AB100 Class AB Power Amplifier

[Dennis Hui]

The original schematics posted by Mr. Pass on the first page ( https://www.diyaudio.com/forums/att...-ab100-class-ab-power-amplifier-ab100-001-gif ) shows 221 for R35.

 

[flamethrower1]

Yes saw that as well, only added to the confusion.
Wil roll with that

 

[fredeb]

R35 should be 10e , or just bridge the gap with a jumper . The 10e works well in my experience , lifting signal ground .

 

[flamethrower1]

Well shucks, looks like I get to try my unwelding techniques, glad they are somewhat isolated

 

[fredeb]

Correct schematic for Prasi pcb

Well shucks, looks like I get to try my unwelding techniques, glad they are somewhat isolated

Hey @flamethrower1 , here is the last schematic from Prasi , that should be used with his boards . It has the R3 correction of his previous schematic @ the correct 1k , not 100e .

Post 11234 of this thread : AB100 Class AB Power Amplifier

Values are correct for all Prasi boards . The schematic just indicates 2x big caps per rail compared to the 1x cap per rail version

 

[flamethrower1]

That is the schematic I am using, lessoned learned, trust what it says.
The BOM I downloaded called it out as 220.
I guess if that is the only hiccup, all is good.

 

[OldDIY]

In the "M" manual AN-483B for audio amplifiers using Darlington BJT, Vbe uses mpsa13 (also Darlington). Perhaps this prevents thermal runaway.

 

[Abx74]

Hi,

are these quasi heatsink enough to built a AB100 "light" (+/- 24Vdc)


Thanks


Damien

 

[flamethrower1]

Going to finish up my bards tonight, what is the resistor value of R37?
That is the one that parallels the inductor.

 

[flamethrower1]

Forgot, I am using Prasis original boards

 

[prasi]

hi flamethrower,
10R-1W/2W would be ok to use and can be directly soldered to inductor legs if size is big.
regards
prasi

 

[flamethrower1]

ab100

Well, since I had to order another resistor, I did not totally finish my boards.
They are however close enough to take the chassis apart cut some ventilation holes and get this out to be anodized.
This project involved a butt load of soldering, good practice anyway.

 

[flamethrower1]

Boards completed

 

[manniraj]

Can we get away with a 2W power resistors for 1R as I have good quality metal oxide ones. I hope it should be fine considering that the bias current is going to be 20mA?

Also the diodes 1N4739 and 1N5408 can they be replaced with other diodes found common 1W types like 1N4742/44 or higher voltage, please let me know.

Thanks

 

[osscar]

Flmethrower1 - your amp looks good!
I place two 3W MF resistors in parallel on my DIY PCB. Maybe you can stack two 2W or 3W resistors (with some space between them) on Prasi/Pass boards ?

 

[Nelson Pass]

Can we get away with a 2W power resistors for 1R as I have good quality metal oxide ones. I hope it should be fine considering that the bias current is going to be 20mA?

Also the diodes 1N4739 and 1N5408 can they be replaced with other diodes found common 1W types like 1N4742/44 or higher voltage, please let me know.

Yes on both counts

 

[manniraj]

Yes on both counts

Thanks Papa, will use the 2W resistors and also the 1N4742 diodes

 

[prasi]

Boards look beautiful... (i am yet to familiarize myself with new diyaudio software, I don't know how this will be posted)

 

[prasi]

I had a feeling something went wrong with my reply in above post...

 

[decramer]

A small question: as I have 10pcs BDX65A and 10pcs BDX64A + 10pcs MJ4034 and 10pcs MJ4031, would that be a good idea to replace the TIP´s