OPAMP VU Meter Buffer

[audiotechyo]

Hello all,

I have an amp I want to add a VU meter to. In the interest of keeping my sound as clean as possible I decided I needed a buffer circuit, I have come across this circuit but I need some help understanding how it works. The design I had originally came up with on my own did not have 90% of what this design has, and I am curious why.

Thanks,
JD

 

[multisync]

the op amp is powered from a single supply. To bias the opamp properly the inputs have to be at 1/2 VCC thats what the power supply does. The opamp has balanced inputs to connect to a balanced preamp or a bridged poweramp. The output of the opamp is AC coupled and the output positive or negative peaks are rectified and connected to the meter. There is a peak detector to tell you when you have reached a certain level or clipping occurs. Leds are faster that an averaging meter movement.

 

[audiotechyo]

So the 47k is for the balanced input spec? Or is it just to keep from loading the circuit? What if I wanted to use this on say, the output of a tube amplifer? That wouldnt be bridged outputs, so Im not really sure how to deal with that. Also the caps on the inputs are for the AC coupling then right?

 

[audiotechyo]

I am willing to pay someone to help me understand this circuit, I am also very interested in books on the topic, can anyone provide books that talk about audio buffers?

 

[Ian Finch]

If you are willing to pay, then you'll find VU circuit designs and a lot of other very useful audio related design discussion in this title too:
https://www.amazon.com/Small-Signal...p-0367468956/dp/0367468956/ref=dp_ob_title_bk

 

[audiotechyo]

I had actually looked at that book and was thinking about buying it, Im glad you recommended it, I will go ahead and grab it. Thanks!