Power amp under development

Jump to Latest
B

bawang

Member
Joined 2001
Discrepency in NMOS200

Quasi,

Decided to build your NMOS200 as per your website. However, there are discrepencies between the values of components in the schematic and PCB parts placing diagrams, such as C2, C3, R6..... I may have missed others. Is it possible for you to elaborate? What are other changes in values? I am compiling the parts list now. Thanks for the effort to share the designs, this is what DIY is all about.
 
M

medogrizli

Member
Joined 2006
Maybe its stupid question but can you compare this vertical mosfet amplifier to lateral mosfet or classic bipolar?
-THD

and subjective sound quality

thanks :D

And letc presume that I am making switching supply: the problem are two different voltages that need to be feedback-ed to SG3525 IC

two feedbacks are not possbile or?
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
Re: Discrepency in NMOS200

bawang said:
Quasi,

Decided to build your NMOS200 as per your website. However, there are discrepencies between the values of components in the schematic and PCB parts placing diagrams, such as C2, C3, R6..... I may have missed others. Is it possible for you to elaborate? What are other changes in values? I am compiling the parts list now. Thanks for the effort to share the designs, this is what DIY is all about.
Click to expand...


Good eye Bawang,

For me creating the PCB is often like creating a new circuit and sometimes I think of different things. Anyway the amp will work fine with any of these components. For the record though the schematic is correct ie;

- C2 should be 330pF although 270pF won't make any difference.

- R6 should be 33R although 47R is fine. Maybe we should meet in the middle and make it 39R :D

- C3 should be 330pF, but guess what, it probably doesn't matter too much. The amp is a very stable design.

Any constructors who used component values from either the schematic or layout do not need to worry. Your amp will work perfectly as these are not critical value components.

And that folks is the reality of audio design. Some things are important and must be calculated. Other stuff is just the whim of the designer. This is the beauty of of DIY (and the cause of so much debate I suspect).

Cheers
Quasi
or Q
or Que
or .....
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
medogrizli said:
Maybe its stupid question but can you compare this vertical mosfet amplifier to lateral mosfet or classic bipolar?
-THD

and subjective sound quality

thanks :D

And letc presume that I am making switching supply: the problem are two different voltages that need to be feedback-ed to SG3525 IC

two feedbacks are not possbile or?
Click to expand...


You cannot compare output stages on a single basis alone. Each type correctly designed and driven will give excellent results. If you ask for my personal opinion, I prefer using a bi-polar transistor output stage in terms of sound quality, but enjoy the robustness of mosfets. Check out Jmateus' build here of the bi-polar version http://www.diyaudio.com/forums/showthread.php?postid=1159619#post1159619 and here http://www.diyaudio.com/forums/showthread.php?postid=1162081#post1162081

A mosfet's SOAR is virtually its power dissipation (V * I) whereas a transistors is something else. At higher voltages a mosfet will always beat a similarly rated transistor.

Regarding the switched power supply; Audio amplifiers are very tolerant of small voltage variations. It would be ok to monitor only one of the rails knowing the other will be close enough.

Cheers
Q
 
M

medogrizli

Member
Joined 2006
quasi said:



You cannot compare output stages on a single basis alone. Each type correctly designed and driven will give excellent results. If you ask for my personal opinion, I prefer using a bi-polar transistor output stage in terms of sound quality, but enjoy the robustness of mosfets. Check out Jmateus' build here of the bi-polar version http://www.diyaudio.com/forums/showthread.php?postid=1159619#post1159619 and here http://www.diyaudio.com/forums/showthread.php?postid=1162081#post1162081

A mosfet's SOAR is virtually its power dissipation (V * I) whereas a transistors is something else. At higher voltages a mosfet will always beat a similarly rated transistor.

Regarding the switched power supply; Audio amplifiers are very tolerant of small voltage variations. It would be ok to monitor only one of the rails knowing the other will be close enough.

Cheers
Q
Click to expand...


Thanks

About switching supply

But there is a difference in the schematics: on your web page there is just one voltage +/-75 V but on the first page of this topic there is two voltage schmeatic
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
medogrizli said:
Thanks

About switching supply

But there is a difference in the schematics: on your web page there is just one voltage +/-75 V but on the first page of this topic there is two voltage schmeatic
Click to expand...


You should not attempt to build the circuit on page 1 (1,866 posts ago), it is not a well performing amp. During this thread the amp was developed into what it is today. There is a logical progression from that first post to the final design schematic and layout. So if you like this amp build the version on the web page.

I have posted another amp that uses a split positive rail. This thread can be found here; http://www.diyaudio.com/forums/showthread.php?postid=991050#post991050 but this topology is completely different.

Cheers
Q
 
J

Juan Spektor

Member
Joined 2007
hi, just want to tell you all that the amp is working fine.
just that im using a 33+33 power suply (don`t ask why, just know that i have a very bad week), and want to know if is not danger use that low voltage, i mean what could happend if i run the wiht low voltage? (i think i made the same question 3 times but i don't know if you will understand me)
Thanks to all


PD:sorry my bad english
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
Juan Spektor said:
hi, just want to tell you all that the amp is working fine.
just that im using a 33+33 power suply (don`t ask why, just know that i have a very bad week), and want to know if is not danger use that low voltage, i mean what could happend if i run the wiht low voltage?.......
Click to expand...

Hi Huan,

The amp will work fine with +/- 33v but if you intend running this voltage you should reduce the value of R7 to around 4k7. If you intend runing on higher voltages later then leave the 10k in there.

It sounds like you blew something up, maybe a power supply? Anyway I'm glad that your amp is working.

Cheers
Q
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
Re: Discrepency in NMOS200

bawang said:
Quasi,

Decided to build your NMOS200 as per your website. However, there are discrepencies between the values of components in the schematic and PCB parts placing diagrams, such as C2, C3, R6..... I may have missed others. Is it possible for you to elaborate? What are other changes in values? I am compiling the parts list now. Thanks for the effort to share the designs, this is what DIY is all about.
Click to expand...

See also http://www.diyaudio.com/forums/showthread.php?postid=1230705#post1230705

Corrections have been made and updated on the web site. Feel free to download documents from there.

Cheers
Q
 
M

medogrizli

Member
Joined 2006
quasi said:



You should not attempt to build the circuit on page 1 (1,866 posts ago), it is not a well performing amp. During this thread the amp was developed into what it is today. There is a logical progression from that first post to the final design schematic and layout. So if you like this amp build the version on the web page.

I have posted another amp that uses a split positive rail. This thread can be found here; http://www.diyaudio.com/forums/showthread.php?postid=991050#post991050 but this topology is completely different.

Cheers
Q
Click to expand...

What is difference in performance of AMP that has single power supply single +/- voltage between those that have +10 voltage of imput stage

What abotu schematics on your web page: are they all working and updated
 
quasi

quasi

Member
Joined 2004
sites.google.com/site/quasisdiyaudiosite/
medogrizli said:


What is difference in performance of AMP that has single power supply single +/- voltage between those that have +10 voltage of imput stage

What abotu schematics on your web page: are they all working and updated
Click to expand...

That amp is also good, but I have not yet built a stereo combination. It has been tested on the bench and seems to perform well. However it is not as easy to set up as the amp in this thread and it takes longer for the bias current to settle. If this is your first high power amp build then build one of the amps in this thread.

All schematics, layouts and other information on my web page are the latest versions. I have just updated to include a construction guide for the Nmos350 / 500.

Cheers
Q
 
M

medogrizli

Member
Joined 2006
quasi said:


That amp is also good, but I have not yet built a stereo combination. It has been tested on the bench and seems to perform well. However it is not as easy to set up as the amp in this thread and it takes longer for the bias current to settle. If this is your first high power amp build then build one of the amps in this thread.

All schematics, layouts and other information on my web page are the latest versions. I have just updated to include a construction guide for the Nmos350 / 500.

Cheers
Q
Click to expand...

If I understood it well you suggestod to build that which uses +10V for imput circuit or that on your web page that ahs only one voltage?
 
keypunch

keypunch

Member
Joined 2004
medogrizli said:


If I understood it well you suggestod to build that which uses +10V for imput circuit or that on your web page that ahs only one voltage?
Click to expand...

medogrizli,

If I may jump in here, what quasi is suggesting is you build one of the NMOS amps in this thread, not the one with the +10 volt positive side rail. The NMOS of this thread are the NMOS350, NMOS500 and NMOS200.

If this is really your first amp you are building I would think you should start with the NMOS200. The reason is simply because the NMOS200 uses lower voltage DC rails which would be safer for you as a first AMP project.

The NMOS designs by quasi is an excellent first amp for three reasons. The design is very stable, you have excellent flexibility with parts whilst still keeping the third reason of excellent performance/sonics. If you use different parts for transistors just be sure to pay attention to the pinouts of the alternate parts used as often the order is different to the parts the PCB was designed for, i.e. BCE, CEB, ECB, et al.


Regards,

John L. Males
Willowdale, Ontario
Canada
16 June 2007 13:52
Official Quasi Thread Researcher
 
You must log in or register to reply here.
Top Bottom