QUASI Amplifier for Beginners

ok...i guess i'd be keeping this one for future use...
one more thing,
how do i know that an amp is capable of running in bridge mode???...coz there are some that say not all amps can run on this mode...
or they can but not for too long...
With this bridge buffer you can use any two identical amps in bridge, only minimal speaker impedance must be doubled.
Regards
 
hi eesbiboi
greetings well i bridged amplifier from eaustralia 300 watts per channel 8 output transistors 2n3773 put more outputs bigger heatsinks 8 0hms load i use it in 4 ohms
works well built it 23 years ago still works
thanking you
andrew lebon

very nice... it was really long time ago...i guess i was still -2yr old back then...:):):)
for maximum stability and safety operation then i must add more power and a bigger heatsink for the amp...
 
Hello sir

can i use this amplifier for keyboard and guitar (100watt 8ohms load)

does it work for continues program with two 2n3773

i have 35-0-35 transformer can i use for this amplifier

i found a circuit in the web but it did not worked to me output transistors are getting very hot even at medium sound (see attachment) hope yours will run cool

please attach a fresh schematic with bias adjusting with modifications as per my requirement
sorry for my bad English
 

Attachments

  • 100w amplifier-circuit.jpg
    100w amplifier-circuit.jpg
    75.8 KB · Views: 1,864
Hello sir

can i use this amplifier for keyboard and guitar (100watt 8ohms load)

does it work for continues program with two 2n3773

i have 35-0-35 transformer can i use for this amplifier

i found a circuit in the web but it did not worked to me output transistors are getting very hot even at medium sound (see attachment) hope yours will run cool

please attach a fresh schematic with bias adjusting with modifications as per my requirement
sorry for my bad English

You can use this amp for keyboard and guitar, and it will work with 35-0-35 transformer with two 2N3773 on 8ohms load. Amplifier run cool at medium sound. There is no fresh schematic.
Regards
 
i am confusing between these two schematics which one is correct?

what is Iq of this amp?
what is offset at output?
what is the wattage of the remaining resistors?

Both schematics are correct, only difference is connection of PNP driver emiter, on second schematics connection is same as PCB circuit.
Iq is 20mA, and this is VAS Iq, output stage work in class B
Offset at the output is +/-10mV (+/-20mVmax) without matching diff pair.
Resistors wattage is 0,25W if no other notification.
Regards
 
what is the Iq of this amp when i use only one pair of 2n3773
What is the range of frequency of this amplifier?
can you give me (schematic) pre-amplifier having two mic inputs and two AUX inputs

while using one pair of 2n3773 at voltage of +/-48 what is the power of this amp

can i use 16ohms 100watt speaker
 
what is the Iq of this amp when i use only one pair of 2n3773
What is the range of frequency of this amplifier?
can you give me (schematic) pre-amplifier having two mic inputs and two AUX inputs

while using one pair of 2n3773 at voltage of +/-48 what is the power of this amp

can i use 16ohms 100watt speaker

This amp is perfect for you, build it and come with questions leter.
Preamp is in thread:
http://www.diyaudio.com/forums/solid-state/167363-mic-line-eq-preamps.html
use two of them and mix with resistors before master volume pot.
Regards
 
I heard that class B is worst amplifier for audio applications because they produce distortion at low and high volumes

but you are telling me that it is perfect for me

I don't know whether this amplifier performs well

If you surely tell that this will give perfect sound and quality i will proceed to start doing this amp

otherwise if you have another amplifier like class D or H please send
 
Last edited:
ClassB biasing for the output stage saves heat and causes crossover distortion.
The distortion sounds worse at higher frequencies. It also becomes a higher proportion of the signal when the signal is quiet.

A full range amplifier biased to ClassB will, generally, not sound as nice as a ClassAB biased amplifier.

A bass only amplifier biased to ClassB may not sound any different to a ClassAB biased amplifier because the mid and treble signals are not being amplified and because the bass is not heard if it is only playing quietly (Fletcher & Munsen & others).
 
This amp has awfull THD ratios, not only because it s
working in Class B, but also because of an huge overcompensation.
No way it can be branded hifi, not even as a bass box amplifier....

In a way, it can only disappoint even the most enthusiast beginner..
A sad gift to give them such a misdesign...
 

Attachments

  • APEX QUASI.zip
    51.4 KB · Views: 694
This amp has awfull THD ratios, not only because it s
working in Class B, but also because of an huge overcompensation.
No way it can be branded hifi, not even as a bass box amplifier....

In a way, it can only disappoint even the most enthusiast beginner..
A sad gift to give them such a misdesign...

Beginners will be hapy with this amp, work at first swich every time, powerfull, great stability, no adjust, available parts... and THD ratio is inaudable anyway.
Regards