AB100 Class AB Power Amplifier

[Abx74]

Some gerber flies are available here https://www.diyaudio.com/forums/pass-labs/227503-ab100-class-ab-power-amplifier-38.html#post5432289
I don't know if the PCB is ok or if corrections are needed.

Damien

 

[domyboy]

Thanks Jim, are gerbers available anywhere or do we need to make it ourselves.

I have no problem sharing mine if its of interest. I also have spare PCB's but posting them internationally will be cost inhibitive. Let me tidy up the schematic and board layout and i'll upload them.😎

 

[Nelson Pass]

Not to step on toes, but here are my files.

Board is 2.85" x 9.725" and the Gerbers are in the format that pcbway.com
seems to be happy with.

 

[Abx74]

Thanks Mr Pass !

 

[domyboy]

Not to step on toes, but here are my files.

Board is 2.85" x 9.725" and the Gerbers are in the format that pcbway.com
seems to be happy with.

Nice, that's saved me tidying up my eagle schematic mess.😛

I do have a question Nelson regarding Q3; is there a particular reason why the 2SC2590 is used in this place? Why not just use a ZTX450? I suspect it may be the higher voltage capability of the 2SC2590.
Unfortunately i do not have any 2SA1110/2SC2590 hence I've been trying different transistors in the IPS and VAS to hear any differences. The 2SA1837/2SC4793 in the VAS is sounding better than the MJE340/350. I have also used a 2N6517 in Q3's place.
I haven't cranked the volume right up yet though 😀

Cheers
Dom

 

[manniraj]

Not to step on toes, but here are my files.

Board is 2.85" x 9.725" and the Gerbers are in the format that pcbway.com
seems to be happy with.

Thanks Papa, also please share the schematic of the same 🙂

 

[Nelson Pass]

It's not a very special transistor, but the ZTX450 is probably not adequate
from a dissipation standpoint.

Here is a list of subs

Bipolar Transistor Cross-reference Search | Equivalent Transistors

Bipolar Transistor Cross-reference Search | Equivalent Transistors

and there are plenty that will work fine without being a direct sub.

Here's the schematic again.

 

[gdan]

Nelson,

Do you see any problem if the rails of the amplifier go down to +/- 25V ?

thanks in advance
George

 

[Nelson Pass]

If it get noisy, you can reduce R8 to 3.3K, but probably not needed.

And lower rails gives opportunity for higher OS bias.

 

[kennybee]

Do you think diy store will eventually offer the AB100 pcb?

 

[gdan]

If it get noisy, you can reduce R8 to 3.3K, but probably not needed.

And lower rails gives opportunity for higher OS bias.

Nelson, Many Thanks for the reply.

I was thinking exactly like this, to reduce the rails to +/-25 to 30 Volts, to use only 2 pairs of output transistors per channel and to increase the bias to 150 mA or so per transistor.

 

[osscar]

It works fine in simulator with 24 -+ V

 

[Dennis Hui]

Is it possible to modify this for lower voltage gain (say, 20dB or 26dB)?

Thanks,
Dennis

 

[osscar]

My version have lower gain. I increase r3 from 100 r to 1k.

 

[Dennis Hui]

Thanks!

 

[Nelson Pass]

Do you think diy store will eventually offer the AB100 pcb?

If they want to, they are welcome to it.

 

[JSA1971]

If they want to, they are welcome to it.

Thank you Nelson! I think this would make a great project addition to the DIY Store.

 

[manniraj]

If they want to, they are welcome to it.

Do I need to look for any current replacements from your schematic of the mosfets and transistors? Or should I go with the rated ones as per your schematic.

thanks again.

 

[Nelson Pass]

There are only bipolar transistors in that design.

For equivalents and replacements, you can take a look at the links
I provided, and there is plenty of leeway in the selection.

 

[manniraj]

There are only bipolar transistors in that design.

For equivalents and replacements, you can take a look at the links
I provided, and there is plenty of leeway in the selection.

Thank you.