Power amp under development

[andrewlebon]

hi diyers
greetings has any one made quasis actrk 600 made it 2 years ago
having biasing problems
1 it has 50 OHMS PRESET 100 OHMS PRESET AVAILABLE IF I PARALLEL 100 OHM
RESISTOR IS IT OK ANY HELP WILL BE APPRECIATED
THANKING YOU
ANDREW LEBON JUST GOT MOSFETS IRF450 IRF 460 SO I DECIDED TO REVIVE
THIS NICE AMP

 

[ravslanka]

hi diyers
greetings has any one made quasis actrk 600 made it 2 years ago
having biasing problems
1 it has 50 OHMS PRESET 100 OHMS PRESET AVAILABLE IF I PARALLEL 100 OHM
RESISTOR IS IT OK ANY HELP WILL BE APPRECIATED
THANKING YOU
ANDREW LEBON JUST GOT MOSFETS IRF450 IRF 460 SO I DECIDED TO REVIVE
THIS NICE AMP

hi andrewlebon,
have you read the thread Another quasi-complementary design.
http://www.diyaudio.com/forums/solid-state/53264-another-quasi-complementary-design.html

go to post http://www.diyaudio.com/forums/soli...uasi-complementary-design-51.html#post1611034

regards

tavs

be a vegeterian.......

 

[wattaniya]

what about nmos 247 4pairs of fets

 

[NMOS]

Hi Guys

Attachment Double Layer NMOS PCB Layout and schematic

have add

1. Balanced Input and Volume control Poti

2. Crowbar

3. VI Limiter Short Circuit Protect

4. Soft Start / Turn on Delay fast off without Relay ( Transistor T5 )

5. Cascoding VAS ( T7 , T8) and Bootstrap

 

[papyreloaded]

hello, i am about to finish building this amp but i have 1 missing irfp450. instead, i have an irfp260n. can i use that(3 irfp450 +1 irfp260n), maybe with modifying the gate resistor value?
PS i'm in a hurry and any help would be much appreciated. thanks

 

[NMOS]

hello, i am about to finish building this amp but i have 1 missing irfp450. instead, i have an irfp260n. can i use that(3 irfp450 +1 irfp260n), maybe with modifying the gate resistor value?
PS i'm in a hurry and any help would be much appreciated. thanks

AMP is working with 2 pcs. per channel too - actually have only use 2 pcs. IRFP460 each channel

You can mix IRFP450 with IRFP260n with HI-FI output power, but it can be IRFP260n fail in HiGH POWER PA use

 

[east electronics]

tick tock tick tock

 

[papyreloaded]

ok, thanks, got it- so it works but obviously it's not a recommended approach. i'll check it out tomorrow, now i'm a bit too tired 🙂
just a curiosity: why would irfp260n fail? will the load be inequally distributed between the mosfets, since they are not the same model? or is the irfp260n going to be out of SOA?
the amp is going to work on 8 ohm load( so 4 mos instead of 6 would suffice) at about +-60v supply

 

[papyreloaded]

tick tock tick tock

exactly! 🙂😕

 

[NUKE89]

Hi all and happy new year 🙂

I am currently thinking of building a 2x 350Watt @8Ωμ amplifier...And i have some questions. And unfortunately it is difficult to read the 360 pages in this thread...

1) First of all is this a decent amplifier or it is a better one? I mean, that one seems easy enough and not too expsensive...

2) I am gooing to use irfp260. Is this a problem? Do i have to make changes like using 0.22Ωμ resistors?

3) Which is the final pcb and schematics? i currently have this :
http://rapidshare.com/files/440492084/nchan_mos_project_06_05_06_191_170_300_watt.pdf

4) Does anyone have any pcb with VU meter, preamplifier or anything else?

Thanks a lot and i hope i didnt tire u too much 🙂

 

[AndrewT]

go to Quasi's own website and look at all the versions there.
Find the one that suits you and download the latest sch and PCB layout.
All are reputed to be good.

 

[NUKE89]

Hi. Thanks for your prompt reply. But the thing is quasi's page doesnt anwser any of my questions at all...

And i really cant tell what the difference is between nmos350 and actr600 ...

i am really amateut though...

 

[NMOS]

Hi. Thanks for your prompt reply. But the thing is quasi's page doesnt anwser any of my questions at all...

And i really cant tell what the difference is between nmos350 and actr600 ...

i am really amateut though...

actr600 is previous design and more efficient in dissipation compare to a lot of class ab amplifier.

1. Build NMOS 350 and add bootstrap, you will get more output power

2. Add Class H Step driver to increase efficiency, you can get with 3 IRFP 460 about 900W RMS@4 ohm otherwise you need for Class AB up 6 - 8 pcs. IRFP 460 and have a lot of heat

My NMOS is working with +/- 90 V DC and sound amazing

 

[asia]

nmos
can you share class h step

2. Add Class H Step driver to increase efficiency, you can get with 3 IRFP 460 about 900W RMS@4 ohm otherwise you need for Class AB up 6 - 8 pcs. IRFP 460 and have a lot of heat

 

[wattaniya]

for nmos200 how many voltage ac required?
for power supply 4700uf 63v cap is ok or higher need?

 

[tvparts]

Hi Quasi - So you never posted to let us know how your bass guitar amp turned out. Are you still using it? Just curious.

 

[andrewlebon]

hi nmos
greetings have you made actr600 i made it have biasing problems any tips for rectifying fault have you made and tested it with step driver any feedback will be helpful for me to complete this wonderful amp of quassis
thanking you
andrew lebon

 

[quasi]

Hi Nazirdigi,

The Nmos200 is limited to DC rails of +/-50v. Tis means that your transformer secondaries must be no more than 37 volts. Capacitors rated at 63 volts will be ok.

Cheers
Quasi

 

[quasi]

Hi TVparts,

I have never built a bass guitar amp, I think you have confused me for someone else.

Cheers
Quasi

 

[quasi]

Hi Andrew,

What sort of problems are you having? Can you share some measurements with me?

Cheers
Quasi