My MOSFET amplifier designed for music. - 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 10th March 2008, 11:05 AM   #1
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Default My MOSFET amplifier designed for music.

Hi, Well after having seen all the amazing projects and designs you guys have come up with I thought I would share my design on these pages. First and foremost this was designed for music reproduction in a domestic setting and without wanting to "hijack" another current thread, YES amplifiers do sound different, that is why I spent so much time in the development of this one. This amp is without doubt "musical" in all the best sense of that term, it's ability to recreate a believable soundstage is absolutely compelling. If anyone is interested in what it looks like and further details there are some piccys in the "Post your solid state pics here" forum. (About post 283) The thinking behind this project draws on the work of the late John Linsley Hood whose designs and thinking I much admired.
Regards Karl

--------------------------------------------------------------------------------------------------------------------------------------------------------

This index of the thread should help you find the relevant important notes and general information.

1. The circuit diagram in this, post #1 is correct. The only omission is a 10 ohm 2 watt carbon/metal film across the output coil.

2. The TL071 opamp must not be substituted. This type works correctly on the single negative 12 volt rail. Other device types may not do so.

3. A speaker relay incorporating a switch on delay is essential due to the action of the servo and the single ended input stage. This can be extremely simple consisting of a FET, a C-R network and relay. Post #273 in another thread shows the idea of solid state relays developed into a working example. Credit for the idea of the SS relay goes to those mentioned in that thread.
My MOSFET amplifier designed for music.

4. alex mm' brilliant PCB designs. Post #300
My MOSFET amplifier designed for music.

5. The FET pinouts, post #113
My MOSFET amplifier designed for music.

6. Squarewave testing, posts #157 to 161
My MOSFET amplifier designed for music.

7. Heatsinks, post #164
My MOSFET amplifier designed for music.

8. A glowing endorsement, post #186 and this,
My MOSFET amplifier designed for music.
Is Mooly's Amp Safe To Build?

9. Spicing it up... LTspice files, post #312
My MOSFET amplifier designed for music.

10. And finally some of my benchmarks and my thoughts on how it sounds. The adventures of getting the design to where it stands today, post #107
My MOSFET amplifier designed for music.


-------------------------------------------------------------------------------------------------------------------------------------------------------
Attached Images
File Type: jpg final.jpg (82.6 KB, 15560 views)

Last edited by Mooly; 24th November 2012 at 06:38 PM. Reason: Index to relevant areas in the thread.
  Reply With Quote
Old 10th March 2008, 11:08 AM   #2
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
This is the Preamp in outline form (I am only just getting to grips with a PCB Software package) all the original work was hand drawn. The series /shunt switching works brilliantly and give total isolation between inputs. Even with something ridiculous like a 10volt peak/peak squarewave as an input, there is no audible breakthrough even with volume on max.
Attached Images
File Type: jpg ppcc.jpg (49.9 KB, 13842 views)
  Reply With Quote
Old 10th March 2008, 02:50 PM   #3
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Hi, Mooly

You don't need R24 and R23...
__________________
Jorge
  Reply With Quote
Old 10th March 2008, 03:24 PM   #4
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Quote:
Originally posted by Tube_Dude
Hi, Mooly

You don't need R24 and R23...

... and C3
  Reply With Quote
Old 10th March 2008, 03:39 PM   #5
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Quote:
Originally posted by darkfenriz



... and C3
Hi Darkfenriz, how are you?

I agree , the servo is "in charge" of taking care of the offset...

Anyway, C3 in the schematic is with the polarity inverted...
__________________
Jorge
  Reply With Quote
Old 10th March 2008, 06:32 PM   #6
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hi Tube_Dude, you know, I wondered that at the time, my reason for including them was to provide more? if thats the right word isolation for the MOSFET's . They do reduce efficiency though. I would like to develop this design further, possibly running the front end (Up to Q3 and Q5) on a higher rail with shunt regulation (Power supply rejection is one area that could be improved).
Darkfenriz, wish I could do away with the electrolytic in the feedback arm, as you say the servo is in charge, but the base voltage of Q1 is around -6volts, so C3 is unfortunately needed (polarity is correct on circuit with about 5 volts across it) . That's the price you pay for using a single ended input stage but one that's well worth it. The TL071 works fine with only a single negative rail in this application, many other Op-Amps won't and would need + & - supply.
Thanks for the input
Karl
  Reply With Quote
Old 10th March 2008, 07:02 PM   #7
diyAudio Member
 
jerome69's Avatar
 
Join Date: Feb 2008
Location: Lyon
Hello Karl,

Very good !

Regards.
  Reply With Quote
Old 10th March 2008, 07:54 PM   #8
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
I'm fine, Jorge
Just a little overworked, underpaid, bored and lazy last days.
How are you?
  Reply With Quote
Old 10th March 2008, 07:57 PM   #9
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
Molly
the -6V on Q1 base will go up closer to zero if you remove the capacitor, like -1.5V or so...
  Reply With Quote
Old 11th March 2008, 08:00 AM   #10
diyAudio Member
 
mikefromaus's Avatar
 
Join Date: Dec 2007
Default nice

OK now we need someone to design a PCB .
I have tried designing a few using ExpressPCB but it seems to end up a mess!
I have many of the 2sk1058/j162 waiting for something like this!!
  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 03:26 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