Mic Pre Questions

[widgetwhite]

Ok.......

I finally completed the SSL9k PSU with +-18 & phantom which kinda got me a bit more confident with etching PCB's using photoresist and uv (or a strong halogen lamp :roll: ), and im stuck with the preamp to build for it!!!

Ideally, i was tempted by a class A discrete job with a melcor /2520 style module and using an OEP trafo upfront on it buuuuuuuuutttt :twisted:

anything else i should consider??? I didnt want to use IC based stuff and i really wanted to play with transformer based designs if poss...

At the end of the day, the mics i use arent anything special (modded oktavas , md421,etc,etc,etc) and are used for recording 12 string, electric geetar, vox and a bit of percussion....

any thoughts :green: ???

 

[pucho812]

hmmm make your own pre?

 

[Family Hoof]

http://www.forsselltech.com/schematics.htm

http://www.jensentransformers.com/apps_sc.html

 

[widgetwhite]

thanks jens :grin: i hadnt seen those links before, so i couldnt have been looking very hard!!!

my only worry is that most of the discrete opamps ive seen use -+24 whereas ive only got -+18.

maybe ill leave the pre alone for the mo and get a higher trans and regs..... :?

 

[Family Hoof]

widgetwhite,

The 990 and 990A discrete opamps available from John Hardy in 18V versioins. Those Jensen DC servo preamps would work well with these. In fact, half of John Hardy's business is making Jensen Dual Servo preamps and building opamps for them. This design has been public domain since 1979 and sounds very good. I bet you could e-mail Jensen and ask for help if necessary, as long as they know you'll be buying some transformers from them too.

I haven't started playing with opamps yet so I don't know of many projects. I do know that the API/Melcor based 312 is about the simplest of them all and does run on +/-18 like you said. It is also probably one of the easier projects you can do here. So much information around! Before spending more money why don't you just give a shot and have some fun. Fabio Bauman has info and PCBs for building your own API/Melcor opamps for very little $ in parts if you decide the Hardy design is too complicated and don't want to pay $50 a piece for those opamps.

 

[widgetwhite]

ill go for the melcor i think....

it looks fairly easy and a lot of fun thrown in!!

Thanks for the help , much appreciated ! :thumb:

 

[cannikin]

quick question...

where did you find the 2.5k pots for the 9k?

 

[asm]

Omeg doesnt sell them anymore, you have to do a lorin 2x12 rotary and pop the resistors in yourself.

http://www.groupdiy.com/index.php?topic=4731&highlight=ssl+9k

took me a while to find that link.