amp input.
The sound is definitely better without caps no matter how expensive they are.
  Reply With Quote
Old 9th November 2012, 01:21 PM   #30
Igla is offline Igla  Slovenia
diyAudio Member
 
Join Date: Jun 2003
Location: Slovenia
Master AndrewT; there is no need to be rude. After all, we are talking about lousy chip amps and not about something your life depends on, right?
  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
DC Blocking Capacitors dome406 Chip Amps 18 4th May 2011 05:07 PM
Hypex SMPS DC Error detection and DC blocking cap bypass MaartenJ Class D 4 7th January 2011 10:58 AM
DC blocking cap in feedback path or DC servo? roender Solid State 27 19th September 2007 09:40 AM
Favorite film capacitors for DC blocking? The Peasant Parts 18 1st December 2006 04:37 PM
DC blocking capacitors soundNERD Chip Amps 4 25th October 2005 01:36 AM


New To Site? Need Help?

All times are GMT. The time now is 11:25 AM.


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