RCA LMI- 32215 A - for recording studio.

Chocopower

Member
2010-04-14 12:38 pm
Hi there!

Time ago i get this old RCA tube preamp really cheap and hence i dont have the power amp section i decided to build an external power supply so i can use it as a recording studio preamp.
Everything is working, but my question is about where you´ll mod the circuit to make it more useful for recording.

Diagrama do pré-amplificador RCA LMI- 32215 A.

thanks in advance and sorry for my english.

David, from Spain.
 
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31697B

Disabled Account
2012-05-19 12:53 am
Start with replacing all the electrolytic caps.... C1, C38,39 and power supply filter caps (40mfd). They are likely all dried out and not reliable. new cap designs are better also than those old timers.

Then clean all the switch contacts and I/O contacts. Replace plate load R's with lower noise metal film types. Replace pots with conductive plastic type or switched R.

The usual things for an old model.

Thx-RNMarsh
 
Last edited:

Chocopower

Member
2010-04-14 12:38 pm
Start with replacing all the electrolytic caps.... C1, C38,39 and power supply filter caps (40mfd). They are likely all dried out and not reliable. new cap designs are better also than those old timers.

Then clean all the switch contacts and I/O contacts. Replace plate load R's with lower noise metal film types. Replace pots with conductive plastic type or switched R.

The usual things for an old model.

Thx-RNMarsh

Thanks for you reply!
All cap job and safe mods had been done.
As stock schematic, it´s working perfect.
Now i just want to know if is posible, with minor mods, make it more "studio friendly".
I dont wanna make an agressive mod.
I love to keep this old guys as original as possible.
As well, in next future, i would like to put an in/out balanced transformers so it can be use with modern mics.