100W Ultimate Fidelity Amplifier

[apexaudio]

Dear Mile,

Thanks for the nice, compact, portable design. What is the recommended supply voltage and current for B80 to drive a 2 ohms subwoofer?

Thanks

Nice work, use +/-35V/5A

 

[PetruV]

WIll this work with more pairsAnd is the pcb at page 3 good

 

[apexaudio]

Auto BIAS

with this circuit add to AX14 no need to set bias and no need for bias transistor on heatsink with outputs.

 

[rizqi]

ax xe layout sprint

Hi,

here is the screenshot of the PCB (Sprint Layout). I can share all the Layout-files or PDF but it is NOT tested. I have one PCB in progress.

regards Olaf

Nice design... can u send to me your layout with sprint...
I'll test your layout...
Pls sent to mail : ugho_mdlx@yahoo.com

Thx n regards

 

[QQ12e5k1]

with this circuit add to AX14 no need to set bias and no need for bias transistor on heatsink with outputs.

Tested?
Can it apply on AX20?

Regards

 

[apexaudio]

This 'auto bias' circuit can be use on any amp.

 

[olafk]

Nice design... can u send to me your layout with sprint...
I'll test your layout...
Pls sent to mail : ugho_mdlx@yahoo.com

Thx n regards

See Post #1764

regards Olaf

 

[olafk]

But be careful. In my prototype is an error, which I have not yet found!
regards Olaf

 

[apexaudio]

But be careful. In my prototype is an error, which I have not yet found!
regards Olaf

Do you use wire jumper?
Regards

 

[olafk]

Yes, now. The first time I had really forgotten. And later the circuit did not work. A 100R/2W-Resistor in the positive supply (instead of the fuse) send smoke.
regards

 

[44250]

100r 2W should send smoke,at that place you should place about 20R 5 - 10W with voltmeter connected in parallel so that you could monitor the voltage across the resistor. it may be that bias trim. was set to adjust say 250mA of current so 100r and 250mA would produce 6,26W and 25V at that resistor,but on 20r that would be 1,25W and 5V on voltmeter.

 

[olafk]

You are right. I will test it on the weekend. I had lately only little time for hobbies.
regards Olaf

 

[cjkpkg]

with this circuit add to AX14 no need to set bias and no need for bias transistor on heatsink with outputs.

I am still learning - so forgive the noob question but is this auto bias scheme "fixed" or "variable"?

How do you set the target value?

 

[apexaudio]

I am still learning - so forgive the noob question but is this auto bias scheme "fixed" or "variable"?

How do you set the target value?

Bias is fixed but you can change resistor 3k3 with 3k6, 3k9, 4k3... to set target value.

 

[mrdevil83]

Hello apexaudio.

Can you give me some advice in what transistors i can us instead of the mje340/mje350 pair?

I can't find this transistors (the mje 340 i found only at my local parts store)

I tried using BD139/BD140 but the amplifier distorts a lot at even about 10% of the ouput power.

So i have mounted some KTA1023/KTC1027 found in an auto amplifier.
the 2sc4793/2sa1837 (can't find them either) i have replaced with bd243c/bd244c.

The suply voltage i am using is +/- 42v.

Thanks.

 

[apexaudio]

Hello apexaudio.

Can you give me some advice in what transistors i can us instead of the mje340/mje350 pair?

I can't find this transistors (the mje 340 i found only at my local parts store)

I tried using BD139/BD140 but the amplifier distorts a lot at even about 10% of the ouput power.

So i have mounted some KTA1023/KTC1027 found in an auto amplifier.
the 2sc4793/2sa1837 (can't find them either) i have replaced with bd243c/bd244c.

The suply voltage i am using is +/- 42v.

Thanks.

There is some eror on your amp, it must work with BD139/140 and BD243C/244C.
Regards

 

[apexaudio]

D12 made in Serbia

 

[cjkpkg]

OK I changed out the PSU I etched in favor of peter Daniel's universal PSU with vishay GBC rectifiers. 22,000uF x2 per rail and voltage has settled in at about 42.

I decided to try biasing the crap out of it and have been running 1.6A per channel for a couple hours and holy cow this amp ROCKS.

Preamp is an aikido 6cg7 input 5687 output.

The iPod, vinyl, and satellite music all sound fabulous.

I will have to debug my diy PSU...I thought it would have been quiet but it hummed like a mutha.

 

[olafk]

Do you use wire jumper?
Regards

Amplifier is running. I made the complete wiring (PSU, Amp...) new and had to changed R16 from 1k to 1k5 to adjust the bias. Layout seems to be correct.

regards Olaf

 

[panggih]

Mr, Mike ax14 I've completed three times, but I have a problem, when I turned, shouted directly ax14 mixed humm.please help me.
ax14 mine exactly with this picture.