My MOSFET amplifier designed for music. - Page 13 - 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 18th June 2008, 10:13 AM   #121
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hello Michael,
Slow down To have it playing you must have the outputs connected up. Yes ?

Read carefully,

Measuring the voltages across R17 and 22 (without the outputs connected) was just a way of checking that all was working O.K.
Did you move those 270 ohm gate resistors up to the legs on the FET's by the way. Good !

With the FET's connected and the pot set back to zero ohms is the output at zero volts DC. Do not connect any speaker while doing this and have nothing connected to the input as well. Post the reading I am interested in what it is
The pot is used to set the current in the output stage -- not voltage-- and the easiest way to set this is to measure the voltage across one of the 0.22 ohm resistors that go to the FET's.
You need to turn the pot to give around 22 millivolts across either resistor, it does not matter which you use. That will give a current of 100ma - dont worry if it seems to alter as the FET'S warm up -- just get it somewhere near.
Let me know how you get on.
  Reply With Quote
Old 18th June 2008, 10:24 AM   #122
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Hi, Space2000,

I saw your picture in post#111, it's better not use those long extension wires. Especially the gates of a mosfet, should be very short to the driver.
  Reply With Quote
Old 18th June 2008, 10:28 AM   #123
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
David means that you can safely do that with Vertical MOSFETs, but with Lateral MOSFETS it is Off Limits.
If you manage to keep it from oscillating like that you're One Cool dude.
__________________
The buck stops Here
  Reply With Quote
Old 18th June 2008, 10:43 AM   #124
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Space is the Veroboard King around here.
  Reply With Quote
Old 18th June 2008, 10:46 AM   #125
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hi Jacco, I said it was stable, even like that Did no one pick up on the wiring in the Photo to the FET's.
  Reply With Quote
Old 18th June 2008, 12:35 PM   #126
diyAudio Member
 
Join Date: Mar 2008
hi mooly,

As you have seen on the picture, it was only for showing that it is assembled. Actually I had changed the cables into very short and all are separated. I had to change where ever as it’s require. it’s operate quite cold, not really gets hot. I don't know why you all worry about vro-board. I even made 500w RMS used only vroboard, microchip with LCD and it is operating very, very well. I made for my uncle with two pair of 2sc5200/2sa1943 sumsym amp using 70v and he is using almost three months now without having any problem. That was also on vr-board but well constructed. Until now he is very pleased with that amp. I even got surprise the sound quality coming out from that amp, very clean.

I never use only vro board. I use some places thick copper plate to have higher amp where ever need to use.

Mooly actually i need to do more and check more. I just made it just try to get the sound first then later I will tune more btr for performance. This is the way I do all time.

Thanks for your help. Sound will be more btr when I will use proper circuit and power supply.

Great amp, very nice….

Best regards,
michael
  Reply With Quote
Old 18th June 2008, 03:37 PM   #127
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hello Michael,
Pleased to here you have got it all working. Just remember to recheck and adjust the pot as before for 22 millivolts if you run it on a higher voltage supply.
Run's a bit cooler than the Class A

Well done.

Regards Karl
  Reply With Quote
Old 19th June 2008, 11:32 AM   #128
diyAudio Member
 
Join Date: Mar 2008
hi mooly,

today i have tuned even more btr then last time. it will takes time to do. now even more nice music sound can produce. the vocal still not get sweet. now i am operating on 36vdc. heat is not get worst. quite stable now. bass is not very deep. anyway over all very nice, very musical..

many thanks for help.

best regards
michael
  Reply With Quote
Old 19th June 2008, 11:42 AM   #129
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hello Michael,
You still having fun Do make sure you do as per the previous post, if you have not got the 22 millivolts across the 0.1 ohms there will be crossover distortion.
What I did not show on the circuit was a 10 ohm 2 watt across the output coil. It should really be present but may not make any audible difference.
Have you grounded it all properly, keeping the input and PSU ground "separate".
  Reply With Quote
Old 19th June 2008, 10:34 PM   #130
diyAudio Member
 
Join Date: Mar 2008
hi mooly,

i didn't understand which one you are rfring about 0.1 ohms. i did correctly the zobel, i use 2watts 10ohms. there is no problem.


thank you.
  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



New To Site? Need Help?

All times are GMT. The time now is 07:34 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