EZ1290 Transformer Colour Mod?

[PatchDog]

I've recently done a couple mods to my EZ1290 but I'd like to get a bit more colour out of the Iron, switchable.

Any suggestions on good/better ways to achieve this?

Anyone tried a pad over the output Transformer secondary, in order to be able to run it more 'hot' for example?

Or perhaps done the Neve DC Bias thing?

Is a non 1:1 transformer even applicable for these?

I did try this mod, I saw Ian (Ruff Records) suggested that putting a series resistor on a TX primary would induce more harmonics. So I put a 1k pot on the primary of the output TX (VTB 1148) to do some tests. Anything past 350ohms was unusable. In the end I installed a pin socket where I can install a removable resistor connected to a switch (on/off).



This for sure adds more harmonics, also reduces HF and seemingly the dynamic range, but I'm not sold on the sound yet but need to do more experimentation.

No Series Resistor (100hz sine wave) VS 330Ohm Resistor Series Primary

 

[jabe]

It might be worth trying an inline pad after the pre as a way to test pushing the OT harder without modifying things.

 

[ruffrecords]

The problem with adding series resistance to the primary of a Neve output transformer is that it carries dc. The resistor will change colour more due to altering the bias conditions than anything it does to the transformer characteristics. The series resistor mod I suggested was really only for transformers carrying signal only.

Cheers

Ian

 

[vitopower]

Output pad did it for me. IIRC less than 20db is slight compromise w/impedance, but I think I went with 14db.

Also a switch for the input tx options opens up some new territory.

 

[PatchDog]

Output pad did it for me. IIRC less than 20db is slight compromise w/impedance, but I think I went with 14db.

Also a switch for the input tx options opens up some new territory.

Nice! Can you tell me the resistor values you used? What type of pad?

I did wire up a pad on the output but it didn't work for some reason, I'm not sure why but I must have missed something since the pad should work, it was the DIYRE version:


When you say "a switch for the input tx" do you mean a pad? Or changing the impedance wiring?

 

[vitopower]

http://www.uneeda-audio.com/pads/

If you haven't used this link before, it is a great resource for all things pad related.

I likely used a U-pad, but I'm away right now.

I was referring to the different impedance options on the input transformer via a switch.