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Old 21st April 2007, 06:28 AM   #1
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Default Non Bootstraped amplifier 60W

I have been working on this amp for a while it works great and has a great sound to it. My neighbor has a pair of klipschorns and wow.

Here is the schematic of the amp + power supply and speaker detection circuit. http://byrne.isa-geek.com/brendan/amp.bmp
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Old 21st April 2007, 10:14 AM   #2
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Talking What a Silly Design!

Quote:
Originally posted by IrishboyM4
I have been working on this amp for a while it works great and has a great sound to it. My neighbor has a pair of klipschorns and wow.

Here is the schematic of the amp + power supply and speaker detection circuit. http://byrne.isa-geek.com/brendan/amp.bmp
If I am correct then you have

one NPN differential[you dont even know how to draw a differential pair for easy reading]
Then again NPN differential connected to a PNP differential[but where are collector resistors for NPN differential 2NA410] which inturns connected to Vas followed by EF and then output stage, but why 180ohms for base resistors, it should be like 2.2 ohms or 4.7 ohms max..
Is is really working in reallity....??
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Old 21st April 2007, 06:11 PM   #3
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The amp works great. It is currently driving a 4Ohm load to considerable volume as i am typing this. Please note that i use two of the NTE2328-NTE2329 pairs for more current handling. Yes its overkill, but it keeps everything running cool. I know i need to work on my schematic drawing. The extra differentials are for signal conditioning and getting the negative feedback correct.
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Old 21st April 2007, 06:18 PM   #4
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The 180Ohm resistors are to protect the output devices if the drivers fail. They only take about .5db of power so it doesn't make a huge difference.
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Old 21st April 2007, 08:45 PM   #5
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Default Pictures please Irishboy.... i would be happy to take a look at it


Internally, externally, rigth side, left side,vision from up..back panel, supply, wiring, general vision, details, the speakers, the listening room, the house, your car, dog, the fleas..everything.

Others wants too..but they want only the board.

ahahahha

Please....images man!

regards,

Carlos
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Old 22nd April 2007, 07:14 AM   #6
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Here it is. Yes I know its all laid out and that will do heck to the distortion, but for some reason when tested its below .02 (Best the oscilloscope can do. The speakers are JVC SP-97WD. If anyone has specs for these let me know because I need them.

http://byrne.isa-geek.com/brendan/images/1.jpg
http://byrne.isa-geek.com/brendan/images/2.jpg
http://byrne.isa-geek.com/brendan/images/3.jpg


And here is my dog. LOL

http://byrne.isa-geek.com/images/lucy.jpg
Well that was her, she is bigger now.
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Old 22nd April 2007, 08:57 AM   #7
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Quote:
Originally posted by IrishboyM4
The amp works great. It is currently driving a 4Ohm load to considerable volume as i am typing this. Please note that i use two of the NTE2328-NTE2329 pairs for more current handling. Yes its overkill, but it keeps everything running cool. I know i need to work on my schematic drawing. The extra differentials are for signal conditioning and getting the negative feedback correct.

Well, if it works fine then it is different from the schematic you posted above. That 180 ohms will limit severely the available base drive for the outputs. It will work, but only for low levels especially in 4 ohms load.

For full power in 4 ohms at 30V peak you need 7.5A output current. Assume the output transistors have a gain of 50 at that current means 150mA base current. That would mean 27V across the 180 ohms. Where does that come from?

Jan Didden
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Old 22nd April 2007, 09:42 AM   #8
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Default You have made my day Irishboy....all that stuff shows me you are a real constructor


And this would be your name in place of Irish boy.....thank you as you have shared with me your images, in special your nice dog.

There are so many "simulators" doing electronics...... also so many people that cannot do simple things, only perfect boards with perfect brand new parts, needing to buy transformers, cases and all stuff to do something that you made me smile deep inside my heart, because so simple and nice your are.

You have that good passion for audio., not a snobish need to show your work as pretty...a very rare folk.

You have a friend on me.

Current to the bases are very small to the drivers...if your 180 ohms stop resistors were place into the drivers base, for sure will work better there, as output base current, beeing larger, will bave biggers losses with 180 ohms resistance....... 18 ohms would be better, 1.8 ohms will be perfect....also will work fine if you replace that one (those 180 ohms) with a wire jumper.

Your standard 180 ohms will produce nice sonics into treble...result may be magic...but will make you loose some power too.

From now on i will be watching your posts...you have a friend in me.

regards,

Carlos

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Old 22nd April 2007, 05:10 PM   #9
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Hi IrishboyM4,

Sorry friend, but about that 180 Ohms. I take it they are at least 10W jobs? Just to make sure you have the values right - and pardon us for asking, because if arithmetic is followed the circuit can only give 20W out.

If the NTE 2328 has a B of 30 (reasonable assumption) then arithmetic would show 13V over the 4 ohm load, i.e. 3.5A . For that Ib would be 3.5/30 = 120mA. 120mA through 180 ohm gives 21V, the rest of your h.t., allowing for 1V drop across the emitter 0.33 Ohm. So please see our problem.

I am not a buzzard sitting just waiting for bait, but it would also seem that your input impedance is about 0.5 ohm at 1 KHz - you are driving at the virtual earth point of a feedback circuit. What are you driving with, if this works?

So please bear with us if we seem dubious about certain component values!

Regards
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Old 22nd April 2007, 08:15 PM   #10
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The 180Ohm resistors are only .5watt and they don't even get warm. The gain of the NTE2328 is 55 minimum. Well I just took them out and it doesn't seem to make a huge difference but it does seem that it has more gain. The idle current is also higher and I need to adjust it. There does seem to be a little more power, but not huge. With the 180 Ohm resistors the amp would come to within 2 volts of the rail, without them it comes within .5V and that is when its driving the load.

By the way I'm only 15 so i haven't been doing this for very long.

Here is the updated schematic.schemaichttp://byrne.isa-geek.com/brendan/amp.bmp
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