QUAD 707 - DIY

[foxint]

Guys. I also bought this amp the one in my picture.

I can only find the + out. Where is the - out for the speakers? I plan to run the + and - to a speaker protector. Got me stumped.

Any suggestions. Does anyone have a hook up diagram?

Thank you

 

[aleksobs45]

The - OUT is PGND olso!

 

[foxint]

Thank you. So to confirm:

Connect +30VDC to VCC+
Connect -30VDC to VEE-
Connect 0VDC to PGND

Connect + speaker out to OUT + and
Connect - speaker out to PGN

All very confusing.

 

[aleksobs45]

Yes, it's right!

 

[foxint]

thanks

 

[ChuckT]

This is the Quad 707, the LJM version is unmodified, except for the different components used.

That's not true, I have the 606 2023 version, it doesn't have the 20uH inductor to ground and it has decoupling cap for the opamp. There are other difference as well

 

[ChuckT]

I would like to know how to reduce gain for the 606 board. LJM already uses 10R instead of 7.5R for R11. How much higher value can I go and do I need to change another resistor value?

BTW. I removed fuse case and modified it to add 2 Elna silmic cap, very nice improvement. The Quad boards really need some nice local decoupling.