Passive EQ/Mixer

[lassoharp]

I think I'll design a passive mic preamp...  ;D

JR

Well. That would be a very quick design.

A step-up transformer. ;D

Great, so I can just put a step up transformer at output of my passive mixer and I'm good to go?  8)

No need worrying about all that messy active circuitry.

JR

Sorry.. I should just avoid this thread...   The customer is always right...

I did an experiment with a modern super high output tube mic wired to a ~1:7 step-up.  In front of a bass drum it basically cut mustard in terms of signal level output.  Didn't get to compare it to a normal mic pre.  Impedance scenario doesn't look good for console input paths.  It was ok with feeding a  250K pot on a power amp input. Just for the heck of it.

 

[eskimo]

I actually built a console with passive mic pres and passive mix amp. And since everything was passive, a passive EQ fit just like a glow.

Tried it out with some classical music to really experience the fidelity. Put on a vinyl recording of John Cage's 4'33''.

Wow. Just wow.

I never knew things could sound that good.

Added just a hair around 10K with the EQ and things really took off. Copywriters like to use words like "warm" and "air". But lemme tell you, you can't get "air" like this with active designs. There simply is no comparison.

It's only 4 channels now, but once I get hold of some trafos, I'm expanding it to 8.

 

[lassoharp]

I actually built a console with passive mic pres and passive mix amp. And since everything was passive, a passive EQ fit just like a glow.

Tried it out with some classical music to really experience the fidelity. Put on a vinyl recording of John Cage's 4'33''.

Wow. Just wow.

I never knew things could sound that good.

Added just a hair around 10K with the EQ and things really took off. Copywriters like to use words like "warm" and "air". But lemme tell you, you can't get "air" like this with active designs. There simply is no comparison.

It's only 4 channels now, but once I get hold of some trafos, I'm expanding it to 8.

. . . if it weren't for those pesky power amps!    ;D

 

[abbey road d enfer]

I actually built a console with passive mic pres and passive mix amp. And since everything was passive, a passive EQ fit just like a glow.

Tried it out with some classical music to really experience the fidelity. Put on a vinyl recording of John Cage's 4'33''.

Wow. Just wow.

I never knew things could sound that good.

Added just a hair around 10K with the EQ and things really took off. Copywriters like to use words like "warm" and "air". But lemme tell you, you can't get "air" like this with active designs. There simply is no comparison.

It's only 4 channels now, but once I get hold of some trafos, I'm expanding it to 8.

. . . if it weren't for those pesky power amps!    ;D

No need for them. Just connect the output of your passive/passive/passive recording chain to a high-efficiency horn-loaded system. It'll move your pants. I bet you'll have to turn down the volume on your passive controller.

 

[terrapin]

Wow-I'm impressed that my post could inspire such delicious sarcasm.

I wish I had the time, money and skills to build 10 1084 style EQ's to feed in to my summing bus, but I don't.

Thanks to everone who offered advice, lassoharp and CJ, you've given me some ideas to toy with.  CJ, thanks for those EQ sections-I've got lots of switches and inductors lying around that I could start messing with.

 

[haima]

go for it terrapin! - the worst thing that could happen is that you'll learn something...  

you might ultimately find that things work better with a simple active buffer or a make up gain stage or two - but that's not great loss... it'll still probably sound awesome, be unique and simpler than 10x 1084.

good luck! and keep us posted

 

[shmuu102]

any chance someone could PM me a copy of NYD's schematics?

this is the next project i am going to build..... Thanks

 

[haima]

I'm pretty sure NYD took his schems for this down - and didn't want it shared?