Altec 436C EMI Mods

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Joined
Aug 13, 2009
Messages
6
Hi Guys!
New here to the forum! I am based in Western North Carolina. Work @ a lovely analog studio tucked away here in the mountains. I have begun a Pultec build for my studio. I used to have a Pultec and miss it dearly. It looks like an easier design than the Sta Level! Our Sta Levels are a mess inside! Anyway, we also have 3 Altec 436 C's. They are all stock. I've been reading up a little bit on the RS124 Mods that were done at EMI in the 60's. I get the gist of what was done to these things. I love the 436 stock but I'd at least like to try this on one of the other ones. Was wondering if anyone has done this and has some research they would like to share?

I searched the site. Didn't see any mod info. Cheers!

PS- Anyone have a drill sheet for the back of the Pultecs?
 
Hi got some Questions re EMI mods so am posting on this thread as thread title suits ,Ive read through all the stuff on the other threads too all interesting.....a while back somewhere on the web I read about what is supposed to be the EMI mods I made some notes & am wondering if anyone can help me interpret some of them, they all seem sensible mods to add to a 436 anyway....il list the notes I made & then my questions if anyone has any ideas......
Im just looking to improve a 436 circuit not too worried about the ease of use and front panel type sensible mods just looking for sound flavour not that there anything wrong with original, I suspect the mods are pretty ordinary but sort after due to Beatles connection I dont suppose il write great songs if I mod my vari mu.....

Input valve re biased......would that mean changing resistance on the cathode

T pad on output............ I understand this sensible useful addition

Recovery & hold circuit..... I think I understand this one along with changing release times and so on

better power supply added.....yeah get that one

recovery take off relocated for less distortion ????? whats that about ?

caps that couple to diode values changed 3 times.......yeah I get that, I have 6 different values that I can switch on my Vari Mu comps

6CG7 grids switched......dont understand this one ??.....maybe swap caps to pin 2 & 7 ....that would change output polarity ?

Balance pot added to first valve.....yeah I think we all add that mod

feedback added to output.....intersting a capacitor & resistor perhaps ? ....Id prob prefer without that myself

Diode type changed ? just different brand or different valve......interesting

If anyone can give me a better Idea of what these mean weather EMI or whoever it will be good to learn...Many thanks






 
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