Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: kagliostro on February 10, 2014, 10:56:26 am

Title: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: kagliostro on February 10, 2014, 10:56:26 am

This attached is the schematic of an old transistor Mic Mixer by Geloso

is possible to convert it in Line Mixer and how ?

Thanks

K

Title: Re: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: kagliostro on February 11, 2014, 05:19:59 pm

Thanks Drgonzonm

I was asking about something to do as to preserve the original circuit

I'm asking about a mod as to be able to adequate the existing circuit to higher level signal (if doable)

Thanks Again

K

Title: Re: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: PRR on February 11, 2014, 09:37:21 pm

Clip one end of the 200uFd emitter caps.

Preamp gain drops from almost-100 to almost-1.

However drgonzonm has a point. A line level mixer often does not need any preamp, and going from input jack to mix-pot may be cleaner. Since the mix-bus pots are "inverted" (input at wiper, bus on the top), you need 5K or 10K between input and pot wiper.

Title: Re: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: kagliostro on February 12, 2014, 02:42:02 am

Many thanks PRR

Quote

you need 5K or 10K between input and pot wiper

this 5-10k resistor is in place of the AC107 circuit, is that correct ?

K

Title: Re: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: PRR on February 13, 2014, 12:25:35 am

.

Title: Re: Old Geloso Mic Mixer conversion to Line Mixer - How ??
Post by: kagliostro on February 13, 2014, 08:17:01 am

PRR as always you are very kind

Thanks Again

K