100W Ultimate Fidelity Amplifier

[still4given]

+/-50mV offset fluctuacions is ok without DC servo... can you post scope measurements?
Regards

Yes, I will post some shots in the morning. It's midnight here.

 

[AndrewT]

Offset jumping around with music playing is not a real problem. That would happen on any amp. Offset is only measurable with zero input or input grounded, no?

Glad it plays music and sounds good. Strange how rail fluctuations cause offset changes. Unless rail fluctuations were asymmetric.

No.
A changing offset is an AC signal.
adding an AC signal that is determined by the changes in mains voltage is adding non harmonic distortion to your wanted audio signal.

If wandering offset is inherent to a particular topology and interaction with mains voltage variation then to me that points to the need for voltage regulation of the voltage sensitive stage.

 

[AndrewT]

+/-50mV offset fluctuacions is ok without DC servo... can you post scope measurements?
Regards

+/-50mVdc of offset variation is roughly equivalent to adding a random 30mVac signal to your output.
That is likely to be only 10dB to 20dB below the average audio signal at the output.

That is a vast amount of avoidable added AC signal.

 

[apexaudio]

+/-50mVdc of offset variation is roughly equivalent to adding a random 30mVac signal to your output.
That is likely to be only 10dB to 20dB below the average audio signal at the output.

That is a vast amount of avoidable added AC signal.

Slow offset fluctuation is inaudable.

 

[AndrewT]

Might be inaudible as a fundamental frequency, but what is that doing to the amplifier's ability to process the audio signal and what does that excessive LF output do to the bass speakers ability to process the audio signal?

And how do you know it is only an extreme LF effect? Mains voltage variations are fast events.

 

[I love the sound]

Go to AX20

Thanks Mille. Today i will make the pcb. I will be back with pictures. sorry for my english

 

[apexaudio]

F8S

Just for fun.

 

[I love the sound]

Hy sir Mile what changes need to make for tip35 tip36 as output In AX 11?
Thanks

[/IMG]

 

[apexaudio]

Hy sir Mile what changes need to make for tip35 tip36 as output In AX 11?
Thanks

No changes,
Regards

 

[Idefixes]

Hi Mr Miles is there any chance to be able to drive ALF16N16W/ALF16P16W (double die lateral mosfet) through FX8? The deal is to drive 4 ohms speakers with +/-35Vdc rail

Marc

 

[I love the sound]

Go to AX20

Sir can i use this AX20 for my transistors? Is this a good pcb and layout? Thanks

 

[apexaudio]

Hi Mr Miles is there any chance to be able to drive ALF16N16W/ALF16P16W (double die lateral mosfet) through FX8? The deal is to drive 4 ohms speakers with +/-35Vdc rail

Marc

Yes you can drive 4 ohms speakers with +/-35V rail.
Regards

 

[apexaudio]

Sir can i use this AX20 for my transistors? Is this a good pcb and layout? Thanks

Yes you can use this pcb,
Regards

 

[Idefixes]

Yes you can drive 4 ohms speakers with +/-35V rail.
Regards

Just to be clear : with using ALF16 (double die latmosfet) instead SK1058/SJ162?

Marc

 

[apexaudio]

Just to be clear : with using ALF16 (double die latmosfet) instead SK1058/SJ162?

Marc

Yes ALF16 is SK1058/SJ162 pair in same case.
Regards

 

[Idefixes]

Yes ALF16 is SK1058/SJ162 pair in same case.
Regards

That's a good news.

Thanks Mr Miles.

 

[dobrivoje]

Yes ALF16 is SK1058/SJ162 pair in same case.
Regards

No, Mile, ALF16 are double dye, but same polarity, there are ALF 16N and ALF 16P. You can choose TO264 or TO3, 160V or 200V.
16 is the number of Amperes.

I made my FX8 with ALF08NP, both N and P type in same case, but they are rated at 8 Amperes.

 

[Idefixes]

No, Mile, ALF16 are double dye, but same polarity, there are ALF 16N and ALF 16P. You can choose TO264 or TO3, 160V or 200V.
16 is the number of Amperes.

I made my FX8 with ALF08NP, both N and P type in same case, but they are rated at 8 Amperes.

Yes a i missed that ALF16 are double die = 2 same transistor type in one package...so i would be same situation as 2 output paires instead one

Marc

 

[still4given]

+/-50mV offset fluctuacions is ok without DC servo... can you post scope measurements?
Regards

I converted the second channel. I have taken some scope shots and am posting them below. I also played about 12 songs through it. It really sounds quite lovely. Whoever complains about the bass from lateral MOSFETs needs better speakers. This amp goes deep and the bass is tight. Really, really nice sounding amp.

I also monitored the offset more closely and it is actually quite acceptable.

 

[Ripcord]

Still4given, is this the conversion that you did to the second channel?

I pulled the trimmer and installed two 150R SMD resistors in its place. Then I pulled R5 and replaced it with a 25k trimmer.