YardBird OPA627/637 BUF634 preamp/headphone amp

Russ White

Member

Joined 2005

twistedpearaudio.com

2005-11-22 11:16 pm

#1

• 2005-11-22 11:16 pm

• #1

By Request here are the pdfs for the YardBird:

First here is how the board looks.

 

Attachments

• 
  yb.png

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Russ White

Member

Joined 2005

twistedpearaudio.com

2005-11-22 11:17 pm

#2

• 2005-11-22 11:17 pm

• #2

Copper PDF

Here is the copper side:

 

Attachments

• copper.pdf

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Russ White

Member

Joined 2005

twistedpearaudio.com

2005-11-22 11:19 pm

#3

• 2005-11-22 11:19 pm

• #3

Component PDF

Here is the component side mirrored for toner transfer:

 

Attachments

• comp.pdf

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dsavitsk

diyAudio Member

Joined 2005

diyaudio.ecp.cc

2005-11-23 12:25 am

#4

• 2005-11-23 12:25 am

• #4

Is there a reason to not bias the opamps into class A? It does wonders for the opa627.

 

Russ White

Member

Joined 2005

twistedpearaudio.com

2005-11-23 2:53 am

#5

• 2005-11-23 2:53 am

• #5

The reason is that you can apply the bias to the buf634, which has an impact on the FB loop to the 627/637. 🙂 No need to apply more bias, though it would be very easy to do so, simple put a resistor between the negative rail and the output of the opamp. 🙂

Cheers!
Russ