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Old 22nd April 2003, 09:45 PM   #1
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Default New Amplifier circuit - Problam

Hii all !!

i have a Amp circuit...... i build it .... but is dont work good... now what i need to add or change to this circuit to make it work good.... - I mean normal sound quality...
now i have th parts:

Ne5532
2sc5200/a1943
MJE15030/31
BC639/640
and a lot of resistors and capacitors.....

thanks of help me... is is very importent...
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Old 23rd April 2003, 02:18 AM   #2
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For starters, you have no DC bias path off the emitters of
the first pair of 639's and 640's. Also, you seriously need
some resistance off the collectors of the 639's and 640's to
the emitters of the following devices (or the rails) to stabilize
the bias and gain.
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Old 23rd April 2003, 04:24 AM   #3
Diode is offline Diode  United States
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No feedback? No real bias? Honestly, I'm surprised it works at all. Out of all of the great recommednations you have been given over time, why did you pick this one? This isn't a nasty question, it's serious..... Why?
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Old 23rd April 2003, 06:06 AM   #4
sajti is offline sajti  Hungary
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Wink OK Let's make power amplifier!

Hi DJ,

fiirst You have to make: change the connection of the 2k7 resistors. Connect the upper one to the emitter cap of the first BC640, and connect the lower to the emitter cap of the BC639. With this modification You give bias for the first stage. But PLEASE DON'T SWITCH ON YOUR AMPLIFIER after this modification!
Do the following steps too:

1, Remove the 47 ohm resistors from the power supply!
2, Add 270 ohms resistors between the base, and emitter of the second BC639/640 pairs
3, Add 120 ohm resistors between the supply rails, and the emitter of the second BC639/640 pairs. This will generate 5mA collector current for the second stage.
4, Add 4 diode, and 220ohm potmeter between the collectors of the second pair of BC639/640. This will create the bias adjustment for the output stages.
First time set the potmeter to zero!
5, Add feedback to Your amplifier! This will be simple resistor-resitor divider between the output and the inverting input on the NE5532.

With this modification You will be closer to the real amplifier, but I'm not sure that it will works properly

Sajti
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Old 23rd April 2003, 11:52 AM   #5
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Sajti

Thanks for u, all !

but it will more easy for me if i can edit my picture....

because in words it is hard.... ok?

thanks u !!!!!!!!!!!!!!!!!!
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Old 23rd April 2003, 03:01 PM   #6
sajti is offline sajti  Hungary
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OK,
I will try to give You some pictures about the changes, but unfortunately it takes time.

Sajti
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Old 23rd April 2003, 08:54 PM   #7
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i will wait..... thanks u !
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Old 23rd April 2003, 09:06 PM   #8
Netlist is offline Netlist  Belgium
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Default Re: New Amplifier circuit - Problam

Quote:
Originally posted by Dj BASS AMP
Hii all !!

i have a Amp circuit...... i build it ....
Hi, DJ

Is this your own design?
Nice and simple attempt if you ask me!
With a little help you will make it!.

/Hugo - carry on
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Old 23rd April 2003, 10:24 PM   #9
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i dont make this design........ i just build it.... and not work good...
soo... i need some help to make it work... - to cut or add part.... to make it work...

the part that i have:

2sc5200 2sa1943 x8
ne5532 x6
bc639/640 x30
mje15030/31 x 8
and a lot resistors and capacitors...
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Old 24th April 2003, 12:09 AM   #10
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Hii all
sajti i make the fix... it is like this?? :
and i dont understand what is "potmeter"
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