Very simple quasi complimentary MOSFET amplifier

[lydlaug]

Thanks, zman.

Have you, or anyone else build the Big Quasi?
I wonder if there is reason to believe that this gives a better and more punchy bass reproduction, which I regard as the only weak point in this construction.
Maybe Hugh or Ranchu can chime in for a comment?

Lydlaug.

 

[2pist]

So this version added one additional BJT output? The board I used had one of each. I need to read up on the latest threads I suppose..

 

[motokok]

A bump from the dead. Can someone state the approximate output power into 8ohms and 4ohms for the base version?

 

[AKSA]

Your requested Lazarus returns!` It will do 100W into 8R and almost double into 4R, but watch out, the weak link is the C5200 quasi and should be doubled for a four ohm load, and a FQA40N25 higher rated nmos for M1 for lower impedance loads.
Cheers,
HD

 

[xrk971]

Highly recommended build. Sounds fantastic. A little tricky on the initial setup compared to some of Hugh’s other amps but well worth the effort.

 

[motokok]

Thanks, @xrk971. I downloaded your clip files and listened to them all. This amp was certainly my favorite; everything just sounded very right. A bit intimidated at the multiple PCBs but will go through the thread slowly.

 

[zman01]

motokok,

I have a fully built set of PCBs that can let go of; if you are interested, please PM me.

Good luck with the build.

 

[motokok]

Very kind @zman01 , but probably not cost effective for you to post to me. What layout did you use?

 

[xrk971]

I think I have spare PCBs I can send you for postage if you are interested. The nice smooth curves curly layout. I think layout by Thiagomogi.

 

[xrk971]

I just went looking for these spare PCBs and cannot seem to locate them. Sorry.

 

[zman01]

Very kind @zman01 , but probably not cost effective for you to post to me. What layout did you use?

motokok,

IIRC the build that I did used the Dacz layout.

 

[motokok]

Very kind, again, gents, but no worries. I will take the time to read the whole thread; maybe do a condensed write-up of what I collate, in advance of planning any future build steps.

 

[avtech]

It is quite cheap to get some PCBs made and shipped using the gerbers posted in the thread.
Usually postage is the part that costs the most, but can be very cheap if you are prepared to wait for slow-mail.

There are a few PCB versions to choose from:
Post 2157
Post 2154

I have been using the Phunk 'Borg' on and off for some time now and it's been a solid performer.

I do have some of those boards left over, but it'd be cheaper to get a new set manufactured by the likes JLCPCB or PCBWAY than postage from Oz.

 

[AKSA]

Hi Avtech,
Could I please buy a couple of the Phunk pcbs from you?
Please let me know at aspen01@optusnet.com.au.
Many thanks,
Hugh

 

[avtech]

Hi Hugh,

Seeing your name is already on the board, and the contribution you made to the design, I'm happy to send you a pair FOC:

I'll send you an email for your address.

Cheers

 

[Mister Audio]

Hello there,
I am posting this primarily so I can later find this THREAD easily later.
I have an interest in a 'super simple' MOSFET amp in the near future.
First I need to read through all the posts
PS.
Weren't the Perreaux power amps about as simple as they get ???

 

[chermann]

Hi

I want to build this amp in the near future...

i did ordered the Dacz VSQA pcb. it should be this documents, right?
are here changes to do?

Q1 without reading 139 pages, is there a final BOM?
Q2 N ch Mosfet FQA044N10-133 okay i guess? BJT will be a 2CS5200 Toshiba
Q3 Which green LED are preferred?

thanks in advance
kr
chris

 

[zman01]

Good to see the interest around this amp.

chermann,

Here is what I found from my notes from a few years back - the numbers at the end of the each line is the part # from Element14 (Farnell in UK and Newark in the USA) - you will need to check and see if this component list is ok, as I don't remember if I went with this list or made changes to it when ordering:

(the quantities are for a single channel - for a stereo build you will need to order 2x)

R1: 1 x 470K Ohm 1/4watt: 1126990
R2: 1 x 1K Ohm 1/4watt: 1126919
R3: 1 x 10 Ohm 1/4watt: 1126917
R5:1 x 33K Ohm 1/4watt: 1126974
R6: 1 x 10K Ohm 1 watt: 1833138
R7: 1 x 680 Ohm 1/4watt: 1127004
R8: 1 x 68 Ohm 1/4watt: 1127003
R9: 1 x 1.8K Ohm 1W: 1565356
R10: 1 x 68K Ohm 1/4 watt: 1127005
R11: 1 x 470 Ohm 1/4 watt: 1126987
R12: 1 x 2.2K Ohm 1/2 watt: 1129093
R13: 1 x 1.2K Ohm 1/4 watt: 1126929
R14: 1 x 150 Ohm 1/4 watt: 1126936
R15: 1 x 1.5K Ohm 1/4 watt: 1126937
R16: 1 x 150 Ohm 1/4 watt: 1126936
R17: 1 x 2.2 Ohm, 1/4 watt: 9473971
R18: 1 x 47 Ohm, 1/4 watt: 1812999
R19: 1 x 120 Ohm, 1/4 watt: 1126928
R20, R21: 2 x 0.33 ohm 5 watt: 1903893 or 3542702
R22, R23: 1 x 10 Ohm 2 watt: 1738611 or 9338039


C1: 1 x Electrolytic Capacitor, 15uf 63V: 1823662
C2: 1 x Film capacitor, 220pF: 247840
C3: 1 x Electrolytic Capacitor, 22uf 63V: 1834169
C4: 1 x Electrolytic Capacitor, 1000uf, 16V: 1304250
C5: 1 x Mica Capacitor, 33pf: 1311572
C6: 1 x Electrolytic Capacitor, 100uf, 50V: 1690876
C7: 1 x Electrolytic Capacitor, 47uf 63V: 1822704
C8: Optional
C9: 1 x Film Capacitor, 22nF 63V: 9752978
C10: 1 x Film capacitor, 220pF: 2478401
C11, C12, C13: 3 x Film Capacitor, 100nF 1199673
C14, C15: 2 x CAPACITOR 470UF, 100V: 1304248


D1, D2, D3, D8: 4 x Rectifier Diode, 1N4007: 1651091
D5: 1 x 12V Zener Diode: 2125942
D6: 1 x 1N4148 Diode: 9843680
D7: 1 x 3V3 Zener Diode: 1700928
D9, D10: 2 x 1N4148 Diode: 9843680


Q1: 1 x 2N5401: 1862542
Q2: 1 x KSC1845: 2453946
Q3, Q5: 2 x KSA1381ESTU: 2453937
Q4: 1 x BD139: 1015770
Q6: 1 x IRFP250: 8649278
Q7: 1 x 2SC5200 / NJW0281G: 2101384

LED: 1 x Blue LED, KINGBRIGHT L-964QBDL-D: 2373467
LED: 1 x Green LED, KINGBRIGHT: 2335730
VR1: 1 x Trim pot 200 Ohm: 9608575
VR2: 1 x Trim pot 1K Ohm: 1141401

 

[chermann]

Thank you

 

[jvhb]

If you read/search through the thread, you will find answers to all (or most at least) questions regarding components etc...

A few years back, I build a few examples, and tested and compared with different mosfet and BJT outputs. It didn't actually make a big difference as I recall, at least not regarding THD and harmonic profile. The results are somewhere in here