tubes n needles

[silurato]

Hi everyone.

i'm going to mount a needle- level meter on my HBW amp, monitoring signal on line stage input. Driver is simple, a buffer/opamp rectifier drive a peak-envelope filter.

So i wonder... how it can be done with tubes? i know it gotta be difficult, and expensive, definitely not convenient; but i'm really curious: does anyone have some vintage schematics?

 

[Sch3mat1c]

Tubes can do way better: 6AL5 and a 6E5.

Tim

 

[SHiFTY]

Yeah I love to shoot up with ma tubes.

Oh, sorry, wrong topic.

 

[Simpleton]

Maybe this one?

http://www.valvediy.com/slipg1.html

Cheers!

 

[SHiFTY]

I built a tube leve meter using this schem

EM81

although I omitted the 350-470K and ran it off the speaker connector.

 

[silurato]

Thank you all

i'm going to build this project:

http://sound.westhost.com/project55.htm

Magik Eyes are GORGEOUS!!!!

...but what about needles?

 

[Sch3mat1c]

If you want to use a meter with tubes, use 6AL5s for signal rectifying diodes (or 1N4148 if you don't care) and do it passively, or add, at worst, a preamp/driver stage consisting of a gain stage with cathode follower hanging off it. Or you can put the diode(s) before an amplifier, though you have to pay more attention to DC stability. You might want to read up on VTVM (Vacuum Tube VoltMeter) schematics, too.

Tim