Tubetec said:
I also saw the R cores , some specifically wound for tube voltages , I was tempted but Im unsure about interwinding insulation,anyway it was more like 60-70 euros each for these including shipping ,
Ill most likely order extra screening cans for these E-I ones in the end , Im also planning to run them at around 50% maximum current for lower noise.
Transformer winding isnt much of a thing here anymore , cost of labour means and transformers or motors under a couple of hundred euros are simply replaced . Aside from simple 1:1 transformers you cant really get anything off the shelf for tube stuff here in Ireland .
I might be interested in trying some transformers from eastern europe ,for the money its good value even compared to off the shelf or simple dual secondary type stuff , Id also be very interested in the possibillity buying materials like lams and bobbins
from there , I work in a winding shop already ,so I have access to all the copper I need ,but its almost exclusivly motors we handle in our shop ,
Maybe if you pass me along the details im pm My3gger , I'll shoot them a work email later on in the week .
Could you post a pic of some of the toroids you had made up ?
Interesting, i will do my best for what you asked. Interwinding insulation for this toroids (writing about better winder imo) is specified at more than 4KV. I notice very low V drop when LT is loaded at about 70%, for example 7,5V winding into LDO at 1V drop gives 5,8V plugged anywhere for years. HT is fine too, since i'm using cap multipliers tube builds have lower perceived noise than solid state, so i don't always bother measuring noise. Beside, they don't heat like some others.
Static shield between pri and sec comes with ground wire, magnetic is a few turns of core material. Can't remember what exactly they do about tap shielding, my guess is the same thing as for pri:sec, drain to the same ground.?
Winder i like best is electrical engineer who likes audio, i'm happy to get you in contact with him (call seems to be better before sending specifications or questions...). I'm sure he can and is willing to wind high quality toroids when provided with correct details, sometimes i get his suggestions because they do supplies beside toroids.
It really interests me what are best practices when winding audio power toroids, despite good results with non shielded. Signal OTs were used in lots of German gear, i asked here a few times but no one gave any directions. I've seen how windings are distributed because of capacitances, pics didn't show shielding which should help further.
We tend to rewind EI trafos and motors which cost a lot less than couple hundred of eur, of course it depends who is repairing... Power trafos for audio stuff are always ordered custom localy, except for audiophiles ) One more thing i noticed is that we still have lots of practical knowledge and more stuff is getting repaired, compared to richer countries.
I searched EI lams for small signal output trafos, all are too thick made of iron, we don't even dream of 49Ni or similar. Best were old M lams no one has now, bobbins were not a problem in small quantity. No one really makes low level OTs, i've seen a power OTs. Never asked for power trafo materials or finished ones, toroids work very well and are cheap.