100W Ultimate Fidelity Amplifier

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hassan4119

Member
Joined 2010
apexaudio said:
Replace 150R resistor with 330R.
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hi mr apex ...i do this....replase with 370R...i have not 330R....but its good..sound be very beter base and treble is power full..perfect....power mosfet's dont hot afer 15 minutes.mje350/2n5551's not hot..just a few warm..can i use 470R for beter sound?
oh i forget tell that...when i turn on power pup nois is lower.how i can kill pup noise when power be on?
mr apex you made me happy...tnx...i send best wishes for you from ultimate land..
 
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Gurpreet Turna

Gurpreet Turna

Member
Joined 2017
A3

apexaudio said:
A3 Pcb size 50x90mm.
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Hello Mr Miles, What is output power of A3. I can't found shematic of A3, please can u post the A3 amplifier shematic.
Regards
Gurpreet
 

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A

anoopkrajan

Member
Joined 2016
Inductor data

anoopkrajan said:
Hello Mr Miles,
Does AX14 need Zobel Network if yes, values of resistor and inductor data, cos in the circuit it is not shown and can you briefly tell how to bias AX14.
Thanks and regards.
Anoop.
PS: Is there any scope for a new PCB design ? Because I have done a new design.
Click to expand...


I'm really sorry was in a hurry so I asked about Zobel Network, actually I was only asking about the output inductor and its winding data and if there is any resistor then its value too.
Regards,
Anoop
 
S

sumeshak

Member
Joined 2014
Apex P30 Success....!!!

Hi,
Completed Apex P30. Transparent sound....Feels Happy!!!
Thanks to Mr. Mile and everyone supported during the build...!
Regards,
Sumesh
 

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bullittstang

bullittstang

Member
Joined 2013
Paid Member
bullittstang said:
So - I populated a whole new board, testing every component I took out of the old board and replaced if out of spec. I used all new BD139, KSA/KSC and IRFPs along with (1) of the 3 2N5551s that seemed a little low on gain.

The SAME issue persists - anything higher than ~50Vdc PSU on I can't get the bias to stay constant, It slowly moves upward +25mV (then I turn it off)

- on note, is that the other channel I can reduce the bias much lower, like down to 1mV, where this "problem" channel will not go lower than 8mV, regardless of PSU voltage (35, 40, or (48.5, which 60V PSU w 60W DBT in series - bias won't go below 12.5mV)

What I did differently this time:
-I mounted the BD139 with flying leads on top of the IRFP240
-I don't have a O-scope - so I can't test oscillation that way
-I don't have a curve tracer - only a cheap transistor tester, so I grouped the transistors by Hfe so the gain wouldn't be way off on any of them. Also confirmed with B&K multi-meter tester that has transistor function
-Oscillation - I will try increasing C6 and C1/C2 to higher values this weekend and hopefully will fix the runaway.
Click to expand...

FH11 UPDATE - it totally works and sounds very good---BUT I still have an issue with the bias on one channel (re-built channel). The bias goes no lower then 8.5mV on smallest PSU (+/-35Vdc), and 19mV on +/-65Vdc PSU. Plays fine on both voltages with no DC offset issues or thermal runaway, but the other channel bias can be set at 9mV at +/-65Vdc (as low as 4mV on +/-35Vdc) after warm up.

I have not changed any capacitors - only put the BD139 on flying leads and attached to the hottest running IRFP240.

Can I change something to be able to set the bias lower? When I listen to music at +/-65Vdc, it starts at 22mV and after about 10 minutes settles down to ~18.5mV. When playing music I can get it to 30mV at 80% volume (which is very loud) but don't want to blow it up again, so I have kept pretty low.

Hoping if I can get the bias down like the other channel, ~10mV after warm-up, would give additional SOA.

BTW - heat sink/transistors don't get over 100-degree F, with both channels running at 90-95db for 30 mins. Which I generally wouldn't play that loud. So I don't think there is anything wrong with the amplifiers, I appear to have some variance in part matching contributing to the bias differences.
 
H

hassan4119

Member
Joined 2010
e
bullittstang said:
FH11 UPDATE - it totally works and sounds very good---BUT I still have an issue with the bias on one channel (re-built channel). The bias goes no lower then 8.5mV on smallest PSU (+/-35Vdc), and 19mV on +/-65Vdc PSU. Plays fine on both voltages with no DC offset issues or thermal runaway, but the other channel bias can be set at 9mV at +/-65Vdc (as low as 4mV on +/-35Vdc) after warm up.

I have not changed any capacitors - only put the BD139 on flying leads and attached to the hottest running IRFP240.

Can I change something to be able to set the bias lower? When I listen to music at +/-65Vdc, it starts at 22mV and after about 10 minutes settles down to ~18.5mV. When playing music I can get it to 30mV at 80% volume (which is very loud) but don't want to blow it up again, so I have kept pretty low.

Hoping if I can get the bias down like the other channel, ~10mV after warm-up, would give additional SOA.

BTW - heat sink/transistors don't get over 100-degree F, with both channels running at 90-95db for 30 mins. Which I generally wouldn't play that loud. So I don't think there is anything wrong with the amplifiers, I appear to have some variance in part matching contributing to the bias differences.
Click to expand...
i made fh11...in first i see that mje350 & 2n5551 be very hot...i have hi bias sound not very clear....but mr apex tell me replase 150R with 330R...i do this and result be very good....it work properly and sound be clear and good ..
but i have just a few hom nois
pleas see my pcb design in this link:
http://s4.picofile.com/file/8363574750/IMG_20190403_192542.jpg
 
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