hi again a40 is about to complete now just finishing the preamp. i also made ax14 for low power bookshelf speaker with bjt preamp and a psu but i have a problem here when ax14 is directly connected to source there is no hum but when preamp is connected it gives reasonably loud hum but the sound is ok and not distorted. i have attached the schematics.
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example
example upload image so that the pictures will remain here 🙂
example upload image so that the pictures will remain here 🙂
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Just make sure your input wiring to the amp is far from
Toroid and power source wiring.
Toroid and power source wiring.
ax14 does not have input shunt resistor like other amps therefor intput floats when there is no source connected and the preamp does not do anything to pull down the input of ax14
the hissing sound goes of when source is connected but not with preamp. also the preamp and ax14 is powered by same power supply. firts i thought the hum is due to regulators as i have faced that problem earlier with linear regulators.
It still sounds like a ground loop. Have you tried powering the preamp with a separate transformer?
Hello Mr.Alex!
One question...why you use 1uf/100v instead of 100uf/63V that 2 capacitor upper to fuses
Thank you and best regards!
hello Mr.Alex
I have a question
Why you use 1uf/100V instead of 100uf/63V
The capacitors in upper side of fuses
Thank you and best regards!
I have a question
Why you use 1uf/100V instead of 100uf/63V
The capacitors in upper side of fuses
Thank you and best regards!
hi everyone
i wanna build high quality 120W@4r amplifier with 5200and 1943 transistors but im a bit confused which one i should choose! which one do you suggest and what are the differences between ax14 and ax16 and ax18?
thanks
i wanna build high quality 120W@4r amplifier with 5200and 1943 transistors but im a bit confused which one i should choose! which one do you suggest and what are the differences between ax14 and ax16 and ax18?
thanks
yes its groundloop will powering with annother transformer resolve the problem?
no,you must find out a new way to connect GND from psu,amp and preamp. it is usually being done on one place,at psu GND,and-or using 10r resistors as gnd lift-up.
Ax14 and psu fx 100
Hello guys wheil lockdown I made ax 14 and .fx100.its sound so sweet like a chocolate.no hiss no hummm.thanks miles sir.but suggest me about speaker protection.fx 100 psu have only short circuit protection.
1st which protection will work with ax 14.
2nd if I make 555 protection .is it required pro adapter ?
Guys for u reply
Hello guys wheil lockdown I made ax 14 and .fx100.its sound so sweet like a chocolate.no hiss no hummm.thanks miles sir.but suggest me about speaker protection.fx 100 psu have only short circuit protection.
1st which protection will work with ax 14.
2nd if I make 555 protection .is it required pro adapter ?
Guys for u reply
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that psu has short-cut protection,delay-on,klip indication and dc-protection.
yes,with ne555 in this case you would need pro-adapter board.
yes,with ne555 in this case you would need pro-adapter board.
Here is the newly christened FH9 schematic from post 7228 but change Vbe multiplier MPSA42 to BD139 and have it mounted in between the two FETs on heatsink as temp sensor.
A new layout would be very nice. Thanks!
What is the max safe PSU voltage for FH9 if is BD139/140 used? On that sch is +/-50V? Thanks,
The BD139/140's are rated to +80v/-80v, so you could take this to +/-53v and just make sure you have sufficient heatsinking for the MOSFETs. Although I used higher rated parts for the HV version, it probably will work fine. Make sure your rail caps are properly rated for the voltage. You can get 125w out of this amp easily with +/-50v rail voltage.
It is a terriifc sounding amp, simple and cheap as chips to make. Have fun.
I got 34.5Vrms into 8ohms with a +/-53v SMPS. Or a tad under 150w.
It is a terriifc sounding amp, simple and cheap as chips to make. Have fun.
I got 34.5Vrms into 8ohms with a +/-53v SMPS. Or a tad under 150w.
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Here is my FH9 running with
A pair of Prasi CRC psu and pair
Of 300va Toroids running dual mono
And it sounds fantastic.
Running roughly 34v on my rails.
A pair of Prasi CRC psu and pair
Of 300va Toroids running dual mono
And it sounds fantastic.
Running roughly 34v on my rails.
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Wow, nice monblock setup for the FH9 there! How many volts are you running and is the setup quiet and hum-free?