Toroid transformer or not

[fireman]

As I said in another post, I will probably try my hand a building a GC pretty soon. This is gonna be my first try at this and I don't want to break the bank. I'm thinking about building 5-7 monoblock amps for our home theater in the future but first I need to show my wife that I can do it within a relatively low budget.

Will there be a big difference in the sound of my amp if I choose to use a "regular" cube style transformer instead of a toroid one ? It seems to me that toroid transformers cost quite a bit more than the regular ones. For this first project, I guess it would probably make sense to buy a regular transformer. It would porbably be cheaper and easier to source in Canada.

BTW, any good tips on where to find affordable transformers in Canada ?

[Elkaid]

Salut Jean-Pierre,

I can't really answer if there's any significant advantages of one type over the other when talking about sound quality... but it may get more difficult to find high current E-Core trannies... Why ? I don't know Probably another member on the forum could answer that.

Here's some places where you can find toroids transformers :

http://www.hammondmanufacturing.com
(sold trough http://www.digikey.ca)

http://www.plitron.com

http://www.victoriamagnetics.com/

I don't really have sources for E-Core transformer suitable for a GainClone project. Maybe you could try http://www.partsexpress.com

I hope this helps

[Tony]

in manila, torroids are almost non-existent, but we manage to build gainclones using e-i cores with good results....

[mrskinny]

I have tried both EI core and toroid transformers with my LM1875 NIGC. Toroids do sound better-smoother,clearer sound.I was surprised that there was a difference at all,but there is. Keep in mind that most EI cores have only a single secondary winding+center tap,which means using a single bridge rectifier with the center tap hooked up to ground for a balanced supply.This was my initial setup,and I can tell you that this is a BAD idea.If you want to keep your costs low,use a single power supply for two channels,there is not much of a difference between this and a dual mono supply.

[skyraider]

In malaysia most of the EI transformers are cheap and bad.... I have to use toroids through mail order. For me, toroids dont create humming as much as EI transformers.

[Tony]

Originally posted by skyraider
In malaysia most of the EI transformers are cheap and bad.... I have to use toroids through mail order. For me, toroids dont create humming as much as EI transformers.

cheap ei trafos can be made to behave, if you mean humming by the trafo itself, you can tighten the screws on the mounting brackets, or you can put wooden shims wedged on the center legs, then polyurethane bath should fix your problem....

on the other hand, if humming is comming from the speakers, then you have ground loop problems....

torroid cores are prone to saturation easy.....

[fireman]

I found these for sale on the Net. Would they work ?



As you can see, they are 115V for the primary and 20 V 2.5 amps for the secondary. Is it enough or would I need a beefier transformer ?

[Sherman]

Originally posted by mrskinny
Keep in mind that most EI cores have only a single secondary winding+center tap,which means using a single bridge rectifier with the center tap hooked up to ground for a balanced supply.This was my initial setup,and I can tell you that this is a BAD idea.

You can use a ct transformer with dual bridges without problem. I've built three different power supplies with ct transformers and all of them use dual bridges.

Just hook it up like this if using Brian's board- use the first AC secondary to connect to AC1H on the board, connect the ct to both AC1N and AC2H and connect the other AC secondary to AC2N. Try it, it works.

[fireman]

Originally posted by fireman
I found these for sale on the Net. Would they work ?

As you can see, they are 115V for the primary and 20 V 2.5 amps for the secondary. Is it enough or would I need a beefier transformer ?

Don't even bother answering it. I just realised that there is only one secondary. So that won't work... Too bad. At 3.50 $ US that would have been interesting. Oh well !!!

[skyraider]

Joan,

"or you can put wooden shims wedged on the center legs, then polyurethane bath should fix your problem...."

mind to elobrate further? I have lots of cheap EI trafos around.. Would be nice if I can use it.
Thanks.