Dx Blame MKIII-Hx - Builder's thread - Page 109 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 25th February 2012, 05:35 PM   #1081
BMW850 is offline BMW850  Netherlands
diyAudio Member
 
BMW850's Avatar
 
Join Date: Aug 2004
Location: North East of the Netherlands
Quote:
Originally Posted by Junie View Post
now i cannot find a 100V in a small package for the capacitor circled in red, can i use a 100uF/50v?
Hi Junie,

I hope this helps, drawing from Carlos.
I use 100volt caps.


Regards,
Rudy
Attached Images
File Type: jpg cap.voltage.jpg (358.0 KB, 425 views)
__________________
Itís not what you know, but who you know ďand where they areĒ

Last edited by BMW850; 25th February 2012 at 05:37 PM.
  Reply With Quote
Old 25th February 2012, 07:08 PM   #1082
evette is offline evette  Canada
diyAudio Member
 
Join Date: Jun 2006
Send a message via Yahoo to evette
Of course you can. Evette
  Reply With Quote
Old 25th February 2012, 08:03 PM   #1083
diyAudio Member
 
Join Date: May 2011
Location: Quebec
Junie, the rating for that capacitor as been established as per if something goes wrong with some of the transistor (I don't recall which one) Carlos has commented it in one of his videos. It's facing very low voltage under normal condition. Mine is 63V
  Reply With Quote
Old 26th February 2012, 01:28 AM   #1084
Junie is offline Junie  Philippines
diyAudio Member
 
Junie's Avatar
 
Join Date: Sep 2010
Location: Dubai, UAE
Cool, thanks.
  Reply With Quote
Old 27th February 2012, 06:27 PM   #1085
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
I've changed 390R resistance to a 2.2 K resistor.
changing the lower NFB resistor from 390r to 2k2 changes the gain margin and phase margin of the closed loop amplifier.

The amplifier is bound to perform differently, before an after the feedback change.

BMW,
your test and reported conclusion are completely flawed.
Your description of the modification is correct and confirms you are listening to two different amplifiers that by design must perform differently.
__________________
regards Andrew T.
  Reply With Quote
Old 27th February 2012, 06:36 PM   #1086
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
That 100uF capacitor that is the DC block in the NFB path could be a 3Vdc component and the amplifier would still perform well.

If one wants to ensure that the low voltage cap in this blocking position is never abused then add a diode across it so that worst case DC voltage across it is <1Vdc.
You can also add an inverse diode across this same capacitor to protect it from voltage abuse (when something goes wrong) from the other polarity.

Some will report that higher voltage electrolytics perform better than lower voltage electrolytics when passing audio signals.
This DC blocking capacitor should have near zero DC voltage across it, when the amplifier is operating properly and should also have near zero AC voltage across it when the amplifier is operating properly.

A DC blocking capacitor that has no DC voltage and no AC voltage across it cannot contribute to the distortion that the amplifier creates.
i.e. A properly sized DC blocking capacitor cannot be heard.
Make it big and use low voltage if the space/cost requires that.
Use the input capacitors to limit the bandwidth of the amplifier.
__________________
regards Andrew T.

Last edited by AndrewT; 27th February 2012 at 06:38 PM.
  Reply With Quote
Old 28th February 2012, 05:58 AM   #1087
diyAudio Member
 
Join Date: Mar 2008
Hi,

completed the other part and PSU. how to add two LEDs on Psu _ and + voltage? my psu DC voltage is 60v.


Click the image to open in full size.

Last edited by space2000; 28th February 2012 at 06:01 AM.
  Reply With Quote
Old 28th February 2012, 07:06 AM   #1088
diyAudio Member
 
Rudi_Ratlos's Avatar
 
Join Date: Jun 2009
Location: Hamburg / Germany
Hi Space2000,

the voltage drop across a standard LED is about 2V.

To let the LED shine with say 5mA, you must calculate the value of a resistor across which 58V (since you are using a +/- 60 VDC PSU) will drop while 5mA is flowing.

Take a 10K resistor, connect the cathode of the LED to GND, the anode of the LED (the anode's leg is the longer one) to one side of the resistor and the other side of the resistor to your positive rail voltage.
Reverse the LED while connecting to the negative power rail.

Best regards - Rudi_Ratlos
  Reply With Quote
Old 28th February 2012, 11:04 AM   #1089
diyAudio Member
 
Join Date: Mar 2008
Quote:
Originally Posted by Rudi_Ratlos View Post
Hi Space2000,

the voltage drop across a standard LED is about 2V.

To let the LED shine with say 5mA, you must calculate the value of a resistor across which 58V (since you are using a +/- 60 VDC PSU) will drop while 5mA is flowing.

Take a 10K resistor, connect the cathode of the LED to GND, the anode of the LED (the anode's leg is the longer one) to one side of the resistor and the other side of the resistor to your positive rail voltage.
Reverse the LED while connecting to the negative power rail.

Best regards - Rudi_Ratlos
Thanks for help.
  Reply With Quote
Old 28th February 2012, 01:31 PM   #1090
Junie is offline Junie  Philippines
diyAudio Member
 
Junie's Avatar
 
Join Date: Sep 2010
Location: Dubai, UAE
Quote:
Originally Posted by AndrewT View Post
That 100uF capacitor that is the DC block in the NFB path could be a 3Vdc component and the amplifier would still perform well.

If one wants to ensure that the low voltage cap in this blocking position is never abused then add a diode across it so that worst case DC voltage across it is <1Vdc.
You can also add an inverse diode across this same capacitor to protect it from voltage abuse (when something goes wrong) from the other polarity.

Some will report that higher voltage electrolytics perform better than lower voltage electrolytics when passing audio signals.
This DC blocking capacitor should have near zero DC voltage across it, when the amplifier is operating properly and should also have near zero AC voltage across it when the amplifier is operating properly.

A DC blocking capacitor that has no DC voltage and no AC voltage across it cannot contribute to the distortion that the amplifier creates.
i.e. A properly sized DC blocking capacitor cannot be heard.
Make it big and use low voltage if the space/cost requires that.
Use the input capacitors to limit the bandwidth of the amplifier.
Andrew, isn't it adding a diode in NFB will rectify the output signal which lead to DC presence in the input stage? Maybe i'm wrong
  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
Dx Blame ST - Builder's thread - post pictures, reviews and comments here please. destroyer X Solid State 1730 15th September 2014 10:01 PM
Dx Blame MKIII Supercharged will soon be released destroyer X Solid State 346 22nd April 2014 03:01 PM
group buy for DX Blame MKIII Hx PCBs ByronInPortland Group Buys 247 5th December 2012 12:05 AM
Group By: DX Blame MKIII Hx boards ByronInPortland Group Buys 9 19th July 2011 07:21 AM
Dx Blame MKII, an obvious evolution from the Dx Blame ES/ST destroyer X Solid State 4 25th September 2010 06:41 PM


New To Site? Need Help?

All times are GMT. The time now is 10:48 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