Amp Camp Pre+Headphone Amp - ACP+

[Ben Mah]

Great news! Ohm's Law is simple but so useful.

 

[SRMcGee]

Post photos here as well, would love to see it!!

6L6:

I posted a quick write-up on the Pass pictures thread, but here are those photos.

Regards to all,
Scott

 

[ItsAllInMyHead]

Beautiful!

 

[Dennis Hui]

Stunning build, Scott!

 

[nicoch58]

SRMcGee nice build
look like psu is on wrong side and better use pot extension kit

 

[JPS64]

Hello Mr. Pass,

like H2 M2x, I´ve designed the ACP+ compatible M2x, so I´m asking for your permission to offer, if builders interested, this board in a future GB.

If interest to low I´ll put all the manufacturing datas online so everybody could order PCB´s and built himself this excellent circuit.


JP

 

[BeardyWan]

max rail voltage

Apologies if I have missed this...

What is the acceptable range of rail voltage and is there any benefit in operating at high voltage than the 24 proposed?

thanks
Beardy

 

[Mark Johnson]

... I´ve designed the ACP+ compatible M2x ...

Since ACP+ is designed to drive 32 ohm headphones, while M2x presents an impedance of about 600 ohms which the daughter card must drive, I think you can safely reduce the output capacitor (C112) without affecting the low frequency response of the amplifier as a whole.

Also have you checked and double-checked your schematic for errors? (the one in post #226) ... I can't quite put my finger on it, but somehow, something just doesn't look right. The original by Nelson Pass is HERE.

 

[JPS64]

Schematics checked again, I don´t see any error.



JP

 

[dl3it]

The emitter connection of the opto isolator is wrong.

 

[JPS64]

I need new googles!

H111 pin 5 needs to be connected with H111 pin 2.

Thanks you,
JP

 

[Mark Johnson]

Are there any other mistakes?

 

[BeardyWan]

Sorry to nudge...Question max rail voltage
Apologies if I have missed this...

What is the acceptable range of rail voltage and is there any benefit in operating at high voltage than the 24 proposed?

thanks
Beardy

 

[6L6]

You could probably go a few volts more with no ill effect, but it wouldn’t gain you much except heat.

 

[BeardyWan]

OK thx.

 

[Gaz2613]

Would love to build this but I want easy to source components. Is there an equivalent drop in replacement for the 2SJ74 and LSJ74?

 

[Zen Mod]

Store

 

[Gaz2613]

Store

I meant cheaper as well as easy to source.

 

[Zen Mod]

then build something else ...... without JFets

 

[Eslheadphone]

When I look at the price of Vacuum Tube's , JFETs look inexpensive . I am looking at a matched quad of LSK170 / LSJ74 at the Diystore for $39 . Yes compared to what they cost years ago they are expensive now. Thanks to Linear Systems and the Diy Store , we can build those wonderful Nelson Pass designs. It's a great time to be a DIYer.