Toroidal vs El PT

[Vlada]

Hi guys, I’ve searched all over web but didn’t find anything about pros and cons of using toroidal transformers over standard El core transformers, the question is about PT.

[kagliostro]

As far as I can know toroidal transformers has less "noise" emissions than standard EI transformers

but recently I've seen that a member at DIYItalia Forum had a lot of noise problems with a toroidal PT built by someone that didn't

followed the necessary technical measures, so buy a "certified" unit

http://www.youtube.com/watch?v=tVZ-j1PtKgI

Franco

[Vlada]

Did anyone have experience with these?

[Colas LeGrippa]

My first ever build has a toroidal transformer from Avel Lindberg that I ordered custom. The amplifier is dead quiet,the most quiet that I have built.  I don't know if it's because of the transformer type or because the chassis is all  aluminum or both, but it's my preferred one.


Colas

[pompeiisneaks]

Torroids are significantly quieter, they just cost more for the same specs due to how much more complex the winding tools are. 

There are some purported drawbacks, though, and I can't remember them off the top of my head, something related to 'core saturation' in EI ones that creates tonal changes that you can't get with toroids as there is no core.  But I'll be damned if I can remember the exact 'issue'  All in all, though, they're significantly better for quieter builds, they have 0 hum, due to no core leakage, due to no core.

~Phil

[SILVERGUN]

.....  All in all, though, they're significantly better for quieter builds, they have 0 hum, due to no core leakage, due to no core.

~Phil

No, they still have a core, it's called a toroidal core

Here's a comparison (created by a company that makes toroidal transformers)
https://www.plitron.com/news/toroidal-advantages/

PDF attached just shows and explains different cores

[pompeiisneaks]

.....  All in all, though, they're significantly better for quieter builds, they have 0 hum, due to no core leakage, due to no core.

~Phil

No, they still have a core, it's called a toroidal core

Here's a comparison (created by a company that makes toroidal transformers)
https://www.plitron.com/news/toroidal-advantages/

PDF attached just shows and explains different cores

Sorry you're right, I used the wrong term, there's no GAP in the core :D  The toroid is the core and has no gap, that's the benefit I was trying to explain :D  EI Transformers have a gap always due to the way they work and are wound etc.

~Phil

[PRR]

E-I stacked for power transformer cores have no actual gap. (E-I stacked for SE does.)

You are correct that the over-lap between E and I is an imperfect joint, and does leak some flux like a gap does. Also the corners and holes are jumping-off points for stray flux.

Modern E-I cores are Grain Oriented, they work great along the direction they were rolled in. But E-I layout has a lot of meat with flux running cross-grain. Between lap-joints and cross-grain, you can't get the full flux capacity. In a toroid ALL the iron works with the grain, no laps, so less iron is needed. In theory this can also allow smaller copper loss (less iron to go-around).

E-I cores remain the most common type.

In practice the difference is almost all about size shape and cost. The toroid may be some smaller and typically much "flatter". Note that if you have stand-up bottles, flat does not allow a lower lid, and the typically larger footprint may be awkward.

[Vlada]

Thank you very much guys. I think I am going to use toroidal, just to experiment a little bit

[92Volts]

There are some purported drawbacks, though, and I can't remember them off the top of my head, something related to 'core saturation' in EI ones that creates tonal changes that you can't get with toroids

Aside from terminology (which you already sorted out), the gap in EI transformers actually makes them saturate less easily... with larger gaps helping to avoid saturation in SE usage which would otherwise be severe.

Saturation can add desirable effects, but too much/too soon limits power and bass response. The problem is toroids saturate so easily they're not usable single-ended... even phase inverter or tube mismatch in a PP amp could cause saturation in a toroidal OPT.

Desirable amounts of saturation are achieved with small EI OPTs (see Fender parts and designs) but toroids may saturate even worse than those.

[Vlada]

The topic is about power transformer, not about output