Can you post a link for the product you talk about, I searched "Taobao e27" didn't find anything.
Ha OK, you have to mount the actual box with connectors and wiring yourself if I get that right.PeteL, I've bought and measured that trafo 5 years ago or more, tried to find to take pic but without success. The key-words are [permalloy] to keep HF THD lower(nanocrystalline, I believe should be even better due to double saturation flux), and [600:600] which corresponds to load impedance. E27 means EI-shaped core 27mm. Don't worry, any trafo like that will have the same THD level or better if you'll buy a bigger core trafo.
In a twist of faith, the addition of ISO-MAX created mains hum where none existed before! The amount of mains noise induced was location dependent which tells me it is picking it up from its environment. I am not clear on the exact mechanism for this pick up.
Is there any way to measure CMMR for this? That is the one area transformers really shine and would help put it's performance into perspective.
I don’t have this unit, but I have some JT11 P1 which I think is what they use. If someone else hasn’t, I’ll run a CMR sweep when I get home from work tonight.Is there any way to measure CMMR for this? That is the one area transformers really shine and would help put it's performance into perspective. I have a DIY tri-amp systems with a computer and unbalanced connections which had ground loop issues (no surprise). I could have converted it all to balanced at great expense in money and time but instead I got a stereo version of an Iso-max and it works perfectly... dead quiet even with my ear next to speakers. Transformers, while old school, still have a place for some applications.
I tried all that already and it made no difference.This is an error of your arrangement. When you use a signal transformer, the I/O’s must not be floating, otherwise you have the hum components through stray capacitance. Try the grounded source and the problem should disappear. The best result is if both input and output are grounded and the trafo only disconnects the loop.
Well, most of the better xformers have at least one shield (and preferably a foil shield, not a blind winding), many have two, one for each side. The CMRR-optimized models from Cinemag for example have >90dB CMRR at 20kHz, and dual shields plus extra wire for the can. On the opposite end, their models with extreme interwinding capacitace via their bilifar windings (for maximum bandwidth) still have 60dB at 20kHz.Quite easy to measure, but transformers tend to have relatively poor CMRR at high frequencies due to their interwinding capacitances.