QUASI Amplifier for Beginners

[apexaudio]

How would this circuit compare to a commercial amplifier such as Audiolab 8200A? I have the 8200A and wonder if I can improve on the sound quality with this design.

If you want improve on the sound quality go to SR200

 

[wattaniya]

apex vu pcb.

 

[apexaudio]

apex vu pcb.

Nice work, thanks.

 

[wattaniya]

RE-SIZED.
if anybody need PDF pls ask. I'll share.

 

[t68kv]

@apexaudio

Will VU work with Quasi?

@nazirdigi
Nice! Can you share the pcb editable file of VU? I will only use it for one channel. TIA

 

[wattaniya]

here it is.

 

[masood]

hi AndrewT
i will use mje15030/31
but i was wondering how my dj amp has bd139/40 with rail voltage 54 volt
they are forced air cooled but without heatsink.
the amp is robust and drive 2 dual 15" cabinets.

dear sanju
i think that dj amplifier are huge ,1000watts and with mosfet transistors.these dj are 16 ohm 12 inches speaker.do you have knowledge about dj commercially available in market.khanks ur masood

 

[lyubcho88]

Hi everyone. Here are some of my amps made ​​by quasi scheme

more pics & information
QUASI amplifier 2x180W | DIY Projects

more pics & information
| DIY Projects

more pics & information
QUASI amp 2x180W peak power | DIY Projects

Regards

 

[apexaudio]

@apexaudio

Will VU work with Quasi?

@nazirdigi
Nice! Can you share the pcb editable file of VU? I will only use it for one channel. TIA

This VU work with any amp without adjust.

 

[44250]

RE-SIZED.
if anybody need PDF pls ask. I'll share.

I´d like to have it!

@ lyubcho88
GREAT JOB DONE by the way,you did it really awsome!

 

[wattaniya]

APEX550 PDF.

 

[44250]

thanks!

RE-SIZED.
if anybody need PDF pls ask. I'll share.

APEX550 PDF.

Thank You very much!

 

[masood]

APEX550 PDF.

dear nazir,
is this protection pcb.thanks regard

 

[wattaniya]

dear nazir,
is this protection pcb.thanks regard

that is power amp pcb.

 

[masood]

that is power amp pcb.

dear sir
do you have this pcb with protection(pcb with relay)as i saw some where?
thanks.sorry for my bad english

 

[masood]

Hi
Need to add a resistor of 0.33ohm/5W on the transistor 2N3773 or 2SC2922 (for Ucc=+/-70V) in the emitter of the negative branch of power supply.
Ceers!

dear sir
can i use these .22ohm2 or 3 watts resistors in place of 5 watts resistor.thanks your ever masood

 

[djk]

The 0.22Ω in each individual transistor will be dissipating about 1W average power assuming 300W/4Ω with four pair of outputs, so a good quality 3W is probably adequate.

Remember that most resistor ratings are specified with a Delta T of 250°C, so a 3W part running at 1W will have a Delta T of 88.3°C above ambient. This will be over the boiling point of water if the amplifier is run at full power for any length of time, but it should be OK.

 

[masood]

dear djk,
thanks

 

[yehan]

Apex the output transistor it is applicable to add as many as I can? Example 10 pair how much power output. Thanks

 

[AndrewT]

Virtually the same power as a single pair.
The maximum output power is determined by Vpk at the output and load impedance. Changing the number of output devices only changes the losses through the amplifier.