Place output transformer next to mains transformer, good idea? (with pics)

[vintageampfixer]

It's always difficult to really listen to something demoed via YouTube - whether it's a speaker or a motorbike! That said, I love the front panel layout and the switched design looks really easy to use with absolutely immediate, at a glance feedback of settings. And that's what's needed (OK, it's what I need) in a live or mix-down situation because when you need to adjust something, even the very best digital stuff is probably less intuitive. Parametric Eq isn't a new concept but focussing on making the product technically competent while being effortless to use should be a winner.

 

[Dylan W]

@igs Did you reverse engineer the OG transformers, or this more of your own design?

 

[igs]

For the input, we used the UTM Industry 10k:10k, which has the same impedance as used in the original unit.
The interstage and output transformers were a bit tricky. I spent a lot of time recreating them (yes, we had an original 825Q unit).
After a few tries, I found the perfect winding for these transformers.
The bandwidth and other parameters are absolutely identical to the originals. I'm proud of this design.

 

[warpie]

For the input, we used the UTM Industry 10k:10k, which has the same impedance as used in the original unit.
The interstage and output transformers were a bit tricky. I spent a lot of time recreating them (yes, we had an original 825Q unit).
After a few tries, I found the perfect winding for these transformers.
The bandwidth and other parameters are absolutely identical to the originals. I'm proud of this design.

So, how did you recreate them? Did you unwind them?

If so, perhaps you'd like to share your findings since this is a DIY community.

 

[igs]

Unfortunately, we couldn't unwind the original transformers because the EAR825Q equalizer didn't belong to us. Nevertheless, we measured the DC resistance (Rdc), inductance, frequency response, etc. The interstage transformer is identical to the output transformer. The primary-secondary ratio is 4.8:1, and the primary to tertiary ratio is 18:1. The tertiary is wound bifilarly, EI57, gapped.