3 Transistor HP Amplifier with low dist

[lineup]

Great work, daemon!

 

[prasi]

That´s an LM317 or similar you´re using, right?
Did you forget the wire from between R20&C12 to the ADJ-pin?

Thanks for your beautiful layouts BTW.
They are a joy to study and look at!

Yes, eagle eyes you have...
Thanks BTW...

 

[lineup]

@prasi

Beautiful schematic.
It also have the correct components as recommended.
But R3 should be 180k

 

[avtech]

Great to see this made into one of your PCBs Prasi. And interesting to see an AC input rather than DC-DC regulation. I'd be interested to see if it makes a difference using linear power rather than an SMPS.

 

[prasi]

I was wondering CRC like input can be used for the LM317? Here is updated schema and layout

 

[lineup]

I don't think you should bother using CRC on the input.
RC is quite alright.

 

[widea]

I have a few TIP41C transistors left, a bit too much power but can they replace the BD139 ones if needed?

 

[lineup]

I think you can use TIP41C.
It will give a little more distortion.
But as there is a feedback the different will not be dramatical.

 

[widea]

I think you can use TIP41C.
It will give a little more distortion.
But as there is a feedback the different will not be dramatical.

Thanks Lineup!

 

[lineup]

I did a testrun simulation with TIP41C.
The result is just the same as BD139 = THD 0.001%
See image.
So there is not at all problem using TIP41C.

 

[widea]

I did a testrun simulation with TIP41C.
The result is just the same as BD139 = THD 0.001%
See image.
So there is not at all problem using TIP41C.

B.t.w., this amplifier should have a catchy name

 

[knauf1919]

Prasi, what capsule did you use for the rectifier bridge?

 

[prasi]

Something like this ,
https://www.mouser.in/ProductDetail/Diodes-Incorporated/DF10M?qs=G5AQjGfRJcIrwPKN/iDgDw==

It's B- Dil package of rectifier

 

[joensd]

Just sold a headphone amplifier and don´t really need another one
but the force is strong with this one!
And it simulates just so well.

Made a little sunday afternoon layout.
2-layers with brute-force GND on both layers.
RC-filters and TL431+pass transistor cause its just another BD139. (the TL431-circuit is from FauxFrench!)
Probably find me a tiny aluminium stripe and attach the transistors to it. (attach insulated!)

If anybody in germany wants some PCBs we could share. I probably only need 2 PCBs.

 

[avtech]

B.t.w., this amplifier should have a catchy name

I named mine T3. Maybe not catchy but helps me remember what's inside

 

[widea]

I named mine T3. Maybe not catchy but helps me remember what's inside

I agree with Joensd "the force is strong with this one".
How about ¨The Force"?

 

[avtech]

Just sold a headphone amplifier and don´t really need another one
but the force is strong with this one!
And it simulates just so well.

Made a little sunday afternoon layout.
2-layers with brute-force GND on both layers.
RC-filters and TL431+pass transistor cause its just another BD139. (the TL431-circuit is from FauxFrench!)
Probably find me a tiny aluminium stripe and attach the transistors to it. (attach insulated!)

If anybody in germany wants some PCBs we could share. I probably only need 2 PCBs.

Why stop at one.. I've got 2 made at the moment with parts for 10 available...

It simulates well but sounds even better!

Thanks for sharing the a version the FauxFrench's circuit. I think I'll give that one a go too!

 

[ernesternest]

Just sold a headphone amplifier and don´t really need another one
but the force is strong with this one!
And it simulates just so well.

Made a little sunday afternoon layout.
2-layers with brute-force GND on both layers.
RC-filters and TL431+pass transistor cause its just another BD139. (the TL431-circuit is from FauxFrench!)
Probably find me a tiny aluminium stripe and attach the transistors to it. (attach insulated!)

If anybody in germany wants some PCBs we could share. I probably only need 2 PCBs.

Hi joensd, would be in with one or two. Cheers, Ernst

 

[joensd]

How about ¨The Force"?

Good idea!
My simulation files have the suffix 3QA (3 Transistors, Class A).
Or maybe R9Q3 (9 resistors, 3 Transistors).
I´ll call mine R9Q3-LUFFJD (short for: schematic: lineup, PSU: FauxFrench, Layout: Jens D.).

If anybody wants to use the gerber files: I want to update them later.
There was too big an interruption in the bottom layer ground plane that I got rid of and placed more vias.

Hi joensd, would be in with one or two. Cheers, Ernst

I literally just ordered 2 other designs from JLCPCB.
Have an upcoming project where I´ll probably order in 2-3 months and maybe include this lineup-design then?
If you should order before me, count me in for 2PCBs. They can be easily shipped in a letter for 0.80€.
JLCPCB costs probably 2$ for 5 PCBs plus 7$ shipping.
I´ll let you know if I change my mind and order anyway. (the force!)

 

[joensd]

Thanks for sharing the a version the FauxFrench's circuit. I think I'll give that one a go too!

The TL431-circuit was suggested by FauxFrench in our amplifier project.
We needed a ~+-15V supply for one opamp (from +-42V) and that is what FauxFrench came up with:
TL431 and pass-transistor for negative voltages.