100W Ultimate Fidelity Amplifier

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#2,982
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#2,983
I'm already finished my board,

- start supply with 12VAC with protect 10Ohm (series with board).
- input short to ground

DC offset measured 3.9V 😱

what first step to do fix this problem?
 

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#2,987
Hi apex,

i'm already fix my DC offset problem, the problem only input to ground not connect to main power ground *sorry for that.
i get 15 mV.

but, now come new problem, the final Transistor very fast to heat, and sound have big huuuummm,
 

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#2,989
Hi Apex,

i solved my problem (hum and very hot TR final),
- first steop, i replace MJE350 and BC547 with new one (this solved not stable DC offset)
- second step, i try to bypass signal ground to power ground and this solved my huuumm problem and DC offset get 50-80mV (of course with no hot TR final)

sound very nice (so warm with deep bass 😀)

NB : my layout for test using 5200/1943 tr final, next step will change using MJ15004/MJ15003.

check this my video test : Ax14 test sound after many troubles - YouTube
 
#2,991
Yes bli John, i will put 1 pair MJ15003/04 too, and will record with my phone again.
this my first time build amp with complex schematic (i'm just enjoy playing with OCL schematic 😀).

thanks for your guides, i hope not make bli john boring with my many questions 😀

NB: i have done try with 1 pair tip2955/tip3055 *sound more mid but bass still deep WoW, this will replace my old ocl board with 3 pair cheap 2955/3055 😀

thanks Bli John, and special for Mile/Apex.

BR// Madde
 

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#2,992
I reread again & found some useful hint... 🙂

don't go more than 30VDC like Apex suggest
apexaudio said:
OK, for 2N3055/MJ2955 outputs use AX14 pcb with +/-30V rail voltage.
Regards
Click to expand...

for bias AX14 :
apexaudio said:
If you can set BIAS to 200mA, replace R17 (1k) with 470R.
Click to expand...

And also this one :

apexaudio said:
+/-24V DC is the lowest operating voltage, if you have +/-32V DC you can use this amp but power will be about 40W on 8R load.
Regards
Click to expand...
 
#2,993
lelut said:
Yes bli John, i will put 1 pair MJ15003/04 too, and will record with my phone again.
this my first time build amp with complex schematic (i'm just enjoy playing with OCL schematic 😀).

thanks for your guides, i hope not make bli john boring with my many questions 😀

NB: i have done try with 1 pair tip2955/tip3055 *sound more mid but bass still deep WoW, this will replace my old ocl board with 3 pair cheap 2955/3055 😀

thanks Bli John, and special for Mile/Apex.

BR// Madde
Click to expand...

Tnanks for pdf files
 
#2,995
Hi Apex,

if i'm use 35VAC and to drive 15" fullrange speaker in 8ohm, this possible to get loud sound in open area?,
what minimum Ampere must i use to my AX version (using 3 pairs TR final MJ15003/04)? and how many watt will given?

thanks Apex,

BR// Madde
 
#2,997
AndrewT said:
Maximum power equals V^2 / Rload, i.e. 35Vac^2 / 8 ~153W

3pr of 250W BJT devices can give a maximum output of ~300W
Click to expand...

Dear Mr. AndrewT, thanks for your answers,
and one more question, i have 500W full range speaker, how many watt power of PA for best drive this speaker (more than 500 watt or less than 500 watt)?
and if less or more than the 500 watt drive this speaker, what will the impact for sound and the speaker?

BR// Madde
 
#2,998
Hi Madde,
the speaker you mention I believe is marked :
"500 watt max power" (tulisan saja)
& I don't think we need 500W amp to drive it, 200 to 300W is more realistic...
If you give it real 500W amp then I believe you will burn it out 😀
(Full range in our town seems not so good, don't turn the bass knob so loud)

The speaker will be just fine with 300W amp if you not drive it until it clip 😀

Usually AndrewT will give you some math, about rails, load & output power...
how many output transistor needed, etc...
So you can estimated how large the power supply, the heatsink, etc

let's waiting for Mr. AndrewT ...
he will explain to you better than me, better than most people I know here 🙂
 
#2,999
I have two of these amps (AX14 with 1 pair of output transistors), and they sound very good, but i'm in need of a subwoofer amp and i'm thinking of bridging them and build a 2 way electronic crossover. Power supply is +/- 50 volts and i think the transformer is capable of 200 watts, this will move an 18 inch speaker in a ported box. I'm thinking of projects 09 and 14 of Elliot (ESP), what do you think?
Thanks
Luigi
 
#3,000
lelut said:
Dear Mr. AndrewT, thanks for your answers,
and one more question, i have 500W full range speaker, how many watt power of PA for best drive this speaker (more than 500 watt or less than 500 watt)?
and if less or more than the 500 watt drive this speaker, what will the impact for sound and the speaker?

BR// Madde
Click to expand...

It is my point of view that speaker's power should be greater than amp's power.

My reasons are that,

1. It will give your amp a headroom for its power, the speaker will not saturate and not distort the sound.
2. If amp is driven at full power/volume, the speaker can handle it without worry of damage.

If amp's power is greater than the speaker's, the reverse of the above are true. Although you can still use a set up like this, but be mindful to set the volume of the amp to the speaker's ability to handle the power. 🙂
 
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