Help with VU meter

[dukasound]

Hi
Can anyone can help me with bridge rectifier for cheap VU meter. Specifications are 500uA, 650ohma.
I wanna use this for level and gain reduction, too.

 

[dukasound]

Nobody knows????

 

[JohnRoberts]

Nobody knows????

This seems to be a pretty common topic... Have you done a search?

JR

 

[dukasound]

This seems to be a pretty common topic... Have you done a search?

JR

I tried with germanium diode rectifier what I had, AA111 with 33uF across + and - and trimer in seriesbefore rectifier to find value for resistor. After comparing with my Sifam meter resistor can be about 1K2 to 1K5 (not 3K6 like on Sifam)

 

[ruffrecords]

I tried with germanium diode rectifier what I had, AA111 with 33uF across + and - and trimer in seriesbefore rectifier to find value for resistor. After comparing with my Sifam meter resistor can be about 1K2 to 1K5 (not 3K6 like on Sifam)

What signal level did you feed it and what did you feed it from?

Cheers

Ian

 

[dukasound]

What signal level did you feed it and what did you feed it from?

Cheers

Ian

I put 1,23V signal in my comp  where is calibrated Sifam VU connected to measure input signal and I saw 0db on meter. Than I adjust gain to measure 0db on VU connected to out. I switch compressor VU to see input and connect my cheap VU with rectifier to measure out. Changing signal on generator to  +3, 0, -3,-7 and -10db  on calibrated VU I saw slightly different db on cheap VU.
Excuse me if I am confused. My question was does this VU can be better with different diode or circuit. I know there is on market buffer for VU but does I use  this VU with buffer for GR reduction measuring.

 

[ruffrecords]

A lot depends on the meter itself. There is a specification for a VU meter. I generally uses a 200uA movement with specified ballistics driven by a metal oxide bridge rectifier feed via a 3K6 resistor. If your meter movement does not conform to this standard then it will indicate differently. This means cheap VU meters often need to be driven by a buffer.

Many compressors use a true VU meter for both level measuring and gain reduction. The circuit design usually assume s true VU meter is used.

Cheers

Ian

 

[dukasound]

A lot depends on the meter itself. There is a specification for a VU meter. I generally uses a 200uA movement with specified ballistics driven by a metal oxide bridge rectifier feed via a 3K6 resistor. If your meter movement does not conform to this standard then it will indicate differently. This means cheap VU meters often need to be driven by a buffer.

Many compressors use a true VU meter for both level measuring and gain reduction. The circuit design usually assume s true VU meter is used.

Cheers

Ian

Any suggestions about type of diode, what I can find on market. When I mean slightly different I mean on -3db on true meter I saw -4db or on -7db on true it was example 8-9db

 

[ruffrecords]

Any suggestions about type of diode, what I can find on market. When I mean slightly different I mean on -3db on true meter I saw -4db or on -7db on true it was example 8-9db

First you need to use a bridge rectifier rather than a single diode. Look for  Schottky barrier diodes as they have a lower forward voltage drop. You should also try without the capacitor.

Cheers

ian